# kb

id: weekend-effect-20260505-18
file: data/en.wikipedia.org/wiki/Weekend_effect-18.md
category: reference
title: Weekend effect
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Weekend_effect
date_saved: 2026-05-05T07:34:08.663129+00:00
instance: kb-cron
parent: weekend-effect-20260505-0
summary:
In 2015, Health Secretary Jeremy Hunt quoted that the 'weekend effect' in the NHS equated to 11,000 excess deaths a year. Some are now reporting the Hunt Effect - that some patients, too scared to attend hospital at weekends because of the weekend effect, have become seriously ill or even died as a direct consequence of waiting until Monday before seeking medical advice. The authors state, "To assume that [the 11,000 deaths] are avoidable would be rash and misleading."The paper was criticised by some clinicians unhappy with the findings, and a comment by a professor of cardiovascular epidemiology suggested that the report was data-driven rather than based on a hypothesis; in fact the 2015 paper was a development from previous work which analysed an earlier data set in 2012. In response to the 'weekend effect' and the lack of seven day elective services, there have been proposals for major reform to contracts of NHS staff. Staff are in support of strengthening weekend services, but junior doctors have criticised these changes as they do not account for the 40% increase in workload. The UK's main doctors union, the British Medical Association, is still negotiating, as they would like assurances that new


id: wells-score-pulmonary-embolism-20260505-0
file: data/en.wikipedia.org/wiki/Wells_score_(pulmonary_embolism)-0.md
category: reference
title: Wells score (pulmonary embolism)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Wells_score_(pulmonary_embolism)
date_saved: 2026-05-05T07:34:09.962673+00:00
instance: kb-cron
parent: wells-score-pulmonary-embolism-20260505-0
summary:
The Wells score is a clinical prediction rule used to classify patients suspected of having pulmonary embolism (PE) into risk groups by quantifying the pre-test probability. It is different than Wells score for DVT (deep vein thrombosis). It was originally described by Wells et al. in 1998, using their experience from creating Wells score for DVT in 1995. Today, there are multiple (revised or simplified) versions of the rule, which may lead to ambiguity. The purpose of the rule is to select the best method of investigation (e.g. D-dimer testing, CT angiography) for ruling in or ruling out the diagnosis of PE, and to improve the interpretation and accuracy of subsequent testing, based on a Bayesian framework for the probability of the diagnosis. The rule is more objective than clinician gestalt, but still includes subjective opinion (unlike e.g. Geneva score). == External links == Wells Score PE Calculator – Free online calculator for clinical use == Original algorithm == Source: Originally it was developed in 1998 to improve the low specificity of V/Q scan results (which then had a more important role in the workup of PE than now). It categorized patients into 3 categories: low / moderate / high


id: worried-well-20260505-0
file: data/en.wikipedia.org/wiki/Worried_well-0.md
category: reference
title: Worried well
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Worried_well
date_saved: 2026-05-05T07:34:11.075850+00:00
instance: kb-cron
parent: worried-well-20260505-0
summary:
The worried well is a term that describes persons who are in relatively good health but believe themselves to be ill or likely to get an illness based on a current circumstance. As a collective noun, the term is typically used for groups of patients, not clearly defined, who are perceived to be using health services inappropriately or disproportionately. The phenomenon is also known as worried well syndrome. The worried well are within ICD-10 code Z71.1—"Person with feared complaint in whom no diagnosis is made." They are distinct from those suffering from hypochondriasis (health anxiety), whose health concerns are chronic and rise to the level of a psychiatric condition; in contrast, anxiety experienced by worried well patients is usually caused by a specific event. == Etymology == The term worried well, according to the Oxford English Dictionary, was first used in a 1970 Scientific American article by physician Sidney Garfield, who described a "variable entry mix into medical care consisting of (1) the well, (2) the ‘worried well’, (3) the ‘early sick’ and (4) the sick." In 1997, The Times wrote that "Mental health experts...have...nicknamed them the ‘worried well’—too disturbed to sail through life's challenges but too well to warrant


id: yentl-syndrome-20260505-0
file: data/en.wikipedia.org/wiki/Yentl_syndrome-0.md
category: reference
title: Yentl syndrome
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Yentl_syndrome
date_saved: 2026-05-05T07:34:12.240911+00:00
instance: kb-cron
parent: yentl-syndrome-20260505-0
summary:
The Yentl syndrome refers to the under-diagnosis of ischemic heart disease (IHD) in women compared to men, as well as the general gender disparity in cardiovascular health research. The name is taken from the 1983 film Yentl starring Barbra Streisand in which her character plays the role of a male in order to receive the education she desires. The phrase was coined in a 1991 academic paper by Dr. Bernadine Healy titled "The Yentl syndrome", where she condemned the characterization of coronary heart disease as only prevalent in males and called for awareness of gender differences in health. Cardiovascular disease (CVD) is the leading cause of death in women worldwide, yet it continues to be under-recognized and under-treated due to a complex interplay of biological, social, and cultural factors. Historically, women's health concerns were often dismissed, and although significant improvements have been made, implicit gender biases persist leading to delays in diagnosis and treatment. Low awareness further contributes to disparities, as many women underestimate their cardiovascular risk and providers may not consistently view CVD as a primary concern. Beyond these systemic issues, biological differences between sexes play an important role. There are also female-specific risk factors for cardiovascular disease to


id: zebra-medicine-20260505-0
file: data/en.wikipedia.org/wiki/Zebra_(medicine)-0.md
category: reference
title: Zebra (medicine)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Zebra_(medicine)
date_saved: 2026-05-05T07:34:13.381602+00:00
instance: kb-cron
parent: zebra-medicine-20260505-0
summary:
Zebra is American medical slang for a surprising, often exotic, medical diagnosis, especially when a more commonplace explanation is more likely. It is shorthand for the aphorism coined in the late 1940s by Theodore Woodward, professor at the University of Maryland School of Medicine, who instructed his medical interns: "When you hear hoofbeats behind you, don't expect to see a zebra." (Alternative phrasing: "When you hear hoofbeats, think of horses, not zebras." Since zebras are much rarer than horses in the United States, the sound of hoofbeats would almost certainly be from a horse.) By 1960, the aphorism was widely known in medical circles. The saying is a warning against the statistical base rate fallacy where the likelihood of something like a disease among the population is not taken into consideration for an individual. Medical novices are predisposed to make rare diagnoses because of (a) the availability heuristic ("events more easily remembered are judged more probable") and (b) the phenomenon first enunciated in Rhetorica ad Herennium (c. 85 BC), "the striking and the novel stay longer in the mind." Thus, the aphorism is an important caution against these biases when teaching medical students to weigh medical evidence. Diagnosticians have noted,


id: abyssal-plain-20260505-0
file: data/en.wikipedia.org/wiki/Abyssal_plain-0.md
category: reference
title: Abyssal plain
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abyssal_plain
date_saved: 2026-05-05T07:34:14.960702+00:00
instance: kb-cron
parent: abyssal-plain-20260505-0
summary:
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 and 6,000 metres (9,800 and 19,700 ft). Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. They are among the flattest, smoothest, and least explored regions on Earth. Abyssal plains are key geologic elements of oceanic basins, the other elements being an elevated mid-ocean ridge and flanking abyssal hills. The creation of the abyssal plain is the result of the spreading of the seafloor (plate tectonics) and the melting of the lower oceanic crust. Magma rises from above the asthenosphere (a layer of the upper mantle), and as this basaltic material reaches the surface at mid-ocean ridges, it forms new oceanic crust, which is constantly pulled sideways by spreading of the seafloor. Abyssal plains result from the blanketing of an originally uneven surface of oceanic crust by fine-grained sediments, mainly clay and silt. Much of this sediment is deposited by turbidity currents that have been channelled from the continental margins along submarine canyons into deeper water. The rest is composed chiefly of pelagic sediments. Metallic nodules are common


id: abyssal-plain-20260505-1
file: data/en.wikipedia.org/wiki/Abyssal_plain-1.md
category: reference
title: Abyssal plain
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abyssal_plain
date_saved: 2026-05-05T07:34:14.960702+00:00
instance: kb-cron
parent: abyssal-plain-20260505-0
summary:
The ocean can be conceptualized as zones, depending on depth, and presence or absence of sunlight. Nearly all life forms in the ocean depend on the photosynthetic activities of phytoplankton and other marine plants to convert carbon dioxide into organic carbon, which is the basic building block of organic matter. Photosynthesis in turn requires energy from sunlight to drive the chemical reactions that produce organic carbon. The stratum of the water column nearest the surface of the ocean (sea level) is referred to as the photic zone. The photic zone can be subdivided into two different vertical regions. The uppermost portion of the photic zone, where there is adequate light to support photosynthesis by phytoplankton and plants, is referred to as the euphotic zone (also referred to as the epipelagic zone, or surface zone). The lower portion of the photic zone, where the light intensity is insufficient for photosynthesis, is called the dysphotic zone (dysphotic means "poorly lit" in Greek). The dysphotic zone is also referred to as the mesopelagic zone, or the twilight zone. Its lowermost boundary is at a thermocline of 12 °C (54 °F), which, in the tropics generally lies between 200 and 1,000 metres (660 and


id: abyssal-plain-20260505-2
file: data/en.wikipedia.org/wiki/Abyssal_plain-2.md
category: reference
title: Abyssal plain
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abyssal_plain
date_saved: 2026-05-05T07:34:14.960702+00:00
instance: kb-cron
parent: abyssal-plain-20260505-0
summary:
Oceanic crust, which forms the bedrock of abyssal plains, is continuously being created at mid-ocean ridges (a type of divergent boundary) by a process known as decompression melting. Plume-related decompression melting of solid mantle is responsible for creating ocean islands like the Hawaiian islands, as well as the ocean crust at mid-ocean ridges. This phenomenon is also the most common explanation for flood basalts and oceanic plateaus (two types of large igneous provinces). Decompression melting occurs when the upper mantle is partially melted into magma as it moves upwards under mid-ocean ridges. This upwelling magma then cools and solidifies by conduction and convection of heat to form new oceanic crust. Accretion occurs as mantle is added to the growing edges of a tectonic plate, usually associated with seafloor spreading. The age of oceanic crust is therefore a function of distance from the mid-ocean ridge. The youngest oceanic crust is at the mid-ocean ridges, and it becomes progressively older, cooler and denser as it migrates outwards from the mid-ocean ridges as part of the process called mantle convection. The lithosphere, which rides atop the asthenosphere, is divided into a number of tectonic plates that are continuously being created and consumed at


id: abyssal-plain-20260505-3
file: data/en.wikipedia.org/wiki/Abyssal_plain-3.md
category: reference
title: Abyssal plain
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abyssal_plain
date_saved: 2026-05-05T07:34:14.960702+00:00
instance: kb-cron
parent: abyssal-plain-20260505-0
summary:
Beginning in 1916, Canadian physicist Robert William Boyle and other scientists of the Anti-Submarine Detection Investigation Committee (ASDIC) undertook research which ultimately led to the development of sonar technology. Acoustic sounding equipment was developed which could be operated much more rapidly than the sounding lines, thus enabling the German Meteor expedition aboard the German research vessel Meteor (1925–27) to take frequent soundings on east-west Atlantic transects. Maps produced from these techniques show the major Atlantic basins, but the depth precision of these early instruments was not sufficient to reveal the flat featureless abyssal plains. As technology improved, measurement of depth, latitude and longitude became more precise and it became possible to collect more or less continuous sets of data points. This allowed researchers to draw accurate and detailed maps of large areas of the ocean floor. Use of a continuously recording fathometer enabled Tolstoy & Ewing in the summer of 1947 to identify and describe the first abyssal plain. This plain, south of Newfoundland, is now known as the Sohm Abyssal Plain. Following this discovery many other examples were found in all the oceans. The Challenger Deep is the deepest surveyed point of all of Earth's oceans; it is at


id: abyssal-plain-20260505-4
file: data/en.wikipedia.org/wiki/Abyssal_plain-4.md
category: reference
title: Abyssal plain
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abyssal_plain
date_saved: 2026-05-05T07:34:14.960702+00:00
instance: kb-cron
parent: abyssal-plain-20260505-0
summary:
Though the plains were once assumed to be vast, desert-like habitats, research over the past decade or so shows that they teem with a wide variety of microbial life. However, ecosystem structure and function at the deep seafloor have historically been poorly studied because of the size and remoteness of the abyss. Recent oceanographic expeditions conducted by an international group of scientists from the Census of Diversity of Abyssal Marine Life (CeDAMar) have found an extremely high level of biodiversity on abyssal plains, with up to 2,000 species of bacteria, 250 species of protozoans, and 500 species of invertebrates (worms, crustaceans and molluscs), typically found at single abyssal sites. New species make up more than 80% of the thousands of seafloor invertebrate species collected at any abyssal station, highlighting our heretofore poor understanding of abyssal diversity and evolution. Richer biodiversity is associated with areas of known phytodetritus input and higher organic carbon flux. Abyssobrotula galatheae, a species of cusk eel in the family Ophidiidae, is among the deepest-living species of fish. In 1970, one specimen was trawled from a depth of 8,370 m (27,460 ft) in the Puerto Rico Trench. The animal was dead, however, upon arrival at the surface.


id: abyssal-plain-20260505-5
file: data/en.wikipedia.org/wiki/Abyssal_plain-5.md
category: reference
title: Abyssal plain
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abyssal_plain
date_saved: 2026-05-05T07:34:14.960702+00:00
instance: kb-cron
parent: abyssal-plain-20260505-0
summary:
Fueled by the chemicals dissolved in the vent fluids, these areas are often home to large and diverse communities of thermophilic, halophilic and other extremophilic prokaryotic microorganisms (such as those of the sulfide-oxidizing genus Beggiatoa), often arranged in large bacterial mats near cold seeps. In these locations, chemosynthetic archaea and bacteria typically form the base of the food chain. Although the process of chemosynthesis is entirely microbial, these chemosynthetic microorganisms often support vast ecosystems consisting of complex multicellular organisms through symbiosis. These communities are characterized by species such as vesicomyid clams, mytilid mussels, limpets, isopods, giant tube worms, soft corals, eelpouts, galatheid crabs, and alvinocarid shrimp. The deepest seep community discovered thus far is in the Japan Trench, at a depth of 7700 meters. Probably the most important ecological characteristic of abyssal ecosystems is energy limitation. Abyssal seafloor communities are considered to be food limited because benthic production depends on the input of detrital organic material produced in the euphotic zone, thousands of meters above. Most of the organic flux arrives as an attenuated rain of small particles (typically, only 0.5–2% of net primary production in the euphotic zone), which decreases inversely with water depth. The small particle flux can


id: abyssal-plain-20260505-6
file: data/en.wikipedia.org/wiki/Abyssal_plain-6.md
category: reference
title: Abyssal plain
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abyssal_plain
date_saved: 2026-05-05T07:34:14.960702+00:00
instance: kb-cron
parent: abyssal-plain-20260505-0
summary:
== Exploitation of resources == In addition to their high biodiversity, abyssal plains are of great current and future commercial and strategic interest. For example, they may be used for the legal and illegal disposal of large structures such as ships and oil rigs, radioactive waste and other hazardous waste, such as munitions. They may also be attractive sites for deep-sea fishing, and extraction of oil and gas and other minerals. Future deep-sea waste disposal activities that could be significant by 2025 include emplacement of sewage and sludge, carbon sequestration, and disposal of dredge spoils. As fish stocks dwindle in the upper ocean, deep-sea fisheries are increasingly being targeted for exploitation. Because deep sea fish are long-lived and slow growing, these deep-sea fisheries are not thought to be sustainable in the long term given current management practices. Changes in primary production in the photic zone are expected to alter the standing stocks in the food-limited aphotic zone. Hydrocarbon exploration in deep water occasionally results in significant environmental degradation resulting mainly from accumulation of contaminated drill cuttings, but also from oil spills. While the oil blowout involved in the Deepwater Horizon oil spill in the Gulf of Mexico originates from a


id: abyssal-zone-20260505-0
file: data/en.wikipedia.org/wiki/Abyssal_zone-0.md
category: reference
title: Abyssal zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abyssal_zone
date_saved: 2026-05-05T07:34:16.154926+00:00
instance: kb-cron
parent: abyssal-zone-20260505-0
summary:
The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. The word abyss comes from the Greek word ἄβυσσος (ábussos), meaning "bottomless". At depths of 4,000–6,000 m (13,000–20,000 ft), this zone remains in perpetual darkness. It covers 83% of the total area of the ocean and 60% of Earth's surface. The abyssal zone has temperatures around 2–3 °C (36–37 °F) through the large majority of its mass. The water pressure can reach up to 76 MPa (750 atm; 11,000 psi). As there is no light, photosynthesis cannot occur, and there are no plants producing molecular oxygen (O2), which instead primarily comes from ice that had melted long ago from the polar regions. The water along the seafloor of this zone is largely devoid of molecular oxygen, resulting in a death trap for organisms unable to quickly return to the oxygen-enriched water above or to survive in the low-oxygen environment. This region also contains a much higher concentration of nutrient salts, like nitrogen, phosphorus, and silica, due to the large amount of dead organic material that drifts down from the ocean zones above and decomposes. The region below the abyssal zone is the sparsely inhabited


id: abyssal-zone-20260505-1
file: data/en.wikipedia.org/wiki/Abyssal_zone-1.md
category: reference
title: Abyssal zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abyssal_zone
date_saved: 2026-05-05T07:34:16.154926+00:00
instance: kb-cron
parent: abyssal-zone-20260505-0
summary:
== Animals == The abyssal zone is made up of many different types of organisms, including microorganisms, crustaceans, molluscs (bivalves, snails, and cephalopods), different classes of fishes, and possibly some animals that have yet to be discovered. Most of the fish species in this zone are described as demersal or benthopelagic fishes. Demersal fish are fish whose habitats are on or near (typically less than five meters from) the seafloor. Most fish species fit into that classification, because the seafloor contains most of the abyssal zone's nutrients; therefore, the most complex food web or greatest biomass would be in this region of the zone. Organisms in the abyssal zone rely on the natural processes of higher ocean layers. When animals from higher ocean levels die, their carcasses occasionally drift down to the abyssal zone, where organisms in the deep can feed on them. When a whale carcass falls down to the abyssal zone, this is called a whale fall. The carcass of the whale can create complex ecosystems for organisms in the depths. Benthic organisms in the abyssal zone would need to have evolved morphological traits that could either keep them out of oxygen-depleted water above the sea floor or


id: abyssal-zone-20260505-2
file: data/en.wikipedia.org/wiki/Abyssal_zone-2.md
category: reference
title: Abyssal zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abyssal_zone
date_saved: 2026-05-05T07:34:16.154926+00:00
instance: kb-cron
parent: abyssal-zone-20260505-0
summary:
== Environmental concerns == Climate change has had negative effects on the abyssal zone. Due to the zone's depth, increasing global temperatures do not affect it as quickly or drastically as the rest of the world, but the zone is still afflicted by ocean acidification. Pollutants, such as plastics, are also present in this zone. Plastics are especially bad for the abyssal zone because these organisms have evolved to eat or try to eat anything that moves or appears to be detritus, resulting in organisms consuming plastics instead of nutrients. Both ocean acidification and pollution are decreasing the already small biomass that resides within the abyssal zone. Another problem caused by humans is overfishing. Even though no fishery can fish for organisms anywhere near the abyssal zone, they can still cause harm in deeper waters. The abyssal zone depends on dead organisms from the upper zones sinking to the seafloor, since the ecosystem lacks producers due to a lack of sunlight. As fish and other animals are removed from the ocean, the frequency and amount of dead material reaching the abyssal zone decreases. Deep sea mining operations could cause problems for the abyssal zone in the future. The talks and


id: albufera-lagoon-20260505-0
file: data/en.wikipedia.org/wiki/Albufera_(lagoon)-0.md
category: reference
title: Albufera (lagoon)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Albufera_(lagoon)
date_saved: 2026-05-05T07:34:17.363720+00:00
instance: kb-cron
parent: albufera-lagoon-20260505-0
summary:
Albufera (Catalan/Valencian, 'lagoon') is the name of several estuarine lagoons in Spain: Albufera de València, on the Gulf of Valencia Albufera Natural Park, Natural Park in Valencia Albufera de Gaianes, in Gaianes (province of Alicante) S'Albufera de Mallorca, on the island of Mallorca S'Albufereta, also on Mallorca S'Albufera des Grau, on Menorca == See also == Albufeira, a city in Portugal


id: archipelago-20260505-0
file: data/en.wikipedia.org/wiki/Archipelago-0.md
category: reference
title: Archipelago
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Archipelago
date_saved: 2026-05-05T07:34:18.531660+00:00
instance: kb-cron
parent: archipelago-20260505-0
summary:
An archipelago ( AR-kə-PEL-ə-goh), sometimes called an island group or island chain, is a chain, cluster, or collection of islands. An archipelago may be in an ocean, a sea, or a smaller body of water. Examples of archipelagos include the Aegean Islands (the origin of the term archipelago), the Canadian Arctic Archipelago, the Stockholm Archipelago, the Malay Archipelago (which includes the Indonesian and Philippine Archipelagos), the Lucayan (Bahamian) Archipelago, the Japanese archipelago, the Hawaiian Archipelago, and the Galapagos. == Etymology == The word archipelago is derived from the Italian arcipelago (used as a proper name for the Aegean Sea), itself perhaps a deformation of the Greek Αιγαίον Πέλαγος. Usage later shifted to refer to the Aegean Islands (since the sea has a large number of islands). The erudite paretymology, deriving the word from Ancient Greek ἄρχι- (arkhi-, "chief") and πέλαγος (pélagos, "sea"), proposed by Buondelmonti, can still be found. == Geographic types == Archipelagos may be found isolated in large bodies of water or neighboring a large land mass. For example, Scotland has more than 700 islands surrounding its mainland, which form an archipelago. Depending on their geological origin, islands forming archipelagos can be referred to as oceanic islands, continental


id: atoll-20260505-0
file: data/en.wikipedia.org/wiki/Atoll-0.md
category: reference
title: Atoll
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Atoll
date_saved: 2026-05-05T07:34:19.794424+00:00
instance: kb-cron
parent: atoll-20260505-0
summary:
An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical parts of the oceans and seas where corals can develop. Most of the approximately 440 atolls in the world are in the Pacific Ocean. Two different, well-cited models, the subsidence model and the antecedent karst model, have been used to explain the development of atolls. According to Charles Darwin's subsidence model, the formation of an atoll is explained by the sinking of a volcanic island around which a coral fringing reef has formed. Over geologic time, the volcanic island becomes extinct and eroded as it subsides completely beneath the surface of the ocean. As the volcanic island subsides, the coral fringing reef becomes a barrier reef that is detached from the island. Eventually, the reef and the small coral islets on top of it are all that is left of the original island, and a lagoon has taken the place of the former volcano. The lagoon is not the former volcanic crater. For the atoll to persist, the coral reef must be maintained at the sea surface,


id: atoll-20260505-1
file: data/en.wikipedia.org/wiki/Atoll-1.md
category: reference
title: Atoll
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Atoll
date_saved: 2026-05-05T07:34:19.794424+00:00
instance: kb-cron
parent: atoll-20260505-0
summary:
=== List of atolls === === Gallery === == Formation == In 1842, Charles Darwin explained the creation of coral atolls in the southern Pacific Ocean based upon observations made during a five-year voyage aboard HMS Beagle from 1831 to 1836. Darwin's explanation suggests that several tropical island types: from high volcanic island, through barrier reef island, to atoll, represented a sequence of gradual subsidence of what started as an oceanic volcano. He reasoned that a fringing coral reef surrounding a volcanic island in the tropical sea will grow upward as the island subsides (sinks), becoming an "almost atoll", or barrier reef island, as typified by an island such as Aitutaki in the Cook Islands, and Bora Bora and others in the Society Islands. The fringing reef becomes a barrier reef for the reason that the outer part of the reef maintains itself near sea level through biotic growth, while the inner part of the reef falls behind, becoming a lagoon because conditions are less favorable for the coral and calcareous algae responsible for most reef growth. In time, subsidence carries the old volcano below the ocean surface and the barrier reef remains. At this point, the island has become


id: barrier-island-20260505-0
file: data/en.wikipedia.org/wiki/Barrier_island-0.md
category: reference
title: Barrier island
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Barrier_island
date_saved: 2026-05-05T07:34:21.177659+00:00
instance: kb-cron
parent: barrier-island-20260505-0
summary:
Barrier islands are a coastal landform, a type of dune system and sand island, where an area of sand off the coast has been formed by wave and tidal action parallel to the mainland coast. Barrier islands are commonly formed in long, narrow systems parallel to shorelines and are shaped by waves, tides, sediment movement, and sea-level change, which cause them to shift, grow, or erode over time. They protect coastlines by absorbing energy, and create areas of protected waters where wetlands may flourish. A barrier chain may extend for hundreds of kilometers, with islands periodically separated by tidal inlets. The longest barrier island in the world is Padre Island of Texas, United States, at 113 miles (182 km) long. Sometimes an important inlet may close permanently, transforming an island into a barrier peninsula, often including a barrier beach. Barrier islands are related to other coastal landforms such as barrier beaches and spits, which share similar physical features but differ primarily in their degree of attachment to the mainland and the presence of water on their landward side. Though many are long and narrow, the length and width of barriers and overall morphology of barrier coasts are related to parameters


id: barrier-island-20260505-1
file: data/en.wikipedia.org/wiki/Barrier_island-1.md
category: reference
title: Barrier island
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Barrier_island
date_saved: 2026-05-05T07:34:21.177659+00:00
instance: kb-cron
parent: barrier-island-20260505-0
summary:
=== Critical width concept === Barrier islands are often formed to have a certain width. The term "critical width concept" has been discussed with reference to barrier islands, overwash, and washover deposits since the 1970s. The concept basically states that overwash processes were effective in migration of the barrier only where the barrier width is less than a critical value. The island did not narrow below these values because overwash was effective at transporting sediment over the barrier island, thereby keeping pace with the rate of ocean shoreline recession. Sections of the island with greater widths experienced washover deposits that did not reach the bayshore, and the island narrowed by ocean shoreline recession until it reached the critical width. The only process that widened the barrier beyond the critical width was breaching, formation of a partially subaerial flood shoal, and subsequent inlet closure. Critical barrier width can be defined as the smallest cross-shore dimension that minimizes net loss of sediment from the barrier island over the defined project lifetime. The magnitude of critical width is related to sources and sinks of sand in the system, such as the volume stored in the dunes and the net long-shore and cross-shore sand


id: barrier-island-20260505-2
file: data/en.wikipedia.org/wiki/Barrier_island-2.md
category: reference
title: Barrier island
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Barrier_island
date_saved: 2026-05-05T07:34:21.177659+00:00
instance: kb-cron
parent: barrier-island-20260505-0
summary:
Scientists have proposed numerous explanations for the formation of barrier islands for more than 150 years. There are three major theories: offshore bar, spit accretion, and submergence. No single theory can explain the development of all barriers, which are distributed extensively along the world's coastlines. Scientists accept the idea that barrier islands, including other barrier types, can form by a number of different mechanisms. There appears to be some general requirements for formation. Barrier island systems develop most easily on wave-dominated coasts with a small to moderate tidal range. Coasts are classified into three groups based on tidal range: microtidal, 0–2 meter tidal range; mesotidal, 2–4 meter tidal range; and macrotidal, >4 meter tidal range. Barrier islands tend to form primarily along microtidal coasts, where they tend to be well developed and nearly continuous. They are less frequently formed in mesotidal coasts, where they are typically short with tidal inlets common. Barrier islands are very rare along macrotidal coasts. Along with a small tidal range and a wave-dominated coast, there must be a relatively low gradient shelf. Otherwise, sand accumulation into a sandbar would not occur and instead would be dispersed throughout the shore. An ample sediment supply is also


id: barrier-island-20260505-3
file: data/en.wikipedia.org/wiki/Barrier_island-3.md
category: reference
title: Barrier island
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Barrier_island
date_saved: 2026-05-05T07:34:21.177659+00:00
instance: kb-cron
parent: barrier-island-20260505-0
summary:
=== Wave-dominated === Wave-dominated barrier islands are long, low, and narrow, and usually are bounded by unstable inlets at either end. The presence of longshore currents caused by waves approaching the island at an angle will carry sediment long, extending the island. Longshore currents, and the resultant extension, are usually in one direction, but in some circumstances the currents and extensions can occur towards both ends of the island (as occurs on Anclote Key, Three Rooker Bar, and Sand Key, on the Gulf Coast of Florida). Washover fans on the lagoon side of barriers, where storm surges have over-topped the island, are common, especially on younger barrier islands. Wave-dominated barriers are also susceptible to being breached by storms, creating new inlets. Such inlets may close as sediment is carried in them by longshore currents, but may become permanent if the tidal prism (volumn and force of tidal flow) is large enough. Older barrier islands that have accumulated dunes are less subject to washovers and opening of inlets. Wave-dominated islands require an abundant supply of sediment to grow and develop dunes. If a barrier island does not receive enough sediment to grow, repeated washovers from storms will migrate the island towards


id: bay-20260505-0
file: data/en.wikipedia.org/wiki/Bay-0.md
category: reference
title: Bay
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bay
date_saved: 2026-05-05T07:34:23.463029+00:00
instance: kb-cron
parent: bay-20260505-0
summary:
A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a small, circular bay with a narrow entrance. A fjord is an elongated bay formed by glacial action. The term embayment is also used for related features, such as extinct bays or freshwater environments. A bay can be the estuary of a river, such as the Chesapeake Bay, an estuary of the Susquehanna River. Bays may also be nested within each other; for example, James Bay is an arm of Hudson Bay in northeastern Canada. Some bays are large enough to have varied marine geology, such as the Bay of Bengal (2,600,000 km2 or 1,000,000 sq mi) and Hudson Bay (1,230,000 km2 or 470,000 sq mi). The land surrounding a bay often reduces the strength of winds and blocks waves. Bays may have as wide a variety of shoreline characteristics as other shorelines. In some cases, bays have beaches, which "are usually characterized by a steep upper foreshore with a broad, flat fronting terrace". Bays were significant


id: beach-20260505-0
file: data/en.wikipedia.org/wiki/Beach-0.md
category: reference
title: Beach
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach
date_saved: 2026-05-05T07:34:24.791061+00:00
instance: kb-cron
parent: beach-20260505-0
summary:
A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from rock, such as sand, gravel, shingle, pebbles, etc., or biological sources, such as mollusc shells or coralline algae. Sediments settle in different densities and structures, depending on the local wave action and weather, creating different textures, colors and gradients or layers of material. Though some beaches form on inland freshwater locations such as lakes and rivers, most beaches are in coastal areas where wave or current action deposits and reworks sediments. Erosion and changing of beach geologies happens through natural processes, like wave action and extreme weather events. Where wind conditions are correct, beaches can be backed by coastal dunes which offer protection and regeneration for the beach. However, these natural forces have become more extreme due to climate change, permanently altering beaches at very rapid rates. Some estimates describe as much as 50 percent of the earth's sandy beaches disappearing by 2100 due to climate-change driven sea level rise. Sandy beaches occupy about one third of global coastlines. These beaches are popular for recreation, playing important economic and cultural roles—often driving local tourism industries. To


id: beach-20260505-1
file: data/en.wikipedia.org/wiki/Beach-1.md
category: reference
title: Beach
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach
date_saved: 2026-05-05T07:34:24.791061+00:00
instance: kb-cron
parent: beach-20260505-0
summary:
Beaches are the result of wave action by which waves or currents move sand or other loose sediments of which the beach is made as these particles are held in suspension. Alternatively, sand may be moved by saltation (a bouncing movement of large particles). Beach materials come from erosion of rocks offshore, as well as from headland erosion and slumping producing deposits of scree. A coral reef offshore is a significant source of sand particles. Some species of fish that feed on algae attached to coral outcrops and rocks can create substantial quantities of sand particles over their lifetime as they nibble during feeding, digesting the organic matter, and discarding the rock and coral particles which pass through their digestive tracts. The composition of the beach depends upon the nature and quantity of sediments upstream of the beach, and the speed of flow and turbidity of water and wind. Sediments are moved by moving water and wind according to their particle size and state of compaction. Particles tend to settle and compact in still water. Once compacted, they are more resistant to erosion. Established vegetation (especially species with complex network root systems) will resist erosion by slowing the fluid flow


id: beach-20260505-2
file: data/en.wikipedia.org/wiki/Beach-2.md
category: reference
title: Beach
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach
date_saved: 2026-05-05T07:34:24.791061+00:00
instance: kb-cron
parent: beach-20260505-0
summary:
==== Causes ==== Beaches are changed in shape chiefly by the movement of water and wind. Any weather event that is associated with turbid or fast-flowing water or high winds will erode exposed beaches. Longshore currents will tend to replenish beach sediments and repair storm damage. Tidal waterways generally change the shape of their adjacent beaches by small degrees with every tidal cycle. Over time these changes can become substantial leading to significant changes in the size and location of the beach. ==== Effects on flora ==== Changes in the shape of the beach may undermine the roots of large trees and other flora. Many beach adapted species (such as coconut palms) have a fine root system and large root ball which tends to withstand wave and wind action and tends to stabilize beaches better than other trees with a lesser root ball. ==== Effects on adjacent land ==== Erosion of beaches can expose less resilient soils and rocks to wind and wave action leading to undermining of coastal headlands eventually resulting in catastrophic collapse of large quantities of overburden into the shallows. This material may be distributed along the beach front leading to a change in the habitat as


id: beach-20260505-3
file: data/en.wikipedia.org/wiki/Beach-3.md
category: reference
title: Beach
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach
date_saved: 2026-05-05T07:34:24.791061+00:00
instance: kb-cron
parent: beach-20260505-0
summary:
==== Concentration of runoff ==== Beaches provide a filter for runoff from the coastal plain. If the runoff is naturally dispersed along the beach, water borne silt and organic matter will be retained on the land and will feed the flora in the coastal area. Runoff that is dispersed along the beach will tend to percolate through the beach and may emerge from the beach at low tide. The retention of the freshwater may also help to maintain underground water reserves and will resist salt water incursion. If the surface flow of the runoff is diverted and concentrated by drains that create constant flows over the beach above the sea or river level, the beach will be eroded and ultimately form an inlet unless longshore flows deposit sediments to repair the breach. Once eroded, an inlet may allow tidal inflows of salt water to pollute areas inland from the beach and may also affect the quality of underground water supplies and the height of the water table. ==== Deprivation of runoff ==== Some flora naturally occurring on the beach head requires freshwater runoff from the land. Diversion of freshwater runoff into drains may deprive these plants of their water supplies


id: beach-20260505-4
file: data/en.wikipedia.org/wiki/Beach-4.md
category: reference
title: Beach
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach
date_saved: 2026-05-05T07:34:24.791061+00:00
instance: kb-cron
parent: beach-20260505-0
summary:
The extension of this form of leisure to the middle and working classes began with the development of the railways in the 1840s, which offered cheap fares to fast-growing resort towns. In particular, the completion of a branch line to the small seaside town of Blackpool from Poulton led to a sustained economic and demographic boom. A sudden influx of visitors, arriving by rail, led entrepreneurs to build accommodation and create new attractions, leading to more visitors and a rapid cycle of growth throughout the 1850s and 1860s. The growth was intensified by the practice among the Lancashire cotton mill owners of closing the factories for a week every year to service and repair machinery. These became known as wakes weeks. Each town's mills would close for a different week, allowing Blackpool to manage a steady and reliable stream of visitors over a prolonged period in the summer. A prominent feature of the resort was the promenade and the pleasure piers, where an eclectic variety of performances vied for the people's attention. In 1863, the North Pier in Blackpool was completed, rapidly becoming a centre of attraction for upper class visitors. Central Pier was completed in 1868, with a theatre


id: beach-20260505-5
file: data/en.wikipedia.org/wiki/Beach-5.md
category: reference
title: Beach
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach
date_saved: 2026-05-05T07:34:24.791061+00:00
instance: kb-cron
parent: beach-20260505-0
summary:
=== Artificial beaches === Some beaches are artificial; they are either permanent or temporary (For examples, see Copenhagen, Hong Kong, Manila, Monaco, Nottingham, Paris, Rotterdam, Singapore, Tianjin, and Toronto). The soothing qualities of a beach and the pleasant environment offered to the beachgoer are replicated in artificial beaches, such as "beach style" pools with zero-depth entry and wave pools that recreate the natural waves pounding upon a beach. In a zero-depth entry pool, the bottom surface slopes gradually from above water down to depth. Another approach involves so-called urban beaches, a form of public park becoming common in large cities. Urban beaches attempt to mimic natural beaches with fountains that imitate surf and mask city noises, and in some cases can be used as a play park. Beach nourishment involves pumping sand onto beaches to improve their health. Beach nourishment is common for major beach cities around the world; however the beaches that have been nourished can still appear quite natural and often many visitors are unaware of the works undertaken to support the health of the beach. Such beaches are often not recognized by consumers as artificial. A famous example of beach nourishment came with the replenishment of Waikīkī


id: beach-20260505-6
file: data/en.wikipedia.org/wiki/Beach-6.md
category: reference
title: Beach
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach
date_saved: 2026-05-05T07:34:24.791061+00:00
instance: kb-cron
parent: beach-20260505-0
summary:
=== Corduroy (beach ladder) === A corduroy road or beach ladder (or board and chain) is an array of planks (usually hardwood or treated timber) laid close together and perpendicular to the direction of traffic flow, and secured at each end by a chain or cable to form a pathway or ramp over the sand dune. Corduroys are cheap and easy to construct and quick to deploy or relocate. They are commonly used for pedestrian access paths and light duty vehicular access ways. They naturally conform to the shape of the underlying beach or dune profile, and adjust well to moderate erosion, especially longshore drift. However, they can cease to be an effective access surface if they become buried or undermined by erosion by surface runoff coming from the beach head. If the corduroy is not wide enough for vehicles using it, the sediment on either side may be displaced creating a spoon drain that accelerates surface runoff and can quickly lead to serious erosion. Significant erosion of the sediment beside and under the corduroy can render it completely ineffective and make it dangerous to pedestrian users who may fall between the planks. === Fabric ramp === Fabric ramps are


id: beach-evolution-20260505-0
file: data/en.wikipedia.org/wiki/Beach_evolution-0.md
category: reference
title: Beach evolution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach_evolution
date_saved: 2026-05-05T07:34:26.041541+00:00
instance: kb-cron
parent: beach-evolution-20260505-0
summary:
Beach evolution is a natural process occurring along shorelines where sea, lake, or river water erodes the land. Beaches form as sand accumulates over centuries through recurrent processes that erode rocky and sedimentary material into sand deposits. River deltas contribute by depositing silt carried from upriver, accreting at the river's outlet to extend lake or ocean shorelines. Catastrophic events such as tsunamis, hurricanes, and storm surges accelerate beach evolution. == Accretion and erosion == === Sudden and rapid processes === ==== Tsunamis and hurricane-driven storm surges ==== Tsunamis can cause significant erosion and sediment displacement. They can strip away years of accumulated sand from beaches and devastate coastal vegetation. These powerful waves can flood inland areas far beyond the typical high-tide mark. Additionally, the swift currents associated with the inundating tsunami can demolish homes and other coastal structures. A storm surge is an onshore gush of water associated with a low pressure weather system. Storm surges can cause beach accretion and erosion. Historically notable storm surges occurred during the North Sea Flood of 1953, Hurricane Katrina, and the 1970 Bhola cyclone. ==== Volcanism and earthquakes related sea-level changes ==== Both geological events and the climate can change (progressively or suddenly)


id: beach-evolution-20260505-1
file: data/en.wikipedia.org/wiki/Beach_evolution-1.md
category: reference
title: Beach evolution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach_evolution
date_saved: 2026-05-05T07:34:26.041541+00:00
instance: kb-cron
parent: beach-evolution-20260505-0
summary:
Abandonment of shore: do nothing, let the natural process takeover. Managed retreat, also called realignment. Hold the shoreline: by using shoreline hardening techniques to create permanent concrete and rock constructions such as groynes. Move beach seaward: by using hard and soft intervention techniques usually in areas of high economic significance. Limited intervention: usually in areas of low economic significance, often includes the succession of haloseres, including salt marshes and sand dunes. === Coastal engineering === Coastal engineering techniques can be classified into two categories: hard engineering methods and soft engineering methods ==== Hard engineering methods ==== Hard engineering methods are also called "Structural methods". "Move towards the sea" beach accretion can be facilitated by the four main type of hard engineering structures, namely seawall, revetment, groyne or breakwater. Most commonly used hard structures are seawall and series of "headland groyne" (breakwater connected to the shore with groyne). ===== Main types of structures ===== Four main types of structures or accropodes are seawalls, groynes, breakwater and revetments. Headland groynes are a combination of breakwater and groyne. ====== Seawalls ====== Seawalls re-direct most of the incident energy in the form of sloping revetments, resulting in low reflected waves and much reduced turbulence.


id: beach-evolution-20260505-2
file: data/en.wikipedia.org/wiki/Beach_evolution-2.md
category: reference
title: Beach evolution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach_evolution
date_saved: 2026-05-05T07:34:26.041541+00:00
instance: kb-cron
parent: beach-evolution-20260505-0
summary:
====== Concrete objects ====== These are complex reinforced concrete objects, such as A-jack, Akmon, Dolos, Honeycomb sea wall (Seabees), KOLOS, Tetrapod and Xbloc. Simple concrete blocks have been replaced by these complex concrete objects because these objects are more resistant to wave action and require less concrete to produce a superior result. These could be used to build seawalls, groynes, breakwaters, and other structures including residential buildings. Tetrapods used along Marine Drive, Mumbai are an example of complex concrete objects. ====== Gabions ====== Gabions are constructed by wiring boulders and rocks into mesh cages and placed in front of areas vulnerable to erosion, sometimes at cliffs edges or at right angles to the beach. When the ocean lands on the gabion, the water drains through leaving sediment, while the structure absorbs a moderate amount of wave energy. Gabions need to be securely tied to protect the structure. They can be used to build seawalls, groynes, breakwaters, revetments, buildings, underwater reefs, etc., ==== Soft engineering methods ==== Soft engineering uses a "soft" (non-permanent) structure by creating a larger sand reservoir, pushing the shoreline seaward. It gained popularity because it preserved beach resources and avoided the negative effects of hard structures. =====


id: beach-evolution-20260505-3
file: data/en.wikipedia.org/wiki/Beach_evolution-3.md
category: reference
title: Beach evolution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach_evolution
date_saved: 2026-05-05T07:34:26.041541+00:00
instance: kb-cron
parent: beach-evolution-20260505-0
summary:
This Integrated coastal zone management example is based on the "move beach seaward" general planning approach which involves both hard and soft engineering methods. This scenario minimizes the maintenance effort and cost by making optimal use of the coastal geography by incorporating natural coastal geographical features in the engineering design. The cost is kept low by the use of easily available free or cost-effective local material, use of which is already known to or easily acquired by the local workforce. This solution entails beach nourishment (creating recreational area by filling with sand), and further beach expansion and prevention of beach erosion caused by longshore drift and coastal development hazards. The design makes use of a shorter groyne slightly inclined toward the beach in the same direction as downdrift, with a series of "headland groyne" perpendicular to the shore, and a longer "headland groyne" at the end of downdrift side of the beach with smaller "headland groyne" perpendicular to it facing the updrift end of the beach. This example of tropical setting, part of the sea could be reclaimed by building a seawall with revetment (slope) fortified with armament of honeycomb seebee made of concrete with hexagonal holes, parts of seawall


id: beach-evolution-20260505-4
file: data/en.wikipedia.org/wiki/Beach_evolution-4.md
category: reference
title: Beach evolution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beach_evolution
date_saved: 2026-05-05T07:34:26.041541+00:00
instance: kb-cron
parent: beach-evolution-20260505-0
summary:
==== California beaches ==== California's beaches and other shoreline features change according to the availability of beach sand, the wave and current energy impinging on the coast, and other physical processes that affect the movement of sand. A constant supply of sand is necessary for beaches to form and be maintained along this shoreline. Many human activities, including dam construction and river channelization, have reduced the supply of sand that reaches the ocean. This, in turn, has prevented beaches from being replenished and has thus created greater vulnerability for shorelines that have always been subject to varying levels of erosion. There are few practical solutions to improving sand supply from inland sources, so management of shoreline erosion will likely continue to focus at the land/sea interface along the California coastline. Construction of breakwaters, jetties, or groyne fields to protect harbor entrances, maintain beaches, or protect coastal structures have both helped and harmed the movement of sand along the shoreline. Protective armoring formations trap sand and allow beaches to expand up-coast from the device, but can interrupt the flow of sand to beaches located down-coast. ==== France ==== ===== Atlantic coast ===== Some of the coastal defence bunkers of the Atlantic


id: beachrock-20260505-0
file: data/en.wikipedia.org/wiki/Beachrock-0.md
category: reference
title: Beachrock
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beachrock
date_saved: 2026-05-05T07:34:27.242877+00:00
instance: kb-cron
parent: beachrock-20260505-0
summary:
Beachrock is a friable to well-cemented sedimentary rock that consists of a variable mixture of gravel-, sand-, and silt-sized sediment that is cemented with carbonate minerals and has formed along a shoreline. Depending on location, the sediment that is cemented to form beachrock can consist of a variable mixture of shells, coral fragments, rock fragments of different types, and other materials. It can also contain scattered artifacts, pieces of wood, and coconuts. Beachrock typically forms within the intertidal zone within tropical or semitropical regions. However, Quaternary beachrock is also found as far north and south as 60° latitude. == Overview == Beachrock units form under a thin cover of sediment and generally overlie unconsolidated sand. They typically consist of multiple units, representing multiple episodes of cementation and exposure. The mineralogy of beachrocks is mainly high-magnesium calcite or aragonite. The main processes involved in the cementation are : supersaturation with CaCO3 through direct evaporation of seawater, groundwater CO2 degassing in the vadose zone, mixing of marine and meteoric water fluxes and precipitation of micritic calcium carbonate as a byproduct of microbiological activity. On retreating coasts, outcrops of beachrock may be evident offshore where they may act as a barrier against coastal


id: benthic-zone-20260505-0
file: data/en.wikipedia.org/wiki/Benthic_zone-0.md
category: reference
title: Benthic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Benthic_zone
date_saved: 2026-05-05T07:34:28.462475+00:00
instance: kb-cron
parent: benthic-zone-20260505-0
summary:
The benthic zone, from Ancient Greek βένθος (bénthos) 'the depths of the ocean', is the ecological region at the lowest level of a body of water, such as a stream, river, lake, or ocean, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos, or more informally bottom dwellers. They include microorganisms such as bacteria and fungi, as well as larger invertebrates such as crustaceans and polychaetes. Benthos generally live in close relationship with the substrate and many are permanently attached to the bottom. The benthic boundary layer, which includes the bottom layer of water and the uppermost layer of sediment directly influenced by the overlying water, is an integral part of the benthic zone, as it greatly influences the biological activity that takes place there. Examples of contact soil layers include sand bottoms, rocky outcrops, coral, and bay mud. == Physical description == === Oceans === The benthic region of the ocean begins at the shore line (intertidal or littoral zone) and extends downward along the surface of the continental shelf out to sea. Thus, the region incorporates a great variety of physical conditions differing in depth, light penetration and pressure. The benthic


id: benthic-zone-20260505-1
file: data/en.wikipedia.org/wiki/Benthic_zone-1.md
category: reference
title: Benthic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Benthic_zone
date_saved: 2026-05-05T07:34:28.462475+00:00
instance: kb-cron
parent: benthic-zone-20260505-0
summary:
Benthos is the community of organisms that live in the benthic zone, that is, on, in, or near the bottom of a stream, river, lake, or ocean. This community lives in or near marine or freshwater sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths. The term benthos, coined by Haeckel in 1891, comes from the Greek noun βένθος 'depth of the ocean'. Additionally to oceans, benthos is also used in freshwater biology to refer to organisms at the bottom of freshwater bodies of water, such as streams, rivers, and lakes. There is also a redundant, occasionally used synonym, benthon. Benthos is also referred to more loosely and informally as bottom dwellers or bottom feeders. Light is an important energy source for shallow benthic systems. However, because light is absorbed before it can reach deep ocean water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains the benthic food chain; most organisms in the benthic zone are scavengers or detritivores. Many organisms adapted to deep-water pressure cannot survive


id: benthic-zone-20260505-2
file: data/en.wikipedia.org/wiki/Benthic_zone-2.md
category: reference
title: Benthic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Benthic_zone
date_saved: 2026-05-05T07:34:28.462475+00:00
instance: kb-cron
parent: benthic-zone-20260505-0
summary:
Both foraminifera and diatoms have planktonic and benthic forms, that is, they can drift in the water column or live on sediment at the bottom of the ocean. Regardless of form, their shells sink to the seafloor after they die. These shells are widely used as climate proxies. The chemical composition of the shells are a consequence of the chemical composition of the ocean at the time the shells were formed. Past water temperatures can be also be inferred from the ratios of stable oxygen isotopes in the shells, since lighter isotopes evaporate more readily in warmer water leaving the heavier isotopes in the shells. Information about past climates can be inferred further from the abundance of forams and diatoms, since they tend to be more abundant in warm water.The sudden extinction event which killed the dinosaurs 66 million years ago also rendered extinct three-quarters of all other animal and plant species. However, deep-sea benthic forams flourished in the aftermath. In 2020 it was reported that researchers have examined the chemical composition of thousands of samples of these benthic forams and used their findings to build the most detailed climate record of Earth ever. Some endoliths have extremely long lives.


id: benthic-zone-20260505-3
file: data/en.wikipedia.org/wiki/Benthic_zone-3.md
category: reference
title: Benthic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Benthic_zone
date_saved: 2026-05-05T07:34:28.462475+00:00
instance: kb-cron
parent: benthic-zone-20260505-0
summary:
=== Nutrient flux === Sources of food for benthic communities can derive from the water column above these habitats in the form of aggregations of detritus, inorganic matter, and living organisms. These aggregations are commonly referred to as marine snow, and are important for the deposition of organic matter, and bacterial communities. The amount of material sinking to the ocean floor can average 307,000 aggregates per m2 per day. This amount will vary on the depth of the benthos, and the degree of benthic-pelagic coupling. The benthos in a shallow region will have more available food than the benthos in the deep sea. Because of their reliance on it, microbes may become spatially dependent on detritus in the benthic zone. The microbes found in the benthic zone, specifically dinoflagellates and foraminifera, colonize quite rapidly on detritus matter while forming a symbiotic relationship with each other. In the deep sea, which covers 90–95% of the ocean floor, 90% of the total biomass is made up of prokaryotes. To release all the nutrients locked inside these microbes to the environment, viruses are important in making it available to other organisms. The main food sources for the benthos are phytoplankton and organic detrital


id: benthic-zone-20260505-4
file: data/en.wikipedia.org/wiki/Benthic_zone-4.md
category: reference
title: Benthic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Benthic_zone
date_saved: 2026-05-05T07:34:28.462475+00:00
instance: kb-cron
parent: benthic-zone-20260505-0
summary:
Benthic macroinvertebrates have many important ecological functions, such as regulating the flow of materials and energy in river ecosystems through their food web linkages. Because of this correlation between flow of energy and nutrients, benthic macroinvertebrates have the ability to influence food resources on fish and other organisms in aquatic ecosystems. For example, the addition of a moderate amount of nutrients to a river over the course of several years resulted in increases in invertebrate richness, abundance, and biomass. These in turn resulted in increased food resources for native species of fish with insignificant alteration of the macroinvertebrate community structure and trophic pathways. The presence of macroinvertebrates such as Amphipoda also affect the dominance of certain types of algae in Benthic ecosystems as well. In addition, because benthic zones are influenced by the flow of dead organic material, there have been studies conducted on the relationship between stream and river water flows and the resulting effects on the benthic zone. Low flow events show a restriction in nutrient transport from benthic substrates to food webs, and caused a decrease in benthic macroinvertebrate biomass, which lead to the disappearance of food sources into the substrate. Because the benthic system regulates energy


id: cape-geography-20260505-0
file: data/en.wikipedia.org/wiki/Cape_(geography)-0.md
category: reference
title: Cape (geography)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cape_(geography)
date_saved: 2026-05-05T07:34:31.991235+00:00
instance: kb-cron
parent: cape-geography-20260505-0
summary:
In geography, a cape is a headland, peninsula or promontory extending into a body of water, usually a sea. A cape usually represents a marked change in trend of the coastline, often making them important landmarks in sea navigation. This also makes them prone to natural forms of erosion, mainly tidal actions, resulting in a relatively short geological lifespan. == Formation == Capes can be formed by glaciers, volcanoes, and changes in sea level. Erosion plays a large role in each of these methods of formation. Coastal erosion by waves and currents can create capes by wearing away softer rock and leaving behind harder rock formations. Movements of the Earth's crust can uplift land, forming capes. For example, the Cape of Good Hope was formed by tectonic forces. Volcanic eruptions can create capes by depositing lava that solidifies into new landforms. Cape Verde, (also known as Cabo Verde) is an example of a volcanic cape. Glaciers can carve out capes by eroding the landscape as they advance and retreat. Cape Cod in the United States was formed by glacial activity during the last Ice Age. == Importance in navigation == Capes (and other headlands) are conspicuous visual landmarks along a


id: capillary-wave-20260505-0
file: data/en.wikipedia.org/wiki/Capillary_wave-0.md
category: reference
title: Capillary wave
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Capillary_wave
date_saved: 2026-05-05T07:34:33.305688+00:00
instance: kb-cron
parent: capillary-wave-20260505-0
summary:
A capillary wave is a wave traveling along the phase boundary of a fluid, whose dynamics and phase velocity are dominated by the effects of surface tension. Capillary waves are common in nature, and are often referred to as ripples. The wavelength of capillary waves on water is typically less than a few centimeters, with a phase speed in excess of 0.2–0.3 meter/second. A longer wavelength on a fluid interface will result in gravity–capillary waves which are influenced by both the effects of surface tension and gravity, as well as by fluid inertia. Ordinary gravity waves have a still longer wavelength. Light breezes upon the surface of water which stir up such small ripples are also sometimes referred to as 'cat's paws'. On the open ocean, much larger ocean surface waves (seas and swells) may result from coalescence of smaller wind-caused ripple-waves. == Dispersion relation == The dispersion relation describes the relationship between wavelength and frequency in waves. Distinction can be made between pure capillary waves – fully dominated by the effects of surface tension – and gravity–capillary waves which are also affected by gravity. === Capillary waves, proper === The dispersion relation for capillary waves is ω 2 =


id: capillary-wave-20260505-1
file: data/en.wikipedia.org/wiki/Capillary_wave-1.md
category: reference
title: Capillary wave
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Capillary_wave
date_saved: 2026-05-05T07:34:33.305688+00:00
instance: kb-cron
parent: capillary-wave-20260505-0
summary:
==== Derivation ==== As Richard Feynman put it, "[water waves] that are easily seen by everyone and which are usually used as an example of waves in elementary courses [...] are the worst possible example [...]; they have all the complications that waves can have." The derivation of the general dispersion relation is therefore quite involved. There are three contributions to the energy, due to gravity, to surface tension, and to hydrodynamics. The first two are potential energies, and responsible for the two terms inside the parenthesis, as is clear from the appearance of g {\displaystyle g} and σ {\displaystyle \sigma } . For gravity, an assumption is made of the density of the fluids being constant (i.e., incompressibility), and likewise g {\displaystyle g} (waves are not high enough for gravitation to change appreciably). For surface tension, the deviations from planarity (as measured by derivatives of the surface) are supposed to be small. For common waves both approximations are good enough. The third contribution involves the kinetic energies of the fluids. It is the most complicated and calls for a hydrodynamic framework. Incompressibility is again involved (which is satisfied if the speed of the waves is much less than the


id: coast-20260505-0
file: data/en.wikipedia.org/wiki/Coast-0.md
category: reference
title: Coast
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coast
date_saved: 2026-05-05T07:34:34.633460+00:00
instance: kb-cron
parent: coast-20260505-0
summary:
A coast (also called the coastline, shoreline, or seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, such as that caused by waves. The geological composition of rock and soil dictates the type of shore that is created. Earth has about 620,000.0 km (385,250.1 mi) of coastline. Coasts are important zones in natural ecosystems, often home to a wide range of biodiversity. On land, they harbor ecosystems, such as freshwater or estuarine wetlands, that are important for birds and other terrestrial animals. In wave-protected areas, coasts harbor salt marshes, mangroves, and seagrasses, all of which can provide nursery habitat for finfish, shellfish, and other aquatic animals. Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessile animals (e.g. mussels, starfish, barnacles) and various kinds of seaweeds. In physical oceanography, a shore is the wider fringe that is geologically modified by the action of the body of water past and present, and the beach is at the edge of the shore, including the intertidal zone


id: coast-20260505-1
file: data/en.wikipedia.org/wiki/Coast-1.md
category: reference
title: Coast
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coast
date_saved: 2026-05-05T07:34:34.633460+00:00
instance: kb-cron
parent: coast-20260505-0
summary:
Tides often determine the range over which sediment is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, and areas with lower tidal ranges produce deposition at a smaller elevation interval. The tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves; however, tidal bores can erode as the waves surge up the river estuaries from the ocean. Geologists classify coasts on the basis of tidal range into macrotidal coasts with a tidal range greater than 4 m (13 ft); mesotidal coasts with a tidal range of 2 to 4 m (6.6 to 13 ft); and microtidal coasts with a tidal range of less than 2 m (7 ft). The distinction between macrotidal and mesotidal coasts is more important. Macrotidal coasts lack barrier islands and lagoons, and are characterized by funnel-shaped estuaries containing sand ridges aligned with tidal currents. Wave action is much more important for determining bedforms of sediments deposited along mesotidal and microtidal coasts than in macrotidal coasts. Waves erode coastline as they break on shore releasing their energy; the larger the wave the more energy it releases and the more


id: coast-20260505-2
file: data/en.wikipedia.org/wiki/Coast-2.md
category: reference
title: Coast
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coast
date_saved: 2026-05-05T07:34:34.633460+00:00
instance: kb-cron
parent: coast-20260505-0
summary:
==== Destructive and constructive waves ==== Swash is the shoreward flow after the break, backwash is the water flow back down the beach. The relative strength of flow in the swash and backwash determines what size grains are deposited or eroded. This is dependent on how the wave breaks and the slope of the shore. Depending on the form of the breaking wave, its energy can carry granular material up the beach and deposit it, or erode it by carrying more material down the slope than up it. Steep waves that are close together and break with the surf plunging down onto the shore slope expend much of their energy lifting the sediment. The weak swash does not carry it far up the slope, and the strong backwash carries it further down the slope, where it either settles in deeper water or is carried along the shore by a longshore current induced by an angled approach of the wave-front to the shore. These waves which erode the beach are called destructive waves. Low waves that are further apart and break by spilling, expend more of their energy in the swash which carries particles up the beach, leaving less energy for


id: coast-20260505-3
file: data/en.wikipedia.org/wiki/Coast-3.md
category: reference
title: Coast
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coast
date_saved: 2026-05-05T07:34:34.633460+00:00
instance: kb-cron
parent: coast-20260505-0
summary:
"Coastal waters" (or "coastal seas") is a term that carries different meanings depending upon the context, ranging from a geographic reference to the waters within a few kilometers of the coast, to describing the entire continental shelf that may stretch for more than a hundred kilometers from land. The term is used in a different manner when describing legal and economic boundaries, such as territorial waters and international waters, or when describing the geography of coastal landforms or the ecological systems operating through the continental shelf (marine coastal ecosystems). The dynamic fluid nature of the ocean means that all components of the whole ocean system are ultimately connected, although certain regional classifications are useful and relevant. The waters of the continental shelves represent such a region. The term "coastal waters" has been used in a wide variety of different ways in different contexts. In European Union environmental management it extends from the coast to just a few nautical miles while in the United States the US EPA considers this region to extend much further offshore. "Coastal waters" has specific meanings in the context of commercial coastal shipping, and somewhat different meanings in the context of naval littoral warfare. Oceanographers and


id: cold-seep-20260505-0
file: data/en.wikipedia.org/wiki/Cold_seep-0.md
category: reference
title: Cold seep
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cold_seep
date_saved: 2026-05-05T07:34:36.156842+00:00
instance: kb-cron
parent: cold-seep-20260505-0
summary:
A cold seep (sometimes called a cold vent) is an area of the ocean floor where seepage of fluids rich in hydrogen sulfide, methane, and other hydrocarbons occurs, often in the form of a brine pool. Cold does not mean that the temperature of the seepage is lower than that of the surrounding sea water; on the contrary, its temperature is often slightly higher. The "cold" is relative to the very warm (at least 60 °C or 140 °F) conditions of a hydrothermal vent. Cold seeps constitute a biome supporting several endemic species. Cold seeps develop unique topography over time, where reactions between methane and seawater create carbonate rock formations and reefs. These reactions may also be dependent on bacterial activity. Ikaite, a hydrous calcium carbonate, can be associated with oxidizing methane at cold seeps. == Types == Types of cold seeps can be distinguished according to the depth, as shallow cold seeps and deep cold seeps. Cold seeps can also be distinguished in detail, as follows: oil/gas seeps gas seeps: methane seeps gas hydrate seeps brine seeps are formed in brine pools pockmarks mud volcanoes == Formation and ecological succession == Cold seeps occur over fissures on the seafloor


id: cold-seep-20260505-1
file: data/en.wikipedia.org/wiki/Cold_seep-1.md
category: reference
title: Cold seep
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cold_seep
date_saved: 2026-05-05T07:34:36.156842+00:00
instance: kb-cron
parent: cold-seep-20260505-0
summary:
=== The Benthic Filter === The organisms living at cold seeps have a large impact on the carbon cycle and on climate. Chemosynthetic organisms, specifically methanogenic (methane-consuming) organisms, prohibit the methane seeping up from beneath the seafloor from being released into the water above. Since methane is such a potent greenhouse gas, methane release could cause global warming when gas hydrate reservoirs destabilized. The consumption of methane by aerobic and anaerobic seafloor life is called "the benthic filter". The first part of this filter is the anaerobic bacteria and archaea underneath the seafloor that consume methane through the anaerobic oxidation of methane (AOM). If the flux of methane flowing through the sediment is too large, and the anaerobic bacteria and archaea are consuming the maximum amount of methane, then the excess methane is consumed by free-floating or symbiotic aerobic bacteria above the sediment at the seafloor. The symbiotic bacteria have been found in organisms such as tube worms and clams living at cold seeps; these organisms provide oxygen to the aerobic bacteria as the bacteria provide energy they obtain from the consumption of methane. Understanding how efficient the benthic filter is can help predict how much methane escapes the seafloor


id: cold-seep-20260505-2
file: data/en.wikipedia.org/wiki/Cold_seep-2.md
category: reference
title: Cold seep
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cold_seep
date_saved: 2026-05-05T07:34:36.156842+00:00
instance: kb-cron
parent: cold-seep-20260505-0
summary:
==== Discoveries ==== The chemosynthetic communities of the Gulf of Mexico have been studied extensively since the 1990s, and communities first discovered on the upper slope are likely the best understood seep communities in the world. The history of the discovery of these remarkable animals has all occurred since the 1980s. Each major discovery was unexpected―from the first hydrothermal vent communities anywhere in the world to the first cold seep communities in the Gulf of Mexico. Communities were discovered in the eastern Gulf of Mexico in 1983 using the crewed submersible DSV Alvin, during a cruise investigating the bottom of the Florida Escarpment in areas of "cold" brine seepage, where they unexpectedly discovered tubeworms and mussels. Two groups fortuitously discovered chemosynthetic communities in the central Gulf of Mexico nearly concurrently in November and December 1984. During investigations in late December on the research vessel R/V Gyre cruise 84-G-12, by Texas A&M University, two bottom trawls were conducted to determine the effects of oil seepage on benthic ecology (until this investigation, all effects of oil seepage were assumed to be detrimental). Trawls unexpectedly recovered extensive collections of chemosynthetic organisms, including tubeworms and clams. a month earlier, LGL Ecological Research Associates was


id: cold-seep-20260505-3
file: data/en.wikipedia.org/wiki/Cold_seep-3.md
category: reference
title: Cold seep
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cold_seep
date_saved: 2026-05-05T07:34:36.156842+00:00
instance: kb-cron
parent: cold-seep-20260505-0
summary:
The widespread nature of Gulf of Mexico chemosynthetic communities was first documented during contracted investigations by the Geological and Environmental Research Group (GERG) of Texas A&M University for the Offshore Operators Committee. This survey remains the most widespread and comprehensive, although numerous additional communities have been documented since that time. Industry exploration for energy reserves in the Gulf of Mexico has also documented numerous new communities through a wide range of depths, including the deepest-known occurrence in the Central Gulf of Mexico in Alaminos Canyon Block 818 at a depth of 2,750 metres (9,020 feet). The occurrence of chemosynthetic organisms dependent on hydrocarbon seepage has been documented in water depths as shallow as 290 metres (950 feet) and as deep as 2,744 metres (9,003 feet). This depth range specifically places chemosynthetic communities in the deepwater region of the Gulf of Mexico, which is defined as water depths greater than 305 metres (1,001 feet). Chemosynthetic communities are not found on the continental shelf, although they do appear in the fossil record in water shallower than 200 metres (660 feet). One theory explaining this is that predation pressure has varied substantially over the time period involved (Callender and Powell 1999). More than


id: cold-seep-20260505-4
file: data/en.wikipedia.org/wiki/Cold_seep-4.md
category: reference
title: Cold seep
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cold_seep
date_saved: 2026-05-05T07:34:36.156842+00:00
instance: kb-cron
parent: cold-seep-20260505-0
summary:
==== Stability ==== According to Sassen (1997) the role of hydrates at chemosynthetic communities has been greatly underestimated. The biological alteration of frozen gas hydrates was first discovered during the MMS study entitled "Stability and Change in Gulf of Mexico Chemosynthetic Communities". It is hypothesized that the dynamics of hydrate alteration could play a major role as a mechanism for regulation of the release of hydrocarbon gases to fuel biogeochemical processes and could also play a substantial role in community stability. Recorded bottom-water temperature excursions of several degrees in some areas such as the Bush Hill site (4–5 °C at 500-metre (1,600-foot) depth) are believed to result in dissociation of hydrates, resulting in an increase in gas fluxes (MacDonald et al., 1994). Although not as destructive as the volcanism at vent sites of the mid-ocean ridges, the dynamics of shallow hydrate formation and movement will clearly affect sessile animals that form part of the seepage barrier. There is potential of a catastrophic event where an entire layer of shallow hydrate could break free of the bottom and considerably affect local communities of chemosynthetic fauna. At deeper depths (>1,000 metres (3,300 feet)), the bottom-water temperature is colder (by approximately 3 °C)


id: cold-seep-20260505-5
file: data/en.wikipedia.org/wiki/Cold_seep-5.md
category: reference
title: Cold seep
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cold_seep
date_saved: 2026-05-05T07:34:36.156842+00:00
instance: kb-cron
parent: cold-seep-20260505-0
summary:
MacDonald et al. (1990) has described four general community types. These are communities dominated by Vestimentiferan tube worms (Lamellibrachia c.f. barhami and Escarpia spp.), mytilid mussels (Seep Mytilid Ia, Ib, and III, and others), vesicomyid clams (Vesicomya cordata and Calyptogena ponderosa), and infaunal lucinid or thyasirid clams (Lucinoma sp. or Thyasira sp.). Bacterial mats are present at all sites visited to date. These faunal groups tend to display distinctive characteristics in terms of how they aggregate, the size of aggregations, the geological and chemical properties of the habitats in which they occur, and, to some degree, the heterotrophic fauna that occur with them. Many of the species found at these cold seep communities in the Gulf of Mexico are new to science and remain undescribed. Individual lamellibrachid tube worms, the longer of two taxa found at seeps, can reach lengths of 3 metres (9.8 feet) and live hundreds of years (Fisher et al., 1997; Bergquist et al., 2000). Growth rates determined from recovered marked tube worms have been variable, ranging from no growth of 13 individuals measured one year to a maximum growth of 9.6 cm/yr (3.8 in/yr) in a Lamellibrachia individual (MacDonald, 2002). Average growth rate was 2.19 cm/yr


id: cold-seep-20260505-6
file: data/en.wikipedia.org/wiki/Cold_seep-6.md
category: reference
title: Cold seep
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cold_seep
date_saved: 2026-05-05T07:34:36.156842+00:00
instance: kb-cron
parent: cold-seep-20260505-0
summary:
Cold-seep communities in the western Atlantic Ocean have also been described from a few dives on mud volcanoes and diapirs between 1,000 and 5,000 m (3,300–16,400 ft) depth in the Barbados accretionary prism area and from the Blake Ridge diapir off North Carolina. More recently, seep communities have been discovered in the eastern Atlantic, on a giant pockmark cluster in the Gulf of Guinea near the Congo deep channel, and also on other pockmarks of the Congo margin, Gabon margin and Nigeria margin and in the Gulf of Cádiz. The occurrence of chemosymbiotic biota in the extensive mud volcano fields of the Gulf of Cádiz was first reported in 2003. The chemosymbiotic bivalves collected from the mud volcanoes of the Gulf of Cadiz were reviewed in 2011. Cold seeps are also known from the Northern Atlantic Ocean, even ranging into the Arctic Ocean, off Canada and Norway. Extensive faunal sampling has been conducted from 400 and 3,300 m (1,300–10,800 ft) in the Atlantic Equatorial Belt from the Gulf of Mexico to the Gulf of Guinea including the Barbados accretionary prism, the Blake Ridge diapir, and in the Eastern Atlantic from the Congo and Gabon margins and the recently explored Nigeria


id: cold-seep-20260505-7
file: data/en.wikipedia.org/wiki/Cold_seep-7.md
category: reference
title: Cold seep
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cold_seep
date_saved: 2026-05-05T07:34:36.156842+00:00
instance: kb-cron
parent: cold-seep-20260505-0
summary:
=== In the Mediterranean === The first biological evidence for reduced environments in the Mediterranean Sea was the presence of Lucinidae and Vesicomyidae bivalve shells cored on the top of the Napoli mud volcano (33°43′52″N 24°40′52″E; "Napoli" is only a name of a seamount. It is located south of Crete), located at 1,900 m deep on the Mediterranean Ridge in the subduction zone of the African Plate. This was followed by the description of a new Lucinidae bivalve species, Lucinoma kazani, associated with bacterial endosymbionts. In the southeastern Mediterranean, communities of polychaetes and bivalves were also found associated with cold seeps and carbonates near Egypt and the Gaza Strip at depths of 500–800 m, but no living fauna was collected. The first in situ observations of extensive living chemosynthetic communities in the eastern Mediterranean Sea prompted cooperation between biologists, geochemists, and geologists. During submersible dives, communities comprising large fields of small bivalves (dead and alive), large siboglinid tube worms, isolated or forming dense aggregations, large sponges, and associated endemic fauna were observed in various cold seep habitats associated with carbonate crusts at 1,700–2,000 m depth. Two mud volcano fields were first explored, one along the Mediterranean Ridge, where most of


id: cold-seep-20260505-8
file: data/en.wikipedia.org/wiki/Cold_seep-8.md
category: reference
title: Cold seep
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cold_seep
date_saved: 2026-05-05T07:34:36.156842+00:00
instance: kb-cron
parent: cold-seep-20260505-0
summary:
==== New Zealand ==== Off the mainland coast of New Zealand, shelf-edge instability is enhanced in some locations by cold seeps of methane-rich fluids that likewise support chemosynthetic faunas and carbonate concretions. Dominant animals are tubeworms of the family Siboglinidae and bivalves of families Vesicomyidae and Mytilidae (Bathymodiolus). Many of its species appear to be endemic. Deep bottom trawling has severely damaged cold seep communities, and those ecosystems are threatened. Cold seeps are found at depths down to 2,000 m, and the topographic and chemical complexity of the habitats are not yet mapped. The scale of new-species discovery in these poorly-studied or unexplored ecosystems is likely to be high. === In the East Pacific === In the deep sea, the COMARGE project has studied the biodiversity patterns along and across the Chilean margin through a complexity of ecosystems such as methane seeps and oxygen minimum zones, reporting that such habitat heterogeneity may influence the biodiversity patterns of the local fauna. Seep fauna include bivalves of families Lucinidae, Thyasiridae, Solemyidae (Acharax sp.), and Vesicomyidae (Calyptogena gallardoi) and polychaetes (Lamellibrachia sp. and two other polychaete species). Furthermore, in these soft reduced sediments below the oxygen minimum zone off the Chilean margin, a


id: cold-seep-20260505-9
file: data/en.wikipedia.org/wiki/Cold_seep-9.md
category: reference
title: Cold seep
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cold_seep
date_saved: 2026-05-05T07:34:36.156842+00:00
instance: kb-cron
parent: cold-seep-20260505-0
summary:
== Environmental impacts == Major threats that cold seep ecosystems and their communities face today are seafloor litter, chemical contaminants, and climate change. Seafloor litter alters the habitat by providing hard substrate where none was available before or by overlying the sediment, thereby inhibiting gas exchange and interfering with organisms on the bottom of the sea. Studies of marine litter in the Mediterranean include surveys of seabed debris on the continental shelf, slope, and bathyal plain. In most studies, plastic items accounted for much of the debris, sometimes as much as 90% or more of the total, owing to their ubiquitous use and poor degradability. Weapons and bombs have also been discarded at sea, and their dumping in open waters contributes to seafloor contamination. Another major threat to the benthic fauna is the presence of lost fishing gear, such as nets and longlines, which contribute to ghost fishing and can damage fragile ecosystems such as cold-water corals. Chemical contaminants such as persistent organic pollutants, toxic metals (e.g., Hg, Cd, Pb, Ni), radioactive compounds, pesticides, herbicides, and pharmaceuticals are also accumulating in deep-sea sediments. Topography (such as canyons) and hydrography (such as cascading events) play a major role in the transportation


id: continental-margin-20260505-0
file: data/en.wikipedia.org/wiki/Continental_margin-0.md
category: reference
title: Continental margin
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Continental_margin
date_saved: 2026-05-05T07:34:37.444285+00:00
instance: kb-cron
parent: continental-margin-20260505-0
summary:
A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. The continental margin consists of three different features: the continental rise, the continental slope, and the continental shelf. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. Continental margins constitute about 28% of the oceanic area. == Subzones == The continental shelf is the relatively shallow water area found in proximity to continents; it is the portion of the continental margin that transitions from the shore out towards the ocean. Continental shelves are believed to make up 7% of the sea floor. The width of continental shelves worldwide varies in the range of 0.03–1500 km. The continental shelf is generally flat, and ends at the shelf break, where there is a drastic increase in slope angle: The mean angle of continental shelves worldwide is 0° 07′, and typically steeper closer to the coastline than it is near the shelf break. At the shelf break begins the continental slope, which can be 1–5 km above the deep-ocean floor. The continental slope often exhibits features called submarine canyons. Submarine canyons often cut into the


id: continental-shelf-20260505-0
file: data/en.wikipedia.org/wiki/Continental_shelf-0.md
category: reference
title: Continental shelf
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Continental_shelf
date_saved: 2026-05-05T07:34:38.658115+00:00
instance: kb-cron
parent: continental-shelf-20260505-0
summary:
A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island is known as an "insular shelf." The continental margin, between the continental shelf and the abyssal plain, comprises a steep continental slope, surrounded by the flatter continental rise, in which sediment from the continent above cascades down the slope and accumulates as a pile of sediment at the base of the slope. Extending as far as 500 km (310 mi) from the slope, it consists of thick sediments deposited by turbidity currents from the shelf and slope. The continental rise's gradient is intermediate between the gradients of the slope and the shelf. Under the United Nations Convention on the Law of the Sea, the name continental shelf was given a legal definition as the stretch of the seabed adjacent to the shores of a particular country to which it belongs. == Topography == The shelf usually ends at a point of increasing slope (called the shelf break). The sea floor below the break is the continental slope.


id: continental-shelf-20260505-1
file: data/en.wikipedia.org/wiki/Continental_shelf-1.md
category: reference
title: Continental shelf
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Continental_shelf
date_saved: 2026-05-05T07:34:38.658115+00:00
instance: kb-cron
parent: continental-shelf-20260505-0
summary:
In shallower water with stronger tides and away from river mouths, tidal turbulence overcomes the stratifying influence of surface heating, and the water column remains well mixed for the entire seasonal cycle. In contrast, in deeper water, the surface heating wins out in summer, to produce seasonal stratification with a warm surface layer overlying the isolated deep water. (The well mixed and seasonally stratifying regimes are separated by persistent features called tidal mixing fronts.) A third regime which links estuaries to shelf seas, Regions of Freshwater Influence (ROFIs), is found where estuaries enter shelf seas, for example in the Liverpool Bay area of the Irish Sea and Rhine Outflow region of the North Sea. Here, stratification can vary on timescales from the semidiurnal tidal cycle through to the springs-neap tidal cycle due to a process known as "tidal straining". While the North Sea and Irish Sea are two of the better studied shelf seas, they are not necessarily representative of all shelf seas as there is a wide variety of behaviours to be found: Indian Ocean shelf seas are dominated by major river systems, including the Ganges and Indus rivers. The shelf seas around New Zealand are complicated because the


id: continental-shelf-20260505-2
file: data/en.wikipedia.org/wiki/Continental_shelf-2.md
category: reference
title: Continental shelf
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Continental_shelf
date_saved: 2026-05-05T07:34:38.658115+00:00
instance: kb-cron
parent: continental-shelf-20260505-0
summary:
== References == Atkinson, Larry P.; Lee, Thomas N.; Blanton, Jackson O.; Chandler, William S. (30 May 1983). "Climatology of the southeastern United States continental shelf waters". Journal of Geophysical Research: Oceans. 88 (C8): 4705–4718. Bibcode:1983JGR....88.4705A. doi:10.1029/JC088iC08p04705. de Haas, Henk; van Weering, Tjeerd C.E; de Stigter, Henko (March 2002). "Organic carbon in shelf seas: sinks or sources, processes and products". Continental Shelf Research. 22 (5): 691–717. Bibcode:2002CSR....22..691D. doi:10.1016/S0278-4343(01)00093-0. "shelf break – geology". Encyclopædia Britannica. Figueiredo, Alberto Garcia; Pacheco, Carlos Eduardo Pereira; de Vasconcelos, Sérgio Cadena; da Silva, Fabiano Tavares (2016). "Continental Shelf Geomorphology and Sedimentology". Geology and Geomorphology: 13–31. doi:10.1016/B978-85-352-8444-7.50009-3. ISBN 9788535284447. Gattuso, Jean-Pierre; Gentili, B.; Duarte, C. M.; Kleypas, J. A.; Middelburg, J. J.; Antoine, D. (2006). "Light availability in the coastal ocean: impact on the distribution of benthic photosynthetic organisms and their contribution to primary production". Biogeosciences. 3 (4). European Geosciences Union: 489–513. Bibcode:2006BGeo....3..489G. doi:10.5194/bg-3-489-2006. hdl:20.500.11937/23744. S2CID 13715554. hal-00330315. Retrieved 1 July 2021. Gross, M. Grant (1972). Oceanography: A View of the Earth. Englewood Cliffs: Prentice-Hall. ISBN 978-0-13-629659-1. Retrieved 12 January 2016. Guihou, K.; Polton, J.; Harle, J.; Wakelin, S.; O'Dea, E.; Holt, J. (January 2018). "Kilometric Scale Modeling of the North West European Shelf Seas: Exploring the


id: continental-shelf-pump-20260505-0
file: data/en.wikipedia.org/wiki/Continental_shelf_pump-0.md
category: reference
title: Continental shelf pump
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Continental_shelf_pump
date_saved: 2026-05-05T07:34:39.905353+00:00
instance: kb-cron
parent: continental-shelf-pump-20260505-0
summary:
In oceanic biogeochemistry, the continental shelf pump is proposed to operate in the shallow waters of the continental shelves, acting as a mechanism to transport carbon (as either dissolved or particulate material) from surface waters to the interior of the adjacent deep ocean. == Overview == Originally formulated by Tsunogai et al. (1999), the pump is believed to occur where the solubility and biological pumps interact with a local hydrography that feeds dense water from the shelf floor into sub-surface (at least subthermocline) waters in the neighbouring deep ocean. Tsunogai et al.'s (1999) original work focused on the East China Sea, and the observation that, averaged over the year, its surface waters represented a sink for carbon dioxide. This observation was combined with others of the distribution of dissolved carbonate and alkalinity and explained as follows : the shallowness of the continental shelf restricts convection of cooling water as a consequence, cooling is greater for continental shelf waters than for neighbouring open ocean waters this leads to the production of relatively cool and dense water on the shelf the cooler waters promote the solubility pump and lead to an increased storage of dissolved inorganic carbon this extra carbon storage is


id: coral-reef-20260505-0
file: data/en.wikipedia.org/wiki/Coral_reef-0.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Coral belongs to the class Anthozoa in the animal phylum Cnidaria, which includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons that support and protect the coral. Most reefs grow best in warm, shallow, clear, sunny, and agitated water. Coral reefs first appeared 485 million years ago, at the dawn of the Early Ordovician, displacing the microbial and sponge reefs of the Cambrian. Sometimes called rainforests of the sea, shallow coral reefs form some of Earth's most diverse ecosystems. They occupy less than 0.1% of the world's ocean area, about half the area of France. Yet, they provide a home for at least 25% of all marine species, including fish, mollusks, worms, crustaceans, echinoderms, sponges, tunicates and other cnidarians. Coral reefs flourish in ocean waters that provide few nutrients. They are most commonly found at shallow depths in tropical waters, but deep water and cold water coral reefs exist on smaller scales in other areas. Shallow tropical coral reefs


id: coral-reef-20260505-1
file: data/en.wikipedia.org/wiki/Coral_reef-1.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
=== Material === As the name implies, coral reefs are made up of coral skeletons from mostly intact coral colonies. As other chemical elements present in corals become incorporated into the calcium carbonate deposits, aragonite is formed. However, shell fragments and the remains of coralline algae such as the green-segmented genus Halimeda can add to the reef's ability to withstand damage from storms and other threats. Such mixtures are visible in structures such as Eniwetok Atoll. === In the geologic past === The times of maximum reef development were in the Middle Cambrian (513–501 Ma), Devonian (416–359 Ma) and Carboniferous (359–299 Ma), owing to extinct order Rugosa corals, and Late Cretaceous (100–66 Ma) and Neogene (23 Ma–present), owing to order Scleractinia corals. Not all reefs in the past were formed by corals: those in the Early Cambrian (542–513 Ma) resulted from calcareous algae and archaeocyathids (small animals with conical shape, probably related to sponges) and in the Late Cretaceous (100–66 Ma), when reefs formed by a group of bivalves called rudists existed; one of the valves formed the main conical structure and the other, much smaller valve acted as a cap. Measurements of the oxygen isotopic composition of the aragonitic


id: coral-reef-20260505-2
file: data/en.wikipedia.org/wiki/Coral_reef-2.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
Atolls or atoll reefs are a more or less circular or continuous barrier reef that extends all the way around a lagoon without a central island. They are usually formed from fringing reefs around volcanic islands. Over time, the island erodes away and sinks below sea level. Atolls may also be formed by the sinking of the seabed or rising of the sea level. A ring of reefs results, which encloses a lagoon. Atolls are numerous in the South Pacific, where they usually occur in mid-ocean, for example, in the Caroline Islands, the Cook Islands, French Polynesia, the Marshall Islands, and Micronesia. Atolls are found in the Indian Ocean, for example, in the Maldives, the Chagos Islands, the Seychelles, and around Cocos Island. The entire Maldives consists of 26 atolls. === Other reef types or variants === Apron reef – short reef resembling a fringing reef, but more sloped; extending out and downward from a point or peninsular shore. The initial stage of a fringing reef. Bank reef – isolated, flat-topped reef larger than a patch reef and usually on mid-shelf regions and linear or semi-circular in shape; a type of platform reef. Patch reef – common, isolated, comparatively small


id: coral-reef-20260505-3
file: data/en.wikipedia.org/wiki/Coral_reef-3.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
The reef surface is the shallowest part of the reef. It is subject to surge and tides. When waves pass over shallow areas, they shoal, as shown in the adjacent diagram. This means the water is often agitated. These are the precise conditions under which corals flourish. The light is sufficient for photosynthesis by the symbiotic zooxanthellae, and agitated water brings plankton to feed the coral. The off-reef floor is the shallow sea floor surrounding a reef. This zone occurs next to reefs on continental shelves. Reefs around tropical islands and atolls drop abruptly to great depths and do not have such a floor. Usually sandy, the floor often supports seagrass meadows, which are important foraging areas for reef fish. The reef drop-off is, for its first 50 m, habitat for reef fish who find shelter on the cliff face and plankton in the water nearby. The drop-off zone primarily occurs around oceanic islands and atolls. The reef face is the zone above the reef floor or the reef drop-off. This zone is often the reef's most diverse area. Coral and calcareous algae provide complex habitats and areas that offer protection, such as cracks and crevices. Invertebrates and epiphytic algae


id: coral-reef-20260505-4
file: data/en.wikipedia.org/wiki/Coral_reef-4.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
The Great Barrier Reef—largest, comprising over 2,900 individual reefs and 900 islands stretching for over 2,600 kilometers (1,600 mi) off Queensland, Australia The Mesoamerican Barrier Reef System—second largest, stretching 1,000 kilometers (620 mi) from Isla Contoy at the tip of the Yucatán Peninsula down to the Bay Islands of Honduras The New Caledonia Barrier Reef—second longest double barrier reef, covering 1,500 kilometers (930 mi) The Andros, Bahamas Barrier Reef—third largest, following the east coast of Andros Island, Bahamas, between Andros and Nassau The Red Sea—includes 6,000-year-old fringing reefs located along a 2,000 km (1,240 mi) coastline The Florida Reef Tract—largest continental US reef and the third-largest coral barrier reef, extends from Soldier Key, located in Biscayne Bay, to the Dry Tortugas in the Gulf of Mexico Blake Plateau has the world's largest known deep-water coral reef, comprising a 6.4 million-acre reef that stretches from Miami to Charleston, S. C. Its discovery was announced in January 2024. Pulley Ridge—deepest photosynthetic coral reef, Florida Numerous reefs around the Maldives The Philippines coral reef area, the second-largest in Southeast Asia, is estimated at 26,000 square kilometres. They are populated by over 900 reef fish species and 400 scleractinian coral species, 12 of which


id: coral-reef-20260505-5
file: data/en.wikipedia.org/wiki/Coral_reef-5.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
Corals reproduce both sexually and asexually. An individual polyp uses both reproductive modes within its lifetime. Corals reproduce sexually by either internal or external fertilization. The reproductive cells are found on the mesenteries, membranes that radiate inward from the layer of tissue that lines the stomach cavity. Some mature adult corals are hermaphroditic; others are exclusively male or female. A few species change sex as they grow. Internally fertilized eggs develop in the polyp for a period ranging from days to weeks. Subsequent development produces a tiny larva, known as a planula. Externally fertilized eggs develop during synchronized spawning. Polyps across a reef simultaneously release eggs and sperm into the water en masse. Spawn disperse over a large area. The timing of spawning depends on the time of year, water temperature, and tidal and lunar cycles. Spawning is most successful when there is little variation between high and low tide. The less water movement, the better the chance for fertilization. The release of eggs or planula usually occurs at night and is sometimes in phase with the lunar cycle (three to six days after a full moon). The period from release to settlement lasts only a few days, but some


id: coral-reef-20260505-6
file: data/en.wikipedia.org/wiki/Coral_reef-6.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
In The Structure and Distribution of Coral Reefs, published in 1842, Darwin described how coral reefs were found in some tropical areas but not others, with no obvious cause. The largest and strongest corals grew in parts of the reef exposed to the most violent surf, and corals were weakened or absent where loose sediment accumulated. Tropical waters contain few nutrients yet a coral reef can flourish like an "oasis in the desert". This has given rise to the ecosystem conundrum, sometimes called "Darwin's paradox": "How can such high production flourish in such nutrient poor conditions?" Coral reefs support over one-quarter of all marine species. This diversity results in complex food webs, with large predator fish eating smaller forage fish, which eat yet smaller zooplankton, and so on. However, all food webs ultimately depend on plants, which serve as primary producers. Coral reefs typically produce 5–10 grams of carbon per square meter per day (gC·m−2·day−1) biomass. One reason for the unusual clarity of tropical waters is their nutrient deficiency and drifting plankton. Further, the sun shines year-round in the tropics, warming the surface layer, making it less dense than subsurface layers. The warmer water is separated from deeper, cooler water


id: coral-reef-20260505-7
file: data/en.wikipedia.org/wiki/Coral_reef-7.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
== Biodiversity == Coral reefs form some of the world's most productive ecosystems, providing complex and varied marine habitats that support a wide range of organisms. Fringing reefs just below low tide level have a mutually beneficial relationship with mangrove forests at high tide level and sea grass meadows in between: the reefs protect the mangroves and seagrass from strong currents and waves that would damage them or erode the sediments in which they are rooted, while the mangroves and sea grass protect the coral from large influxes of silt, fresh water and pollutants. This level of environmental variety benefits many coral reef animals, which, for example, may feed on seagrass and use the reefs for protection or breeding. Reefs are home to a variety of animals, including fish, seabirds, sponges, cnidarians (which includes some types of corals and jellyfish), worms, crustaceans (including shrimp, cleaner shrimp, spiny lobsters and crabs), mollusks (including cephalopods), echinoderms (including starfish, sea urchins and sea cucumbers), sea squirts, sea turtles and sea snakes. Aside from humans, mammals are rare on coral reefs, with visiting cetaceans such as dolphins being the main exception. A few species feed directly on corals, while others graze on algae on


id: coral-reef-20260505-8
file: data/en.wikipedia.org/wiki/Coral_reef-8.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
== Ecosystem services == Coral reefs deliver ecosystem services to tourism, fisheries, and coastline protection. The global economic value of coral reefs has been estimated to be between US$29.8 billion and $375 billion per year. About 500 million people benefit from ecosystem services provided by coral reefs. The economic cost of destroying one square kilometre of coral reef over 25 years has been estimated at between $137,000 and $1,200,000. To improve the management of coastal coral reefs, the World Resources Institute (WRI) developed and published tools to calculate the value of coral reef-related tourism, shoreline protection, and fisheries, partnering with five Caribbean countries. As of April 2011, published working papers covered St. Lucia, Tobago, Belize, and the Dominican Republic. The WRI was "making sure that the study results support improved coastal policies and management planning". The Belize study estimated the value of reef and mangrove services at $395–559 million annually. Bermuda's coral reefs provide economic benefits to the Island worth, on average, $722 million per year, based on six key ecosystem services, according to Sarkis et al. (2010). === Shoreline protection === Coral reefs protect shorelines by absorbing wave energy, and many small islands would not exist without reefs. Coral


id: coral-reef-20260505-9
file: data/en.wikipedia.org/wiki/Coral_reef-9.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
Marine protected areas (MPAs) are areas designated because they provide various kinds of protection to ocean and/or estuarine areas. They are intended to promote responsible fishery management and habitat protection. MPAs can also encompass social and biological objectives, including reef restoration, aesthetics, biodiversity, and economic benefits. The effectiveness of MPAs is still debated. For example, a study investigating the success of a small number of MPAs in Indonesia, the Philippines, and Papua New Guinea found no significant differences between the MPAs and unprotected sites. Furthermore, in some cases they can generate local conflict, due to a lack of community participation, clashing views of the government and fisheries, effectiveness of the area and funding. In some situations, as in the Phoenix Islands Protected Area, MPAs provide revenue to locals. The level of income provided is similar to the income they would have generated without controls. Overall, it appears the MPAs can protect local coral reefs, but that clear management and sufficient funds are required. The Caribbean Coral Reefs – Status Report 1970–2012 states that coral decline may be reduced or even reversed. For this, overfishing needs to be stopped, especially fishing on species key to coral reefs, such as parrotfish. Direct


id: coral-reef-20260505-10
file: data/en.wikipedia.org/wiki/Coral_reef-10.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
Coral gardens take advantage of a coral's natural ability to fragment and continue to grow if the fragments can anchor themselves onto new substrates. This method was first tested by Baruch Rinkevich in 1995 which found success at the time. By today's standards, coral farming has evolved into various forms, but it still aims to cultivate corals. Consequently, coral farming quickly replaced previously used transplantation methods, which involved physically moving sections or entire coral colonies to a new area. Transplantation has seen success in the past, and decades of experiments have led to a high success and survival rate. However, this method still requires removing corals from existing reefs. Given the current state of reefs, this method should generally be avoided if possible. Saving healthy corals from eroding substrates or reefs doomed to collapse could be a significant advantage of using transplantation. Coral gardens generally take on safe forms, no matter where you go. It begins with the establishment of a nursery where operators can observe and care for coral fragments. It goes without saying that nurseries should be established in areas that are going to maximize growth and minimize mortality. Floating offshore coral trees or even aquariums are possible


id: coral-reef-20260505-11
file: data/en.wikipedia.org/wiki/Coral_reef-11.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
=== Heat-tolerant symbionts === Another possibility for coral restoration is gene therapy: inoculating coral with genetically modified bacteria, or naturally occurring heat-tolerant varieties of coral symbiotes, may make it possible to grow corals that are more resistant to climate change and other threats. Warming oceans are forcing corals to adapt to unprecedented temperatures. Those that do not have a tolerance for the elevated temperatures experience coral bleaching and eventually mortality. There is already research aimed at creating genetically modified corals that can withstand a warming ocean. Madeleine J. H. van Oppen, James K. Oliver, Hollie M. Putnam, and Ruth D. Gates described four levels of human intervention for genetically modifying corals, each increasing in intensity. These methods focus on altering the genetics of the zooxanthellae within coral rather than the alternative. The first method is to induce acclimatization of the first generation of corals. The idea is that when adult and offspring corals are exposed to stressors, the zooxanthellae will gain a mutation. This method is based primarily on the chance that the zooxanthellae will acquire the specific trait that will enable them to better survive in warmer waters. The second method focuses on identifying the different kinds of zooxanthellae


id: coral-reef-20260505-12
file: data/en.wikipedia.org/wiki/Coral_reef-12.md
category: reference
title: Coral reef
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coral_reef
date_saved: 2026-05-05T07:34:41.179437+00:00
instance: kb-cron
parent: coral-reef-20260505-0
summary:
Deep-water coral — Corals living in the cold waters of deeper, darker parts of the oceans Mesophotic coral reef — Corals living in the mesopelagic or twilight zone Fossil Coral Reef – National Natural Landmark in Le Roy, New York Census of Coral Reefs – Field project of the Census of Marine Life Catlin Seaview Survey Coral reef organizations Sponge reef – Reefs produced by sea sponges Pseudo-atoll – Island that encircles a lagoon == References == == Further references == Coral Reef Protection: What Are Coral Reefs?. US EPA. UNEP. 2004. Coral Reefs in the South China Sea. UNEP/GEF/SCS Technical Publication No. 2. UNEP. 2007. Coral Reefs Demonstration Sites in the South China Sea. UNEP/GEF/SCS Technical Publication No. 5. UNEP, 2007. National Reports on Coral Reefs in the Coastal Waters of the South China Sea. UNEP/GEF/SCS Technical Publication No. 11. == External links == "Coral Reef Factsheet". Waitt Institute. Archived from the original on 9 June 2015. Retrieved 8 June 2015. Corals and Coral Reefs overview at the Smithsonian Ocean Portal About Corals Archived 26 December 2013 at the Wayback Machine Australian Institute of Marine Science. International Coral Reef Initiative Moorea Coral Reef Long Term Ecological Research Site (US


id: cyclic-steps-20260505-0
file: data/en.wikipedia.org/wiki/Cyclic_steps-0.md
category: reference
title: Cyclic steps
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cyclic_steps
date_saved: 2026-05-05T07:34:42.484931+00:00
instance: kb-cron
parent: cyclic-steps-20260505-0
summary:
Cyclic steps are rhythmic bedforms associated with Froude super-critical flow instability. They are a type of sediment wave, and are created when supercritical sediment-laden water (turbidity currents) travels downslope through sediment beds. Each "step" has a steep drop, and together they tend to migrate upstream. On the ocean floor, this phenomenon was first shown to be possible in 2006, although it was observed in open-channel flows over a decade earlier. Geological features appearing to be submarine cyclic steps have been detected in the northern lowlands of Mars in the Aeolis Mensae region, providing evidence of an ancient Martian ocean. == Formation == There are many parameters which govern the formation of cyclic steps: bed slope, bed porosity, erosion resistance, sediment concentration, and flow rate all play a role. Tilting flumes can be used to create cyclic steps in subaerial laboratory conditions, provided the Froude number is high enough. If the Froude number is lower than required, then antidunes will form instead. Additionally, if the sediment is too fine, then chute-and-pool features will form. In subaqueous conditions, most of the work has traditionally been in building mathematical, rather than physical, models of cyclic step formation. However, cyclic steps have attracted increasing


id: dark-oxygen-20260505-0
file: data/en.wikipedia.org/wiki/Dark_oxygen-0.md
category: reference
title: Dark oxygen
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dark_oxygen
date_saved: 2026-05-05T07:34:43.702448+00:00
instance: kb-cron
parent: dark-oxygen-20260505-0
summary:
Dark oxygen production refers to the generation of molecular oxygen (O2) through processes that do not involve light-dependent oxygenic photosynthesis. The name therefore uses a different sense of 'dark' than that used in the phrase "biological dark matter" (for example) which indicates obscurity to scientific assessment rather than the photometric meaning. While the majority of Earth's oxygen is produced by plants and photosynthetically active microorganisms via photosynthesis, dark oxygen production occurs via a variety of abiotic and biotic processes and may support aerobic metabolism in dark, anoxic environments. The theory for dark oxygen production by manganese nodules on the abyssal seafloor is controversial, with scientists disagreeing about its validity. == Abiotic production == Abiotic production of dark oxygen can occur through several mechanisms, such as: Water radiolysis: This process typically takes place in dark geological ecosystems, such as aquifers, where the decay of radioactive elements in surrounding rock leads to the breakdown of water molecules, producing O2. Oxidation of surface-bound radicals: On silicon-bearing minerals like quartz, surface-bound radicals can undergo oxidation, contributing to O2 production. In addition to direct O2 formation, these processes often produce reactive oxygen species (ROS), such as hydroxyl radicals (OH•), superoxide (O2•-), and hydrogen peroxide (H2O2).


id: dead-zone-ecology-20260505-0
file: data/en.wikipedia.org/wiki/Dead_zone_(ecology)-0.md
category: reference
title: Dead zone (ecology)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_zone_(ecology)
date_saved: 2026-05-05T07:34:44.955451+00:00
instance: kb-cron
parent: dead-zone-ecology-20260505-0
summary:
Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes. Hypoxia occurs when dissolved oxygen (DO) concentration falls to or below 2 mg of O2/liter. When a body of water experiences hypoxic conditions, aquatic flora and fauna begin to change behavior in order to reach sections of water with higher oxygen levels. Once DO declines below 0.5 mg O2/liter in a body of water, mass mortality occurs. With such a low concentration of DO, these bodies of water fail to support the aquatic life living there. Historically, many of these sites were naturally occurring. However, in the 1970s, oceanographers began noting increased instances and expanses of dead zones. These occur near inhabited coastlines, where aquatic life is most concentrated. Coastal regions, such as the Baltic Sea, the northern Gulf of Mexico, and the Chesapeake Bay, as well as large enclosed water bodies like Lake Erie, have been affected by deoxygenation due to eutrophication. Excess nutrients are put into these systems by rivers, ultimately from urban and agricultural runoff and exacerbated by deforestation. These nutrients lead to high productivity that produces organic material that sinks to the bottom and is respired. The respiration of that organic material uses


id: dead-zone-ecology-20260505-1
file: data/en.wikipedia.org/wiki/Dead_zone_(ecology)-1.md
category: reference
title: Dead zone (ecology)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_zone_(ecology)
date_saved: 2026-05-05T07:34:44.955451+00:00
instance: kb-cron
parent: dead-zone-ecology-20260505-0
summary:
Limnologist David Schindler, whose research at the Experimental Lakes Area led to the banning of harmful phosphates in detergents, warned about algal blooms and dead zones, "The fish-killing blooms that devastated the Great Lakes in the 1960s and 1970s haven't gone away; they've moved west into an arid world in which people, industry, and agriculture are increasingly taxing the quality of what little freshwater there is to be had here....This isn't just a prairie problem. Global expansion of dead zones caused by algal blooms is rising rapidly." The major groups of algae are cyanobacteria, green algae, dinoflagellates, coccolithophores and diatom algae. An increase in the input of nitrogen and phosphorus generally causes cyanobacteria to bloom. Other algae are consumed and thus do not accumulate to the same extent as cyanobacteria. Cyanobacteria are not good food for zooplankton and fish and hence accumulate in water, die, and then decompose. The bacterial degradation of their biomass consumes the oxygen in the water, thereby creating the state of hypoxia. Dead zones can be caused by natural and by anthropogenic factors. Natural causes include coastal upwelling, changes in wind, and water circulation patterns. Other environmental factors that determine the occurrence or intensity of a


id: dead-zone-ecology-20260505-2
file: data/en.wikipedia.org/wiki/Dead_zone_(ecology)-2.md
category: reference
title: Dead zone (ecology)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_zone_(ecology)
date_saved: 2026-05-05T07:34:44.955451+00:00
instance: kb-cron
parent: dead-zone-ecology-20260505-0
summary:
The most notable effects of eutrophication are vegetal blooms, sometimes toxic, loss of biodiversity and anoxia, which can lead to the massive death of aquatic organisms. Due to the hypoxic conditions present in dead zones, marine life within these areas tends to be scarce. Most fish and motile organisms tend to emigrate out of the zone as oxygen concentrations fall, and benthic populations may experience severe losses when oxygen concentrations are below 0.5 mg l−1 O2. In severe anoxic conditions, microbial life may experience dramatic shifts in community identity as well, resulting in an increased abundance of anaerobic organisms as aerobic microbes decrease in number and switch energy sources for oxidation such as nitrate, sulfate, or iron reduction. Sulfur reduction is a particular concern as hydrogen sulfide is toxic and stresses most organisms within the zone further, exacerbating mortality risks. Low oxygen levels can have severe effects on survivability of organisms inside the area while above lethal anoxic conditions. Studies conducted along the Gulf Coast of North America have shown hypoxic conditions lead to reduction of reproductive rates and growth rates in a variety of organisms including fish and benthic invertebrates. Organisms able to leave the area typically do so


id: dead-zone-ecology-20260505-3
file: data/en.wikipedia.org/wiki/Dead_zone_(ecology)-3.md
category: reference
title: Dead zone (ecology)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_zone_(ecology)
date_saved: 2026-05-05T07:34:44.955451+00:00
instance: kb-cron
parent: dead-zone-ecology-20260505-0
summary:
=== Jellyfish blooms === Despite most other life forms being killed by the lack of oxygen, jellyfish can thrive and are sometimes present in dead zones in vast numbers. Jellyfish blooms produce large quantities of mucus, leading to major changes in food webs in the ocean since few organisms feed on them. The organic carbon in mucus is metabolized by bacteria which return it to the atmosphere in the form of carbon dioxide in what has been termed a "jelly carbon shunt". The potential worsening of jellyfish blooms as a result of human activities has driven new research into the influence of dead zones on jelly populations. The primary concern is the potential for dead zones to serve as breeding grounds for jelly populations as a result of the hypoxic conditions driving away competition for resources and common predators of jellyfish. The increased population of jellyfish could have high commercial costs with loss of fisheries, destruction and contamination of trawling nets and fishing vessels, and lowered tourism revenue in coastal systems. === Seagrass beds === Globally, seagrass has been declining rapidly. It is estimated that 21% of the 71 known seagrass species have decreasing population trends and 11% of those


id: dead-zone-ecology-20260505-4
file: data/en.wikipedia.org/wiki/Dead_zone_(ecology)-4.md
category: reference
title: Dead zone (ecology)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_zone_(ecology)
date_saved: 2026-05-05T07:34:44.955451+00:00
instance: kb-cron
parent: dead-zone-ecology-20260505-0
summary:
Researchers from Baltic Nest Institute published in one of PNAS issues reports that the dead zones in the Baltic Sea have grown from approximately 5,000 km2 to more than 60,000 km2 in recent years. Some of the causes behind the elevated increase of dead zones can be attributed to the use of fertilizers, large animal farms, the burning of fossil fuels, and effluents from municipal wastewater treatment plants. With its massive size, the Baltic Sea is best analyzed in sub-areas rather than as a whole. In a paper published in 2004, researchers specifically divided the Baltic Sea into 9 sub-areas, each having its own specific characteristics. The 9 sub-areas are discerned as follows: Gulf of Bothnia, Archipelago region, Gulf of Finland, Gulf of Riga, Gulf of Gdansk, Swedish East-coast, Central Baltic, Belt Sea region, and Kattegat. Each sub-area has responded differently to nutrient additions and eutrophication; however, there are a few general patterns and measures for the Baltic Sea as a whole. As the researchers Rönnberg and Bonsdorff state, "Irrespective of the area-specific effects of the increased loads of nutrients to the Baltic Sea, the sources are more or less similar in the whole region. The extent and the severity


id: dead-zone-ecology-20260505-5
file: data/en.wikipedia.org/wiki/Dead_zone_(ecology)-5.md
category: reference
title: Dead zone (ecology)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_zone_(ecology)
date_saved: 2026-05-05T07:34:44.955451+00:00
instance: kb-cron
parent: dead-zone-ecology-20260505-0
summary:
=== Lower St. Lawrence Estuary === A dead zone exists in the Lower St. Lawrence River area from east the Saguenay River to east of Baie Comeau, greatest at depths over 275 metres (902 ft) and noticed since the 1930s. The main concern for Canadian scientists is the impact on fish found in the area. === Oregon === There is a hypoxic zone covering the coasts of Oregon and Washington that reached peak size in 2006 at an area of over 1,158 square miles. Strong surface winds between April and September cause frequent upwelling that results in an increase of algae blooms, rendering the hypoxia a seasonal occurrence. The upwelling has contributed to lower temperatures within the zone. The dead zone has resulted in sea organisms such as crabs and fish relocating and an interference with commercial fishing. Organisms that cannot relocate have been found to suffocate, leaving them useless for fishermen. In 2009, one scientist described "thousands and thousands" of suffocated, crabs, worms, and sea stars along the seafloor of the hypoxic zone. In 2021, 1.9 million dollars were put into monitoring and continuing to study the hypoxic conditions in the area that the dead zone occurs in. ===


id: dead-zone-ecology-20260505-6
file: data/en.wikipedia.org/wiki/Dead_zone_(ecology)-6.md
category: reference
title: Dead zone (ecology)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_zone_(ecology)
date_saved: 2026-05-05T07:34:44.955451+00:00
instance: kb-cron
parent: dead-zone-ecology-20260505-0
summary:
==== Economic impact ==== Some assert that the dead zone threatens lucrative commercial and recreational fisheries in the Gulf of Mexico. "In 2009, the dockside value of commercial fisheries in the Gulf was $629 million. Nearly three million recreational fishers further contributed about $10 billion to the Gulf economy, taking 22 million fishing trips." The seafood production is not only hurting states located on the Gulf of Mexico but the U.S. as a whole. It is reported that the Gulf of Mexico dead zone is costing the U.S. seafood and tourism industries about $82 million a year. Louisiana is ranked second in seafood production behind Alaska, and this impact can be devastating for the nations seafood production since the Gulf of Mexico sources 40% of the nations seafood. Scientists are not in universal agreement that nutrient loading has a negative impact on fisheries. Grimes makes a case that nutrient loading enhances the fisheries in the Gulf of Mexico. Courtney et al. hypothesize that nutrient loading may have contributed to the increases in red snapper in the northern and western Gulf of Mexico. In 2017, Tulane University offered a $1 million challenge grant for growing crops with less fertilizer. ==== History


id: dead-zone-ecology-20260505-7
file: data/en.wikipedia.org/wiki/Dead_zone_(ecology)-7.md
category: reference
title: Dead zone (ecology)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_zone_(ecology)
date_saved: 2026-05-05T07:34:44.955451+00:00
instance: kb-cron
parent: dead-zone-ecology-20260505-0
summary:
== Prediction and Use of AI for Dead Zones == Dead zones are hard to predict since they use multiple environmental factors. They use nutrient runoff, rainfall, water temperature, and dissolved oxygen levels. Due to this, traditional modeling uses field sampling and satellite observations in order to see major changes. Though this does not measure rapid change, it won't be able to see complete coverage of major areas. Due to this issue, there has been research using artificial intelligence (AI) and machine learning models to increase prediction accuracy and areas that are at risk. This can help see what areas risk of hypoxia before it develops. AI can examine large environmental databases to recognize patters associated with dead zone formations. Machine learning algorithms process information like nitrogen and phosphorus concentrations, precipitation rates, and more, to estimate where low oxygen conditions occur and when. These systems come in handy when monitoring data are incomplete or unavailable allowing researchers to estimate missing data and improve prediction rates. Researchers at Louisiana state University have developed AI-based tools to predict nutrient pollution in watersheds connected to Gulf of Mexico. These tools use machine learning to estimate nutrient runoff from rivers and agriculture land. This


id: dead-zone-ecology-20260505-8
file: data/en.wikipedia.org/wiki/Dead_zone_(ecology)-8.md
category: reference
title: Dead zone (ecology)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_zone_(ecology)
date_saved: 2026-05-05T07:34:44.955451+00:00
instance: kb-cron
parent: dead-zone-ecology-20260505-0
summary:
== Biotechnology Application == There are some options that can aid in the reversal process of a dead zone and eventual recovery of water quality and benthic communities through applied biotechnology methodology if a given management project can apply it if the conditions of a dead-zone fit within the criteria. One of the more natural options is established filter feeding species within a marine community that are nearby a impacted ecological area transitioned into a dead zone that can then spread and possibly establish a population there in which recovery time can vary as they filter out access nitrogen and phosphorus. Given that many filter feeding species have different tolerance levels due to the extreme hypoxic conditions, it can be determined through research of how various species respond behaviorally to those specific conditions and deduce the most appropriate species based on a dead-zone of interest to recover. An 8-day study was done on eastern oysters (Crassostrea virginica) and soft-shell clams (Mya arenaria) to assess their reactions to hypoxic and heatwave conditions. While this study was meant for establishing an understanding of behavioral patterns in warming conditions for filter-feeding species, this type of approach can be conducted on other filter-feeding species


id: dead-zone-ecology-20260505-9
file: data/en.wikipedia.org/wiki/Dead_zone_(ecology)-9.md
category: reference
title: Dead zone (ecology)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_zone_(ecology)
date_saved: 2026-05-05T07:34:44.955451+00:00
instance: kb-cron
parent: dead-zone-ecology-20260505-0
summary:
== Further reading == Growing 'dead zone' Confirmed by Underwater Robots in the Gulf of Oman, phys.org, April 2018 Hendy, Ian (August 2017), Gulf of Mexico 'dead zone' is already a disaster – but it could get worse, The Conversation Bryant, Lee (April 2015), Ocean 'dead zones' are spreading – and that spells disaster for fish, The Conversation Deprecated link at archive.today (archived January 29, 2013) Suzie Greenhalgh and Amanda Sauer (WRI), "Awakening the 'Dead Zone': An investment for agriculture, water quality, and climate change" 2003 Reyes Tirado (July 2008) Dead Zones: How Agricultural Fertilizers are Killing our Rivers, Lakes and Oceans. Greenpeace publications. See also: "Dead Zones: How Agricultural Fertilizers are Killing our Rivers, Lakes and Oceans". Greenpeace Canada. July 7, 2008. Archived from the original on September 8, 2010. Retrieved August 3, 2010. MSNBC report on dead zones, March 29, 2004 Joel Achenbach, "A 'Dead Zone' in The Gulf of Mexico: Scientists Say Area That Cannot Support Some Marine Life Is Near Record Size", The Washington Post, July 31, 2008 Joel Achenbach, "'Dead Zones' Appear In Waters Worldwide: New Study Estimates More Than 400", The Washington Post, August 15, 2008 == External links == Louisiana Universities Marine Consortium


id: deep-sea-20260505-0
file: data/en.wikipedia.org/wiki/Deep_sea-0.md
category: reference
title: Deep sea
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep_sea
date_saved: 2026-05-05T07:34:46.246452+00:00
instance: kb-cron
parent: deep-sea-20260505-0
summary:
The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 m (660 ft) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combination of low temperatures, darkness, and high pressure. The deep sea is considered the least explored Earth biome as the extreme conditions make the environment difficult to access and explore. Organisms living within the deep sea have a variety of adaptations to survive in these conditions. Organisms can survive in the deep sea through a number of feeding methods including scavenging, predation and filtration, with a number of organisms surviving by feeding on marine snow. Marine snow is organic material that has fallen from upper waters into the deep sea. In 1960, the bathyscaphe Trieste descended to the bottom of the Mariana Trench near Guam, at 10,911 m (35,797 ft; 6.780 mi), the deepest known spot in any ocean. If Mount Everest (8,848 m or 29,029 ft or 5.498 mi) were submerged there, its peak would be more than 2 km (1.2 mi) beneath the surface. After the Trieste was retired, the Japanese remote-operated vehicle (ROV) Kaikō was


id: deep-sea-20260505-1
file: data/en.wikipedia.org/wiki/Deep_sea-1.md
category: reference
title: Deep sea
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep_sea
date_saved: 2026-05-05T07:34:46.246452+00:00
instance: kb-cron
parent: deep-sea-20260505-0
summary:
Regions below the epipelagic are divided into further zones, beginning with the bathyal zone (also considered the continental slope) which spans from 200 to 3,000 meters (660 to 9,840 ft) below sea level and is essentially transitional, containing elements from both the shelf above and the abyss below. Below this zone, the deep sea consists of the abyssal zone (ocean depth between 3–6 km; 1.9–3.7 mi) and the hadal zone (6–11 km; 3.7–6.8 mi). Food consists of falling organic matter known as 'marine snow' and carcasses derived from the productive zone above, and is scarce both in terms of spatial and temporal distribution. Instead of relying on gas for their buoyancy, many deep-sea species have jelly-like flesh consisting mostly of glycosaminoglycans, which provides them with very low density. It is also common among deep water squid to combine the gelatinous tissue with a flotation chamber filled with a coelomic fluid made up of the metabolic waste product ammonium chloride, which is lighter than the surrounding water. The midwater fish have special adaptations to cope with these conditions—they are small, usually being under 25 centimetres (10 in); they have slow metabolisms and unspecialized diets, preferring to sit and wait for food


id: deep-sea-20260505-2
file: data/en.wikipedia.org/wiki/Deep_sea-2.md
category: reference
title: Deep sea
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep_sea
date_saved: 2026-05-05T07:34:46.246452+00:00
instance: kb-cron
parent: deep-sea-20260505-0
summary:
=== Adaptation to hydrostatic pressure === Deep-sea fish have different adaptations in their proteins, anatomical structures, and metabolic systems to survive in the Deep sea, where the inhabitants have to withstand great amount of hydrostatic pressure. While other factors like food availability and predator avoidance are important, the deep-sea organisms must have the ability to maintain well-regulated metabolic system in the face of high pressures. In order to adjust for the extreme environment, these organisms have developed unique characteristics. Proteins are affected greatly by the elevated hydrostatic pressure, as they undergo changes in water organization during hydration and dehydration reactions of the binding events. This is due to the fact that most enzyme-ligand interactions form through charged or polar non-charge interactions. Because hydrostatic pressure affects both protein folding and assembly and enzymatic activity, the deep sea species must undergo physiological and structural adaptations to preserve protein functionality against pressure. Actin is a protein that is essential for different cellular functions. The α-actin serves as a main component for muscle fiber, and it is highly conserved across numerous different species. Some Deep-sea fish developed pressure tolerance through the change in mechanism of their α-actin. In some species that live in depths


id: deep-sea-fish-20260505-0
file: data/en.wikipedia.org/wiki/Deep-sea_fish-0.md
category: reference
title: Deep-sea fish
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep-sea_fish
date_saved: 2026-05-05T07:34:47.616452+00:00
instance: kb-cron
parent: deep-sea-fish-20260505-0
summary:
Deep-sea fish are fish that live in the darkness below the sunlit surface waters, that is below the epipelagic or photic zone of the sea. The lanternfish is, by far, the most common deep-sea fish. Other deep-sea fishes include the flashlight fish, cookiecutter shark, bristlemouths, anglerfish, viperfish, and some species of eelpout. Only about 2% of known marine species inhabit the pelagic environment. This means that they live in the water column as opposed to the benthic organisms that live in or on the sea floor. Deep-sea organisms generally inhabit bathypelagic (1–4 km; 0.62–2.49 mi deep) and abyssopelagic (4–6 km; 2.5–3.7 mi deep) zones. However, characteristics of deep-sea organisms, such as bioluminescence can be seen in the mesopelagic (200–1,000 m; 660–3,280 ft deep) zone as well. The mesopelagic zone is the disphotic zone, meaning light there is minimal but still measurable. The oxygen minimum layer exists somewhere between a depth of 700 and 1,000 metres (2,300 and 3,300 ft) depending on the place in the ocean. This area is also where nutrients are most abundant. The bathypelagic and abyssopelagic zones are aphotic, meaning that no light penetrates this area of the ocean. These zones make up about 75% of the


id: deep-sea-fish-20260505-1
file: data/en.wikipedia.org/wiki/Deep-sea_fish-1.md
category: reference
title: Deep-sea fish
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep-sea_fish
date_saved: 2026-05-05T07:34:47.616452+00:00
instance: kb-cron
parent: deep-sea-fish-20260505-0
summary:
In the deep ocean, the waters extend far below the epipelagic zone, and support very different types of pelagic fishes adapted to living in these deeper zones. In deep water, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. Its origin lies in activities within the productive photic zone. Marine snow includes dead or dying plankton, protists (diatoms), fecal matter, sand, soot and other inorganic dust. The "snowflakes" grow over time and may reach several centimetres in diameter, travelling for weeks before reaching the ocean floor. However, most organic components of marine snow are consumed by microbes, zooplankton and other filter-feeding animals within the first 1,000 metres (3,300 ft) of their journey, that is, within the epipelagic zone. In this way, marine snow may be considered the foundation of deep-sea mesopelagic and benthic ecosystems: as sunlight cannot reach them, deep-sea organisms rely heavily on marine snow as an energy source. Since there is no light in the deep sea (aphotic), there is a lack of primary producers. Therefore, most organisms in the bathypelagic rely on the marine snow from regions higher in the vertical column. Some deep-sea pelagic groups, such


id: deep-sea-fish-20260505-2
file: data/en.wikipedia.org/wiki/Deep-sea_fish-2.md
category: reference
title: Deep-sea fish
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep-sea_fish
date_saved: 2026-05-05T07:34:47.616452+00:00
instance: kb-cron
parent: deep-sea-fish-20260505-0
summary:
The fish of the deep-sea have evolved various adaptations to survive in this region. Since many of these fish live in regions where there is no natural illumination, they cannot rely solely on their eyesight for locating prey and mates and avoiding predators; deep-sea fish have evolved appropriately to the extreme sub-photic region in which they live. Many of these organisms are blind and rely on their other senses, such as sensitivities to changes in local pressure and smell, to catch their food and avoid being caught. Those that aren't blind have large and sensitive eyes that can use bioluminescent light. These eyes can be as much as 100 times more sensitive to light than human eyes. Rhodopsin (Rh1) is a protein found in the eye's rod cells that helps animals see in dim light. While most vertebrates usually have one Rh1 opsin gene, some deep-sea fish have several Rh1 genes, and one species, the silver spinyfin (Diretmus argenteus), has 38. This proliferation of Rh1 genes may help deep-sea fish to see in the depths of the ocean. Also, to avoid predation, many species are dark to blend in with their environment. Many deep-sea fish are bioluminescent, with extremely large


id: deep-sea-fish-20260505-3
file: data/en.wikipedia.org/wiki/Deep-sea_fish-3.md
category: reference
title: Deep-sea fish
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep-sea_fish
date_saved: 2026-05-05T07:34:47.616452+00:00
instance: kb-cron
parent: deep-sea-fish-20260505-0
summary:
Below the epipelagic zone, conditions change rapidly. Between 200 m and about 1000 m, light continues to fade until there is almost none. Temperatures fall through a thermocline to temperatures between 3.9 and 7.8 °C (39.0 and 46.0 °F). This is the twilight or mesopelagic zone. Pressure continues to increase, at the rate of one atm (0.1 MPa) every 10 m (33 ft), while nutrient concentrations fall, along with dissolved oxygen and the rate at which the water circulates. Sonar operators, using the newly developed sonar technology during World War II, were puzzled by what appeared to be a false sea floor 300–500 metres (984–1,640 ft) deep by day, and less deep at night. This turned out to be due to millions of marine organisms, most particularly small mesopelagic fish, with swim bladders that reflected the sonar. These organisms migrate up into shallower water at dusk to feed on plankton. The layer is deeper when the moon is out, and can become shallower when clouds pass over the moon. This phenomenon has come to be known as the deep scattering layer. Most mesopelagic fish make daily vertical migrations, moving at night into the epipelagic zone, often following similar migrations of


id: deep-sea-fish-20260505-4
file: data/en.wikipedia.org/wiki/Deep-sea_fish-4.md
category: reference
title: Deep-sea fish
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep-sea_fish
date_saved: 2026-05-05T07:34:47.616452+00:00
instance: kb-cron
parent: deep-sea-fish-20260505-0
summary:
Below the mesopelagic zone it is pitch dark. This is the midnight (or bathypelagic zone), extending from 1,000 metres (3,281 ft) to the bottom deep-water benthic zone. If the water is exceptionally deep, the pelagic zone below 4,000 metres (13,123 ft) is sometimes called the lower midnight (or abyssopelagic zone). Temperatures in this zone range from 1 to 4 °C (34 to 39 °F) and it is completely aphotic. Conditions are somewhat uniform throughout these zones; the darkness is complete, the pressure is crushing, and temperatures, nutrients and dissolved oxygen levels are all low. Bathypelagic fish have special adaptations to cope with these conditions – they have slow metabolisms and unspecialized diets, being willing to eat anything that comes along. They prefer to sit and wait for food rather than waste energy searching for it. The behaviour of bathypelagic fish can be contrasted with the behaviour of mesopelagic fish. Mesopelagic fish are often highly mobile, whereas bathypelagic fish are almost all lie-in-wait predators, normally expending little energy in movement. The dominant bathypelagic fishes are small bristlemouth and anglerfish; fangtooth, viperfish, daggertooth and barracudina are also common. These fishes are small, many about 10 centimetres (3.9 in) long, and not many


id: deep-sea-fish-20260505-5
file: data/en.wikipedia.org/wiki/Deep-sea_fish-5.md
category: reference
title: Deep-sea fish
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep-sea_fish
date_saved: 2026-05-05T07:34:47.616452+00:00
instance: kb-cron
parent: deep-sea-fish-20260505-0
summary:
== Adaptation to high pressure == As a fish moves deeper into the sea, the weight of the water overhead exerts increasing hydrostatic pressure on the fish. This increased pressure amounts to about one atm (0.1 MPa) for every 10 m (33 ft)in depth. For a fish at the bottom of the bathypelagic zone, this pressure amounts to about 400 atm (40 MPa, 6000 psi). Deep-sea organisms possess adaptations at cellular and physiological levels that allow them to survive in environments of great pressure. Not having these adaptations limits the depths at which shallow-water species can operate. High levels of external pressure affects how metabolic processes and biochemical reactions proceed. The equilibrium of many chemical reactions is disturbed by pressure, and pressure can inhibit processes which result in an increase in volume. Water, a key component in many biological processes, is very susceptible to volume changes, mainly because constituents of cellular fluid have an effect on water structure. Thus, enzymatic reactions that induce changes in water organization effectively change the system's volume. Proteins responsible for catalyzing reactions are typically held together by weak bonds and the reactions usually involve volume increases. Species that can tolerate these depths have evolved changes


id: deep-ocean-water-20260505-0
file: data/en.wikipedia.org/wiki/Deep_ocean_water-0.md
category: reference
title: Deep ocean water
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep_ocean_water
date_saved: 2026-05-05T07:34:48.870613+00:00
instance: kb-cron
parent: deep-ocean-water-20260505-0
summary:
Deep ocean water (DOW) is the name for cold, salty water found in the deep sea, starting at 200 m (660 ft) below the surface of Earth's oceans. Ocean water differs in temperature and salinity. Warm surface water is generally saltier than the cooler deep or polar waters; in polar regions, the upper layers of ocean water are cold and fresh. Deep ocean water makes up about 90% of the volume of the oceans. Deep ocean water has a very uniform temperature, around 0–3 °C (32–37 °F), and a salinity of about 3.5% or, as oceanographers state, 35‰ (parts per thousand). In specialized locations, such as the Natural Energy Laboratory of Hawaii, ocean water is pumped to the surface from approximately 900 m (3,000 ft) deep for applications in research, commercial and pre-commercial activities. DOW is typically used to describe ocean water at sub-thermal depths sufficient to provide a measurable difference in water temperature. == Cold-bed agriculture == A potential indirect use of cold ocean water is "cold-bed agriculture". During condensation or ocean thermal energy conversion operations, the water does not reach ambient temperature, because a certain temperature gradient is required to make these processes viable. The water leaving those


id: deep-sea-wood-20260505-0
file: data/en.wikipedia.org/wiki/Deep-sea_wood-0.md
category: reference
title: Deep-sea wood
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deep-sea_wood
date_saved: 2026-05-05T07:34:50.198701+00:00
instance: kb-cron
parent: deep-sea-wood-20260505-0
summary:
Deep-sea wood is the term for wood which sinks to the ocean floor. These wood-falls develop deep sea ecosystems. Deep-sea wood supports unique forms of deep sea community life including chemo-synthetic bacteria. Sources of carbon for these deep sea ecosystems are not limited to sunken wood, but also include kelp and the remains of whales. Much of what is known about deep-sea wood is obtained from experiments by marine biologists, in which wood is forced to the bottom of the ocean for a set amount of time and is then collected later for sampling. == Organisms present == === Wood boring bivalves === Colonization experiments revealed the presence of wood boring bivalves that belong to the subfamily Xylophagainae, such as Xylophaga dorsalis, or other species recently described from deep-sea canyons. They range in shell size from 1 to 10 mm (0.04 to 0.4 in). These bivalves are able to digest wood with the help of symbiotic bacteria in their gills. === Chemosyntheic fauna === Chemosyntheic mussels identified as Idas modiolaeformis were also found in deep sea wood when organic matter settled for at least one year. They are slightly smaller than the bivalves found and range in length from 1


id: demersal-zone-20260505-0
file: data/en.wikipedia.org/wiki/Demersal_zone-0.md
category: reference
title: Demersal zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Demersal_zone
date_saved: 2026-05-05T07:34:51.436336+00:00
instance: kb-cron
parent: demersal-zone-20260505-0
summary:
The demersal zone (from Latin demergere, "to sink") is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of the larger profundal zone. Being just above the ocean floor, the demersal zone is variable in depth and can be part of the photic zone where light can penetrate, and photosynthetic organisms grow, or the aphotic zone, which begins between depths of roughly 200 and 1,000 m (700 and 3,300 ft) and extends to the ocean depths, where no light penetrates. == Fish == The distinction between demersal species of fish and pelagic species is not always clear cut. The Atlantic cod (Gadus morhua) is a typical demersal fish, but can also be found in the open water column, and the Atlantic herring (Clupea harengus) is predominantly a pelagic species but forms large aggregations near the seabed when it spawns on banks of gravel. Two types of fish inhabit the demersal zone: those that are heavier than water and rest on the seabed, and those that have neutral


id: fracture-zone-20260505-0
file: data/en.wikipedia.org/wiki/Fracture_zone-0.md
category: reference
title: Fracture zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fracture_zone
date_saved: 2026-05-05T07:34:52.674187+00:00
instance: kb-cron
parent: fracture-zone-20260505-0
summary:
A fracture zone is a linear feature on the ocean floor—often hundreds, even thousands of kilometers long—resulting from the action of offset mid-ocean ridge axis segments. They are a consequence of plate tectonics. Lithospheric plates on either side of an active transform fault move in opposite directions; here, strike-slip activity occurs. Fracture zones extend past the transform faults, away from the ridge axis; are usually seismically inactive (because both plate segments are moving in the same direction), although they can display evidence of transform fault activity, primarily in the different ages of the crust on opposite sides of the zone. In actual usage, many transform faults aligned with fracture zones are often loosely referred to as "fracture zones" although technically, they are not. They can be associated with other tectonic features and may be subducted or distorted by later tectonic activity. They are usually defined with bathymetric, gravity and magnetic studies. == Structure and formation == Mid-ocean ridges are divergent plate boundaries. As the plates on either side of an offset mid-ocean ridge move, a transform fault forms at the offset between the two ridges. Fracture zones and the transform faults that form them are separate but related features. Transform


id: gas-hydrate-stability-zone-20260505-0
file: data/en.wikipedia.org/wiki/Gas_hydrate_stability_zone-0.md
category: reference
title: Gas hydrate stability zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Gas_hydrate_stability_zone
date_saved: 2026-05-05T07:34:53.961204+00:00
instance: kb-cron
parent: gas-hydrate-stability-zone-20260505-0
summary:
Gas hydrate stability zone, abbreviated GHSZ, also referred to as methane hydrate stability zone (MHSZ) or hydrate stability zone (HSZ), refers to a zone and depth of the marine environment at which methane clathrates naturally exist in the Earth's crust. == Description == Gas hydrate stability primarily depends upon temperature and pressure, however other variables such as gas composition and ionic impurities in water influence stability boundaries. The existence and depth of a hydrate deposit is often indicated by the presence of a bottom-simulating reflector (BSR). A BSR is a seismic reflection indicating the lower limit of hydrate stability in sediments due to the different densities of hydrate saturated sediments, normal sediments and those containing free gas. == Limits == The upper and lower limits of the HSZ, as well as its thickness, depend upon the local conditions in which the hydrate occurs. The conditions for hydrate stability generally restrict natural deposits to polar regions and deep oceanic regions. In polar regions, due to low temperatures, the upper limit of the hydrate stability zone occurs at a depth of approximately 150 meters.1 The maximal depth of the hydrate stability zone is limited by the geothermal gradient. Along continental margins the


id: hadal-zone-20260505-0
file: data/en.wikipedia.org/wiki/Hadal_zone-0.md
category: reference
title: Hadal zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hadal_zone
date_saved: 2026-05-05T07:34:56.432817+00:00
instance: kb-cron
parent: hadal-zone-20260505-0
summary:
The hadal zone, also known as the hadopelagic zone, is the deepest region of the ocean, lying within oceanic trenches. The hadal zone ranges from around 6 to 11 km (3.7 to 6.8 mi; 20,000 to 36,000 ft) below sea level, and exists in long, narrow, topographic V-shaped depressions. The total area occupied by the 46 individual hadal habitats worldwide is less than 0.25% of the world's seafloor, yet trenches account for over 40% of the ocean's depth range. Most hadal habitats are found in the Pacific Ocean, the largest and deepest of the conventional oceanic divisions. == Terminology and definition == Historically, the hadal zone was not recognized as distinct from the abyssal zone, although the deepest sections were sometimes called "ultra-abyssal". During the early 1950s, the Danish Galathea II and Soviet Vityaz expeditions separately discovered a distinct shift in the life at depths of 6,000–7,000 m (20,000–23,000 ft) not recognized by the broad definition of the abyssal zone. The term "hadal" was first proposed in 1956 by Anton Frederik Bruun to describe the parts of the ocean deeper than 6,000 m (20,000 ft), leaving abyssal for the parts at 4,000–6,000 m (13,000–20,000 ft). The name refers to Hades,


id: hadal-zone-20260505-1
file: data/en.wikipedia.org/wiki/Hadal_zone-1.md
category: reference
title: Hadal zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hadal_zone
date_saved: 2026-05-05T07:34:56.432817+00:00
instance: kb-cron
parent: hadal-zone-20260505-0
summary:
== Exploration == The exploration of the hadal zone requires the use of instruments that are able to withstand pressures of up to a thousand or more atmospheres. A few haphazard and non-standard tools have been used to collect limited, but valuable, information about the basic biology of a few hadal organisms. Manned and unmanned submersibles, however, can be used to study the depths in greater detail. Unmanned robotic submersibles may be remotely operated (connected to the research vessel by a cable) or autonomous (freely moving). Cameras and manipulators on submersibles allow researchers to observe and take samples of sediment and organisms. Failures of submersibles under the immense pressure at hadal zone depths have occurred. HROV Nereus is thought to have imploded at a depth of 9,990 meters while exploring the Kermadec Trench in 2014. == Notable missions == The first manned exploration to reach Challenger Deep, the deepest known part of the ocean located in the Mariana Trench, was accomplished in 1960 by Jacques Piccard and Don Walsh. They reached a maximum depth of 10,911 metres (35,797 ft) in the bathyscaphe Trieste. James Cameron also reached the bottom of Mariana Trench in March 2012 using the Deepsea Challenger. The


id: haff-lagoon-20260505-0
file: data/en.wikipedia.org/wiki/Haff_(lagoon)-0.md
category: reference
title: Haff (lagoon)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Haff_(lagoon)
date_saved: 2026-05-05T07:34:57.591702+00:00
instance: kb-cron
parent: haff-lagoon-20260505-0
summary:
Haff (German for "lagoon", pronounced [haf] ) or Bodden may refer to several estuarine lagoons along the Southern Baltic coast: Frisches Haff Großes Haff Kamieński Lagoon or Camminer Bodden Kleines Haff Kurisches Haff Stettiner Haff, also Pommersches Haff or Oderhaff In Northern Germany and the Netherlands, the now obsolete Frisian word hef may refer to the Wadden Sea, which has some properties of a lagoon.


id: iceberg-20260505-0
file: data/en.wikipedia.org/wiki/Iceberg-0.md
category: reference
title: Iceberg
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Iceberg
date_saved: 2026-05-05T07:34:58.808748+00:00
instance: kb-cron
parent: iceberg-20260505-0
summary:
An iceberg is a piece of fresh water ice more than 15 meters (16 yards) long that has broken off a glacier or an ice shelf and is floating freely in open water. Smaller chunks of floating glacially derived ice are called "growlers" or "bergy bits". Much of an iceberg is below the water's surface, which led to the expression "tip of the iceberg" to illustrate a small part of a larger unseen issue. Icebergs are considered a serious maritime hazard. Icebergs vary considerably in size and shape. Icebergs that calve from glaciers in Greenland are often irregularly shaped while Antarctic ice shelves often produce large tabular (table top) icebergs. The largest iceberg in recent history, named B-15, was measured at nearly 300 by 40 kilometres (186 by 25 mi) in 2000. The largest iceberg on record was an Antarctic tabular iceberg measuring 335 by 97 kilometres (208 by 60 mi) sighted 240 kilometres (150 mi) west of Scott Island, in the South Pacific Ocean, by the USS Glacier on November 12, 1956. This iceberg was larger than Belgium. == Etymology == The word iceberg is a partial loan translation from the Dutch word ijsberg, literally meaning ice mountain, cognate


id: iceberg-20260505-1
file: data/en.wikipedia.org/wiki/Iceberg-1.md
category: reference
title: Iceberg
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Iceberg
date_saved: 2026-05-05T07:34:58.808748+00:00
instance: kb-cron
parent: iceberg-20260505-0
summary:
=== Stability === An iceberg may flip, or capsize, as it melts and breaks apart, changing the center of gravity. Capsizing can occur shortly after calving when the iceberg is young and establishing balance. Icebergs are unpredictable and can capsize anytime and without warning. Large icebergs that break off from a glacier front and flip onto the glacier face can push the entire glacier backwards momentarily, producing 'glacial earthquakes' that generate as much energy as an atomic bomb. === Color === Icebergs are generally white because they are covered in snow, but can be green, blue, yellow, black, striped, or even rainbow-colored. Seawater, algae and lack of air bubbles in the ice can create diverse colors. Sediment can create the dirty black coloration present in some icebergs. === Shape === In addition to size classification, icebergs can be classified on the basis of their shapes. The two basic types of iceberg forms are tabular and non-tabular. Tabular icebergs have steep sides and a flat top, much like a plateau, with a length-to-height ratio of more than 5:1. This type of iceberg, also known as an ice island, can be quite large, as in the case of Pobeda Ice Island. Antarctic


id: iceberg-20260505-2
file: data/en.wikipedia.org/wiki/Iceberg-2.md
category: reference
title: Iceberg
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Iceberg
date_saved: 2026-05-05T07:34:58.808748+00:00
instance: kb-cron
parent: iceberg-20260505-0
summary:
=== Commercial use === The idea of towing large icebergs to other regions as a source of water has been raised since at least the 1950s, without having been put into practice. In 2017, a business from the UAE announced plans to tow an iceberg from Antarctica to the Middle East; in 2019 salvage engineer Nick Sloane announced a plan to move one to South Africa at an estimated cost of $200 million. In 2019, a German company, Polewater, announced plans to tow Antarctic icebergs to places like South Africa. Companies have used iceberg water in products such as bottled water, fizzy ice cubes and alcoholic drinks. For example, Iceberg Beer by Quidi Vidi Brewing Company is made from icebergs found around St. John's, Newfoundland. Although annual iceberg supply in Newfoundland and Labrador exceeds the total freshwater consumption of the United States, in 2016 the province introduced a tax on iceberg harvesting and imposed a limit on how much fresh water can be exported yearly. == Oceanography and ecology == The freshwater injected into the ocean by melting icebergs can change the density of the seawater in the vicinity of the iceberg. Fresh melt water released at depth is lighter,


id: intertidal-zone-20260505-0
file: data/en.wikipedia.org/wiki/Intertidal_zone-0.md
category: reference
title: Intertidal zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Intertidal_zone
date_saved: 2026-05-05T07:35:11.460624+00:00
instance: kb-cron
parent: intertidal-zone-20260505-0
summary:
The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various species of life, such as sea stars, sea urchins, and many species of coral with regional differences in biodiversity. Sometimes it is referred to as the littoral zone or seashore, although those can be defined as a wider region. The intertidal zone also includes steep rocky cliffs, sandy beaches, bogs or wetlands (e.g., vast mudflats). This area can be a narrow strip, such as in Pacific islands that have only a narrow tidal range, or can include many meters of shoreline where shallow beach slopes interact with high tidal excursion. The peritidal zone is similar but somewhat wider, extending from above the highest tide level to below the lowest. Organisms in the intertidal zone are well-adapted to their environment, facing high levels of interspecific competition and the rapidly changing conditions that come with the tides. The intertidal zone is also home to several species from many different phyla (Porifera, Annelida, Coelenterata, Mollusca, Arthropoda, etc.). The water


id: intertidal-zone-20260505-1
file: data/en.wikipedia.org/wiki/Intertidal_zone-1.md
category: reference
title: Intertidal zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Intertidal_zone
date_saved: 2026-05-05T07:35:11.460624+00:00
instance: kb-cron
parent: intertidal-zone-20260505-0
summary:
The intertidal region is an important model system for the study of ecology, especially on wave-swept rocky shores. The region contains a high diversity of species, and the zonation created by the tides causes species ranges to be compressed into very narrow bands. This makes it relatively simple to study species across their entire cross-shore range, something that can be extremely difficult in, for instance, terrestrial habitats that can stretch thousands of kilometres. Communities on wave-swept shores also have high turnover due to disturbance, so it is possible to watch ecological succession over years rather than decades. The burrowing invertebrates that make up large portions of sandy beach ecosystems are known to travel relatively great distances in cross-shore directions as beaches change on the order of days, semilunar cycles, seasons, or years. The distribution of some species has been found to correlate strongly with geomorphic datums such as the high tide strand and the water table outcrop. Since the foreshore is alternately covered by the sea and exposed to the air, organisms living in this environment must be adapted to both wet and dry conditions. Intertidal zone biomass reduces the risk of shoreline erosion from high intensity waves. Typical inhabitants


id: island-20260505-0
file: data/en.wikipedia.org/wiki/Island-0.md
category: reference
title: Island
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Island
date_saved: 2026-05-05T07:35:12.739706+00:00
instance: kb-cron
parent: island-20260505-0
summary:
An island or isle is a piece of land, distinct from a continent, completely surrounded by water. There are continental islands, which were formed by being split from a continent by plate tectonics, and oceanic islands, which have never been part of a continent. Oceanic islands can be formed from volcanic activity, grow into atolls from coral reefs, and form from sediment along shorelines, creating barrier islands. River islands can also form from sediment and debris in rivers. Artificial islands are those made by humans, including small rocky outcroppings built out of lagoons and large-scale land reclamation projects used for development. Islands are host to diverse plant and animal life. Oceanic islands have the sea as a natural barrier to the introduction of new species, causing the species that do reach the island to evolve in isolation. Continental islands share animal and plant life with the continent they split from. Depending on how long ago the continental island formed, the life on that island may have diverged greatly from the mainland due to natural selection. Humans have lived on and traveled between islands for thousands of years at a minimum. Some islands became host to humans due to a land


id: island-20260505-1
file: data/en.wikipedia.org/wiki/Island-1.md
category: reference
title: Island
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Island
date_saved: 2026-05-05T07:35:12.739706+00:00
instance: kb-cron
parent: island-20260505-0
summary:
=== Formation in freshwater === A fluvial island is an island that forms from the erosion and sedimentation of debris in rivers; almost all rivers have some form of fluvial islands. These islands may only be a few meters high, and are usually temporary. Changes in the flow speed, water level, and sediment content of the river may affect the rate of fluvial island formation and depletion. Permanent river islands also exist, the largest of which (that is completely inland) is Bananal Island in the Tocantins of Brazil, which has a maximum width of 55 kilometers. Lakes form for a variety of reasons, including glaciers, plate tectonics, and volcanism. Lake islands can form as part of these processes. == Life on islands == The field of insular biogeography studies the ecological processes that take place on islands, with a focus on what factors effect the evolution, extinction, and richness of species. Scientists often study islands as an isolated model of how the process of natural selection takes place. Island ecology studies organisms on islands and their environment. It has yielded important insights for its parent field of ecology since the time of Charles Darwin. === Endemism === In biology, endemism


id: island-20260505-2
file: data/en.wikipedia.org/wiki/Island-2.md
category: reference
title: Island
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Island
date_saved: 2026-05-05T07:35:12.739706+00:00
instance: kb-cron
parent: island-20260505-0
summary:
Species endemic to islands show a common evolutionary trajectory. Foster's rule (also known as the island rule), states that small mammals such as rodents evolve to become larger, known as island gigantism. One such example is the giant tortoise of the Seychelles, though it is unknown if it grew in size before or after reaching the island. Larger animals such as the hippopotamus tend to become smaller, such as in the case of the pygmy hippopotamus. This is known as insular dwarfism. In the case of smaller animals, it has been hypothesized that animals on islands may have fewer predators and competitors, resulting in selection pressure towards larger animals. Larger animals may exhaust food resources quickly due to their size, causing malnutrition in their young, resulting in a selection pressure for smaller animals that require less food. Having fewer predators would mean these animals did not need not be large to survive. === Darwin, the Galápagos, and natural selection === Charles Darwin formulated the theory of natural selection through the study of island ecology. The species he observed on the Galápagos Islands, including tanager birds, contributed to his understanding of how evolution works. He first traveled to the islands as


id: island-20260505-3
file: data/en.wikipedia.org/wiki/Island-3.md
category: reference
title: Island
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Island
date_saved: 2026-05-05T07:35:12.739706+00:00
instance: kb-cron
parent: island-20260505-0
summary:
==== Diet ==== The Polynesian diet got most of its protein from fishing. Polynesians were known to fish close to shore, as well as in deep water. It was reported that Rapa Nui people were known to fish as far as 500 km (310 mi) from shore at coral reefs. Spear, line, and net fishing were all used, to catch tuna as well as sharks and stingrays. Island cultures also cultivate native and non-native crops. Polynesians grew the native yam, taro, breadfruit, banana, coconut and other fruits and vegetables. Different island climates made different resources more important, such as the Hawaiian islands being home to irrigated fields of taro, whereas in some islands, like Tahiti, breadfruit was more widely cultivated and fermented in order to preserve it. There is archeological evidence that Canary Islanders would chew the roots of ferns for sustenance, a practice that wore heavily on their molars. These islanders would also grow barley and raised livestock such as goats. === Island nations and territories === Many island nations have little land and a restricted set of natural resources. However, these nations control some of the largest fisheries in the world, deposits of copper, gold, and nickel, as


id: island-20260505-4
file: data/en.wikipedia.org/wiki/Island-4.md
category: reference
title: Island
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Island
date_saved: 2026-05-05T07:35:12.739706+00:00
instance: kb-cron
parent: island-20260505-0
summary:
For hundreds of years, islands have been created through land reclamation. One of the first recorded instances of this when people of the Solomon Islands created eighty such islands by piling coral and rock in the Lau Lagoon. However, the first permanent artificial island is Al-Sayah island, in Bahrain – created at least 1,200 years ago. One traditional way of constructing islands is with the use of a revetment. Sandbags or stones are dropped with a barge into the sea to bring the land level slightly out of the water. The island area is then filled with sand or gravel, followed by a construction of this revetment to hold it together. Islands have also been constructed with a permanent caisson, a steel or concrete structure built in a closed loop and then filled with sand. Some modern islands have been constructed by pouring millions of tons of sand into the sea, such as with Pearl Island in Qatar or the Palm Islands in Dubai. These islands are usually created for real estate development, and are sold for private ownership or construction of housing. Offshore oil platforms have also been described as a type of island. Some atolls have been covered


id: kinematic-wave-20260505-0
file: data/en.wikipedia.org/wiki/Kinematic_wave-0.md
category: reference
title: Kinematic wave
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Kinematic_wave
date_saved: 2026-05-05T07:35:13.990990+00:00
instance: kb-cron
parent: kinematic-wave-20260505-0
summary:
In gravity and pressure driven fluid dynamical and geophysical mass flows such as ocean waves, avalanches, debris flows, mud flows, flash floods, etc., kinematic waves are important mathematical tools to understand the basic features of the associated wave phenomena. These waves are also applied to model the motion of highway traffic flows. In these flows, mass and momentum equations can be combined to yield a kinematic wave equation. Depending on the flow configurations, the kinematic wave can be linear or non-linear, which depends on whether the wave phase speed is a constant or a variable. A kinematic wave can be described by a simple partial differential equation with a single unknown field variable (e.g., the flow or wave height, h {\displaystyle h} ) in terms of the two independent variables, namely the time ( t {\displaystyle t} ) and the space ( x {\displaystyle x} ) with some parameters (coefficients) containing information about the physics and geometry of the flow. In general, the wave can be advecting and diffusing. However, in simple situations, the kinematic wave is mainly advecting. == Kinematic wave for debris flow == Non-linear kinematic wave for debris flow can be written as follows with complex non-linear


id: knoll-oceanography-20260505-0
file: data/en.wikipedia.org/wiki/Knoll_(oceanography)-0.md
category: reference
title: Knoll (oceanography)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Knoll_(oceanography)
date_saved: 2026-05-05T07:35:15.200691+00:00
instance: kb-cron
parent: knoll-oceanography-20260505-0
summary:
In marine geology, a knoll is defined as a rounded underwater hill, not exceeding 1000 meters in height. Any rounded underwater features exceeding that height are referred to as seamounts. They are believed to cover around 16.3% of the world's seafloor. == Examples == Orphan Knoll Graveyard Seamounts == References ==


id: lagoon-20260505-0
file: data/en.wikipedia.org/wiki/Lagoon-0.md
category: reference
title: Lagoon
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Lagoon
date_saved: 2026-05-05T07:35:16.460249+00:00
instance: kb-cron
parent: lagoon-20260505-0
summary:
A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as a reef, a barrier island or islands, a barrier peninsula, or an isthmus. Lagoons are commonly divided into coastal lagoons (or barrier lagoons) and atoll lagoons. They have also been identified as occurring on mixed-sand and gravel coastlines. There is an overlap between bodies of water classified as coastal lagoons and bodies of water classified as estuaries. Lagoons are common coastal features around many parts of the world. == Definition and terminology == Lagoons are shallow, often elongated bodies of water separated from a larger body of water by a shallow or exposed shoal, coral reef, or similar feature. Some authorities include fresh water bodies in the definition of "lagoon", while others explicitly restrict "lagoon" to bodies of water with some degree of salinity. The distinction between "lagoon" and "estuary" also varies between authorities. Richard A. Davis Jr. restricts "lagoon" to bodies of water with little or no fresh water inflow, and little or no tidal flow, and calls any bay that receives a regular flow of fresh water an "estuary". Davis does state that the terms "lagoon" and


id: littoral-zone-20260505-0
file: data/en.wikipedia.org/wiki/Littoral_zone-0.md
category: reference
title: Littoral zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Littoral_zone
date_saved: 2026-05-05T07:35:17.722778+00:00
instance: kb-cron
parent: littoral-zone-20260505-0
summary:
The littoral zone, also called litoral or nearshore, is the part of an ocean, sea, lake, or river, that is close to the shore. It provides extensive and productive habitats around the world, adjacent to land-water interfaces. In coastal ecology, the littoral zone includes the foreshore (intertidal zone) extending from the high water mark (which is rarely inundated) to the low water mark (where coastal areas become permanently submerged). However, the geographical meaning of littoral zone extends well beyond the intertidal zone to include all neritic waters within the bounds of continental shelves. Continental shelves cover an area of about 7% of the surface area of the oceans. In lake ecosystems, the littoral zone covers about 78% of Earth's total lake area. These zones support abundant plant growth, making them not only structurally distinct from the pelagic (open water) zone but also highly productive. Productivity in both marine and lake littoral zones can reach levels comparable to tropical rainforests. == Definitions and characteristics == The littoral zone has no single definition. What is regarded as the full extent of the littoral zone, and the way the littoral zone is divided into subregions, varies in different contexts. For lakes, the littoral


id: littoral-zone-20260505-1
file: data/en.wikipedia.org/wiki/Littoral_zone-1.md
category: reference
title: Littoral zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Littoral_zone
date_saved: 2026-05-05T07:35:17.722778+00:00
instance: kb-cron
parent: littoral-zone-20260505-0
summary:
The sublittoral zone starts immediately below the eulittoral zone. This zone is permanently covered with seawater and is approximately equivalent to the neritic zone. In physical oceanography, the sublittoral zone refers to coastal regions with significant tidal flows and energy dissipation, including non-linear flows, internal waves, river outflows and oceanic fronts. In practice, this typically extends to the edge of the continental shelf, with depths around 200 meters. In marine biology, the sublittoral zone refers to the areas where sunlight reaches the ocean floor, that is, where the water is never so deep as to take it out of the photic zone. This results in high primary production and makes the sublittoral zone the location of the majority of sea life. As in physical oceanography, this zone typically extends to the edge of the continental shelf. The benthic zone in the sublittoral is much more stable than in the intertidal zone; temperature, water pressure, and the amount of sunlight remain fairly constant. Sublittoral corals do not have to deal with as much change as intertidal corals. Corals can live in both zones, but they are more common in the sublittoral zone. Within the sublittoral, marine biologists also identify the following:


id: littoral-zone-20260505-2
file: data/en.wikipedia.org/wiki/Littoral_zone-2.md
category: reference
title: Littoral zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Littoral_zone
date_saved: 2026-05-05T07:35:17.722778+00:00
instance: kb-cron
parent: littoral-zone-20260505-0
summary:
Many vertebrates (e.g., mammals, waterfowl, reptiles) and invertebrates (insects, etc.) use both the littoral zone as well as the terrestrial ecosystem for food and habitat. Biota that are commonly assumed to reside in the pelagic zone often rely heavily on resources from the littoral zone. Littoral areas of ponds and lakes are typically better oxygenated, structurally more complex, and afford more abundant and diverse food resources than do profundal sediments. All these factors lead to a high diversity of insects and very complex trophic interactions. The great lakes of the world represent a global heritage of surface freshwater and aquatic biodiversity. Species lists for 14 of the world's largest lakes reveal that 15% of the global diversity (the total number of species) of freshwater fishes, 9% of non-insect freshwater invertebrate diversity, and 2% of aquatic insect diversity live in this handful of lakes. The vast majority (more than 93%) of species inhabit the shallow, nearshore littoral zone, and 72% are completely restricted to the littoral zone, even though littoral habitats are a small fraction of total lake areas. Because the littoral zone is important for many recreational and industrial purposes, it is often severely affected by many human activities that


id: longhurst-code-20260505-0
file: data/en.wikipedia.org/wiki/Longhurst_code-0.md
category: reference
title: Longhurst code
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Longhurst_code
date_saved: 2026-05-05T07:35:18.907502+00:00
instance: kb-cron
parent: longhurst-code-20260505-0
summary:
Longhurst code refers to a set of geospatial four-letter geocodes for referencing geographic regions in oceanography. The set of 56 geocodes represent biogeochemical provinces that partition the pelagic environment. It is assumed that each province represents a unique set of environmental conditions. They are named after Alan R. Longhurst, the author of "Ecological Geography of the Sea", the textbook in which these codes are defined. These codes have also been used in bioinformatic databases such as IMGTooltip Integrated Microbial Genomes to represent sample origins for sequenced microbial genomes, as a supplement to latitude and longitude coordinate metrics. == References ==


id: longshore-drift-20260505-0
file: data/en.wikipedia.org/wiki/Longshore_drift-0.md
category: reference
title: Longshore drift
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Longshore_drift
date_saved: 2026-05-05T07:35:20.233864+00:00
instance: kb-cron
parent: longshore-drift-20260505-0
summary:
Longshore drift from longshore current is a geological process that consists of the transportation of sediments (clay, silt, pebbles, sand, shingle, shells) along a coast parallel to the shoreline, which is dependent on the angle of incoming wave direction. Oblique incoming wind squeezes water along the coast, generating a water current that moves parallel to the coast. Longshore drift is simply the sediment moved by the longshore current. This current and sediment movement occurs within the surf zone. The process is also known as littoral drift. Beach sand is also moved on such oblique wind days, due to the swash and backwash of water on the beach. Breaking surf sends water up the coast (swash) at an oblique angle and gravity then drains the water straight downslope (backwash) perpendicular to the shoreline. Thus beach sand can move downbeach in a sawtooth fashion many tens of meters (yards) per day. This process is called "beach drift", but some workers regard it as simply part of "longshore drift" because of the overall movement of sand parallel to the coast. Longshore drift affects numerous sediment sizes as it works in slightly different ways depending on the sediment (e.g. the difference in long-shore drift


id: longshore-drift-20260505-1
file: data/en.wikipedia.org/wiki/Longshore_drift-1.md
category: reference
title: Longshore drift
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Longshore_drift
date_saved: 2026-05-05T07:35:20.233864+00:00
instance: kb-cron
parent: longshore-drift-20260505-0
summary:
=== The sediment budget === The sediment budget takes into consideration sediment sources and sinks within a system. This sediment can come from any source with examples of sources and sinks consisting of: Rivers Lagoons Eroding land sources Artificial sources e.g. nourishment Artificial sinks e.g. mining/extraction Offshore transport Deposition of sediment on shore Gullies through the land This sediment then enters the coastal system and is transported by longshore drift. A good example of the sediment budget and longshore drift working together in the coastal system is inlet ebb-tidal shoals, which store sand that has been transported by long-shore transport. As well as storing sand these systems may also transfer or by pass sand into other beach systems, therefore inlet ebb-tidal (shoal) systems provide good sources and sinks for the sediment budget. Sediment deposition throughout a shoreline profile conforms to the null point hypothesis; where gravitational and hydraulic forces determine the settling velocity of grains in a seaward fining sediment distribution. Long shore occurs in a 90 to 80 degree backwash so it would be presented as a right angle with the wave line. == Natural features == This section consists of features of longshore drift that occur on a


id: longshore-drift-20260505-2
file: data/en.wikipedia.org/wiki/Longshore_drift-2.md
category: reference
title: Longshore drift
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Longshore_drift
date_saved: 2026-05-05T07:35:20.233864+00:00
instance: kb-cron
parent: longshore-drift-20260505-0
summary:
Groynes are shore protection structures, placed at equal intervals along the coastline in order to stop coastal erosion and generally cross the intertidal zone. Due to this, groyne structures are usually used on shores with low net and high annual longshore drift in order to retain the sediments lost in storm surges and further down the coast. There are numerous variations to groyne designs with the three most common designs consisting of: zig-zag groynes, which dissipate the destructive flows that form in wave-induced currents or in breaking waves. T-head groynes, which reduce wave height through wave diffraction. ‘Y’ head, a fish-tail groyne system. === Artificial headlands === Artificial headlands are also shore protection structures, which are created in order to provide a certain amount of protection to beaches or bays. Although the creation of headlands involves accretion of sediments on the up-drift side of the headland and moderate erosion of the down-drift end of the headland, this is undertaken in order to design a stabilised system that allows material to accumulate in beaches further along the shore. Artificial headlands can occur due to natural accumulation or also through artificial nourishment. === Detached breakwaters === Detached breakwaters are shore protection structures,


id: lower-oceanic-crust-20260505-0
file: data/en.wikipedia.org/wiki/Lower_oceanic_crust-0.md
category: reference
title: Lower oceanic crust
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Lower_oceanic_crust
date_saved: 2026-05-05T07:35:21.427862+00:00
instance: kb-cron
parent: lower-oceanic-crust-20260505-0
summary:
The lower oceanic crust is the lower part of the oceanic crust and represents the major part of it (the largest part by volume). It is generally located 4–8 km below the ocean floor and the major lithologies are mafic (ultramafic and gabbroic rocks) which derive from melts rising from the Earth's mantle. This part of the oceanic crust is an important zone for processes such as melt accumulation and melt modification (fractional crystallisation and crustal assimilation). The recycling of this part of the oceanic crust, together with the upper mantle has been suggested as a significant source component for tholeiitic magmas in Hawaiian volcanoes. Although the lower oceanic crust builds the link between the mantle and the MORB, and can't be neglected for the understanding of MORB evolution, the complex processes operating in this zone remain unclear and there is an ongoing debate in Earth Sciences about this. It is 6KM long. == Processes == The lower oceanic crust connects the Earth's mantle with the MORB, where around 60% of the total magma production of the Earth happens. The three main processes happening in this region of the oceanic crust are partial melting of the Earth's mantle, melt accumulation


id: mangrove-20260505-0
file: data/en.wikipedia.org/wiki/Mangrove-0.md
category: reference
title: Mangrove
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mangrove
date_saved: 2026-05-05T07:35:22.795957+00:00
instance: kb-cron
parent: mangrove-20260505-0
summary:
A mangrove is a shrub or tree that grows mainly in coastal saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen and remove salt, allowing them to tolerate conditions that kill most plants. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse due to convergent evolution in several plant families. They occur worldwide in tropical and subtropical coastal areas, mainly between latitudes 30° N and 30° S, with the greatest mangrove area within 5° of the equator. Mangrove plant families first appeared during the Late Cretaceous to Paleocene epochs and became widely distributed in part due to the movement of tectonic plates. The oldest known fossils of mangrove palm date to 75 million years ago. Mangroves are salt-tolerant (halophytic) and are adapted to live in harsh coastal conditions. They contain a complex salt filtration system and a complex root system to cope with saltwater immersion and wave action. They are adapted to the low-oxygen conditions of waterlogged mud, but are most likely to thrive in the upper half of the intertidal zone. The mangrove biome, often


id: mangrove-20260505-1
file: data/en.wikipedia.org/wiki/Mangrove-1.md
category: reference
title: Mangrove
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mangrove
date_saved: 2026-05-05T07:35:22.795957+00:00
instance: kb-cron
parent: mangrove-20260505-0
summary:
=== Limiting salt intake === Red mangroves exclude salt by having significantly impermeable roots that are highly suberised (impregnated with suberin), acting as an ultrafiltration mechanism to exclude sodium salts from the rest of the plant. One study found that roots of the Indian mangrove Avicennia officinalis exclude 90% to 95% of the salt in water taken up by the plant, depositing the excluded salt in the cortex of the root. An increase in the production of suberin and in the activity of a gene regulating cytochrome P450 were observed in correlation with an increase in the salinity of the water to which the plant was exposed. In a frequently cited concept that has become known as the "sacrificial leaf", salt which does accumulate in the shoot (sprout) then concentrates in old leaves, which the plant then sheds. However, recent research on the Red mangrove Rhizophora mangle suggests that the older, yellowing leaves have no more measurable salt content than the other, greener leaves. === Limiting water loss === Because of the limited fresh water available in salty intertidal soils, mangroves limit the amount of water they lose through their leaves. They can restrict the opening of their stomata (pores


id: mangrove-20260505-2
file: data/en.wikipedia.org/wiki/Mangrove-2.md
category: reference
title: Mangrove
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mangrove
date_saved: 2026-05-05T07:35:22.795957+00:00
instance: kb-cron
parent: mangrove-20260505-0
summary:
"At the limits of distribution, the formation is represented by scrubby, usually monotypic Avicennia-dominated vegetation, as at Westonport Bay and Corner Inlet, Victoria, Australia. The latter locality is the highest latitude (38° 45'S) at which mangroves occur naturally. The mangroves in New Zealand, which extend as far south as 37°, are of the same type; they start as low forest in the northern part of the North Island but become low scrub toward their southern limit. In both instances, the species is referred to as Avicennia marina var. australis, although genetic comparison is clearly needed. In Western Australia, A. marina extends as far south as Bunbury (33° 19'S). In the northern hemisphere, scrubby Avicennia gerrninans in Florida occurs as far north as St. Augustine on the east coast and Cedar Point on the west. There are records of A. germinans and Rhizophora mangle for Bermuda, presumably supplied by the Gulf Stream. In southern Japan, Kandelia obovata occurs to about 31 °N (Tagawa in Hosakawa et al., 1977, but initially referred to as K. candel)." == Mangrove forests == Mangrove forests, also called mangrove swamps or mangals, are found in tropical and subtropical tidal areas. Areas where mangroves occur include estuaries


id: mangrove-20260505-3
file: data/en.wikipedia.org/wiki/Mangrove-3.md
category: reference
title: Mangrove
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mangrove
date_saved: 2026-05-05T07:35:22.795957+00:00
instance: kb-cron
parent: mangrove-20260505-0
summary:
Once established, mangrove roots provide an oyster habitat and slow water flow, thereby enhancing sediment deposition in areas where it is already occurring. The fine, anoxic sediments under mangroves act as sinks for a variety of heavy (trace) metals which colloidal particles in the sediments have concentrated from the water. Mangrove removal disturbs these underlying sediments, often creating problems of trace metal contamination of seawater and organisms of the area. Mangrove swamps protect coastal areas from erosion, storm surge (especially during tropical cyclones), and tsunamis. They limit high-energy wave erosion mainly during events such as storm surges and tsunamis. The mangroves' massive root systems are efficient at dissipating wave energy. Likewise, they slow down tidal water so that its sediment is deposited as the tide comes in, leaving all except fine particles when the tide ebbs. In this way, mangroves build their environments. Because of the uniqueness of mangrove ecosystems and the protection against erosion they provide, they are often the object of conservation programs, including national biodiversity action plans. The unique ecosystem found in the intricate mesh of mangrove roots offers a quiet marine habitat for young organisms. In areas where roots are permanently submerged, the organisms they host


id: mangrove-20260505-4
file: data/en.wikipedia.org/wiki/Mangrove-4.md
category: reference
title: Mangrove
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mangrove
date_saved: 2026-05-05T07:35:22.795957+00:00
instance: kb-cron
parent: mangrove-20260505-0
summary:
Mangrove roots harbour a repertoire of microbial taxa that contribute to important ecological functions in mangrove ecosystems. Like typical terrestrial plants, mangroves depend upon mutually beneficial interactions with microbial communities. In particular, microbes residing in developed roots could help mangroves transform nutrients into usable forms before plant assimilation. These microbes also provide mangroves phytohormones for suppressing phytopathogens or helping mangroves withstand heat and salinity. In turn, root-associated microbes receive carbon metabolites from the plant via root exudates, thus close associations between the plant and microbes are established for their mutual benefits. The taxonomic class level shows that most Proteobacteria were reported to come from Gammaproteobacteria, followed by Deltaproteobacteria and Alphaproteobacteria. The diverse function and the phylogenic variation of Gammaproteobacteria, which consisted of orders such as Alteromonadales and Vibrionales, are found in marine and coastal regions and are high in abundance in mangrove sediments functioning as nutrient recyclers. Members of Deltaproteobacteria found in mangrove soil are mostly sulfur-related, consisting of Desulfobacterales, Desulfuromonadales, Desulfovibrionales, and Desulfarculales among others. Highly diverse microbial communities (mainly bacteria and fungi) have been found to inhabit and function in mangrove roots. For example, diazotrophic bacteria in the vicinity of mangrove roots could perform biological nitrogen fixation, which


id: mangrove-20260505-5
file: data/en.wikipedia.org/wiki/Mangrove-5.md
category: reference
title: Mangrove
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mangrove
date_saved: 2026-05-05T07:35:22.795957+00:00
instance: kb-cron
parent: mangrove-20260505-0
summary:
Mangrove forests are one of the most carbon-rich biomes, accounting for 11% of the total input of terrestrial carbon into oceans. Viruses are thought to significantly influence local and global biogeochemical cycles, though as of 2019, little information was available about the community structure, genetic diversity, and ecological roles of viruses in mangrove ecosystems. Viruses are the most abundant biological entities on earth, present in virtually all ecosystems. By lysing their hosts, that is, by rupturing their cell membranes, viruses control host abundance and affect the structure of host communities. Viruses also influence their host diversity and evolution through horizontal gene transfer, selection for resistance and manipulation of bacterial metabolisms. Importantly, marine viruses affect local and global biogeochemical cycles through the release of substantial amounts of organic carbon and nutrients from hosts and assist microbes in driving biogeochemical cycles with auxiliary metabolic genes (AMGs). It is presumed that AMGs augment viral-infected host metabolism and facilitate the production of new viruses. AMGs have been extensively explored in marine cyanophages and include genes involved in photosynthesis, carbon turnover, phosphate uptake and stress response. Cultivation-independent metagenomic analysis of viral communities has identified additional AMGs that are involved in motility, central carbon metabolism, photosystem


id: mangrove-20260505-6
file: data/en.wikipedia.org/wiki/Mangrove-6.md
category: reference
title: Mangrove
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mangrove
date_saved: 2026-05-05T07:35:22.795957+00:00
instance: kb-cron
parent: mangrove-20260505-0
summary:
== Further reading == Saenger, Peter (2002). Mangrove Ecology, Silviculture, and Conservation. Kluwer Academic Publishers, Dordrecht. ISBN 1-4020-0686-1. Thanikaimoni, Ganapathi (1986). Mangrove Palynology UNDP/UNESCO and the French Institute of Pondicherry, ISSN 0073-8336 (E). Tomlinson, Philip B. (1986). The Botany of Mangroves. Cambridge University Press, Cambridge, ISBN 0-521-25567-8. Teas, H. J. (1983). Biology and Ecology of Mangroves. W. Junk Publishers, The Hague. ISBN 90-6193-948-8. Plaziat, Jean-Claude; Cavagnetto, Carla; Koeniguer, Jean-Claude; Baltzer, Frédéric (2001). "History and biogeography of the mangrove ecosystem, based on a critical reassessment of the paleontological record". Wetlands Ecology and Management. 9 (3): 161–180. Bibcode:2001WetEM...9..161P. doi:10.1023/A:1011118204434. S2CID 24980831. Jayatissa, L. P.; Dahdouh-Guebas, F.; Koedam, N. (2002). "A review of the floral composition and distribution of mangroves in Sri Lanka" (PDF). Botanical Journal of the Linnean Society. 138: 29–43. doi:10.1046/j.1095-8339.2002.00002.x. Ellison, Aaron M. (2000). "Mangrove Restoration: Do We Know Enough?". Restoration Ecology. 8 (3): 219–229. Bibcode:2000ResEc...8..219E. doi:10.1046/j.1526-100x.2000.80033.x. S2CID 86352384. Agrawala, Shardul; Hagestad; Marca; Koshy, Kayathu; Ota, Tomoko; Prasad, Biman; Risbey, James; Smith, Joel; Van Aalst, Maarten. 2003. Development and Climate Change in Fiji: Focus on Coastal Mangroves. Organisation of Economic Co-operation and Development, Paris, Cedex 16, France. Barbier, E. B.; Sathirathai, S. (2001). "Valuing Mangrove Conservation in Southern Thailand". Contemporary


id: marine-habitat-20260505-0
file: data/en.wikipedia.org/wiki/Marine_habitat-0.md
category: reference
title: Marine habitat
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_habitat
date_saved: 2026-05-05T07:35:24.136463+00:00
instance: kb-cron
parent: marine-habitat-20260505-0
summary:
A marine habitat is a habitat that supports marine life. Marine life depends in some way on the saltwater that is in the sea (the term marine comes from the Latin mare, meaning sea or ocean). A habitat is an ecological or environmental area inhabited by one or more living species. The marine environment supports many kinds of these habitats. Marine habitats can be divided into coastal and open ocean habitats. Coastal habitats are found in the area that extends from as far as the tide comes in on the shoreline out to the edge of the continental shelf. Most marine life is found in coastal habitats, even though the shelf area occupies only seven percent of the total ocean area. Open ocean habitats are found in the deep ocean beyond the edge of the continental shelf. Alternatively, marine habitats can be divided into pelagic and demersal zones. Pelagic habitats are found near the surface or in the open water column, away from the bottom of the ocean. Demersal habitats are near or on the bottom of the ocean. An organism living in a pelagic habitat is said to be a pelagic organism, as in pelagic fish. Similarly, an organism


id: marine-habitat-20260505-1
file: data/en.wikipedia.org/wiki/Marine_habitat-1.md
category: reference
title: Marine habitat
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_habitat
date_saved: 2026-05-05T07:35:24.136463+00:00
instance: kb-cron
parent: marine-habitat-20260505-0
summary:
In marine systems, ocean currents have a key role determining which areas are effective as habitats, since ocean currents transport the basic nutrients needed to support marine life. Plankton are the life forms that inhabit the ocean that are so small (less than 2 mm) that they cannot effectively propel themselves through the water, but must drift instead with the currents. If the current carries the right nutrients, and if it also flows at a suitably shallow depth where there is plenty of sunlight, then such a current itself can become a suitable habitat for photosynthesizing tiny algae called phytoplankton. These tiny plants are the primary producers in the ocean, at the start of the food chain. In turn, as the population of drifting phytoplankton grows, the water becomes a suitable habitat for zooplankton, which feed on the phytoplankton. While phytoplankton are tiny drifting plants, zooplankton are tiny drifting animals, such as the larvae of fish and marine invertebrates. If sufficient zooplankton establish themselves, the current becomes a candidate habitat for the forage fish that feed on them. And then if sufficient forage fish move to the area, it becomes a candidate habitat for larger predatory fish and other marine


id: marine-habitat-20260505-2
file: data/en.wikipedia.org/wiki/Marine_habitat-2.md
category: reference
title: Marine habitat
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_habitat
date_saved: 2026-05-05T07:35:24.136463+00:00
instance: kb-cron
parent: marine-habitat-20260505-0
summary:
Continental coastlines usually have a continental shelf, a shelf of relatively shallow water, less than 200 metres deep, which extends 68 km on average beyond the coast. Worldwide, continental shelves occupy a total area of about 24 million km2 (9 million sq mi), 8% of the ocean's total area and nearly 5% of the world's total area. Since the continental shelf is usually less than 200 metres deep, it follows that coastal habitats are generally photic, situated in the sunlit epipelagic zone. This means the conditions for photosynthetic processes so important for primary production, are available to coastal marine habitats. Because land is nearby, there are large discharges of nutrient rich land runoff into coastal waters. Further, periodic upwellings from the deep ocean can provide cool and nutrient rich currents along the edge of the continental shelf. As a result, coastal marine life is the most abundant in the world. It is found in tidal pools, fjords and estuaries, near sandy shores and rocky coastlines, around coral reefs and on or above the continental shelf. Coastal fish include small forage fish as well as the larger predator fish that feed on them. Forage fish thrive in inshore waters where high


id: marine-habitat-20260505-3
file: data/en.wikipedia.org/wiki/Marine_habitat-3.md
category: reference
title: Marine habitat
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_habitat
date_saved: 2026-05-05T07:35:24.136463+00:00
instance: kb-cron
parent: marine-habitat-20260505-0
summary:
The relative solidity of rocky shores seems to give them a permanence compared to the shifting nature of sandy shores. This apparent stability is not real over even quite short geological time scales, but it is real enough over the short life of an organism. In contrast to sandy shores, plants and animals can anchor themselves to the rocks. Competition can develop for the rocky spaces. For example, barnacles can compete successfully on open intertidal rock faces to the point where the rock surface is covered with them. Barnacles resist desiccation and grip well to exposed rock faces. However, in the crevices of the same rocks, the inhabitants are different. Here mussels can be the successful species, secured to the rock with their byssal threads. Rocky and sandy coasts are vulnerable because humans find them attractive and want to live near them. An increasing proportion of the humans live by the coast, putting pressure on coastal habitats. === Mudflats === Mudflats are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from


id: marine-habitat-20260505-4
file: data/en.wikipedia.org/wiki/Marine_habitat-4.md
category: reference
title: Marine habitat
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_habitat
date_saved: 2026-05-05T07:35:24.136463+00:00
instance: kb-cron
parent: marine-habitat-20260505-0
summary:
The holdfast is a root-like mass that anchors the thallus to the sea floor, though unlike true roots it is not responsible for absorbing and delivering nutrients to the rest of the thallus; The stipe is analogous to a plant stalk, extending vertically from the holdfast and providing a support framework for other morphological features; The fronds are leaf- or blade-like attachments extending from the stipe, sometimes along its full length, and are the sites of nutrient uptake and photosynthetic activity. In addition, many kelp species have pneumatocysts, or gas-filled bladders, usually located at the base of fronds near the stipe. These structures provide the necessary buoyancy for kelp to maintain an upright position in the water column. The environmental factors necessary for kelp to survive include hard substrate (usually rock), high nutrients (e.g., nitrogen, phosphorus), and light (minimum annual irradiance dose > 50 E m−2). Especially productive kelp forests tend to be associated with areas of significant oceanographic upwelling, a process that delivers cool nutrient-rich water from depth to the ocean's mixed surface layer. Water flow and turbulence facilitate nutrient assimilation across kelp fronds throughout the water column. Water clarity affects the depth to which sufficient light can be


id: marine-habitat-20260505-5
file: data/en.wikipedia.org/wiki/Marine_habitat-5.md
category: reference
title: Marine habitat
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_habitat
date_saved: 2026-05-05T07:35:24.136463+00:00
instance: kb-cron
parent: marine-habitat-20260505-0
summary:
=== Surface microlayer === The surface microlayer of the ocean serves as the transitional area between the atmosphere and the ocean. It covers around 70% of the Earth's surface as it covers most of the ocean waters on the planet. The microlayer is known for its unique biological and chemical properties which give it a small ecosystem of its own and serves as a distinct habitat from the deeper ocean waters. The surface microlayer is not in fact entirely aqueous like the rest of the ocean, but is closer to a kind of hydrated gel composed of concentrated nutrients forming a biological film over the water it covers. This film is rich in microbes which mediate the interactions between the sun, the atmosphere, and the waters below. Although thin, the surface microlayer is critical for life beneath it. Because of the environment rich in microbes and nutrients, larvae of fish and other aquatic animals are often laid in the microlayer to incubate. The plankton in the microlayer are distinctly adapted to withstand high levels of radiation, and serve as buffers to prevent this potentially harmful radiation from reaching the deeper water. Environmental changes such as aerosols or dust storms can


id: marine-habitat-20260505-6
file: data/en.wikipedia.org/wiki/Marine_habitat-6.md
category: reference
title: Marine habitat
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_habitat
date_saved: 2026-05-05T07:35:24.136463+00:00
instance: kb-cron
parent: marine-habitat-20260505-0
summary:
The deep sea starts at the aphotic zone, the point where sunlight loses most of its energy in the water. Many life forms that live at these depths have the ability to create their own light a unique evolution known as bio-luminescence. In the deep ocean, the waters extend far below the epipelagic zone, and support very different types of pelagic life forms adapted to living in these deeper zones. Much of the aphotic zone's energy is supplied by the open ocean in the form of detritus. In deep water, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. Its origin lies in activities within the productive photic zone. Marine snow includes dead or dying plankton, protists (diatoms), fecal matter, sand, soot and other inorganic dust. The "snowflakes" grow over time and may reach several centimetres in diameter, travelling for weeks before reaching the ocean floor. However, most organic components of marine snow are consumed by microbes, zooplankton and other filter-feeding animals within the first 1,000 metres of their journey, that is, within the epipelagic zone. In this way marine snow may be considered the foundation of deep-sea mesopelagic and


id: marine-habitat-20260505-7
file: data/en.wikipedia.org/wiki/Marine_habitat-7.md
category: reference
title: Marine habitat
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_habitat
date_saved: 2026-05-05T07:35:24.136463+00:00
instance: kb-cron
parent: marine-habitat-20260505-0
summary:
There are also negative anthropogenic impacts on deep sea habitats, including trash pollution and chemical pollution. Plastic pollution in particular, is one of the greatest forms of uncontrolled human activity that is visible in our oceans today. Researchers in the Northwestern south China Sea recorded large plastic-dominated litter piles in submarine canyons. These durable plastics can diffuse into smaller organisms and are then inadvertently consumed by humans in the food we eat and water we drink. Another threat to organisms lurking in the deep ocean is ghost fishing, and bycatch. Ghost fishing is the term that refers to any abandoned fishing gear in the ocean that continues to entangle and trap marine organisms. Gill nets for example, have been recorded tangled around deep sea corals and continue ghost fishing for extended periods of time. == Gallery == == See also == Effects of climate change on oceans Future of Marine Animal Populations Maritime forest Seashore wildlife Underwater habitat (underwater habitats for humans) == References == === Sources === Kritzer JP; Sale PF (2006). Marine metapopulations. Academic Press. ISBN 978-0-12-088781-1. Moyle, PB and Cech, JJ (2004) Fishes, An Introduction to Ichthyology. 5th Ed, Benjamin Cummings. ISBN 978-0-13-100847-2. Nybakken JW; Bertness MD


id: marine-botany-20260505-0
file: data/en.wikipedia.org/wiki/Marine_botany-0.md
category: reference
title: Marine botany
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_botany
date_saved: 2026-05-05T07:35:25.495279+00:00
instance: kb-cron
parent: marine-botany-20260505-0
summary:
Marine botany is the study of plant life in a marine environment. It includes the study of marine algae, seagrasses, and other aquatic plants of the ocean, and their distributions and natural environment. It is a branch of marine biology and botany. == Marine ecology == Marine ecology and marine botany's area of study includes: Benthic zone Coral reefs Kelp forests Mangroves Phytoplankton Salt marshes Sea grass Seaweed == See also == Aquatic plants Aquatic ecology "Aquatic Botany" Phycology Index: Marine botany Marine primary production == References ==


id: marine-chemistry-20260505-0
file: data/en.wikipedia.org/wiki/Marine_chemistry-0.md
category: reference
title: Marine chemistry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_chemistry
date_saved: 2026-05-05T07:35:26.772908+00:00
instance: kb-cron
parent: marine-chemistry-20260505-0
summary:
Marine chemistry, also known as ocean chemistry or chemical oceanography, is the study of the chemical composition and processes of the world’s oceans, including the interactions between seawater, the atmosphere, the seafloor, and marine organisms. This field encompasses a wide range of topics, such as the cycling of elements like carbon, nitrogen, and phosphorus, the behavior of trace metals, and the study of gases and nutrients in marine environments. Marine chemistry plays a crucial role in understanding global biogeochemical cycles, ocean circulation, and the effects of human activities, such as pollution and climate change, on oceanic systems. It is influenced by plate tectonics and seafloor spreading, turbidity, currents, sediments, pH levels, atmospheric constituents, metamorphic activity, and ecology. The impact of human activity on the chemistry of the Earth's oceans has increased over time, with pollution from industry and various land-use practices significantly affecting the oceans. Moreover, increasing levels of carbon dioxide in the Earth's atmosphere have led to ocean acidification, which has negative effects on marine ecosystems. The international community has agreed that restoring the chemistry of the oceans is a priority, and efforts toward this goal are tracked as part of Sustainable Development Goal 14. Due to the interrelatedness


id: marine-chemistry-20260505-1
file: data/en.wikipedia.org/wiki/Marine_chemistry-1.md
category: reference
title: Marine chemistry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_chemistry
date_saved: 2026-05-05T07:35:26.772908+00:00
instance: kb-cron
parent: marine-chemistry-20260505-0
summary:
Seafloor spreading on mid-ocean ridges is a global scale ion-exchange system. Hydrothermal vents at spreading centers introduce various amounts of iron, sulfur, manganese, silicon and other elements into the ocean, some of which are recycled into the ocean crust. Helium-3, an isotope that accompanies volcanism from the mantle, is emitted by hydrothermal vents and can be detected in plumes within the ocean. Spreading rates on mid-ocean ridges vary between 10 and 200 mm/yr. Rapid spreading rates cause increased basalt reactions with seawater. The magnesium/calcium ratio will be lower because more magnesium ions are being removed from seawater and consumed by the rock, and more calcium ions are being removed from the rock and released to seawater. Hydrothermal activity at ridge crest is efficient in removing magnesium. A lower Mg/Ca ratio favors the precipitation of low-Mg calcite polymorphs of calcium carbonate (calcite seas). Slow spreading at mid-ocean ridges has the opposite effect and will result in a higher Mg/Ca ratio favoring the precipitation of aragonite and high-Mg calcite polymorphs of calcium carbonate (aragonite seas). Experiments show that most modern high-Mg calcite organisms would have been low-Mg calcite in past calcite seas, meaning that the Mg/Ca ratio in an organism's skeleton varies


id: marine-debris-20260505-0
file: data/en.wikipedia.org/wiki/Marine_debris-0.md
category: reference
title: Marine debris
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_debris
date_saved: 2026-05-05T07:35:28.009276+00:00
instance: kb-cron
parent: marine-debris-20260505-0
summary:
Marine debris, also known as marine litter, is human-created solid material that has deliberately or accidentally been released in seas or the ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping. Naturally occurring debris, such as driftwood and drift seeds, are also present. With the increasing use of plastic, human influence has become an issue as many types of (petrochemical) plastics do not biodegrade quickly, as would natural or organic materials. The largest single type of plastic pollution (~10%) and majority of large plastic in the oceans is discarded and lost nets from the fishing industry. Waterborne plastic poses a serious threat to fish, seabirds, marine reptiles, and marine mammals, as well as to boats and coasts. Dumping, container spillages, litter washed into storm drains and waterways and wind-blown landfill waste all contribute to this problem. This increased water pollution has caused serious negative effects such as discarded fishing nets capturing animals, concentration of plastic debris in massive marine garbage patches, and increasing concentrations of contaminants in the food chain. In efforts


id: marine-debris-20260505-1
file: data/en.wikipedia.org/wiki/Marine_debris-1.md
category: reference
title: Marine debris
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_debris
date_saved: 2026-05-05T07:35:28.009276+00:00
instance: kb-cron
parent: marine-debris-20260505-0
summary:
=== Deep-sea debris === Marine debris is found on the floor of the Arctic ocean. Although an increasing number of studies have been focused on plastic debris accumulation on the coasts, in off-shore surface waters, and that ingested by marine organisms that live in the upper levels of the water column, there is limited information on debris in the mesopelagic and deeper layers. Studies that have been done have conducted research through bottom sampling, video observation via remotely operated vehicles (ROVs), and submersibles. They are also mostly limited to one-off projects that do not extend long enough to show significant effects of deep-sea debris over time. Research thus far has shown that debris in the deep-ocean is in fact impacted by anthropogenic activities, and plastic has been frequently observed in the deep-sea, especially in areas off-shore of heavily populated regions, such as the Mediterranean. Litter, made from diverse materials that are lighter than surface water (such as glasses, metals and some plastics), have been found to spread over the floor of seas and open oceans, where it can become entangled in corals and interfere with other sea-floor life, or even become buried under sediment, making clean-up extremely difficult, especially due


id: marine-debris-20260505-2
file: data/en.wikipedia.org/wiki/Marine_debris-2.md
category: reference
title: Marine debris
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_debris
date_saved: 2026-05-05T07:35:28.009276+00:00
instance: kb-cron
parent: marine-debris-20260505-0
summary:
Not all anthropogenic artifacts placed in the oceans are harmful. Iron and concrete structures typically do little damage to the environment because they generally sink to the bottom and become immobile, and at shallow depths they can even provide scaffolding for artificial reefs. Ships and subway cars have been deliberately sunk for that purpose. Additionally, hermit crabs have been known to use pieces of beach litter as a shell when they cannot find an actual seashell of the size they need. === Impacts from plastic pollution === Many animals that live on or in the sea consume flotsam by mistake, as it often looks similar to their natural prey. Overall, 1288 marine species are known to ingest plastic debris, with fish making up the largest fraction. Bulky plastic debris may become permanently lodged in the digestive tracts of these animals, blocking the passage of food and causing death through starvation or infection. Tiny floating plastic particles also resemble zooplankton, which can lead filter feeders to consume them and cause them to enter the ocean food chain. In addition, plastic in the marine environment that contaminates the food chain can have repercussions on the viability of fish and shellfish species. ===


id: marine-debris-20260505-3
file: data/en.wikipedia.org/wiki/Marine_debris-3.md
category: reference
title: Marine debris
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_debris
date_saved: 2026-05-05T07:35:28.009276+00:00
instance: kb-cron
parent: marine-debris-20260505-0
summary:
=== Mid-ocean clean ups === On the sea, the removal of artificial debris (i.e. plastics) is still in its infancy. However, some projects have been started which used ships with nets (Ocean Voyages Institute/Kaisei 2009 & 2010 and New Horizon 2009) to catch some plastics, primarily for research purposes. There is also Bluebird Marine System's SeaVax which was solar- and wind-powered and had an onboard shredder and cargo hold. The Sea Cleaners' Manta ship is similar in concept. Another method to gather artificial litter has been proposed by The Ocean Cleanup's Boyan Slat. He suggested using platforms with arms to gather the debris, situated inside the current of gyres. The SAS Ocean Phoenix ship is somewhat similar in design. In June 2019, Ocean Voyages Institute, conducted a cleanup utilizing GPS trackers and existing maritime equipment in the North Pacific Subtropical Convergence Zone setting the record for the largest mid-ocean cleanup accomplished in the North Pacific Gyre and removed over 84,000 pounds of polymer nets and consumer plastic trash from the ocean. In May/June 2020, Ocean Voyages Institute conducted a cleanup expedition in the Gyre and set a new record for the largest mid-ocean cleanup accomplished in the North Pacific Gyre


id: marine-debris-20260505-4
file: data/en.wikipedia.org/wiki/Marine_debris-4.md
category: reference
title: Marine debris
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_debris
date_saved: 2026-05-05T07:35:28.009276+00:00
instance: kb-cron
parent: marine-debris-20260505-0
summary:
=== Ownership === Property law, admiralty law and the law of the sea may be of relevance when lost, mislaid, and abandoned property is found at sea. Salvage law rewards salvors for risking life and property to rescue the property of another from peril. On land the distinction between deliberate and accidental loss led to the concept of a "treasure trove". In the United Kingdom, shipwrecked goods should be reported to a Receiver of Wreck, and if identifiable, they should be returned to their rightful owner. == Activism == A large number of groups and individuals are active in preventing or educating about marine debris. For example, 5 Gyres is an organization aimed at reducing plastics pollution in the oceans, and was one of two organizations that recently researched the Great Pacific Garbage Patch. Heal the Bay is another organization, focusing on protecting California's Santa Monica Bay, by sponsoring beach cleanup programs along with other activities. Marina DeBris is an artist focusing most of her recent work on educating people about beach trash. Interactive sites like Adrift demonstrate where marine plastic is carried, over time, on the worlds ocean currents. On 11 April 2013 in order to create awareness, artist


id: marine-ecoregion-20260505-0
file: data/en.wikipedia.org/wiki/Marine_ecoregion-0.md
category: reference
title: Marine ecoregion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_ecoregion
date_saved: 2026-05-05T07:35:29.187903+00:00
instance: kb-cron
parent: marine-ecoregion-20260505-0
summary:
A marine ecoregion is an ecoregion, or ecological region, of the oceans and seas identified and defined based on biogeographic characteristics. == Introduction == A more complete definition describes them as “Areas of relatively homogeneous species composition, clearly distinct from adjacent systems” dominated by “a small number of ecosystems and/or a distinct suite of oceanographic or topographic features”. Ecologically they “are strongly cohesive units, sufficiently large to encompass ecological or life history processes for most sedentary species.” == Marine Ecoregions of the World—MEOW == The global classification system Marine Ecoregions of the World—MEOW was devised by an international team, including major conservation organizations, academic institutions and intergovernmental organizations. The system covers coastal and continental shelf waters of the world, and does not include deep ocean waters. The MEOW system integrated the biogeographic regionalization systems in use at national or continental scale, like Australia's Integrated Marine and Coastal Regionalisation of Australia and the Nature Conservancy’s system in the Americas, although it often uses different names for the subdivisions. This system has a strong biogeographic basis, but was designed to aid in conservation activities for marine ecosystems. Its subdivisions include both the seafloor (benthic) and shelf pelagic (neritic) biotas of each marine


id: marine-ecosystem-20260505-0
file: data/en.wikipedia.org/wiki/Marine_ecosystem-0.md
category: reference
title: Marine ecosystem
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_ecosystem
date_saved: 2026-05-05T07:35:30.386953+00:00
instance: kb-cron
parent: marine-ecosystem-20260505-0
summary:
Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% of the surface of the Earth and account for more than 97% of Earth's water supply and 90% of habitable space on Earth. Seawater has an average salinity of 35 parts per thousand of water. Actual salinity varies among different marine ecosystems. Marine ecosystems can be divided into many zones depending upon water depth and shoreline features. The oceanic zone is the vast open part of the ocean where animals such as whales, sharks, and tuna live. The benthic zone consists of substrates below water where many invertebrates live. The intertidal zone is the area between high and low tides. Other near-shore (neritic) zones can include mudflats, seagrass meadows, mangroves, rocky intertidal systems, salt marshes, coral reefs, kelp forests and lagoons. In the deep water, hydrothermal vents may occur where chemosynthetic sulfur bacteria form the base of the food web. Marine ecosystems are characterized by the biological community of organisms that they are associated with and their physical environment. Classes of organisms found


id: marine-ecosystem-20260505-1
file: data/en.wikipedia.org/wiki/Marine_ecosystem-1.md
category: reference
title: Marine ecosystem
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_ecosystem
date_saved: 2026-05-05T07:35:30.386953+00:00
instance: kb-cron
parent: marine-ecosystem-20260505-0
summary:
Estuaries occur where there is a noticeable change in salinity between saltwater and freshwater sources. This is typically found where rivers meet the ocean or sea. The wildlife found within estuaries is unique as the water in these areas is brackish - a mix of freshwater flowing to the ocean and salty seawater. Other types of estuaries also exist and have similar characteristics as traditional brackish estuaries. The Great Lakes are a prime example. There, river water mixes with lake water and creates freshwater estuaries. Estuaries are extremely productive ecosystems that many humans and animal species rely on for various activities. This can be seen as, of the 32 largest cities in the world, 22 are located on estuaries as they provide many environmental and economic benefits such as crucial habitat for many species, and being economic hubs for many coastal communities. Estuaries also provide essential ecosystem services such as water filtration, habitat protection, erosion control, gas regulation nutrient cycling, and it even gives education, recreation and tourism opportunities to people. ==== Lagoons ==== Lagoons are areas that are separated from larger water by natural barriers such as coral reefs or sandbars. There are two types of lagoons, coastal and


id: marine-ecosystem-20260505-2
file: data/en.wikipedia.org/wiki/Marine_ecosystem-2.md
category: reference
title: Marine ecosystem
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_ecosystem
date_saved: 2026-05-05T07:35:30.386953+00:00
instance: kb-cron
parent: marine-ecosystem-20260505-0
summary:
Organisms that live freely at the surface, termed neuston, include keystone organisms like the golden seaweed Sargassum that makes up the Sargasso Sea, floating barnacles, marine snails, nudibranchs, and cnidarians. Many ecologically and economically important fish species live as or rely upon neuston. Species at the surface are not distributed uniformly; the ocean's surface harbours unique neustonic communities and ecoregions found at only certain latitudes and only in specific ocean basins. But the surface is also on the front line of climate change and pollution. Life on the ocean's surface connects worlds. From shallow waters to the deep sea, the open ocean to rivers and lakes, numerous terrestrial and marine species depend on the surface ecosystem and the organisms found there. The ocean's surface acts like a skin between the atmosphere above and the water below, and harbours an ecosystem unique to this environment. This sun-drenched habitat can be defined as roughly one metre in depth, as nearly half of UV-B is attenuated within this first meter. Organisms here must contend with wave action and unique chemical and physical properties. The surface is utilised by a wide range of species, from various fish and cetaceans, to species that ride on


id: marine-ecosystem-20260505-3
file: data/en.wikipedia.org/wiki/Marine_ecosystem-3.md
category: reference
title: Marine ecosystem
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_ecosystem
date_saved: 2026-05-05T07:35:30.386953+00:00
instance: kb-cron
parent: marine-ecosystem-20260505-0
summary:
=== Human exploitation and development === Coastal marine ecosystems experience growing population pressures with nearly 40% of people in the world living within 100 km of the coast. Humans often aggregate near coastal habitats to take advantage of ecosystem services. For example, coastal capture fisheries from mangroves and coral reef habitats are estimated to be worth a minimum of $34 billion per year. Yet, many of these habitats are either marginally protected or not protected. Mangrove area has declined worldwide by more than one-third since 1950, and 60% of the world's coral reefs are now immediately or directly threatened. Human development, aquaculture, and industrialization often lead to the destruction, replacement, or degradation of coastal habitats. Moving offshore, pelagic marine systems are directly threatened by overfishing. Global fisheries landings peaked in the late 1980s, but are now declining, despite increasing fishing effort. Fish biomass and average trophic level of fisheries landing are decreasing, leading to declines in marine biodiversity. In particular, local extinctions have led to declines in large, long-lived, slow-growing species, and those that have narrow geographic ranges. Biodiversity declines can lead to associated declines in ecosystem services. A long-term study reports the decline of 74–92% of catch per unit


id: marine-energy-20260505-0
file: data/en.wikipedia.org/wiki/Marine_energy-0.md
category: reference
title: Marine energy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_energy
date_saved: 2026-05-05T07:35:31.644809+00:00
instance: kb-cron
parent: marine-energy-20260505-0
summary:
Marine energy, also known as ocean energy, ocean power, or marine and hydrokinetic energy, refers to energy harnessed from waves, tides, salinity gradients, and temperature differences in the ocean. The movement of water in the world's oceans stores vast amounts of kinetic energy, which can be converted into electricity to power homes, transportation, and industries. Marine energy includes wave power, which is derived from surface waves, and tidal power, which is obtained from the kinetic energy of moving water. Offshore wind power, however, is not considered marine energy because it is generated from wind, even if the wind turbines are located over water.The oceans have a tremendous amount of energy and are close to many if not most concentrated populations. Ocean energy has the potential of providing a substantial amount of new renewable energy around the world. While marine energy is a sustainable alternative to fossil fuels, its development can impact marine ecosystems, wildlife, and the physical environment. Potential effects include habitat disruption, noise pollution, and electromagnetic fields from subsea cables, which may require mitigation strategies such as fish-friendly turbine designs and environmental impact assessments. Government policies, economic incentives, and regulatory frameworks contribute significantly to advancing marine energy, with countries


id: marine-energy-20260505-1
file: data/en.wikipedia.org/wiki/Marine_energy-1.md
category: reference
title: Marine energy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_energy
date_saved: 2026-05-05T07:35:31.644809+00:00
instance: kb-cron
parent: marine-energy-20260505-0
summary:
Solar energy from the Sun creates temperature differentials that result in wind. The interaction between wind and the surface of water creates waves, which are larger when there is a greater distance for them to build up. Wave energy potential is greatest between 30° and 60° latitude in both hemispheres on the west coast because of the global direction of wind. When evaluating wave energy as a technology type, it is important to distinguish between the four most common approaches: point absorber buoys, surface attenuators, oscillating water columns, and overtopping devices. The wave energy sector is reaching a significant milestone in the development of the industry, with steps towards commercial viability being taken. The more advanced device developers are currently progressing beyond single unit demonstration devices and are proceeding to array development and multi-megawatt projects. The backing of major utility companies is now manifesting itself through partnerships within the development process, unlocking further investment, and in some cases, international co-operation. At a simplified level, wave energy technology can be located near-shore and offshore. Wave energy converters can also be designed for operation in specific water depth conditions: deep water, intermediate water or shallow water. The fundamental device design will be


id: marine-energy-20260505-2
file: data/en.wikipedia.org/wiki/Marine_energy-2.md
category: reference
title: Marine energy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_energy
date_saved: 2026-05-05T07:35:31.644809+00:00
instance: kb-cron
parent: marine-energy-20260505-0
summary:
Economic Considerations Marine energy is still in the early stages of commercialization, and its economic viability depends on reducing costs and improving efficiency. The high capital expenditure (CapEx) and operational expenditure (OpEx) associated with marine energy projects have historically been barriers to widespread adoption. However, technological advancements, economies of scale, and government support are helping to drive down costs. For example, the levelized cost of energy (LCOE) for tidal and wave energy has decreased significantly in recent years, though it remains higher than that of more established renewable energy sources like wind and solar. Government subsidies, grants, and tax incentives are often used to offset the high initial costs of marine energy projects. These financial mechanisms are designed to encourage private sector investment and accelerate the deployment of marine energy technologies. Government Policies and Regulatory Frameworks Government policies significantly influence the development of marine energy. Many countries have implemented renewable energy targets, feed-in tariffs, and renewable portfolio standards (RPS) to promote the development of marine energy. For instance, the European Union has set ambitious renewable energy targets as part of its Green Deal, with marine energy identified as a key component of its strategy to achieve carbon neutrality by 2050.


id: marine-regression-20260505-0
file: data/en.wikipedia.org/wiki/Marine_regression-0.md
category: reference
title: Marine regression
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_regression
date_saved: 2026-05-05T07:35:32.922810+00:00
instance: kb-cron
parent: marine-regression-20260505-0
summary:
A marine regression is a geological process occurring when areas of submerged seafloor are exposed during a drop in sea level. The opposite event, marine transgression, occurs when flooding from the sea covers previously-exposed land. == Description == According to one hypothesis, regressions may be linked to a "slowdown in sea-floor spreading, leading to a generalized drop in sea level (as the mid-ocean ridges would take up less space)...." That view considers major marine regressions to be one aspect of a normal variation in rates of plate tectonic activity, which leads to major episodes of global volcanism like the Siberian Traps and the Deccan Traps, which in turn cause large extinction events. Evidence of marine regressions and transgressions occurs throughout the fossil record, and the fluctuations are thought to have caused or contributed to several mass extinctions, such as the Permian–Triassic extinction event (250 million years ago, Ma) and Cretaceous–Paleogene extinction event (66 Ma). During the Permian-Triassic extinction, the largest extinction event in the Earth's history, the global sea level fell 250 m (820 ft). A major regression could cause marine organisms in shallow seas to go extinct, but mass extinctions tend to involve both terrestrial and aquatic species, and


id: marine-snow-20260505-0
file: data/en.wikipedia.org/wiki/Marine_snow-0.md
category: reference
title: Marine snow
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_snow
date_saved: 2026-05-05T07:35:34.238748+00:00
instance: kb-cron
parent: marine-snow-20260505-0
summary:
In the deep ocean, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to the aphotic zone below, which is referred to as the biological pump. Export production is the amount of organic matter produced in the ocean by primary production that is not recycled (remineralised) before it sinks into the aphotic zone. Because of the role of export production in the ocean's biological pump, it is typically measured in units of carbon (e.g. mg C m−2 d−1). The term was coined by explorer William Beebe as observed from his bathysphere. As the origin of marine snow lies in activities within the productive photic zone, the prevalence of marine snow changes with seasonal fluctuations in photosynthetic activity and ocean currents. Marine snow can be an important food source for organisms living in the aphotic zone, particularly for organisms that live very deep in the water column. == Composition == Marine snow is made up of a variety of mostly organic matter, including dead or dying animals and phytoplankton, protists, fecal matter, sand, and other inorganic dust. Most


id: marine-snow-20260505-1
file: data/en.wikipedia.org/wiki/Marine_snow-1.md
category: reference
title: Marine snow
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_snow
date_saved: 2026-05-05T07:35:34.238748+00:00
instance: kb-cron
parent: marine-snow-20260505-0
summary:
Planktonic prokaryotes are further defined into two categories, free-living or particle associated. The two are separated by filtration. Particle-associated bacteria are often difficult to study because marine snow aggregates are often ranging in sizes from 0.2 to 200 μm, often rendering sampling efforts difficult. These aggregates are hotspots for microbial activity. Marine bacteria are the most abundant organisms in aggregates followed by cyanobacteria and then nanoflagellates. Aggregates can be enriched about one thousand times more than the surrounding seawater. Seasonal variability can also have an effect on microbial communities of marine snow aggregates with concentrations being the highest during the summer. As illustrated in the diagram, phytoplankton fix carbon dioxide in the euphotic zone using solar energy and produce particulate organic carbon. The particulate organic carbon formed in the euphotic zone is processed by marine microorganisms (microbes), zooplankton and their consumers into organic aggregates (marine snow), which is then exported to the mesopelagic (200–1000 m depth) and bathypelagic zones by sinking and vertical migration by zooplankton and fish. Export flux is defined as the sedimentation out of the surface layer (at approximately 100 m depth) and sequestration flux is the sedimentation out of the mesopelagic zone (at approximately 1000 m


id: mediterranean-seas-20260505-0
file: data/en.wikipedia.org/wiki/Mediterranean_seas-0.md
category: reference
title: Mediterranean seas
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mediterranean_seas
date_saved: 2026-05-05T07:35:35.481636+00:00
instance: kb-cron
parent: mediterranean-seas-20260505-0
summary:
In oceanography, a mediterranean sea ( MED-ih-tə-RAY-nee-ən) is a mostly enclosed sea that has limited exchange of water with outer oceans and whose water circulation is dominated by salinity and temperature differences rather than by winds or tides. The eponymous Mediterranean Sea, for example, is almost completely enclosed by Africa, Asia, and Europe. == List of mediterranean seas by ocean == === Atlantic Ocean === The Arctic Ocean (a.k.a. the Arctic Mediterranean Sea) The American Mediterranean Sea (the combination of the Caribbean Sea and the Gulf of Mexico) Baffin Bay The Baltic Sea The namesake Mediterranean Sea (including the Adriatic Sea, the Aegean Sea (including the Sea of Crete and the Thracian Sea), the Alboran Sea, the Balearic Sea, the Sardinian Sea, the Black Sea, the Ionian Sea, the Ligurian Sea, the Sea of Azov, the Sea of Marmara, and the Tyrrhenian Sea) === Indian Ocean === The Persian Gulf The Red Sea === Pacific Ocean === The Australasian Mediterranean Sea (including the Banda Sea, the Java Sea, the Sulawesi Sea, and the Sulu Sea) == List of mediterranean seas by type == There are two types of mediterranean sea. === Concentration basin === A concentration basin has a higher


id: megatsunami-20260505-0
file: data/en.wikipedia.org/wiki/Megatsunami-0.md
category: reference
title: Megatsunami
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Megatsunami
date_saved: 2026-05-05T07:35:36.838495+00:00
instance: kb-cron
parent: megatsunami-20260505-0
summary:
A megatsunami is an extremely large wave created by a substantial and sudden displacement of material into a body of water. Megatsunamis have different features from ordinary tsunamis. Ordinary tsunamis are caused by underwater tectonic activity (movement of the earth's plates) and therefore occur along plate boundaries and as a result of earthquakes and the subsequent rise or fall in the sea floor that displaces a volume of water. Ordinary tsunamis exhibit shallow waves in the deep waters of the open ocean that increase dramatically in height upon approaching land to a maximum run-up height of around 30 metres (100 ft) in the cases of the most powerful earthquakes. By contrast, megatsunamis occur when a large amount of material suddenly falls into water or anywhere near water (such as via a landslide, meteor impact, or volcanic eruption). They can have extremely large initial wave heights in the hundreds of metres, far beyond the height of any ordinary tsunami. These giant wave heights occur because the water is "splashed" upwards and outwards by the displacement. Examples of modern megatsunamis include the one associated with the 1883 eruption of Krakatoa (volcanic eruption), the 1958 Lituya Bay earthquake and megatsunami (a landslide which


id: megatsunami-20260505-1
file: data/en.wikipedia.org/wiki/Megatsunami-1.md
category: reference
title: Megatsunami
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Megatsunami
date_saved: 2026-05-05T07:35:36.838495+00:00
instance: kb-cron
parent: megatsunami-20260505-0
summary:
A megatsunami is a tsunami with an initial wave amplitude (height) measured in many tens or hundreds of metres. The term "megatsunami" has been defined by media and has no precise definition, although it is commonly taken to refer to tsunamis over 100 metres (328 ft) high. A megatsunami is a separate class of event from an ordinary tsunami and is caused by different physical mechanisms. Normal tsunamis result from displacement of the sea floor due to movements in the Earth's crust (plate tectonics). Powerful earthquakes may cause the sea floor to displace vertically on the order of tens of metres, which in turn displaces the water column above and leads to the formation of a tsunami. Ordinary tsunamis have a small wave height offshore and generally pass unnoticed at sea, forming only a slight swell on the order of 30 centimetres (12 in) above the normal sea surface. In deep water it is possible that a tsunami could pass beneath a ship without the crew of the vessel noticing. As it approaches land, the wave height of an ordinary tsunami increases dramatically as the sea floor slopes upward and the base of the wave pushes the water column above


id: megatsunami-20260505-2
file: data/en.wikipedia.org/wiki/Megatsunami-2.md
category: reference
title: Megatsunami
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Megatsunami
date_saved: 2026-05-05T07:35:36.838495+00:00
instance: kb-cron
parent: megatsunami-20260505-0
summary:
== Recognition of the concept of megatsunami == Before the 1950s, scientists had theorized that tsunamis orders of magnitude larger than those observed with earthquakes could have occurred as a result of ancient geological processes, but no concrete evidence of the existence of these "monster waves" had yet been gathered. Geologists searching for oil in Alaska in 1953 observed that in Lituya Bay, mature tree growth did not extend to the shoreline as it did in many other bays in the region. Rather, there was a band of younger trees closer to the shore. Forestry workers, glaciologists, and geographers call the boundary between these bands a trim line. Trees just above the trim line showed severe scarring on their seaward side, while those from below the trim line did not. This indicated that a large force had impacted all of the elder trees above the trim line, and presumably had killed off all the trees below it. Based on this evidence, the scientists hypothesized that there had been an unusually large wave or waves in the deep inlet. Because this is a recently deglaciated fjord with steep slopes and crossed by a major fault (the Fairweather Fault), one possibility was


id: megatsunami-20260505-3
file: data/en.wikipedia.org/wiki/Megatsunami-3.md
category: reference
title: Megatsunami
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Megatsunami
date_saved: 2026-05-05T07:35:36.838495+00:00
instance: kb-cron
parent: megatsunami-20260505-0
summary:
=== Prehistoric === An astronomical object between 37 and 58 kilometres (23 and 36 mi) wide traveling at 20 kilometres (12.4 mi) per second struck the Earth 3.26 billion years ago east of what is now Johannesburg, South Africa, near South Africa's border with Eswatini, in what was then an Archean ocean that covered most of the planet, creating a crater about 500 kilometres (310 mi) wide. The impact generated a megatsunami that probably extended to a depth of thousands of meters beneath the surface of the ocean and probably rose to the height of a skyscraper when it reached shorelines. The resultant event created the Barberton Greenstone Belt. The asteroid linked to the extinction of dinosaurs, which created the Chicxulub crater in the Yucatán Peninsula approximately 66 million years ago, would have caused a megatsunami over 100 metres (330 ft) tall. The height of the tsunami was limited due to relatively shallow sea in the area of the impact; had the asteroid struck in the deep sea the megatsunami would have likely been 4.6 kilometres (2.9 mi) tall. Among the mechanisms triggering megatsunamis were the direct impact, shockwaves, returning water in the crater with a new push outward and


id: megatsunami-20260505-4
file: data/en.wikipedia.org/wiki/Megatsunami-4.md
category: reference
title: Megatsunami
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Megatsunami
date_saved: 2026-05-05T07:35:36.838495+00:00
instance: kb-cron
parent: megatsunami-20260505-0
summary:
=== Historic === ==== c. 2000 BC: Réunion ==== A landslide on Réunion island, to the east of Madagascar, may have caused a megatsunami. ==== c. 1600 BC: Santorini ==== The Thera volcano erupted, the force of the eruption causing megatsunamis which affected the whole Aegean Sea and the eastern Mediterranean Sea. ==== c. 1100 BC: Lake Crescent ==== An earthquake generated the 7,200,000-cubic-metre (9,400,000 cu yd) Sledgehammer Point Rockslide, which fell from Mount Storm King in what is now Washington in the United States and entered waters at least 140 metres (459 ft) deep in Lake Crescent, generating a megatsunami with an estimated maximum run-up height of 82 to 104 metres (269 to 341 ft). === Modern === ==== 1674: Ambon Island, Banda Sea ==== On 17 February 1674, between 19:30 and 20:00 local time, an earthquake struck the Maluku Islands. Ambon Island received run-up heights of 100 metres (328 ft), making the wave far too large to be caused by the quake itself. Instead, it was probably the result of an underwater landslide triggered by the earthquake. The quake and tsunami killed 2,347 people. ==== 1731: Storfjorden, Norway ==== At 10:00 p.m. on 8 January 1731, a landslide


id: megatsunami-20260505-5
file: data/en.wikipedia.org/wiki/Megatsunami-5.md
category: reference
title: Megatsunami
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Megatsunami
date_saved: 2026-05-05T07:35:36.838495+00:00
instance: kb-cron
parent: megatsunami-20260505-0
summary:
The massive explosion of Krakatoa created pyroclastic flows which generated megatsunamis when they hit the waters of the Sunda Strait on 27 August 1883. The waves reached heights of up to 24 metres (79 feet) along the south coast of Sumatra and up to 42 metres (138 feet) along the west coast of Java. The tsunamis were powerful enough to kill over 30,000 people, and their effect was such that an area of land in Banten had its human settlements wiped out, and they never repopulated. (This area rewilded and was later declared a national park.) The steamship Berouw, a colonial gunboat, was flung over a mile (1.6 km) inland on Sumatra by the wave, killing its entire crew. Two thirds of the island collapsed into the sea after the event. Groups of human skeletons were found floating on pumice numerous times, up to a year after the event. The eruption also generated what is often called the loudest sound in history, which was heard 4,800 kilometres (3,000 mi; 2,600 nmi) away on Rodrigues in the Indian Ocean. ==== 1905: Lovatnet, Norway ==== On 15 January 1905, a landslide on the slope of the mountain Ramnefjellet with a volume of


id: megatsunami-20260505-6
file: data/en.wikipedia.org/wiki/Megatsunami-6.md
category: reference
title: Megatsunami
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Megatsunami
date_saved: 2026-05-05T07:35:36.838495+00:00
instance: kb-cron
parent: megatsunami-20260505-0
summary:
==== 1963: Vajont Dam, Italy ==== On 9 October 1963, a landslide above Vajont Dam in Italy produced a 250 m (820 ft) surge that overtopped the dam and destroyed the villages of Longarone, Pirago, Rivalta, Villanova, and Faè, killing nearly 2,000 people. This is currently the only known example of a megatsunami that was indirectly caused by human activities. ==== 1964: Valdez Arm, Alaska ==== On 27 March 1964, the 1964 Alaska earthquake triggered a landslide that generated a megatsunami which reached a height of 70 metres (230 ft) in the Valdez Arm of Prince William Sound in Southcentral Alaska. ==== 1980: Spirit Lake, Washington, US ==== On 18 May 1980, the upper 400 metres (1,300 ft) of Mount St. Helens collapsed, creating a landslide. This released the pressure on the magma trapped beneath the summit bulge which exploded as a lateral blast, which then released the pressure on the magma chamber and resulted in a plinian eruption. One lobe of the avalanche surged onto Spirit Lake, causing a megatsunami which pushed the lake waters in a series of surges, which reached a maximum height of 260 metres (850 ft) above the pre-eruption water level (about 975 m (3,199


id: megatsunami-20260505-7
file: data/en.wikipedia.org/wiki/Megatsunami-7.md
category: reference
title: Megatsunami
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Megatsunami
date_saved: 2026-05-05T07:35:36.838495+00:00
instance: kb-cron
parent: megatsunami-20260505-0
summary:
==== 2020: Elliot Creek, British Columbia, Canada ==== On 28 November 2020, unseasonably heavy rainfall triggered a landslide of 18,000,000 m3 (24,000,000 cu yd) into a glacial lake at the head of Elliot Creek. The sudden displacement of water generated a 100 m (330 ft) high megatsunami that cascaded down Elliot Creek and the Southgate River to the head of Bute Inlet, covering a total distance of over 60 km (37 mi). The event generated a magnitude 5.0 earthquake and destroyed over 8.5 km (5.3 mi) of salmon habitat along Elliot Creek. The slope had been gradually weakened over time by the retreat of West Grenville Glacier, causing the weight distribution in this area to change. ==== 2023: Dickson Fjord, Greenland ==== On 16 September 2023 a large landslide originating 300–400 m (980–1,310 ft) above sea level entered Dickson Fjord, triggering a tsunami exceeding 200 m (660 ft) in run-up. Run-up of 60 m (200 ft) was observed along a 10 km (6.2 mi) stretch of coast. There was no major damage and there were no casualties. The tsunami was followed by a seiche that lasted for a week. The seiche produced a nine-day disturbance recorded by seismic instruments globally.


id: megatsunami-20260505-8
file: data/en.wikipedia.org/wiki/Megatsunami-8.md
category: reference
title: Megatsunami
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Megatsunami
date_saved: 2026-05-05T07:35:36.838495+00:00
instance: kb-cron
parent: megatsunami-20260505-0
summary:
Geologists Dr. Simon Day and Dr. Steven Neal Ward consider that a megatsunami could be generated during an eruption of Cumbre Vieja on the volcanic ocean island of La Palma, in the Canary Islands, Spain. Day and Ward hypothesize that if such an eruption causes the western flank to fail, a megatsunami could be generated. In 1949, an eruption occurred at three of the volcano's vents – Duraznero, Hoyo Negro, and Llano del Banco. A local geologist, Juan Bonelli-Rubio, witnessed the eruption and recorded details on various phenomenon related to the eruption. Bonelli-Rubio visited the summit area of the volcano and found that a fissure about 2.5 kilometres (1.6 mi) long had opened on the east side of the summit. As a result, the western half of the volcano – which is the volcanically active arm of a triple-armed rift – had slipped approximately 2 metres (7 ft) downwards and 1 metre (3 ft) westwards towards the Atlantic Ocean. In 1971, an eruption occurred at the Teneguía vent at the southern end of the sub-aerial section of the volcano without any movement. The section affected by the 1949 eruption is currently stationary and does not appear to have moved since


id: megatsunami-20260505-9
file: data/en.wikipedia.org/wiki/Megatsunami-9.md
category: reference
title: Megatsunami
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Megatsunami
date_saved: 2026-05-05T07:35:36.838495+00:00
instance: kb-cron
parent: megatsunami-20260505-0
summary:
=== Norway === Although known earlier to the local population, a crack 2 metres (6.6 ft) wide and 500 metres (1,640 ft) in length in the side of the mountain Åkerneset in Norway was rediscovered in 1983 and attracted scientific attention. Located at (62°10'52.28"N, 6°59'35.38"E), it since has widened at a rate of 4 centimetres (1.6 in) per year. Geological analysis has revealed that a slab of rock 62 metres (203 ft) thick and at an elevation stretching from 150 to 900 metres (492 to 2,953 ft) is in motion. Geologists assess that an eventual catastrophic collapse of 18,000,000 to 54,000,000 cubic metres (24,000,000 to 71,000,000 cu yd) of rock into Sunnylvsfjorden is inevitable and could generate megatsunamis of 35 to 100 metres (115 to 328 ft) in height on the fjord′s opposite shore. The waves are expected to strike Hellesylt with a height of 35 to 85 metres (115 to 279 ft), Geiranger with a height of 30 to 70 metres (98 to 230 ft), Tafjord with a height of 14 metres (46 ft), and many other communities in Norway's Sunnmøre district with a height of several metres, and to be noticeable even at Ålesund. The predicted disaster is


id: meroplankton-20260505-0
file: data/en.wikipedia.org/wiki/Meroplankton-0.md
category: reference
title: Meroplankton
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Meroplankton
date_saved: 2026-05-05T07:35:38.143793+00:00
instance: kb-cron
parent: meroplankton-20260505-0
summary:
Meroplankton are a wide variety of aquatic organisms which have both a planktonic stage and at least one other component, such as benthic or nektonic, in their life cycles. Much of the meroplankton consists of larval stages of larger organisms. Meroplankton can be contrasted with holoplankton, which are planktonic organisms that stay in the pelagic zone as plankton throughout their entire life cycle. After a period of time in the plankton, many meroplankton graduate to the nekton or adopt a benthic (often sessile) lifestyle on the seafloor. The larval stages of benthic invertebrates make up a significant proportion of planktonic communities. The planktonic larval stage is particularly crucial to many benthic invertebrate in order to disperse their young. Depending on the particular species and the environmental conditions, larval or juvenile-stage meroplankton may remain in the pelagic zone for durations ranging from hour to months. Not all meroplankton are larvae or juvenile stages of larger organisms. Many dinoflagellates are meroplanktonic, undergoing a seasonal cycle of encystment and dormancy in the benthic zone followed by excystment and reproduction in the pelagic zone before returning to the benthic zone once more. There also exist meroplanktonic diatoms; these have a seasonal resting phase below


id: mid-ocean-ridge-20260505-0
file: data/en.wikipedia.org/wiki/Mid-ocean_ridge-0.md
category: reference
title: Mid-ocean ridge
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mid-ocean_ridge
date_saved: 2026-05-05T07:35:39.450676+00:00
instance: kb-cron
parent: mid-ocean-ridge-20260505-0
summary:
A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about 2,600 meters (8,500 ft) and rises about 2,000 meters (6,600 ft) above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a divergent plate boundary. The rate of seafloor spreading determines the morphology of the crest of the mid-ocean ridge and its width in an ocean basin. The production of new seafloor and oceanic lithosphere results from mantle upwelling in response to plate separation. The melt rises as magma at the linear weakness between the separating plates, and emerges as lava, creating new oceanic crust and lithosphere upon cooling. The first discovered mid-ocean ridge was the Mid-Atlantic Ridge, which is a spreading center that bisects the North and South Atlantic basins; its location was the reason for the name "mid-ocean ridge". Most oceanic spreading centers are not in the middle of their hosting ocean basins, but are traditionally called mid-ocean ridges regardless. Mid-ocean ridges around the globe are linked by plate tectonic boundaries and the trace of the ridges across the ocean floor appears similar to the seam of a baseball. Most mid-ocean


id: mid-ocean-ridge-20260505-1
file: data/en.wikipedia.org/wiki/Mid-ocean_ridge-1.md
category: reference
title: Mid-ocean ridge
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mid-ocean_ridge
date_saved: 2026-05-05T07:35:39.450676+00:00
instance: kb-cron
parent: mid-ocean-ridge-20260505-0
summary:
=== Volcanism === Mid-ocean ridges exhibit active volcanism and seismicity. The oceanic crust is in a constant state of 'renewal' at the mid-ocean ridges by the processes of seafloor spreading and plate tectonics. New magma steadily emerges onto the ocean floor and intrudes into the existing ocean crust at and near rifts along the ridge axes. The rocks making up the crust below the seafloor are youngest along the axis of the ridge and age with increasing distance from that axis. New magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earth's mantle. The isentropic upwelling solid mantle material exceeds the solidus temperature and melts. The crystallized magma forms a new crust of basalt known as MORB for mid-ocean ridge basalt, and gabbro below it in the lower oceanic crust. Mid-ocean ridge basalt is a tholeiitic basalt and is low in incompatible elements. Hydrothermal vents fueled by magmatic and volcanic heat are a common feature at oceanic spreading centers. A feature of the elevated ridges is their relatively high heat flow values, of about 1–10 μcal/cm2s, or roughly 0.04–0.4 W/m2. Most crust in the ocean basins is less than 200 million years


id: mid-ocean-ridge-20260505-2
file: data/en.wikipedia.org/wiki/Mid-ocean_ridge-2.md
category: reference
title: Mid-ocean ridge
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mid-ocean_ridge
date_saved: 2026-05-05T07:35:39.450676+00:00
instance: kb-cron
parent: mid-ocean-ridge-20260505-0
summary:
The first indications that a ridge bisects the Atlantic Ocean basin came from the results of the British Challenger expedition in the nineteenth century. Soundings from lines dropped to the seafloor were analyzed by oceanographers Matthew Fontaine Maury and Charles Wyville Thomson and revealed a prominent rise in the seafloor that ran down the Atlantic basin from north to south. Sonar echo sounders confirmed this in the early twentieth century. It was not until after World War II, when the ocean floor was surveyed in more detail, that the full extent of mid-ocean ridges became known. The Vema, a ship of the Lamont–Doherty Earth Observatory of Columbia University, traversed the Atlantic Ocean, recording echo sounder data on the depth of the ocean floor. A team led by Marie Tharp and Bruce Heezen concluded that there was an enormous mountain chain with a rift valley at its crest, running up the middle of the Atlantic Ocean. Scientists named it the 'Mid-Atlantic Ridge'. Other research showed that the ridge crest was seismically active and fresh lavas were found in the rift valley. Also, crustal heat flow was higher here than elsewhere in the Atlantic Ocean basin. At first, the ridge was thought


id: fesom-20260505-0
file: data/en.wikipedia.org/wiki/FESOM-0.md
category: reference
title: FESOM
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/FESOM
date_saved: 2026-05-05T07:35:40.618673+00:00
instance: kb-cron
parent: fesom-20260505-0
summary:
FESOM (Finite-Element/volumE Sea ice-Ocean Model) is a multi-resolution ocean general circulation model that solves the equations of motion describing the ocean and sea ice using finite-element and finite-volume methods on unstructured computational grids. The model is developed and supported by researchers at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), in Bremerhaven, Germany. == Overview == FESOM implements the idea of using meshes with variable resolution to simulate the circulation of the global ocean with regional focus. Because of the broad range of scales characterizing the ocean circulation, downscaling is commonly needed to describe processes on regional scales. FESOM allows global multi-resolution cross-scale simulations without traditional nesting. The dynamical core of the new version (FESOM2) switches from the finite-element method used in the original version of FESOM to the finite-volume method for the sake of better computational efficiency. Both versions include the Finite-Element Sea Ice Model (FESIM). FESOM is also used as the ocean component of the AWI-CM, the coupled atmosphere-ocean climate model developed at AWI. == History == The prototype version of FESOM appeared in 2004 due to work of Sergey Danilov, Gennady Kivman and Jens Schröter. Ralph Timmermann extended it to a full global


id: modular-ocean-model-20260505-0
file: data/en.wikipedia.org/wiki/Modular_Ocean_Model-0.md
category: reference
title: Modular Ocean Model
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Modular_Ocean_Model
date_saved: 2026-05-05T07:35:41.867801+00:00
instance: kb-cron
parent: modular-ocean-model-20260505-0
summary:
The Modular Ocean Model (MOM) is a three-dimensional ocean circulation model designed primarily for studying the ocean climate system. The model is developed and supported primarily by researchers at the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory (NOAA/GFDL) in Princeton, NJ, USA. == Overview == MOM has traditionally been a level-coordinate ocean model, in which the ocean is divided into boxes whose bottoms are located at fixed depths. Such a representation makes it easy to solve the momentum equations and the well-mixed, weakly stratified layer known as the ocean mixed layer near the ocean surface. However, level coordinate models have problems when it comes to the representation of thin bottom boundary layers (Winton et al., 1998) and thick sea ice. Additionally, because mixing in the ocean interior is largely along lines of constant potential density rather than along lines of constant depth, mixing must be rotated relative to the coordinate grid- a process that can be computationally expensive. By contrast, in codes which represent the ocean in terms of constant-density layers (which represent the flow in the ocean interior much more faithfully)- representation of the ocean mixed layer becomes a challenge. MOM3, MOM4, and MOM5 are used as


id: mycoplankton-20260505-0
file: data/en.wikipedia.org/wiki/Mycoplankton-0.md
category: reference
title: Mycoplankton
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mycoplankton
date_saved: 2026-05-05T07:35:43.130580+00:00
instance: kb-cron
parent: mycoplankton-20260505-0
summary:
Mycoplankton are saprotrophic or parasitic members of the plankton communities of marine and freshwater ecosystems. They are composed of filamentous free-living fungi and yeasts that are associated with planktonic particles or phytoplankton. Similar to bacterioplankton, these aquatic fungi play a significant role in heterotrophic mineralization and nutrient cycling. Mycoplankton can be up to 20 mm in diameter and over 50 mm in length. In a typical milliliter of seawater, there are approximately 103 to 104 fungal cells. This number is greater in coastal ecosystems and estuaries due to nutritional runoff from terrestrial communities. Aquatic fungi are found in a myriad of ecosystems, from mangroves, to wetlands, to the open ocean. The greatest diversity and number of species of mycoplankton is found in surface waters (< 1000 m), and the vertical profile depends on the abundance of phytoplankton. Furthermore, this difference in distribution may vary between seasons due to nutrient availability. Aquatic fungi survive in a constant oxygen deficient environment, and therefore depend on oxygen diffusion by turbulence and oxygen generated by photosynthetic organisms. == Classification == There is a large amount of diversity among aquatic fungi. These fungi were traditionally classified using the groupings "lower" and "higher" fungi. This has


id: nekton-20260505-0
file: data/en.wikipedia.org/wiki/Nekton-0.md
category: reference
title: Nekton
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Nekton
date_saved: 2026-05-05T07:35:44.358378+00:00
instance: kb-cron
parent: nekton-20260505-0
summary:
Nekton or necton (from the Ancient Greek: νηκτόν, romanized: nekton, lit. 'to swim') is any aquatic organism that can actively and persistently propel itself through a water column (i.e. swim) without touching the bottom. They are generally aquatic animals with powerful tails and appendages (e.g. fins, pleopods, flippers or jets) that make them strong enough swimmers to counter ocean currents, and have mechanisms for sufficient lift and/or buoyancy to prevent sinking. Examples of extant nekton include most fish (especially pelagic fish like tuna and sharks), marine mammals (cetaceans, sirenia and pinnipeds) and reptiles (specifically sea turtles), penguins, coleoid cephalopods (squids and cuttlefish) and several species of decapod crustaceans (specifically prawns, shrimp and krill). The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the plankton that are passively carried along by the current. As a guideline, nektonic organisms have a high Reynolds number (greater than 1000) and planktonic organisms a low one (less than 10) . Some organisms begin their life cycle as planktonic eggs and larvae, and transition to nektonic juveniles and adults later in life. This may make distinction difficult when attempting to classify certain plankton-to-nekton species


id: neritic-zone-20260505-0
file: data/en.wikipedia.org/wiki/Neritic_zone-0.md
category: reference
title: Neritic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Neritic_zone
date_saved: 2026-05-05T07:35:45.614344+00:00
instance: kb-cron
parent: neritic-zone-20260505-0
summary:
The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately 200 meters (660 ft) in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated environment for marine life, from plankton up to large fish and corals, while physical oceanography sees it as where the oceanic system interacts with the coast. == Definition (marine biology), context, extra terminology == In marine biology, the neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, refers to the zone of the ocean where sunlight reaches the ocean floor, that is where the water is never so deep as to take it out of the photic zone. It extends from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters (660 feet). Above the neritic zone lie the intertidal (or eulittoral) and supralittoral zones; below it the continental slope begins, descending from the continental shelf to the abyssal plain and the pelagic zone. Within the neritic, marine biologists also identify: The infralittoral zone is the algal-dominated zone down to around five


id: ocean-acidification-20260505-0
file: data/en.wikipedia.org/wiki/Ocean_acidification-0.md
category: reference
title: Ocean acidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acidification
date_saved: 2026-05-05T07:35:46.998480+00:00
instance: kb-cron
parent: ocean-acidification-20260505-0
summary:
Ocean acidification is the ongoing decrease in the pH of the Earth's ocean. Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05. Carbon dioxide emissions from human activities are the primary cause of ocean acidification, with atmospheric carbon dioxide (CO2) levels exceeding 422 ppm (as of 2024). CO2 from the atmosphere is absorbed by the oceans. This chemical reaction produces carbonic acid (H2CO3) which dissociates into a bicarbonate ion (HCO−3) and a hydrogen ion (H+). The presence of free hydrogen ions (H+) lowers the pH of the ocean, increasing acidity (this does not mean that seawater is acidic yet; it is still alkaline, with a pH higher than 8). Marine calcifying organisms, such as mollusks and corals, are especially vulnerable because they rely on calcium carbonate to build shells and skeletons. A change in pH by 0.1 represents a 26% increase in hydrogen ion concentration in the world's oceans (the pH scale is logarithmic, so a change of one in pH units is equivalent to a tenfold change in hydrogen ion concentration). Sea-surface pH and carbonate saturation states vary depending on ocean depth and location. Colder and higher latitude waters are capable


id: ocean-acidification-20260505-1
file: data/en.wikipedia.org/wiki/Ocean_acidification-1.md
category: reference
title: Ocean acidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acidification
date_saved: 2026-05-05T07:35:46.998480+00:00
instance: kb-cron
parent: ocean-acidification-20260505-0
summary:
== Main effects == The ocean's chemistry is changing due to the uptake of anthropogenic carbon dioxide (CO2). Ocean pH, carbonate ion concentrations ([CO32−]), and calcium carbonate mineral saturation states (Ω) have been declining as a result of the uptake of approximately 30% of the anthropogenic carbon dioxide emissions over the past 270 years (since around 1750). This process, commonly referred to as "ocean acidification", is making it harder for marine calcifiers to build a shell or skeletal structure, endangering coral reefs and the broader marine ecosystems. Ocean acidification has been called the "evil twin of global warming" and "the other CO2 problem". Increased ocean temperatures and oxygen loss act concurrently with ocean acidification and constitute the "deadly trio" of climate change pressures on the marine environment. The impacts of this will be most severe for coral reefs and other shelled marine organisms, as well as those populations that depend on the ecosystem services they provide. === Reduction in pH value === Dissolving CO2 in seawater increases the hydrogen ion (H+) concentration in the ocean, and thus decreases ocean pH, as follows: In shallow coastal and shelf regions, a number of factors interplay to affect air-ocean CO2 exchange and resulting


id: ocean-acidification-20260505-2
file: data/en.wikipedia.org/wiki/Ocean_acidification-2.md
category: reference
title: Ocean acidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acidification
date_saved: 2026-05-05T07:35:46.998480+00:00
instance: kb-cron
parent: ocean-acidification-20260505-0
summary:
Already now large quantities of water undersaturated in aragonite are upwelling close to the Pacific continental shelf area of North America, from Vancouver to Northern California. These continental shelves play an important role in marine ecosystems, since most marine organisms live or are spawned there. Other shelf areas may be experiencing similar effects. At depths of 1000s of meters in the ocean, calcium carbonate shells begin to dissolve as increasing pressure and decreasing temperature shift the chemical equilibria controlling calcium carbonate precipitation. The depth at which this occurs is known as the carbonate compensation depth. Ocean acidification will increase such dissolution and shallow the carbonate compensation depth on timescales of tens to hundreds of years. Zones of downwelling are being affected first. In the North Pacific and North Atlantic, saturation states are also decreasing (the depth of saturation is getting more shallow). Ocean acidification is progressing in the open ocean as the CO2 travels to deeper depth as a result of ocean mixing. In the open ocean, this causes carbonate compensation depths to become more shallow, meaning that dissolution of calcium carbonate will occur below those depths. In the North Pacific these carbonate saturations depths are shallowing at a rate


id: ocean-acidification-20260505-3
file: data/en.wikipedia.org/wiki/Ocean_acidification-3.md
category: reference
title: Ocean acidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acidification
date_saved: 2026-05-05T07:35:46.998480+00:00
instance: kb-cron
parent: ocean-acidification-20260505-0
summary:
=== Geologic past === Ocean acidification has occurred previously in Earth's history. It happened during the Capitanian mass extinction, at the end-Permian extinction, during the end-Triassic extinction, and during the Cretaceous–Palaeogene extinction event. Three of the big five mass extinction events in the geologic past were associated with a rapid increase in atmospheric carbon dioxide, probably due to volcanism and/or thermal dissociation of marine gas hydrates. Elevated CO2 levels impacted biodiversity. Decreased CaCO3 saturation due to seawater uptake of volcanogenic CO2 has been suggested as a possible kill mechanism during the marine mass extinction at the end of the Triassic. The end-Triassic biotic crisis is still the most well-established example of a marine mass extinction due to ocean acidification, because (a) carbon isotope records suggest enhanced volcanic activity that decreased the carbonate sedimentation which reduced the carbonate compensation depth and the carbonate saturation state, and a marine extinction coincided precisely in the stratigraphic record, and (b) there was pronounced selectivity of the extinction against organisms with thick aragonitic skeletons, which is predicted from experimental studies. Ocean acidification has also been suggested as a one cause of the end-Permian mass extinction and the end-Cretaceous crisis. Overall, multiple climatic stressors, including ocean


id: ocean-acidification-20260505-4
file: data/en.wikipedia.org/wiki/Ocean_acidification-4.md
category: reference
title: Ocean acidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acidification
date_saved: 2026-05-05T07:35:46.998480+00:00
instance: kb-cron
parent: ocean-acidification-20260505-0
summary:
A coccolithophore is a unicellular, eukaryotic phytoplankton (alga). Understanding calcification changes in coccolithophores may be particularly important because a decline in the coccolithophores may have secondary effects on climate: it could contribute to global warming by decreasing the Earth's albedo via their effects on oceanic cloud cover. A study in 2008 examined a sediment core from the North Atlantic and found that the species composition of coccolithophorids remained unchanged over the past 224 years (1780 to 2004). But the average coccolith mass had increased by 40% during the same period. === Corals === Warm water corals are clearly in decline, with losses of 50% over the last 30–50 years due to multiple threats from ocean warming, ocean acidification, pollution and physical damage from activities such as fishing, and these pressures are expected to intensify. The fluid in the internal compartments (the coelenteron) where corals grow their exoskeleton is also extremely important for calcification growth. When the saturation state of aragonite in the external seawater is at ambient levels, the corals will grow their aragonite crystals rapidly in their internal compartments, hence their exoskeleton grows rapidly. If the saturation state of aragonite in the external seawater is lower than the ambient


id: ocean-acidification-20260505-5
file: data/en.wikipedia.org/wiki/Ocean_acidification-5.md
category: reference
title: Ocean acidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acidification
date_saved: 2026-05-05T07:35:46.998480+00:00
instance: kb-cron
parent: ocean-acidification-20260505-0
summary:
==== Fish larvae ==== Ocean acidification can also have effects on marine fish larvae. It internally affects their olfactory systems, which is a crucial part of their early development. Orange clownfish larvae mostly live on oceanic reefs that are surrounded by vegetative islands. Larvae are known to use their sense of smell to detect the differences between reefs surrounded by vegetative islands and reefs not surrounded by vegetative islands. Clownfish larvae need to be able to distinguish between these two destinations to be able to find a suitable area for their growth. Another use for marine fish olfactory systems is to distinguish between their parents and other adult fish, in order to avoid inbreeding. In an experimental aquarium facility, clownfish were sustained in non-manipulated seawater with pH 8.15 ± 0.07, which is similar to our current ocean's pH. To test for effects of different pH levels, the seawater was modified to two other pH levels, which corresponded with climate change models that predict future atmospheric CO2 levels. In the year 2100 the model projects possible CO2 levels of 1,000 ppm, which correlates with the pH of 7.8 ± 0.05. This experiment showed that when larvae are exposed to a pH


id: ocean-acidification-20260505-6
file: data/en.wikipedia.org/wiki/Ocean_acidification-6.md
category: reference
title: Ocean acidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acidification
date_saved: 2026-05-05T07:35:46.998480+00:00
instance: kb-cron
parent: ocean-acidification-20260505-0
summary:
==== United Kingdom commercial fisheries ==== The shellfish industry is an important part of the United Kingdom economy. In 2013, the shellfish industry contributed 37% of total landings by value. England and Scotland are the highest producers of shellfish within the United Kingdom. It has been found that annually fishers catch 66,000 t and 61,000 t. In terms of value, the wild-captured shellfish are worth 203 million pounds per year. However, ocean acidification is causing a decrease in the growth of many shellfish species. This is causing a drastic economic loss in the United Kingdom economy. It is predicted that by 2100 there will be an economy-wide economic loss of shellfish production in the United Kingdom. The direct potential loss ranges from 14 to 28 percent of fishery output. That is a total loss of about 23 to 88 million pounds. The financial losses vary regionally due to different patterns of wild-caught shellfish and the exploitation of species with differing sensitivities to ocean acidification. Shellfish resources in the United Kingdom will require regional, national, or international solutions to reduce the impacts of ocean acidification on shellfish species and stabilize the economy. ==== US commercial fisheries ==== The value of fish


id: ocean-acidification-20260505-7
file: data/en.wikipedia.org/wiki/Ocean_acidification-7.md
category: reference
title: Ocean acidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acidification
date_saved: 2026-05-05T07:35:46.998480+00:00
instance: kb-cron
parent: ocean-acidification-20260505-0
summary:
==== Electrochemical methods ==== Electrochemical methods, or electrolysis, can strip carbon dioxide directly from seawater. Electrochemical process are a type of ocean alkalinity enhancement, too. Some methods focus on direct CO2 removal (in the form of carbonate and CO2 gas) while others increase the alkalinity of seawater by precipitating metal hydroxide residues, which absorbs CO2 in a matter described in the ocean alkalinity enhancement section. The hydrogen produced during direct carbon capture can then be upcycled to form hydrogen for energy consumption, or other manufactured laboratory reagents such as hydrochloric acid. However, implementation of electrolysis for carbon capture is expensive and the energy consumed for the process is high compared to other CDR techniques. In addition, research to assess the environmental impact of this process is ongoing. Some complications include toxic chemicals in wastewaters, and reduced DIC in effluents; both of these may negatively impact marine life. == Policies and goals == === Global policies === As awareness about ocean acidification grows, policies geared towards increasing monitoring efforts of ocean acidification have been drafted. Previously in 2015, ocean scientist Jean-Pierre Gattuso had remarked that "The ocean has been minimally considered at previous climate negotiations. Our study provides compelling arguments for


id: ocean-acidification-20260505-8
file: data/en.wikipedia.org/wiki/Ocean_acidification-8.md
category: reference
title: Ocean acidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acidification
date_saved: 2026-05-05T07:35:46.998480+00:00
instance: kb-cron
parent: ocean-acidification-20260505-0
summary:
== History == Research into the phenomenon of ocean acidification, as well as awareness raising about the problem, has been going on for several decades. The fundamental research really began with the creation of the pH scale by Danish chemist Søren Peder Lauritz Sørensen in 1909. By around the 1950s the massive role of the ocean in absorbing fossil fuel CO2 was known to specialists, but not appreciated by the greater scientific community. Throughout much of the 20th century, the dominant focus has been the beneficial process of oceanic CO2 uptake, which has enormously ameliorated climate change. The concept of "too much of a good thing" has been late in developing and was triggered only by some key events, and the oceanic sink for heat and CO2 is still critical as the primary buffer against climate change. In the early 1970s questions over the long-term impact of the accumulation of fossil fuel CO2 in the sea were already arising around the world and causing strong debate. Researchers commented on the accumulation of fossil CO2 in the atmosphere and sea and drew attention to the possible impacts on marine life. By the mid-1990s, the likely impact of CO2 levels rising so


id: ocean-acoustic-tomography-20260505-0
file: data/en.wikipedia.org/wiki/Ocean_acoustic_tomography-0.md
category: reference
title: Ocean acoustic tomography
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acoustic_tomography
date_saved: 2026-05-05T07:35:48.279270+00:00
instance: kb-cron
parent: ocean-acoustic-tomography-20260505-0
summary:
Ocean acoustic tomography is a technique used to measure temperatures and currents over large regions of the ocean. On ocean basin scales, this technique is also known as acoustic thermometry. The technique relies on precisely measuring the time it takes sound signals to travel between two instruments, one an acoustic source and one a receiver, separated by ranges of 100–5,000 kilometres (54–2,700 nmi). If the locations of the instruments are known precisely, the measurement of time-of-flight can be used to infer the speed of sound, averaged over the acoustic path. Changes in the speed of sound are primarily caused by changes in the temperature of the ocean, hence the measurement of the travel times is equivalent to a measurement of temperature. A 1 °C (1.8 °F) change in temperature corresponds to about 4 metres per second (13 ft/s) change in sound speed. An oceanographic experiment employing tomography typically uses several source-receiver pairs in a moored array that measures an area of ocean. == Motivation == Seawater is an electrical conductor, so the oceans are opaque to electromagnetic energy (e.g., light or radar). The oceans are fairly transparent to low-frequency acoustics, however. The oceans conduct sound very efficiently, particularly sound at


id: ocean-acoustic-tomography-20260505-1
file: data/en.wikipedia.org/wiki/Ocean_acoustic_tomography-1.md
category: reference
title: Ocean acoustic tomography
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_acoustic_tomography
date_saved: 2026-05-05T07:35:48.279270+00:00
instance: kb-cron
parent: ocean-acoustic-tomography-20260505-0
summary:
== Acoustic thermometry == Acoustic thermometry is an idea to observe the world's ocean basins, and the ocean climate in particular, using trans-basin acoustic transmissions. "Thermometry", rather than "tomography", has been used to indicate basin-scale or global scale measurements. Prototype measurements of temperature have been made in the North Pacific Basin and across the Arctic Basin. Starting in 1983, John Spiesberger of the Woods Hole Oceanographic Institution, and Ted Birdsall and Kurt Metzger of the University of Michigan developed the use of sound to infer information about the ocean's large-scale temperatures, and in particular to attempt the detection of global warming in the ocean. This group transmitted sounds from Oahu that were recorded at about ten receivers stationed around the rim of the Pacific Ocean over distances of 4,000 km (2,500 mi). These experiments demonstrated that changes in temperature could be measured with an accuracy of about 20 millidegrees. Spiesberger et al. did not detect global warming. Instead they discovered that other natural climatic fluctuations, such as El Nino, were responsible in part for substantial fluctuations in temperature that may have masked any slower and smaller trends that may have occurred from global warming. The Acoustic Thermometry of Ocean Climate


id: ocean-current-20260505-0
file: data/en.wikipedia.org/wiki/Ocean_current-0.md
category: reference
title: Ocean current
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_current
date_saved: 2026-05-05T07:35:49.743977+00:00
instance: kb-cron
parent: ocean-current-20260505-0
summary:
An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents move both horizontally, on scales that can span entire oceans, as well as vertically, with vertical currents (upwelling and downwelling) playing an important role in the movement of nutrients and gases, such as carbon dioxide, between the surface and the deep ocean. Ocean currents are classified by temperature as either warm currents or cold currents. They are also classified by their velocity, dimension, and direction as either drifts, currents, or streams. Drifts, such as the North Atlantic Drift Current, involve the forward movement of surface ocean water under the influence of the prevailing wind. Currents, such as the Labrador Current, involve the movement of oceanic water in a more definite direction at a greater velocity than drifts. Streams, such as the Gulf Stream, involve movement of larger masses of ocean water with greater velocity than drifts or currents. Ocean currents are patterns of water movement that influence climate zones and


id: ocean-current-20260505-1
file: data/en.wikipedia.org/wiki/Ocean_current-1.md
category: reference
title: Ocean current
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_current
date_saved: 2026-05-05T07:35:49.743977+00:00
instance: kb-cron
parent: ocean-current-20260505-0
summary:
== Effects on climate and ecology == Ocean currents affect temperatures throughout the world. For example, the ocean current that brings warm water up the north Atlantic to northwest Europe also cumulatively and slowly blocks ice from forming along the seashores, which would also block ships from entering and exiting inland waterways and seaports, hence ocean currents play a decisive role in influencing the climates of regions through which they flow. Ocean currents are important in the study of marine debris. Upwellings and cold ocean water currents flowing from polar and sub-polar regions bring in nutrients that support plankton growth, which are crucial prey items for several key species in marine ecosystems. Ocean currents are also important in the dispersal and distribution of many organisms, including those with pelagic egg or larval stages. An example is the life-cycle of the European Eel. Terrestrial species, for example tortoises and lizards, can be carried on floating debris by currents to colonise new terrestrial areas and islands. == Ocean currents and climate change == The continued rise of atmospheric temperatures is anticipated to have various effects on the strength of surface ocean currents, wind-driven circulation and dispersal patterns. Ocean currents play a significant


id: ocean-current-20260505-2
file: data/en.wikipedia.org/wiki/Ocean_current-2.md
category: reference
title: Ocean current
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_current
date_saved: 2026-05-05T07:35:49.743977+00:00
instance: kb-cron
parent: ocean-current-20260505-0
summary:
Baffin Island Current – Arctic Ocean current Beaufort Gyre – Wind-driven ocean current in the Arctic Ocean polar region East Greenland Current – Current from Fram Strait to Cape Farewell off the eastern coat of Greenland East Iceland Current – Cold water ocean current that forms as a branch of the East Greenland Current Labrador Current – Western North Atlantic Ocean current North Icelandic Jet – Deep-reaching current that flows along the continental slope of Iceland Norwegian Current – Current that flows northeasterly along the Atlantic coast of Norway Transpolar Drift Stream – Current in the Arctic Ocean West Greenland Current – Weak cold water current that flows to the north along the west coast of Greenland West Spitsbergen Current – Warm, salty current that runs poleward just west of Spitsbergen Currents of the Atlantic Ocean Angola Current – Temporary ocean surface current Antilles Current – Ocean current Atlantic meridional overturning circulation – System of surface and deep currents in the Atlantic Ocean Azores Current – Ocean current in the North Atlantic Ocean Benguela Current – Ocean current in the South Atlantic Brazil Current – Water current along Brazil's southern coast Canary Current – Wind-driven surface current that is part


id: ocean-current-20260505-3
file: data/en.wikipedia.org/wiki/Ocean_current-3.md
category: reference
title: Ocean current
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_current
date_saved: 2026-05-05T07:35:49.743977+00:00
instance: kb-cron
parent: ocean-current-20260505-0
summary:
Beaufort Gyre – Wind-driven ocean current in the Arctic Ocean polar region Indian Ocean Gyre – Major oceanic gyre in the Indian Ocean North Atlantic Gyre – Major circular system of ocean currents North Pacific Gyre – Major circulating system of ocean currents Ross Gyre – Circulating system of ocean currents in the Ross Sea South Atlantic Gyre – Subtropical gyre in the south Atlantic Ocean South Pacific Gyre – Major circulating system of ocean currents Weddell Gyre – One of two gyres within the Southern Ocean == See also == Currentology – Science that studies the internal movements of water masses Deep ocean water – Cold, salty water deep below the surface of Earth's oceans Fish migration – Movement of fishes from one part of a water body to another on a regular basis Geostrophic current – Oceanic flow in which the pressure gradient force is balanced by the Coriolis effect Latitude of the Gulf Stream and the Gulf Stream north wall index List of ocean circulation models Marine habitats § Ocean currents Marine current power – Extraction of power from ocean currents Ocean gyre – Any large system of circulating ocean surface currents Physical oceanography – Study of


id: ocean-deoxygenation-20260505-0
file: data/en.wikipedia.org/wiki/Ocean_deoxygenation-0.md
category: reference
title: Ocean deoxygenation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_deoxygenation
date_saved: 2026-05-05T07:35:51.047511+00:00
instance: kb-cron
parent: ocean-deoxygenation-20260505-0
summary:
Ocean deoxygenation is the reduction of the oxygen content in different parts of the ocean due to human activities. There are two areas where this occurs. Firstly, it occurs in coastal zones where eutrophication has driven some quite rapid (in a few decades) declines in oxygen to very low levels. This type of ocean deoxygenation is also called dead zones. Secondly, ocean deoxygenation occurs also in the open ocean. In that part of the ocean, there is nowadays an ongoing reduction in oxygen levels. As a result, the naturally occurring low oxygen areas (so called oxygen minimum zones (OMZs)) are now expanding slowly. This expansion is happening as a consequence of human caused climate change. The resulting decrease in oxygen content of the oceans poses a threat to marine life, as well as to people who depend on marine life for nutrition or livelihood. A decrease in ocean oxygen levels affects how productive the ocean is, how nutrients and carbon move around, and how marine habitats function. As the oceans become warmer this increases the loss of oxygen in the oceans. This is because the warmer temperatures increase ocean stratification. The reason for this lies in the multiple connections between


id: ocean-deoxygenation-20260505-1
file: data/en.wikipedia.org/wiki/Ocean_deoxygenation-1.md
category: reference
title: Ocean deoxygenation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_deoxygenation
date_saved: 2026-05-05T07:35:51.047511+00:00
instance: kb-cron
parent: ocean-deoxygenation-20260505-0
summary:
While oxygen minimum zones (OMZs) occur naturally, they can be exacerbated by human impacts like climate change and land-based pollution from agriculture and sewage. The prediction of current climate models and climate change scenarios is that substantial warming and loss of oxygen throughout the majority of the upper ocean will occur. Global warming increases ocean temperatures, especially in shallow coastal areas. As water temperature increases, its ability to hold oxygen decreases, resulting in lower oxygen concentrations. This compounds the effects of eutrophication in coastal zones described above. Open ocean areas with no oxygen have grown more than 1.7 million square miles in the last 50 years, and coastal waters have seen a tenfold increase in low-oxygen areas in the same time. Measurements of dissolved oxygen in coastal and open-ocean waters over the past 50 years have revealed a marked decline in oxygen content. This decline is associated with expanding spatial extent, expanding vertical extent, and prolonged duration of oxygen-poor conditions in all regions of the global oceans. Examinations of the spatial extent of OMZs in the past through paleoceanographical methods clearly show that the spatial extent of OMZs has expanded through time, and this expansion is coupled to ocean warming


id: ocean-deoxygenation-20260505-2
file: data/en.wikipedia.org/wiki/Ocean_deoxygenation-2.md
category: reference
title: Ocean deoxygenation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_deoxygenation
date_saved: 2026-05-05T07:35:51.047511+00:00
instance: kb-cron
parent: ocean-deoxygenation-20260505-0
summary:
=== Vertical extent of low oxygen conditions === The vertical extent of low oxygen conditions is also variable, and areas of persistent low oxygen have annual variation in the upper and lower limits of oxygen-poor waters. Typically, OMZs are expected to occur at depths of about 200 to 1,000 meters. The upper limit of OMZs is characterized by a strong and rapid gradient in oxygenation, called the oxycline. The depth of the oxycline varies between OMZs, and is mainly affected by physical processes such as air-sea fluxes and vertical movement in the thermocline depth. The lower limit of OMZs is associated with the reduction in biological oxygen consumption, as the majority of organic matter is consumed and respired in the top 1,000 m of the vertical water column. Shallower coastal systems may see oxygen-poor waters extend to bottom waters, leading to negative effects on benthic communities. Many persistent OMZs have increased in thickness over the last five decades. This happened because the upper limit of the OMZ became shallower and also because the OMZ expanded downward. === Variations in temporal duration === The temporal duration of oxygen-poor conditions can vary on seasonal, annual, or multi-decadal scales. Hypoxic conditions in coastal


id: ocean-deoxygenation-20260505-3
file: data/en.wikipedia.org/wiki/Ocean_deoxygenation-3.md
category: reference
title: Ocean deoxygenation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_deoxygenation
date_saved: 2026-05-05T07:35:51.047511+00:00
instance: kb-cron
parent: ocean-deoxygenation-20260505-0
summary:
Vertical expansion of tropical OMZs has reduced the area between the OMZ and surface. This means that many species that live near the surface, such as fish, could be affected periodically. Ongoing research is investigating how OMZ expansion affects food webs in these areas. Studies on OMZ expansion in the tropical Pacific and Atlantic have observed negative effects on fish populations and commercial fisheries that likely occurred from reduced habitat when the OMZ moved to a shallower depth. A fish's behavior in response to ocean deoxygenation is based upon their tolerance to oxygen poor conditions. Species with low anoxic tolerance tend to undergo habitat compression in response to the expansion of OMZs. Fish species with a low tolerance for low oxygen conditions may move to live nearer the ocean surface where oxygen concentration will usually be higher. Biological responses to habitat compression can be varied. Some species of billfish, predatory pelagic predators such as sailfish and marlin, that have undergone habitat compression actually have increased growth since their prey, smaller pelagic fish, experienced the same habitat compression, resulting in increased prey vulnerability to billfishes. Fish with tolerance to anoxic conditions, such as jumbo squid and lanternfish, can remain active in


id: ocean-dynamics-20260505-0
file: data/en.wikipedia.org/wiki/Ocean_dynamics-0.md
category: reference
title: Ocean dynamics
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_dynamics
date_saved: 2026-05-05T07:35:52.277542+00:00
instance: kb-cron
parent: ocean-dynamics-20260505-0
summary:
Ocean dynamics define and describe the flow of water within the oceans. Ocean temperature and motion fields can be separated into three distinct layers: mixed (surface) layer, upper ocean (above the thermocline), and deep ocean. Ocean dynamics has traditionally been investigated by sampling from instruments in situ. The mixed layer is nearest to the surface and can vary in thickness from 10 to 500 meters. This layer has properties such as temperature, salinity and dissolved oxygen which are uniform with depth reflecting a history of active turbulence (the atmosphere has an analogous planetary boundary layer). Turbulence is high in the mixed layer. However, it becomes zero at the base of the mixed layer. Turbulence again increases below the base of the mixed layer due to shear instabilities. At extratropical latitudes this layer is deepest in late winter as a result of surface cooling and winter storms and quite shallow in summer. Its dynamics is governed by turbulent mixing as well as Ekman transport, exchanges with the overlying atmosphere, and horizontal advection. The upper ocean, characterized by warm temperatures and active motion, varies in depth from 100 m or less in the tropics and eastern oceans to in excess of 800


id: ocean-fertilization-20260505-0
file: data/en.wikipedia.org/wiki/Ocean_fertilization-0.md
category: reference
title: Ocean fertilization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_fertilization
date_saved: 2026-05-05T07:35:53.616567+00:00
instance: kb-cron
parent: ocean-fertilization-20260505-0
summary:
Ocean fertilization or ocean nourishment refers to both natural and intentional processes that replenish iron and other nutrients in the upper ocean, which in turn stimulate the growth of phytoplankton and in some circumstances draw down large amounts of carbon dioxide (CO2) through photosynthesis. Intentional ocean fertilization is biomimicry of natural processes that have removed atmospheric CO2 before ice ages as well as after volcanic eruptions, whale defecation, and near hydrothermal vents. The introduction of nutrients to the upper ocean increases marine food production as well as removing carbon dioxide from the atmosphere. Ocean nutrient fertilization, for example iron fertilization, (OIF) can stimulate photosynthesis in phytoplankton. The phytoplankton converts the ocean's dissolved carbon dioxide into carbohydrate, some of which has been shown to sink into the deeper ocean. More than a dozen open-sea experiments confirmed that adding iron to the ocean increases photosynthesis in phytoplankton by up to 30 times. Ocean iron fertilization is one of the more well-researched carbon dioxide removal (CDR) approaches, and supported by climate restoration proponents. However, there is uncertainty about this approach regarding the duration of the effective oceanic carbon sequestration. A National Academies of Science, Engineering and Medicine (NASEM) 2021 study on marine CDR


id: ocean-fertilization-20260505-1
file: data/en.wikipedia.org/wiki/Ocean_fertilization-1.md
category: reference
title: Ocean fertilization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_fertilization
date_saved: 2026-05-05T07:35:53.616567+00:00
instance: kb-cron
parent: ocean-fertilization-20260505-0
summary:
== Approaches == Phytoplankton require a variety of nutrients. These include macronutrients such as nitrate and phosphate (in relatively high concentrations) and micronutrients such as iron and zinc (in much smaller quantities). Nutrient requirements vary across phylogenetic groups (e.g., diatoms require silicon) but may not individually limit total biomass production. Co-limitation (among multiple nutrients) may also mean that one nutrient can partially compensate for a shortage of another. Silicon does not affect total production, but can change the timing and community structure with follow-on effects on remineralization times and subsequent mesopelagic nutrient vertical distribution. High-nutrient, low-chlorophyll (HNLC) waters occupy the oceans' subtropical gyre systems, approximately 40 per cent of the surface, where wind-driven downwelling and a strong thermocline impede nutrient resupply from deeper water. Nitrogen fixation by cyanobacteria provides a major source of N. In effect, it ultimately prevents the ocean from losing the N required for photosynthesis. Phosphorus has no substantial supply route, making it the ultimate limiting macronutrient. The sources that fuel primary production are deep water stocks and runoff or dust-based. === Iron === === Phosphorus === In the very long term, phosphorus "is often considered to be the ultimate limiting macronutrient in marine ecosystems" and has


id: ocean-fertilization-20260505-2
file: data/en.wikipedia.org/wiki/Ocean_fertilization-2.md
category: reference
title: Ocean fertilization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_fertilization
date_saved: 2026-05-05T07:35:53.616567+00:00
instance: kb-cron
parent: ocean-fertilization-20260505-0
summary:
=== Volcanic ash === Volcanic ash adds nutrients to the surface ocean. This is most apparent in nutrient-limited areas. Research on the effects of anthropogenic and aeolian iron addition to the ocean surface suggests that nutrient-limited areas benefit most from a combination of nutrients provided by anthropogenic, eolian and volcanic deposition. Some oceanic areas are comparably limited in more than one nutrient, so fertilization regimes that includes all limited nutrients is more likely to succeed. Volcanic ash supplies multiple nutrients to the system, but excess metal ions can be harmful. The positive impacts of volcanic ash deposition are potentially outweighed by their potential to do harm. Clear evidence documents that ash can be as much as 45 percent by weight in some deep marine sediments. In the Pacific Ocean estimates claim that (on a millennial-scale) the atmospheric deposition of air-fall volcanic ash was as high as the deposition of desert dust. This indicates the potential of volcanic ash as a significant iron source. In August 2008 the Kasatochi volcanic eruption in the Aleutian Islands, Alaska, deposited ash in the nutrient-limited northeast Pacific. This ash (including iron) resulted in one of the largest phytoplankton blooms observed in the subarctic. Fisheries scientists


id: ocean-fertilization-20260505-3
file: data/en.wikipedia.org/wiki/Ocean_fertilization-3.md
category: reference
title: Ocean fertilization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_fertilization
date_saved: 2026-05-05T07:35:53.616567+00:00
instance: kb-cron
parent: ocean-fertilization-20260505-0
summary:
==== Impact on fisheries ==== Adding urea to the ocean can cause phytoplankton blooms that serve as a food source for zooplankton and in turn feed for fish. This may increase fish catches. However, if cyanobacteria and dinoflagellates dominate phytoplankton assemblages that are considered poor quality food for fish then the increase in fish quantity may not be large. Some evidence links iron fertilization from volcanic eruptions to increased fisheries production. Other nutrients would be metabolized along with the added nutrient(s), reducing their presence in fertilized waters. Krill populations have declined dramatically since whaling began. Sperm whales transport iron from the deep ocean to the surface during prey consumption and defecation. Sperm whales have been shown to increase the levels of primary production and carbon export to the deep ocean by depositing iron-rich faeces into surface waters of the Southern Ocean. The faeces causes phytoplankton to grow and take up carbon. The phytoplankton nourish krill. Reducing the abundance of sperm whales in the Southern Ocean, whaling resulted in an extra 2 million tonnes of carbon remaining in the atmosphere each year. ==== Ecosystem disruption ==== Many locations, such as the Tubbataha Reef in the Sulu Sea, support high marine biodiversity.


id: ocean-thermal-energy-conversion-20260505-0
file: data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-0.md
category: reference
title: Ocean thermal energy conversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
date_saved: 2026-05-05T07:35:54.854158+00:00
instance: kb-cron
parent: ocean-thermal-energy-conversion-20260505-0
summary:
Ocean thermal energy conversion (OTEC) is a renewable energy technology that harnesses the temperature difference between the warm surface waters of the ocean and the cold depths to run a heat engine to produce electricity. It is a unique form of clean energy generation that has the potential to provide a consistent and sustainable source of power. Although it has challenges to overcome, OTEC has the potential to provide a consistent and sustainable source of clean energy, particularly in tropical regions with access to deep ocean water. == Description == OTEC uses the ocean thermal gradient between cooler deep and warmer shallow or surface seawaters to run a heat engine and produce useful work, usually in the form of electricity. OTEC can operate with a very high capacity factor and so can operate in base load mode. The denser cold water masses, formed by ocean surface water interaction with cold atmosphere in quite specific areas of the North Atlantic and the Southern Ocean, sink into the deep sea basins and spread in entire deep ocean by the thermohaline circulation. Upwelling of cold water from the deep ocean is replenished by the downwelling of cold surface sea water. Among ocean energy


id: ocean-thermal-energy-conversion-20260505-1
file: data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-1.md
category: reference
title: Ocean thermal energy conversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
date_saved: 2026-05-05T07:35:54.854158+00:00
instance: kb-cron
parent: ocean-thermal-energy-conversion-20260505-0
summary:
In 1974, The U.S. established the Natural Energy Laboratory of Hawaii Authority (NELHA) at Keahole Point on the Kona coast of Hawaii. Hawaii is the best US OTEC location, due to its warm surface water, access to very deep, very cold water, and high electricity costs. The laboratory has become a leading test facility for OTEC technology. In the same year, Lockheed received a grant from the U.S. National Science Foundation to study OTEC. This eventually led to an effort by Lockheed, the US Navy, Makai Ocean Engineering, Dillingham Construction, and other firms to build the world's first and only net-power producing OTEC plant, dubbed "Mini-OTEC" For three months in 1979, a small amount of electricity was generated. NELHA operated a 250 kW demonstration plant for six years in the 1990s. With funding from the United States Navy, a 105 kW plant at the site began supplying energy to the local power grid in 2015. A European initiative EUROCEAN - a privately funded joint venture of 9 European companies already active in offshore engineering - was active in promoting OTEC from 1979 to 1983. Initially a large scale offshore facility was studied. Later a 100 kW land based installation was


id: ocean-thermal-energy-conversion-20260505-2
file: data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-2.md
category: reference
title: Ocean thermal energy conversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
date_saved: 2026-05-05T07:35:54.854158+00:00
instance: kb-cron
parent: ocean-thermal-energy-conversion-20260505-0
summary:
== Currently operating OTEC plants == In March 2013, Saga University with various Japanese industries completed the installation of a new OTEC plant. Okinawa Prefecture announced the start of the OTEC operation testing at Kume Island on April 15, 2013. The main aim is to prove the validity of computer models and demonstrate OTEC to the public. The testing and research will be conducted with the support of Saga University until the end of FY 2016. IHI Plant Construction Co. Ltd, Yokogawa Electric Corporation, and Xenesys Inc were entrusted with constructing the 100 kilowatt class plant within the grounds of the Okinawa Prefecture Deep Sea Water Research Center. The location was specifically chosen in order to utilize existing deep seawater and surface seawater intake pipes installed for the research center in 2000. The pipe is used for the intake of deep sea water for research, fishery, and agricultural use. The plant consists of two 50 kW units in double Rankine configuration. The OTEC facility and deep seawater research center are open to free public tours by appointment in English and Japanese. Currently, this is one of only two fully operational OTEC plants in the world. This plant operates continuously when


id: ocean-thermal-energy-conversion-20260505-3
file: data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-3.md
category: reference
title: Ocean thermal energy conversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
date_saved: 2026-05-05T07:35:54.854158+00:00
instance: kb-cron
parent: ocean-thermal-energy-conversion-20260505-0
summary:
Open-cycle OTEC uses warm surface water directly to make electricity. The warm seawater is first pumped into a low-pressure container, which causes it to boil. In some schemes, the expanding vapor drives a low-pressure turbine attached to an electrical generator. The vapor, which has left its salt and other contaminants in the low-pressure container, is pure fresh water. It is condensed into a liquid by exposure to cold temperatures from deep-ocean water. This method produces desalinized fresh water, suitable for drinking water, irrigation or aquaculture. In other schemes, the rising vapor is used in a gas lift technique of lifting water to significant heights. Depending on the embodiment, such vapor lift pump techniques generate power from a hydroelectric turbine either before or after the pump is used. In 1984, the Solar Energy Research Institute (now known as the National Renewable Energy Laboratory) developed a vertical-spout evaporator to convert warm seawater into low-pressure steam for open-cycle plants. Conversion efficiencies were as high as 97% for seawater-to-steam conversion (overall steam production would only be a few percent of the incoming water). In May 1993, an open-cycle OTEC plant at Keahole Point, Hawaii, produced close to 80 kW of electricity during a net


id: ocean-thermal-energy-conversion-20260505-4
file: data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-4.md
category: reference
title: Ocean thermal energy conversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
date_saved: 2026-05-05T07:35:54.854158+00:00
instance: kb-cron
parent: ocean-thermal-energy-conversion-20260505-0
summary:
=== Floating === Floating OTEC facilities operate off-shore. Although potentially optimal for large systems, floating facilities present several difficulties. The difficulty of mooring plants in very deep water complicates power delivery. Cables attached to floating platforms are more susceptible to damage, especially during storms. Cables at depths greater than 1000 meters are difficult to maintain and repair. Riser cables, which connect the sea bed and the plant, need to be constructed to resist entanglement. As with shelf-mounted plants, floating plants need a stable base for continuous operation. Major storms and heavy seas can break the vertically suspended cold-water pipe and interrupt warm water intake as well. To help prevent these problems, pipes can be made of flexible polyethylene attached to the bottom of the platform and gimballed with joints or collars. Pipes may need to be uncoupled from the plant to prevent storm damage. As an alternative to a warm-water pipe, surface water can be drawn directly into the platform; however, it is necessary to prevent the intake flow from being damaged or interrupted during violent motions caused by heavy seas. Connecting a floating plant to power delivery cables requires the plant to remain relatively stationary. Mooring is an acceptable


id: ocean-thermal-energy-conversion-20260505-5
file: data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-5.md
category: reference
title: Ocean thermal energy conversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
date_saved: 2026-05-05T07:35:54.854158+00:00
instance: kb-cron
parent: ocean-thermal-energy-conversion-20260505-0
summary:
=== Hainan === On April 13, 2013, Lockheed contracted with the Reignwood Group to build a 10 megawatt plant off the coast of southern China to provide power for a planned resort on Hainan island. A plant of that size would power several thousand homes. The Reignwood Group acquired Opus Offshore in 2011 which forms its Reignwood Ocean Engineering division which also is engaged in development of deepwater drilling. === Japan === Currently the only continuously operating OTEC system is located in Okinawa Prefecture, Japan. The Governmental support, local community support, and advanced research carried out by Saga University were key for the contractors, IHI Plant Construction Co. Ltd, Yokogawa Electric Corporation, and Xenesys Inc, to succeed with this project. Work is being conducted to develop a 1MW facility on Kume Island requiring new pipelines. In July 2014, more than 50 members formed the Global Ocean reSource and Energy Association (GOSEA) an international organization formed to promote the development of the Kumejima Model and work towards the installation of larger deep seawater pipelines and a 1MW OTEC Facility. The companies involved in the current OTEC projects, along with other interested parties have developed plans for offshore OTEC systems as well.


id: ocean-thermal-energy-conversion-20260505-6
file: data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-6.md
category: reference
title: Ocean thermal energy conversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
date_saved: 2026-05-05T07:35:54.854158+00:00
instance: kb-cron
parent: ocean-thermal-energy-conversion-20260505-0
summary:
=== Chilled-soil agriculture === OTEC technology supports chilled-soil agriculture. When cold seawater flows through underground pipes, it chills the surrounding soil. The temperature difference between roots in the cool soil and leaves in the warm air allows plants that evolved in temperate climates to be grown in the subtropics. Dr. John P. Craven, Dr. Jack Davidson and Richard Bailey patented this process and demonstrated it at a research facility at the Natural Energy Laboratory of Hawaii Authority (NELHA). The research facility demonstrated that more than 100 different crops can be grown using this system. Many normally could not survive in Hawaii or at Keahole Point. Japan has also been researching agricultural uses of Deep Sea Water since 2000 at the Okinawa Deep Sea Water Research Institute on Kume Island. The Kume Island facilities use regular water cooled by Deep Sea Water in a heat exchanger run through pipes in the ground to cool soil. Their techniques have developed an important resource for the island community as they now produce spinach, a winter vegetable, commercially year round. An expansion of the deep seawater agriculture facility was completed by Kumejima Town next to the OTEC Demonstration Facility in 2014. The new facility


id: ocean-thermal-energy-conversion-20260505-7
file: data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-7.md
category: reference
title: Ocean thermal energy conversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
date_saved: 2026-05-05T07:35:54.854158+00:00
instance: kb-cron
parent: ocean-thermal-energy-conversion-20260505-0
summary:
== Thermodynamics == A rigorous treatment of OTEC reveals that a 20 °C temperature difference will provide as much energy as a hydroelectric plant with 34 m head for the same volume of water flow. The low temperature difference means that water volumes must be very large to extract useful amounts of heat. A 100MW power plant would be expected to pump on the order of 12 million gallons (44,400 tonnes) per minute. For comparison, pumps must move a mass of water greater than the weight of the battleship Bismarck, which weighed 41,700 tonnes, every minute. This makes pumping a substantial parasitic drain on energy production in OTEC systems, with one Lockheed design consuming 19.55 MW in pumping costs for every 49.8 MW net electricity generated. For OTEC schemes using heat exchangers, to handle this volume of water the exchangers need to be enormous compared to those used in conventional thermal power generation plants, making them one of the most critical components due to their impact on overall efficiency. A 100 MW OTEC power plant would require 200 exchangers each larger than a 20-foot shipping container making them the single most expensive component. === Variation of ocean temperature with depth


id: ocean-thermal-energy-conversion-20260505-8
file: data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-8.md
category: reference
title: Ocean thermal energy conversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
date_saved: 2026-05-05T07:35:54.854158+00:00
instance: kb-cron
parent: ocean-thermal-energy-conversion-20260505-0
summary:
Warm water mass flow rate, M w ˙ = M T m w ˙ ˙ {\displaystyle {\dot {M_{w}}}={\dot {M_{T}{\dot {m_{w}}}}}\,} Cold water mass flow rate M c ˙ = M T m C ˙ ˙ {\displaystyle {\dot {{\dot {M_{c}}}={\dot {M_{T}m_{C}}}}}\,} === Closed Anderson cycle === As developed starting in the 1960s by J. Hilbert Anderson of Sea Solar Power, Inc., in this cycle, QH is the heat transferred in the evaporator from the warm sea water to the working fluid. The working fluid exits the evaporator as a gas near its dew point. The high-pressure, high-temperature gas then is expanded in the turbine to yield turbine work, WT. The working fluid is slightly superheated at the turbine exit and the turbine typically has an efficiency of 90% based on reversible, adiabatic expansion. From the turbine exit, the working fluid enters the condenser where it rejects heat, -QC, to the cold sea water. The condensate is then compressed to the highest pressure in the cycle, requiring condensate pump work, WC. Thus, the Anderson closed cycle is a Rankine-type cycle similar to the conventional power plant steam cycle except that in the Anderson cycle the working fluid is never superheated more than


id: ocean-thermal-energy-conversion-20260505-9
file: data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-9.md
category: reference
title: Ocean thermal energy conversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion
date_saved: 2026-05-05T07:35:54.854158+00:00
instance: kb-cron
parent: ocean-thermal-energy-conversion-20260505-0
summary:
=== Dissolved gases === The performance of direct contact heat exchangers operating at typical OTEC boundary conditions is important to the Claude cycle. Many early Claude cycle designs used a surface condenser since their performance was well understood. However, direct contact condensers offer significant disadvantages. As cold water rises in the intake pipe, the pressure decreases to the point where gas begins to evolve. If a significant amount of gas comes out of solution, placing a gas trap before the direct contact heat exchangers may be justified. Experiments simulating conditions in the warm water intake pipe indicated about 30% of the dissolved gas evolves in the top 8.5 meters (28 ft) of the tube. The trade-off between pre-deaeration of the seawater and expulsion of non-condensable gases from the condenser is dependent on the gas evolution dynamics, deaerator efficiency, head loss, vent compressor efficiency and parasitic power. Experimental results indicate vertical spout condensers perform some 30% better than falling jet types. === Microbial fouling === Because raw seawater must pass through the heat exchanger, care must be taken to maintain good thermal conductivity. Biofouling layers as thin as 25 to 50 micrometres (0.00098 to 0.00197 in) can degrade heat exchanger performance


id: ocean-zoning-20260505-0
file: data/en.wikipedia.org/wiki/Ocean_zoning-0.md
category: reference
title: Ocean zoning
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ocean_zoning
date_saved: 2026-05-05T07:35:56.233356+00:00
instance: kb-cron
parent: ocean-zoning-20260505-0
summary:
Ocean zoning is a policy approach for environmental resource management in oceanic environments. This, often big picture, approach to ocean management allocates areas for various ocean uses. Types of zones can include areas designated for marine protected areas (including marine reserves), aquaculture, various types of fishing, shipping, recreation (including scuba diving), mooring/anchoring, and energy production (including offshore wind power). The process of marine spatial planning can result in ocean zones being legally established. Benefits of ocean zoning can include reducing conflict between users, safeguarding ecologically important areas, enabling commercial activity to develop with certainty, and supporting international cooperation. Balancing environmental, economic, security, social, and cultural interests in delineation of zone boundaries remains a key challenge of ocean zoning. == References == == External links == Open Channels - Forum for Ocean Planning and Management SeaSketch - Software tools to support collaborative ocean planning


id: oceanic-basin-20260505-0
file: data/en.wikipedia.org/wiki/Oceanic_basin-0.md
category: reference
title: Oceanic basin
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_basin
date_saved: 2026-05-05T07:35:57.426803+00:00
instance: kb-cron
parent: oceanic-basin-20260505-0
summary:
In hydrology, an oceanic basin (or ocean basin) is anywhere on Earth that is covered by seawater. Geologically, most of the ocean basins are large geologic basins that are below sea level. Most commonly the ocean is divided into basins following the continents distribution: the North and South Atlantic (together approximately 75 million km2/ 29 million mi2), North and South Pacific (together approximately 155 million km2/ 59 million mi2), Indian Ocean (68 million km2/ 26 million mi2) and Arctic Ocean (14 million km2/ 5.4 million mi2). Also recognized is the Southern Ocean (20 million km2/ 7 million mi2). All ocean basins collectively cover 67% of the Earth's surface, and together they contain almost 97% of all water on the planet. They have an average depth of almost 4 km (about 2.5 miles). == Definitions of boundaries == === Boundaries based on continents === "Limits of Oceans and Seas", published by the International Hydrographic Office in 1953, is a document that defined the ocean's basins as they are largely known today. The main ocean basins are the ones named in the previous section. These main basins are divided into smaller parts. Some examples are: the Baltic Sea (with three subdivisions), the


id: oceanic-basin-20260505-1
file: data/en.wikipedia.org/wiki/Oceanic_basin-1.md
category: reference
title: Oceanic basin
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_basin
date_saved: 2026-05-05T07:35:57.426803+00:00
instance: kb-cron
parent: oceanic-basin-20260505-0
summary:
Convergent boundary: the plates collide, and eventually the denser one slides underneath the lighter one, a process known as subduction. This type of interaction can take place between an oceanic and an oceanic crust, creating a so-called oceanic trench. It can also take place between an oceanic and a continental crust, forming a mountain range in the continent like the Andes, and it can take place between a continental and continental crust, resulting in large mountain chains, like the Himalayas. Divergent boundary: the plates move apart from each other. If this occurs on land a rift is formed, which eventually becomes a rift valley. The most active divergent boundaries lie under the sea. In the ocean, if magma or molten rock ascent from the mantle and fill the gap created by two diverging plates, a mid-ocean ridge is formed. Transform boundary: also called transform fault, occurs when the movement between the plates is horizontal, so no crust is created or destroyed. It can happen both, on land and in the sea, but most of the faults are in the oceanic crust. === Size of trenches === The Earth's deepest trench is the Mariana Trench which extends for about 2500 km


id: oceanic-crust-20260505-0
file: data/en.wikipedia.org/wiki/Oceanic_crust-0.md
category: reference
title: Oceanic crust
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_crust
date_saved: 2026-05-05T07:35:58.651013+00:00
instance: kb-cron
parent: oceanic-crust-20260505-0
summary:
Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. The crust lies above the rigid uppermost layer of the mantle. The crust and the rigid upper mantle layer together constitute oceanic lithosphere. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium. It is thinner than continental crust, or sial, generally less than 10 kilometers thick; however, it is denser, having a mean density of about 3.0 grams per cubic centimeter as opposed to continental crust which has a density of about 2.7 grams per cubic centimeter. The uppermost crust is the result of the cooling of magma derived from mantle material below the plate. The magma is injected into the spreading center, which consists mainly of a partly solidified crystal mush derived from earlier injections, forming magma lenses that are the source of the sheeted dikes that feed the overlying pillow lavas. As the lavas cool they are, in most instances, modified chemically by seawater. These eruptions occur mostly at


id: oceanic-crust-20260505-1
file: data/en.wikipedia.org/wiki/Oceanic_crust-1.md
category: reference
title: Oceanic crust
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_crust
date_saved: 2026-05-05T07:35:58.651013+00:00
instance: kb-cron
parent: oceanic-crust-20260505-0
summary:
=== Life cycle === Oceanic crust is continuously being created at mid-ocean ridges. As continental plates diverge at these ridges, magma rises into the upper mantle and crust. As the continental plates move away from the ridge, the newly formed rocks cool and start to erode with sediment gradually building up on top of them. The youngest oceanic rocks are at the oceanic ridges, and they get progressively older away from the ridges. As the mantle rises it cools and melts, as the pressure decreases and it crosses the solidus. The amount of melt produced depends only on the temperature of the mantle as it rises. Hence most oceanic crust is the same thickness (7±1 km). Very slow spreading ridges (<1 cm·yr−1 half-rate) produce thinner crust (4–5 km thick) as the mantle has a chance to cool on upwelling and so it crosses the solidus and melts at lesser depth, thereby producing less melt and thinner crust. An example of this is the Gakkel Ridge under the Arctic Ocean. Thicker than average crust is found above plumes as the mantle is hotter and hence it crosses the solidus and melts at a greater depth, creating more melt and a thicker


id: oceanic-plateau-20260505-0
file: data/en.wikipedia.org/wiki/Oceanic_plateau-0.md
category: reference
title: Oceanic plateau
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_plateau
date_saved: 2026-05-05T07:35:59.916062+00:00
instance: kb-cron
parent: oceanic-plateau-20260505-0
summary:
An oceanic or submarine plateau is a large, relatively flat elevation that is higher than the surrounding relief with one or more relatively steep sides. There are 184 oceanic plateaus in the world, covering an area of 18,486,600 km2 (7,137,700 sq mi) or about 5.11% of the oceans. The South Pacific region around Australia and New Zealand contains the greatest number of oceanic plateaus (see map). Oceanic plateaus produced by large igneous provinces are often associated with hotspots, mantle plumes, and volcanic islands — such as Iceland, Hawaii, Cape Verde, and Kerguelen. The three largest plateaus, the Caribbean, Ontong Java, and Mid-Pacific Mountains, are located on thermal swells. Other oceanic plateaus, however, are made of rifted continental crust, for example the Falkland Plateau, Lord Howe Rise, and parts of Kerguelen, Seychelles, and Arctic ridges. Plateaus formed by large igneous provinces were formed by the equivalent of continental flood basalts such as the Deccan Traps in India and the Snake River Plain in the United States. In contrast to continental flood basalts, most igneous oceanic plateaus erupt through young and thin (6–7 km (3.7–4.3 mi)) mafic or ultra-mafic crust and are therefore uncontaminated by felsic crust and representative for their mantle


id: oceanic-trench-20260505-0
file: data/en.wikipedia.org/wiki/Oceanic_trench-0.md
category: reference
title: Oceanic trench
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_trench
date_saved: 2026-05-05T07:36:01.226469+00:00
instance: kb-cron
parent: oceanic-trench-20260505-0
summary:
Oceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They are typically 50 to 100 kilometers (30 to 60 mi) wide and 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about 50,000 km (31,000 mi) of oceanic trenches worldwide, mostly around the Pacific Ocean, but also in the eastern Indian Ocean and a few other locations. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of 10,994 m (36,070 ft) below sea level. Oceanic trenches are a feature of the Earth's distinctive plate tectonics. They mark the locations of convergent plate boundaries, along which lithospheric plates move towards each other at rates that vary from a few millimeters to over ten centimeters per year. Oceanic lithosphere moves into trenches at a global rate of about 3 km2 (1.2 sq mi) per year. A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to and about 200 km (120 mi) from a volcanic arc. Much of the fluid trapped in


id: oceanic-trench-20260505-1
file: data/en.wikipedia.org/wiki/Oceanic_trench-1.md
category: reference
title: Oceanic trench
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_trench
date_saved: 2026-05-05T07:36:01.226469+00:00
instance: kb-cron
parent: oceanic-trench-20260505-0
summary:
Oceanic trenches are 50 to 100 kilometers (30 to 60 mi) wide and have an asymmetric V-shape, with the steeper slope (8 to 20 degrees) on the inner (overriding) side of the trench and the gentler slope (around 5 degrees) on the outer (subducting) side of the trench. The bottom of the trench marks the boundary between the subducting and overriding plates, known as the basal plate boundary shear or the subduction décollement. The depth of the trench depends on the starting depth of the oceanic lithosphere as it begins its plunge into the trench, the angle at which the slab plunges, and the amount of sedimentation in the trench. Both starting depth and subduction angle are greater for older oceanic lithosphere, which is reflected in the deep trenches of the western Pacific. Here the bottoms of the Marianas and the Tonga–Kermadec trenches are up to 10–11 kilometers (6.2–6.8 mi) below sea level. In the eastern Pacific, where the subducting oceanic lithosphere is much younger, the depth of the Peru-Chile trench is around 7 to 8 kilometers (4.3 to 5.0 mi). Though narrow, oceanic trenches are remarkably long and continuous, forming the largest linear depressions on earth. An individual trench


id: oceanic-trench-20260505-2
file: data/en.wikipedia.org/wiki/Oceanic_trench-2.md
category: reference
title: Oceanic trench
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_trench
date_saved: 2026-05-05T07:36:01.226469+00:00
instance: kb-cron
parent: oceanic-trench-20260505-0
summary:
=== Erosive versus accretionary margins === Convergent margins are classified as erosive or accretionary, and this has a strong influence on the morphology of the inner slope of the trench. Erosive margins, such as the northern Peru-Chile, Tonga-Kermadec, and Mariana trenches, correspond to sediment-starved trenches. The subducting slab erodes material from the lower part of the overriding slab, reducing its volume. The edge of the slab experiences subsidence and steepening, with normal faulting. The slope is underlain by relative strong igneous and metamorphic rock, which maintains a high angle of repose. Over half of all convergent margins are erosive margins. Accretionary margins, such as the southern Peru-Chile, Cascadia, and Aleutians, are associated with moderately to heavily sedimented trenches. As the slab subducts, sediments are "bulldozed" onto the edge of the overriding plate, producing an accretionary wedge or accretionary prism. This builds the overriding plate outwards. Because the sediments lack strength, their angle of repose is gentler than the rock making up the inner slope of erosive margin trenches. The inner slope is underlain by imbricated thrust sheets of sediments. The inner slope topography is roughened by localized mass wasting. Cascadia has practically no bathymetric expression of the outer rise and


id: oceanic-trench-20260505-3
file: data/en.wikipedia.org/wiki/Oceanic_trench-3.md
category: reference
title: Oceanic trench
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_trench
date_saved: 2026-05-05T07:36:01.226469+00:00
instance: kb-cron
parent: oceanic-trench-20260505-0
summary:
=== Mantle interactions === Interactions with the mantle discontinuities play a significant role in slab rollback. Stagnation at the 660-km discontinuity causes retrograde slab motion due to the suction forces acting at the surface. Slab rollback induces mantle return flow, which causes extension from the shear stresses at the base of the overriding plate. As slab rollback velocities increase, circular mantle flow velocities also increase, accelerating extension rates. Extension rates are altered when the slab interacts with the discontinuities within the mantle at 410 km and 660 km depth. Slabs can either penetrate directly into the lower mantle, or can be retarded due to the phase transition at 660 km depth creating a difference in buoyancy. An increase in retrograde trench migration (slab rollback) (2–4 cm/yr) is a result of flattened slabs at the 660-km discontinuity where the slab does not penetrate into the lower mantle. This is the case for the Japan, Java and Izu–Bonin trenches. These flattened slabs are only temporarily arrested in the transition zone. The subsequent displacement into the lower mantle is caused by slab pull forces, or the destabilization of the slab from warming and broadening due to thermal diffusion. Slabs that penetrate directly into


id: oceanic-trench-20260505-4
file: data/en.wikipedia.org/wiki/Oceanic_trench-4.md
category: reference
title: Oceanic trench
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_trench
date_saved: 2026-05-05T07:36:01.226469+00:00
instance: kb-cron
parent: oceanic-trench-20260505-0
summary:
== Bibliography == Allwrardt, Allan O. (1993). "Evolution of the tectogene concept, 1930–1965" (PDF). Proceedings of the Fifth International Congress on the History of Oceanography. Retrieved 29 September 2021. Amos, Jonathan (11 May 2021). "Oceans' extreme depths measured in precise detail". News. BBC. Retrieved 2 October 2021. Bangs, N. L.; Morgan, J. K.; Tréhu, A. M.; Contreras-Reyes, E.; Arnulf, A. F.; Han, S.; Olsen, K. M.; Zhang, E. (November 2020). "Basal Accretion Along the South Central Chilean Margin and Its Relationship to Great Earthquakes". Journal of Geophysical Research: Solid Earth. 125 (11). Bibcode:2020JGRB..12519861B. doi:10.1029/2020JB019861. S2CID 225154312. Bodine, J.H.; Watts, A.B (1979). "On lithospheric flexure seaward of the Bonin and Mariana trenches". Earth and Planetary Science Letters. 43 (1): 132–148. Bibcode:1979E&PSL..43..132B. doi:10.1016/0012-821X(79)90162-6. Christensen, UR (1996). "The Influence of Trench Migration on Slab Penetration into the Lower Mantle". Earth and Planetary Science Letters. 140 (1–4): 27–39. Bibcode:1996E&PSL.140...27C. doi:10.1016/0012-821x(96)00023-4. Dastanpour, Mohammad (March 1996). "The Devonian System in Iran: a review". Geological Magazine. 133 (2): 159–170. Bibcode:1996GeoM..133..159D. doi:10.1017/S0016756800008670. S2CID 129199671. Dvorkin, Jack; Nur, Amos; Mavko, Gary; Ben-Avraham, Zvi (1993). "Narrow subducting slabs and the origin of backarc basins". Tectonophysics. 227 (1–4): 63–79. Bibcode:1993Tectp.227...63D. doi:10.1016/0040-1951(93)90087-Z. Einsele, Gerhard (2000). Sedimentary Basins: Evolution, Facies, and Sediment Budget


id: oceanic-trench-20260505-5
file: data/en.wikipedia.org/wiki/Oceanic_trench-5.md
category: reference
title: Oceanic trench
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_trench
date_saved: 2026-05-05T07:36:01.226469+00:00
instance: kb-cron
parent: oceanic-trench-20260505-0
summary:
== Further reading == Ellouz-Zimmermann, N.; Deville, E.; Müller, C.; Lallemant, S.; Subhani, A. B.; Tabreez, A. R. (2007). "Impact of Sedimentation on Convergent Margin Tectonics: Example of the Makran Accretionary Prism (Pakistan)". Thrust Belts and Foreland Basins. Frontiers in Earth Sciences. pp. 327–350. doi:10.1007/978-3-540-69426-7_17. ISBN 978-3-540-69425-0. Fisher, R. L.; Hess, H. H. (1963). "Trenches". In M. N. Hill (ed.). The Sea v. 3 The Earth Beneath the Sea. New York: Wiley-Interscience. pp. 411–436. Hamilton, W. B. (1988). "Plate tectonics and island arcs". Geological Society of America Bulletin. Vol. 100, no. 10. pp. 1503–1527. Hawkins, J. W.; Bloomer, S. H.; Evans, C. A.; Melchior, J. T. (1984). "Evolution of Intra-Oceanic Arc-Trench Systems". Tectonophysics. 102 (1–4): 175–205. Bibcode:1984Tectp.102..175H. doi:10.1016/0040-1951(84)90013-1. Jarrard, R. D. (1986). "Relations among subduction parameters". Reviews of Geophysics. 24 (2): 217–284. Bibcode:1986RvGeo..24..217J. doi:10.1029/RG024i002p00217. Ladd, J.W.; Holcombe, T. L.; Westbrook, G. K.; Edgar, N. T. (1990). "Caribbean Marine Geology: Active margins of the plate boundary". In Dengo, G.; Case, J. (eds.). The Geology of North America. Vol. H: The Caribbean Region. Geological Society of America. pp. 261–290. Lemenkova, Paulina (2021). "Topography of the Aleutian Trench south-east off Bowers Ridge, Bering Sea, in the context of the geological development of North


id: oceanic-zone-20260505-0
file: data/en.wikipedia.org/wiki/Oceanic_zone-0.md
category: reference
title: Oceanic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oceanic_zone
date_saved: 2026-05-05T07:36:02.393656+00:00
instance: kb-cron
parent: oceanic-zone-20260505-0
summary:
The oceanic zone is typically defined as the area of the ocean lying beyond the continental shelf (e.g. the neritic zone), but operationally is often referred to as beginning where the water depths drop to below 200 metres (660 ft), seaward from the coast into the open ocean with its pelagic zone. It is the region of open sea beyond the edge of the continental shelf and includes 65% of the ocean's completely open water. The oceanic zone has a wide array of undersea terrain, including trenches that are often deeper than Mount Everest is tall, as well as deep-sea volcanoes and basins. While it is often difficult for life to sustain itself in this type of environment, many species have adapted and do thrive in the oceanic zone. The open ocean is vertically divided into four zones: the sunlight zone, twilight zone, midnight zone, and abyssal zone. == Sub zones == The Mesopelagic (disphotic) zone, which is where only small amounts of light penetrate, lies below the Epipelagic zone. This zone is often referred to as the "Twilight Zone" due to its scarce amount of light. Temperatures in the Mesopelagic zone range from 5 to 4 °C (41 to


id: paleoceanography-20260505-0
file: data/en.wikipedia.org/wiki/Paleoceanography-0.md
category: reference
title: Paleoceanography
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Paleoceanography
date_saved: 2026-05-05T07:36:03.665799+00:00
instance: kb-cron
parent: paleoceanography-20260505-0
summary:
Paleoceanography is the study of the history of the oceans in the geologic past with regard to biology, chemistry, circulation, geology, and patterns of biological productivity and sedimentation. Paleoceanographic studies using environment models and different proxies enable the scientific community to assess the role of the oceanic processes in the global climate by the re-construction of past climate at various intervals. Paleoceanographic research is also intimately tied to paleoclimatology. == Source and methods of information == Paleoceanography makes use of so-called proxy methods as a way to infer information about the past state and evolution of the world's oceans. Several geochemical proxy tools include long-chain organic molecules (e.g. alkenones), stable and radioactive isotopes, and trace metals. Additionally, sediment cores rich with fossils and shells (tests) can also be useful; the field of paleoceanography is closely related to sedimentology and paleontology. === Sea-surface temperature === Sea-surface temperature (SST) records can be extracted from deep-sea sediment cores using oxygen isotope ratios and the ratio of magnesium to calcium (Mg/Ca) in shell secretions from plankton, from long-chain organic molecules such as alkenone, from tropical corals near the sea surface, and from mollusk shells. Oxygen isotope ratios (δ18O) are useful in reconstructing SST because


id: paleoceanography-20260505-1
file: data/en.wikipedia.org/wiki/Paleoceanography-1.md
category: reference
title: Paleoceanography
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Paleoceanography
date_saved: 2026-05-05T07:36:03.665799+00:00
instance: kb-cron
parent: paleoceanography-20260505-0
summary:
=== Ocean circulation === Several proxy methods have been used to infer past ocean circulation and changes to it. They include carbon isotope ratios, cadmium/calcium (Cd/Ca) ratios, protactinium/thorium isotopes (231Pa and 230Th), radiocarbon activity (δ14C), neodymium isotopes (143Nd and 144Nd), and sortable silt (fraction of deep-sea sediment between 10 and 63 μm). Carbon isotope and cadmium/calcium ratio proxies are used because variability in their ratios is due partly to changes in bottom-water chemistry, which is in turn related the source of deep-water formation. These ratios, however, are influenced by biological, ecological, and geochemical processes which complicate circulation inferences. All proxies included are useful in inferring the behavior of the meridional overturning circulation. For example, McManus et al. [2004] used protactinium/thorium isotopes (231Pa and 230Th) to show that the Atlantic Meridional Overturning Circulation had been nearly (or completely) shut off during the last glacial period. 231Pa and 230Th are both formed from the radioactive decay of dissolved uranium in seawater, with 231Pa able to remain supported in the water column longer than 230Th: 231Pa has a residence time ~100–200 years while 230Th has one ~20–40 years. In today's Atlantic Ocean and current overturning circulation, 230Th transport to the Southern Ocean is


id: pelagic-sediment-20260505-0
file: data/en.wikipedia.org/wiki/Pelagic_sediment-0.md
category: reference
title: Pelagic sediment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pelagic_sediment
date_saved: 2026-05-05T07:36:04.868239+00:00
instance: kb-cron
parent: pelagic-sediment-20260505-0
summary:
Pelagic sediment or pelagite is a fine-grained sediment that accumulates as the result of the settling of particles to the floor of the open ocean, far from land. These particles consist primarily of either the microscopic, calcareous or siliceous shells of phytoplankton or zooplankton; clay-size siliciclastic sediment; or some mixture of these, along with detritus (marine snow) included. Trace amounts of meteoric dust and variable amounts of volcanic ash also occur within pelagic sediments. Based upon the composition of the ooze, there are three main types of pelagic sediments: siliceous oozes, calcareous oozes, and red clays. The composition of pelagic sediments is controlled by three main factors. The first factor is the distance from major landmasses, which affects their dilution by terrigenous, or land-derived, sediment. The second factor is water depth, which affects the preservation of both siliceous and calcareous biogenic particles as they settle to the ocean bottom. The final factor is ocean fertility, which controls the amount of biogenic particles produced in surface waters. == Oozes == In case of marine sediments, ooze does not refer to a sediment's consistency, but to its composition, which directly reflects its origin. Ooze is pelagic sediment that consists of at least


id: pelagic-zone-20260505-0
file: data/en.wikipedia.org/wiki/Pelagic_zone-0.md
category: reference
title: Pelagic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pelagic_zone
date_saved: 2026-05-05T07:36:06.087361+00:00
instance: kb-cron
parent: pelagic-zone-20260505-0
summary:
The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word pelagic is derived from Ancient Greek πέλαγος (pélagos) 'open sea'. The pelagic zone can be thought of as an imaginary cylinder or water column between the surface of the sea and the bottom. Conditions in the water column change with depth: pressure increases; temperature and light decrease; salinity, oxygen, micronutrients (such as iron, magnesium and calcium) all change. In a manner analogous to stratification in the Earth's atmosphere, the water column can be divided vertically into up to five different layers (illustrated in the diagram), with the number of layers depending on the depth of the water. Marine life is affected by bathymetry (underwater topography) such as the seafloor, shoreline, or a submarine seamount, as well as by proximity to the boundary between the ocean and the atmosphere at the ocean surface, which brings light for photosynthesis, predation from above, and wind stirring up waves and setting currents in motion. The pelagic zone refers to the open, free waters away from the shore, where marine life can swim freely in any direction unhindered by topographical constraints. The


id: pelagic-zone-20260505-1
file: data/en.wikipedia.org/wiki/Pelagic_zone-1.md
category: reference
title: Pelagic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pelagic_zone
date_saved: 2026-05-05T07:36:06.087361+00:00
instance: kb-cron
parent: pelagic-zone-20260505-0
summary:
=== Pelagic invertebrates === Some examples of pelagic invertebrates include krill, copepods, jellyfish, decapod larvae, hyperiid amphipods, rotifers and cladocerans. Thorson's rule states that benthic marine invertebrates at low latitudes tend to produce large numbers of eggs developing to widely dispersing pelagic larvae, whereas at high latitudes such organisms tend to produce fewer and larger lecithotrophic (yolk-feeding) eggs and larger offspring. === Pelagic fish === Pelagic fish live in the water column of coastal, ocean, and lake waters, but not on or near the bottom of the sea or the lake. They can be contrasted with demersal fish, which do live on or near the bottom, and coral reef fish. Pelagic fish are often migratory forage fish, which feed on plankton, and the larger predatory fish that follow and feed on the forage fish. Migratory fish come up to the more dense prey areas of the pelagic zones to feed, and then descend at night to avoid predators. Examples of migratory forage fish are herring, anchovies, capelin, and menhaden. Examples of larger pelagic fish which prey on the forage fish are billfish, tuna, and oceanic sharks. === Pelagic reptiles === Hydrophis platurus, the yellow-bellied sea snake, is the only one


id: pelagic-zone-20260505-2
file: data/en.wikipedia.org/wiki/Pelagic_zone-2.md
category: reference
title: Pelagic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pelagic_zone
date_saved: 2026-05-05T07:36:06.087361+00:00
instance: kb-cron
parent: pelagic-zone-20260505-0
summary:
Remotely operated vehicles (ROVs) are used for sampling and examining the deep pelagic sea in ways that other techniques cannot match. An ROV is an unoccupied machine equipped with lights, cameras, sensors, or arms, which allows for detailed and live observations of its surroundings and of pelagic organisms. It can conduct experiments and collect samples. These machine are limited in ground coverage, as well as expensive and hard to control, so few research groups use them. They can also be loud, bright, and big, causing organisms to avoid them. === Additional methods === Some other sampling and observation methods are: predator gut examinations, analysis of environmental DNA, organisms that get washed up on shore from upwelling, analyzing sediments cores, and pelagic longline fishing. == References == == Further reading == Ryan, Paddy "Deep-sea creatures" Te Ara – the Encyclopedia of New Zealand, updated 21 September 2007 "Pelagic-zone (oceanography)" Encyclopædia Britannica Online. 21 March 2009. Grantham HS, Game ET, Lombard AT, et al. (2011) "Accommodating Dynamic Oceanographic Processes and Pelagic Biodiversity in Marine Conservation Planning" PLOS One 6(2): e16552. doi:10.1371/journal.pone.0016552. Wrobel, David; Mills, Claudia (2003) [1998]. Pacific Coast Pelagic Invertebrates: A Guide to the Common Gelatinous Animals. Sea Challengers and Monterey


id: list-of-peninsulas-20260505-0
file: data/en.wikipedia.org/wiki/List_of_peninsulas-0.md
category: reference
title: List of peninsulas
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_peninsulas
date_saved: 2026-05-05T07:36:07.459713+00:00
instance: kb-cron
parent: list-of-peninsulas-20260505-0
summary:
A peninsula (Latin: paeninsula from paene "almost" and insula "island") is a piece of land that is bordered mostly by water but connected to mainland. The surrounding water is usually understood to be continuous, though not necessarily named as such. A peninsula can also be a headland, cape, island promontory, bill, point, or spit. A point is generally considered a tapering piece of land projecting into a body of water that is less prominent than a cape. In English, the plural of peninsula is peninsulas or, less commonly, peninsulae. A river which courses through a very tight meander is also sometimes said to form a "peninsula" within the (almost closed) loop of water. Presented below is a list of peninsulas. == Africa == === Macaronesia === Jandía, Fuerteventura, Canary Islands, Spain Macizo de Anaga, Tenerife, Canary Islands, Spain Ponta de São Lourenço, Madeira Island, Portugal === North Africa === === Somali Peninsula === The Horn of Africa is a peninsula in Northeast Africa that juts into the Guardafui Channel, and is the easternmost projection of the African continent. It denotes the region containing the countries of Djibouti, Eritrea, Ethiopia, and Somalia. Buri Peninsula, Eritrea Ras Hafun, Somalia Ras Kasar, Eritrea


id: list-of-peninsulas-20260505-1
file: data/en.wikipedia.org/wiki/List_of_peninsulas-1.md
category: reference
title: List of peninsulas
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_peninsulas
date_saved: 2026-05-05T07:36:07.459713+00:00
instance: kb-cron
parent: list-of-peninsulas-20260505-0
summary:
==== Ontario ==== ==== Quebec ==== Gaspé Peninsula Ungava Peninsula === Caribbean === ==== Haiti ==== Peninsule de Tiburon, Haiti Peninsule de Mole-St-Nicolas, Haiti ==== Dominican Republic ==== Peninsula de Samaná, Dominican Republic ==== Puerto Rico ==== Barrio Obrero, Puerto Rico ==== Cuba ==== Zapata Peninsula, Cuba Guanahacabibes Peninsula, Cuba Hicacos Peninsula, Cuba ==== Saint Lucia ==== Vigie Peninsula, St Lucia === Costa Rica === Nicoya Peninsula, Costa Rica Osa Peninsula, Costa Rica === Greenland === Wegener Peninsula Hayes Halvo Ingnerit Nuussuaq Peninsula Sigguup Nunaa (Svartenhuk Halvø) === Mexico === Baja California Peninsula, Mexico, containing the states of Baja California and Baja California Sur Yucatán Peninsula, partly separating the Gulf of Mexico from the Caribbean === Panama === === United States === ==== Alaska ==== Alaska Peninsula Cleveland Peninsula Kenai Peninsula Seward Peninsula Lisburne Peninsula ==== California ==== ==== Florida ==== Florida is a well-known example of a large peninsula, with its land area divided between the larger Florida peninsula and the smaller Florida Panhandle on the north and west. It has several smaller peninsulas within it: The St. Johns River creates a large peninsula over 75 miles (121 km) in length that stretches from eastern Jacksonville down to the


id: photic-zone-20260505-0
file: data/en.wikipedia.org/wiki/Photic_zone-0.md
category: reference
title: Photic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photic_zone
date_saved: 2026-05-05T07:36:08.714083+00:00
instance: kb-cron
parent: photic-zone-20260505-0
summary:
The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological processes that supply nutrients into the upper water column. The photic zone is home to the majority of aquatic life due to the activity (primary production) of the phytoplankton. The thicknesses of the photic and euphotic zones vary with the intensity of sunlight as a function of season and latitude and with the degree of water turbidity. The bottommost, or aphotic, zone is the region of perpetual darkness that lies beneath the photic zone and includes most of the ocean waters. == Photosynthesis in photic zone == In the photic zone, the photosynthesis rate exceeds the respiration rate. This is due to the abundant solar energy which is used as an energy source for photosynthesis by primary producers such as phytoplankton. These phytoplankton grow extremely quickly because of sunlight's heavy influence, enabling it to be produced at a fast rate. In fact, ninety five percent of photosynthesis in the ocean occurs in the photic zone. Therefore, if we go deeper, beyond the photic


id: photic-zone-20260505-1
file: data/en.wikipedia.org/wiki/Photic_zone-1.md
category: reference
title: Photic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photic_zone
date_saved: 2026-05-05T07:36:08.714083+00:00
instance: kb-cron
parent: photic-zone-20260505-0
summary:
== Photic zone darkening == A study done by the University of Pittsburgh found that in recent years there was a significant darkening of the photic zone between the years 2003 and 2022 with the ocean becoming more green, especially in low-latitude oceans. Though researchers are uncertain of the cause, it's been widely proposed this is due to Climate change, there are conflicted conclusions on whether the raised temperatures and increased carbon dioxide emissions lead to a decrease or an increase of primary productivity. Though this change in ocean color was predicted through modeling in 2010, it was not confirmed until new satellite-based technologies made it possible in 2023. Though climate change may be the root cause, researchers have formulated theories for what specifically is causing this greening and consequential change in the photic zone depth, including unbalanced Phytoplankton, zooplankton, algae, and other microorganism populations; increase in Ocean stratification; and changes to the ocean current circulation. Combined, these changes may also increase the amount of Colored dissolved organic matter which would account for the ocean greening. Researchers are conflicted on whether runoff from land has any significant effect on the greening with some arguing it is too widespread for runoff


id: photic-zone-20260505-2
file: data/en.wikipedia.org/wiki/Photic_zone-2.md
category: reference
title: Photic zone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photic_zone
date_saved: 2026-05-05T07:36:08.714083+00:00
instance: kb-cron
parent: photic-zone-20260505-0
summary:
Phytoplankton are unicellular microorganisms which form the base of the ocean food chains. They are dominated by diatoms, which grow silicate shells called frustules. When diatoms die their shells can settle on the seafloor and become microfossils. Over time, these microfossils become buried as opal deposits in the marine sediment. Paleoclimatology is the study of past climates. Proxy data is used in order to relate elements collected in modern-day sedimentary samples to climatic and oceanic conditions in the past. Paleoclimate proxies refer to preserved or fossilized physical markers which serve as substitutes for direct meteorological or ocean measurements. An example of proxies is the use of diatom isotope records of δ13C, δ18O, δ30Si (δ13Cdiatom, δ18Odiatom, and δ30Sidiatom). In 2015, Swann and Snelling used these isotope records to document historic changes in the photic zone conditions of the north-west Pacific Ocean, including nutrient supply and the efficiency of the soft-tissue biological pump, from the modern day back to marine isotope stage 5e, which coincides with the last interglacial period. Peaks in opal productivity in the marine isotope stage are associated with the breakdown of the regional halocline stratification and increased nutrient supply to the photic zone. The initial development of the


id: plankton-20260505-0
file: data/en.wikipedia.org/wiki/Plankton-0.md
category: reference
title: Plankton
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plankton
date_saved: 2026-05-05T07:36:10.175954+00:00
instance: kb-cron
parent: plankton-20260505-0
summary:
Plankton (from the Greek planktos, meaning "drifter" or "wanderer") are organisms that drift in water (or air) but are unable to actively propel themselves against currents (or wind). Marine plankton include drifting organisms that inhabit the saltwater of oceans and the brackish waters of estuaries. Freshwater plankton are similar to marine plankton, but are found in lakes and rivers. An individual plankton organism in the plankton is called a plankter. Plankton includes organisms from species across all the major biological kingdoms, ranging in size from the microscopic (such as bacteria, archaea, protozoa and microscopic algae and fungi) to larger organisms (such as jellyfish and ctenophores). This is because plankton are defined by their ecological niche and level of motility rather than by any phylogenetic or taxonomic classification. The plankton category differentiates organisms from those that can swim against a current, called nekton, and those that live on the deep sea floor, called benthos. Organisms that float on or near the water's surface are called neuston. Neuston that drift as water currents or wind take them, and lack the swimming ability to counter this, form a special subgroup of plankton. Mostly plankton just drift where currents take them, though some, like


id: plankton-20260505-1
file: data/en.wikipedia.org/wiki/Plankton-1.md
category: reference
title: Plankton
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plankton
date_saved: 2026-05-05T07:36:10.175954+00:00
instance: kb-cron
parent: plankton-20260505-0
summary:
Plankton is mostly made up of planktonic microorganisms less than one millimetre across, most visible only through a microscope. Microorganisms have been variously estimated to make up about 70%, or about 90%, of the total ocean biomass. Taken together they form the marine microbiome. Over billions of years this microbiome has evolved many life styles and adaptations and come to participate in the global cycling of almost all chemical elements. Microplankton are ecological linchpins in the marine food web. They are crucial to nutrient recycling in the way they act as decomposers. They are also responsible for nearly all photosynthesis that occurs in the ocean, as well as the cycling of carbon, nitrogen, phosphorus and other nutrients and trace elements. Microplankton sequesters large amounts of carbon and produce much of the world's oxygen. It is estimated marine viruses kill 20% of ocean microplankton biomass every day. Viruses are the main agents responsible for the rapid destruction of harmful algal blooms which often kill other marine life. The number of viruses in the plankton decreases further offshore and deeper into the water, where there are fewer host organisms. === Terminology === The name plankton was coined by German marine biologist Victor


id: plankton-20260505-2
file: data/en.wikipedia.org/wiki/Plankton-2.md
category: reference
title: Plankton
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plankton
date_saved: 2026-05-05T07:36:10.175954+00:00
instance: kb-cron
parent: plankton-20260505-0
summary:
Plankton are also found at the ocean surface. Organisms that live at or just below the air-sea interface are called neuston. They float either on the water's surface (epineuston) or swim in the top few centimeters (hyponeuston). Many neuston qualify to be categorised as part of the broader plankton community, because they drift largely as currents or wind dictate, lacking strong enough swimming ability to counter them. Neustonic animals are primarily adapted to float upside-down on the ocean surface, similar to an inverted benthos, and form a unique subset of the zooplankton community, which plays a pivotal role in the functioning of marine ecosystems. Neustonic zooplankton are partially responsible for the active energy flux between superficial and deep layers of the ocean.Neustonic plankton is also a food source for marine zooplankton and fish migrating from the deep layers and seabirds. ==== In deep ocean ==== In 2025, researchers discovered microbial communities inhabiting the ocean conveyor belt, even at great depths in the ocean. Ocean currents are generated by surface wind and storms down to about 500 m (1,600 ft) below the surface. But the average depth of the ocean goes far below to 3.7 km (2.3 mi). At these greater


id: plankton-20260505-3
file: data/en.wikipedia.org/wiki/Plankton-3.md
category: reference
title: Plankton
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plankton
date_saved: 2026-05-05T07:36:10.175954+00:00
instance: kb-cron
parent: plankton-20260505-0
summary:
=== Zooplankton === Zooplankton (from Greek zoon, or animal) are small protozoans or metazoans (e.g. crustaceans and other animals) that feed on other plankton. Some of the eggs and larvae of larger nektonic animals, such as fish, crustaceans, and annelids, are included here. === Mixoplankton === Mixoplankton (from Greek mixis, or mixture) have a mixed trophic strategy. In recent years, there has been a growing recognition that perhaps the majority of plankton can act in both the above modes. Traditionally, plankton were divided into just the first two broad trophic groups: plant-like phytoplankton which make their own food, usually by photosynthesis, and animal-like zooplankton that eat other plankton. In recent years, there has been a recognition that many plankton, perhaps over half, are mixotrophic. Plankton have traditionally been categorized as producer, consumer, and recycler groups, but some plankton are able to benefit from more than just one trophic level. This mixed trophic strategy means mixoplankton can act as both producers and consumers, either at the same time or switching between modes of nutrition in response to ambient conditions. In this manner, mixoplankton can use photosynthesis for growth when nutrients and light are abundant, but switch to eating phytoplankton, zooplankton or


id: plankton-20260505-4
file: data/en.wikipedia.org/wiki/Plankton-4.md
category: reference
title: Plankton
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plankton
date_saved: 2026-05-05T07:36:10.175954+00:00
instance: kb-cron
parent: plankton-20260505-0
summary:
Pseudoplankton are organisms that attach themselves to planktonic organisms or other floating objects, such as drifting wood, buoyant shells of organisms such as Spirula, or man-made flotsam. Examples include goose barnacles and the bryozoan Jellyella. By themselves these animals cannot float, which contrasts them with true planktonic organisms, such as Velella and the Portuguese Man o' War, which are buoyant. Pseudoplankton are often found in the guts of filtering zooplankters. === Tychoplankton === Tychoplankton are organisms, such as free-living or attached benthic organisms and other non-planktonic organisms, that are carried into the plankton through a disturbance of their benthic habitat, or by winds and currents. This can occur by direct turbulence or by disruption of the substrate and subsequent entrainment in the water column. Tychoplankton are, therefore, a primary subdivision for sorting planktonic organisms by duration of lifecycle spent in the plankton, as neither their entire lives nor particular reproductive portions are confined to planktonic existence. Tychoplankton are sometimes called accidental plankton. === Mineralized plankton === === By life cycle === ==== Holoplankton ==== Holoplankton are organisms that are planktic for their entire life cycle. Holoplankton can be contrasted with meroplankton, which are planktic organisms that spend part of their


id: plankton-20260505-5
file: data/en.wikipedia.org/wiki/Plankton-5.md
category: reference
title: Plankton
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plankton
date_saved: 2026-05-05T07:36:10.175954+00:00
instance: kb-cron
parent: plankton-20260505-0
summary:
The absorption efficiency (AE) of plankton is the proportion of food absorbed by the plankton that determines how available the consumed organic materials are in meeting the required physiological demands. Depending on the feeding rate and prey composition, variations in absorption efficiency may lead to variations in fecal pellet production, and thus regulates how much organic material is recycled back to the marine environment. Low feeding rates typically lead to high absorption efficiency and small, dense pellets, while high feeding rates typically lead to low absorption efficiency and larger pellets with more organic content. Another contributing factor to dissolved organic matter (DOM) release is respiration rate. Physical factors such as oxygen availability, pH, and light conditions may affect overall oxygen consumption and how much carbon is loss from zooplankton in the form of respired CO2. The relative sizes of zooplankton and prey also mediate how much carbon is released via sloppy feeding. Smaller prey are ingested whole, whereas larger prey may be fed on more "sloppily", that is more biomatter is released through inefficient consumption. There is also evidence that diet composition can impact nutrient release, with carnivorous diets releasing more dissolved organic carbon (DOC) and ammonium than omnivorous diets.


id: plankton-20260505-6
file: data/en.wikipedia.org/wiki/Plankton-6.md
category: reference
title: Plankton
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plankton
date_saved: 2026-05-05T07:36:10.175954+00:00
instance: kb-cron
parent: plankton-20260505-0
summary:
== Plankton Manifesto == In 2024, the United Nations Global Compact's Ocean Stewardship Coalition launched the Plankton Manifesto, collaboratively developed by over 30 international experts. It outlines strategic recommendations to guide global efforts at safeguarding plankton and harnessing their potential to address planetary climate change issues, as well as pollution and biodiversity loss. It emphasizes plankton's critical role as the foundation of marine ecosystems, producing about 50% of Earth's oxygen and sequestering 30–50 billion metric tonnes of carbon annually. Key recommendations include: Enhanced research and monitoring: Leveraging technologies like DNA sequencing, bioinformatics, satellite monitoring, and AI image analysis to improve understanding of plankton dynamics and create a global plankton atlas. Plankton-based solutions: Promoting innovative applications, such as using plankton for water purification, bioplastics, fertilizers, and animal feed to support sustainable industries. Policy integration: Urging governments, United Nations agencies, and businesses to include plankton in climate and biodiversity frameworks, with endorsements sought at COP29, COP16, and the 2025 United Nations Ocean Conference. Public awareness: Fostering "plankton literacy" through education and interdisciplinary initiatives to highlight their role in food security and ecosystem health. Collaboration: Encouraging cross-sectoral partnerships among academia, industry, and governments to fund research and protect plankton from threats like nutrient


id: marine-pollution-20260505-0
file: data/en.wikipedia.org/wiki/Marine_pollution-0.md
category: reference
title: Marine pollution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_pollution
date_saved: 2026-05-05T07:36:11.497461+00:00
instance: kb-cron
parent: marine-pollution-20260505-0
summary:
Marine pollution occurs when substances used or spread by humans, such as industrial, agricultural, and residential waste; particles; noise; excess carbon dioxide; or invasive organisms enter the ocean and cause harmful effects there. The majority of this waste (80%) comes from land-based activity, although marine transportation significantly contributes as well. It is a combination of chemicals and trash, most of which comes from land sources and is washed or blown into the ocean. This pollution results in damage to the environment, to the health of all organisms, and to economic structures worldwide. Since most inputs come from land, via rivers, sewage, or the atmosphere, it means that continental shelves are more vulnerable to pollution. Air pollution is also a contributing factor, as it carries iron, carbonic acid, nitrogen, silicon, sulfur, pesticides, and dust particles into the ocean. The pollution often comes from nonpoint sources such as agricultural runoff, wind-blown debris, and dust. These nonpoint sources are largely due to runoff that enters the ocean through rivers, but wind-blown debris and dust can also play a role, as these pollutants can settle into waterways and oceans. Pathways of pollution include direct discharge, land runoff, ship pollution, bilge pollution, dredging (which can


id: marine-pollution-20260505-1
file: data/en.wikipedia.org/wiki/Marine_pollution-1.md
category: reference
title: Marine pollution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_pollution
date_saved: 2026-05-05T07:36:11.497461+00:00
instance: kb-cron
parent: marine-pollution-20260505-0
summary:
=== Land runoff === Surface runoff from farming, as well as urban runoff and runoff from the construction of roads, buildings, ports, channels, and harbours, can carry soil and particles laden with carbon, nitrogen, phosphorus, and minerals. This nutrient-rich water can cause fleshy algae and phytoplankton to thrive in coastal areas; known as algal blooms, which have the potential to create hypoxic conditions by using all available oxygen. In the coast of southwest Florida, harmful algal blooms have existed for over 100 years. These algal blooms have been a cause of species of fish, turtles, dolphins, and shrimp to die and cause harmful effects on humans who swim in the water. Polluted runoff from roads and highways can be a significant source of water pollution in coastal areas. About 75% of the toxic chemicals that flow into Puget Sound are carried by stormwater that runs off paved roads and driveways, rooftops, yards and other developed land. In California, there are many rainstorms that runoff into the ocean. These rainstorms occur from October to March, and these runoff waters contain petroleum, heavy metals, pollutants from emissions, etc. In China, there is a large coastal population that pollutes the ocean through land


id: marine-pollution-20260505-2
file: data/en.wikipedia.org/wiki/Marine_pollution-2.md
category: reference
title: Marine pollution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_pollution
date_saved: 2026-05-05T07:36:11.497461+00:00
instance: kb-cron
parent: marine-pollution-20260505-0
summary:
=== Deep sea mining === Some of the potential toxic metals include copper, zinc, cadmium, lead as well as rare earth elements such as lanthanum and yttrium. Following the release of toxins there is an increase of noise, light, sediment le dan plumes and elements that have the potential to impact the ecosystems. Deep sea minerals (DSM) can be extremely beneficial, it can cause wealth, raising living standards as well as economic opportunities for both current and future generations. In addition, if the wealth is poorly managed it can have the potential to cause great economic and social damage. The instability of price and production levels of minerals can cause an external economic shock leading to a significant backlash on the domestic economy. == Types of pollution == === Marine debris pollution === === Plastic pollution === === Ocean acidification === === Nutrient pollution === Eutrophication is an increase in chemical nutrients, typically compounds containing nitrogen or phosphorus, in an ecosystem. It can result in an increase in the ecosystem's primary productivity (excessive plant growth and decay), and further effects including lack of oxygen and severe reductions in water quality, fish, and other animal populations. Nutrient pollution, a form of


id: marine-pollution-20260505-3
file: data/en.wikipedia.org/wiki/Marine_pollution-3.md
category: reference
title: Marine pollution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_pollution
date_saved: 2026-05-05T07:36:11.497461+00:00
instance: kb-cron
parent: marine-pollution-20260505-0
summary:
Apart from plastics, there are particular problems with other toxic pollutants that either do not break down or only very slowly in the marine environment. Examples of persistent toxicants are PCBs, DDT, TBT, pesticides, furans, dioxins, phenols, radioactive waste, and PFAS. Heavy metals are metallic chemical elements that have a relatively high density and are toxic or poisonous at low concentrations. Examples are mercury, lead, copper and cadmium. Some toxicants can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation. They are also known to accumulate in benthic environments, such as estuaries and bay muds: a geological record of human activities of the last century. DDT is a very toxic chemical that was used as a pesticide in mass quantities throughout the United States and is known to be neurotoxic, a reproductive toxin, an endocrine disruptor, and a carcinogen. DDT is a major focus of the book Silent Spring published by Rachel Carson in 1962. This is often attributed to launching the modern environmental movement and setting the stage for the creation of the EPA in 1970. DDT was banned in the U.S. two years later in 1972. Unfortunately, large quantities had already entered


id: marine-pollution-20260505-4
file: data/en.wikipedia.org/wiki/Marine_pollution-4.md
category: reference
title: Marine pollution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_pollution
date_saved: 2026-05-05T07:36:11.497461+00:00
instance: kb-cron
parent: marine-pollution-20260505-0
summary:
Marine life can be susceptible to noise or the sound pollution from sources such as passing ships, oil exploration seismic surveys, and naval low-frequency active sonar. Sound travels more rapidly and over larger distances in the sea than in the atmosphere. Between 1950 and 1975, ambient noise at one location in the Pacific Ocean increased by about ten decibels (that is a tenfold increase in intensity). Underwater noise pollution is unevenly distributed across marine environments, with the highest con-centrations occurring in shipping lanes, port areas, and densely trafficked ocean routes. These areas experience sustained high ambient noise levels due to the dominance of older and larger vessels, which emit significant low-frequency noise (10 to 500 Hz) caused by engine vibrations, propeller cavitation, and hull turbulence. While advancements in ship design have shown potential to reduce noise emissions, older, noisier vessels remain prevalent in major shipping routes, largely due to economic and logistical constraints. Additionally, the overall increase in global shipping activity in the 20th century contributed to a rise of approximately 12 decibels in ambient noise levels in the Northern Hemisphere, particularly in the low-frequency range, which propagates over long distances with minimal attenuation. Studies in the Southern Hemisphere do


id: marine-pollution-20260505-5
file: data/en.wikipedia.org/wiki/Marine_pollution-5.md
category: reference
title: Marine pollution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_pollution
date_saved: 2026-05-05T07:36:11.497461+00:00
instance: kb-cron
parent: marine-pollution-20260505-0
summary:
== Mitigation == Much anthropogenic pollution ends up in the ocean. The 2011 edition of the United Nations Environment Programme Year Book identifies as the main emerging environmental issues the loss to the oceans of massive amounts of phosphorus, "a valuable fertilizer needed to feed a growing global population", and the impact billions of pieces of plastic waste are having globally on the health of marine environments. Bjorn Jennssen (2003) notes in his article, "Anthropogenic pollution may reduce biodiversity and productivity of marine ecosystems, resulting in reduction and depletion of human marine food resources". There are two ways the overall level of this pollution can be mitigated: either the human population is reduced, or a way is found to reduce the ecological footprint left behind by the average human. If the second way is not adopted, then the first way may be imposed as the world ecosystems falter. The second way is for humans, individually, to pollute less. That requires social and political will, together with a shift in awareness so more people respect the environment and are less disposed to abuse it. At an operational level, regulations, and international government participation is needed. It is often very difficult to


id: marine-pollution-20260505-6
file: data/en.wikipedia.org/wiki/Marine_pollution-6.md
category: reference
title: Marine pollution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_pollution
date_saved: 2026-05-05T07:36:11.497461+00:00
instance: kb-cron
parent: marine-pollution-20260505-0
summary:
In 1948, Harry Truman signed a law formerly known as the Federal Water Pollution Control Act that allowed the federal government to control marine pollution in United States of America. In 1972, the Marine Protection, Research, and Sanctuaries Act of 1972 (MPRSA) was passed by the United States Congress, and regulates ocean dumping of waste in US waters. The 1954 Convention for the Prevention of Pollution of the Sea by Oil and the 1973 International Convention for the Prevention of Pollution by Ships were weakly enforced due to a lack of respect for the laws from flag states. In 1973 and 1978, MARPOL 73/78 was a treaty written to control vessel pollution, especially regarding oil. In 1983, the International Convention for the Prevention of Pollution from Ships enforced the MARPOL 73/78 treaty internationally. The 1982 United Nations Convention on the Law of the Sea (UNCLOS) was established to protect the marine environment by governing states to control their pollution to the ocean. It put restrictions on the amount of toxins and pollutants that come from all ships internationally. In 2006, the Marine Debris Research, Prevention and Reduction Ac. It was established by the National Oceanic and Atmospheric Administration (NOAA) to


id: raised-beach-20260505-0
file: data/en.wikipedia.org/wiki/Raised_beach-0.md
category: reference
title: Raised beach
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Raised_beach
date_saved: 2026-05-05T07:36:12.792673+00:00
instance: kb-cron
parent: raised-beach-20260505-0
summary:
A raised beach, coastal terrace, or perched coastline is a relatively flat, horizontal or gently inclined surface of marine origin, mostly an old abrasion platform which has been lifted out of the sphere of wave activity (sometimes called "tread"). Thus, it lies above or under the current sea level, depending on the time of its formation. It is bounded by a steeper ascending slope on the landward side and a steeper descending slope on the seaward side (sometimes called "riser"). Due to its generally flat shape, it is often used for anthropogenic structures such as settlements and infrastructure. A raised beach is an emergent coastal landform. Raised beaches and marine terraces are beaches or wave-cut platforms raised above the shoreline by a relative fall in the sea level. Around the world, a combination of tectonic coastal uplift and Quaternary sea-level fluctuations has resulted in the formation of marine terrace sequences, most of which were formed during separate interglacial highstands that can be correlated to marine isotope stages (MIS). A marine terrace commonly retains a shoreline angle or inner edge, the slope inflection between the marine abrasion platform and the associated paleo sea cliff. The shoreline angle represents the maximum shoreline


