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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Coast | 4/4 | https://en.wikipedia.org/wiki/Coast | reference | science, encyclopedia | 2026-05-05T07:34:34.633460+00:00 | kb-cron |
"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 marine biologists have yet other takes. Coastal waters have a wide range of marine habitats from enclosed estuaries to the open waters of the continental shelf.
Similarly, the term littoral zone has no single definition. It is the part of a sea, lake, or river that is close to the shore. In coastal environments, the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged.
Coastal waters can be threatened by coastal eutrophication and harmful algal blooms.
== In geology == The identification of bodies of rock formed from sediments deposited in shoreline and nearshore environments (shoreline and nearshore facies) is extremely important to geologists. These provide vital clues for reconstructing the geography of ancient continents (paleogeography). The locations of these beds show the extent of ancient seas at particular points in geological time, and provide clues to the magnitudes of tides in the distant past. Sediments deposited in the shoreface are preserved as lenses of sandstone in which the upper part of the sandstone is coarser than the lower part (a coarsening upwards sequence). Geologists refer to these are parasequences. Each records an episode of retreat of the ocean from the shoreline over a period of 10,000 to 1,000,000 years. These often show laminations reflecting various kinds of tidal cycles. Some of the best-studied shoreline deposits in the world are found along the former western shore of the Western Interior Seaway, a shallow sea that flooded central North America during the late Cretaceous Period (about 100 to 66 million years ago). These are beautifully exposed along the Book Cliffs of Utah and Colorado.
=== Geologic processes === The following articles describe the various geologic processes that affect a coastal zone:
== Wildlife ==
=== Animals ===
Larger animals that live in coastal areas include puffins, sea turtles and rockhopper penguins, among many others. Sea snails and various kinds of barnacles live on rocky coasts and scavenge on food deposited by the sea. Some coastal animals are used to humans in developed areas, such as dolphins and seagulls who eat food thrown for them by tourists. Since the coastal areas are all part of the littoral zone, there is a profusion of marine life found just off-coast, including sessile animals such as corals, sponges, starfish, mussels, seaweeds, fishes, and sea anemones. There are many kinds of seabirds on various coasts. These include pelicans and cormorants, who join up with terns and oystercatchers to forage for fish and shellfish. There are sea lions on the coast of Wales and other countries.
==== Coastal fish ====
=== Plants === Many coastal areas are famous for their kelp beds. Kelp is a fast-growing seaweed that can grow up to half a meter a day in ideal conditions. Mangroves, seagrasses, macroalgal beds, and salt marsh are important coastal vegetation types in tropical and temperate environments respectively. Restinga is another type of coastal vegetation.
== Threats ==
Coasts also face many human-induced environmental impacts and coastal development hazards. The most important ones are:
Pollution which can be in the form of water pollution, nutrient pollution (leading to coastal eutrophication and harmful algal blooms), oil spills or marine debris that is contaminating coasts with plastic and other trash. Sea level rise, and associated issues like coastal erosion and saltwater intrusion.
=== Pollution ===
The pollution of coastlines is connected to marine pollution which can occur from a number of sources: Marine debris (garbage and industrial debris); the transportation of petroleum in tankers, increasing the probability of large oil spills; small oil spills created by large and small vessels, which flush bilge water into the ocean.
==== Marine pollution ====
==== Marine debris ====
==== Microplastics ====
=== Sea level rise due to climate change ===
== Global goals == International attention to address the threats of coasts has been captured in Sustainable Development Goal 14 "Life Below Water" which sets goals for international policy focused on preserving marine coastal ecosystems and supporting more sustainable economic practices for coastal communities. Likewise, the United Nations has declared 2021–2030 the UN Decade on Ecosystem Restoration, but restoration of coastal ecosystems has received insufficient attention.
== See also ==
Bank (geography) Beach cleaning Coastal and Estuarine Research Federation European Atlas of the Seas Intertidal zone Land reclamation List of countries by length of coastline List of U.S. states by coastline Offshore or Intertidal zone Ballantine Scale Coastal path Shorezone
== References ==
== Further reading == Scheffers, Anja M.; Scheffers, Sander R.; Kelletat, Dieter H. (2012). The Coastlines of the World with Google Earth: Understanding our Environment. New York: Springer. ISBN 978-94-007-0737-5.
== External links == Woods Hole Oceanographic Institution - organization dedicated to ocean research, exploration, and education