Marine coastal ecosystems Coral reefs Coral reefs are one of the most well-known marine ecosystems in the world, with the largest being the
Great Barrier Reef. These reefs are composed of large coral colonies of a variety of species living together. The corals form multiple symbiotic relationships with the organisms around them.
Mangroves Mangroves are trees or shrubs that grow in low-oxygen soil near coastlines in tropical or subtropical latitudes. They are an extremely productive and complex ecosystem that connects the land and sea. Mangroves consist of species that are not necessarily related to each other and are often grouped for the characteristics they share rather than genetic similarity. Because of their proximity to the coast, they have all developed adaptions such as salt excretion and root aeration to live in salty, oxygen-depleted water. In 2007, kelp forests were also discovered in
tropical waters near
Ecuador. Physically formed by brown
macroalgae, kelp forests provide a unique habitat for marine organisms and are a source for understanding many ecological processes. Over the last century, they have been the focus of extensive research, particularly in
trophic ecology, and continue to provoke important ideas that are relevant beyond this unique ecosystem. For example, kelp forests can influence coastal
oceanographic patterns and provide many
ecosystem services. However, the influence of humans has often contributed to kelp
forest degradation. Of particular concern are the effects of
overfishing nearshore ecosystems, which can release
herbivores from their normal population regulation and result in the
overgrazing of kelp and other algae. This can rapidly result in transitions to
barren landscapes where relatively few species persist. Already due to the combined effects of
overfishing and
climate change, kelp forests have all but disappeared in many especially vulnerable places, such as
Tasmania's east coast and the coast of
Northern California. The implementation of
marine protected areas is one management strategy useful for addressing such issues, since it may limit the impacts of fishing and buffer the ecosystem from additive effects of other environmental stressors.
Estuaries 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. 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.
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 oceanic/atoll lagoons. A coastal lagoon is, as the definition above, simply a body of water that is separated from the ocean by a barrier. An atoll lagoon is a circular coral reef or several coral islands that surround a lagoon. Atoll lagoons are often much deeper than coastal lagoons. Most lagoons are very shallow meaning that they are greatly affected by changes in precipitation, evaporation and wind. This means that salinity and temperature are widely varied in lagoons and that they can have water that ranges from fresh to hypersaline. The soil in these marshes is often made up of mud and a layer of organic material called peat. Peat is characterized as waterlogged and root-filled decomposing plant matter that often causes low oxygen levels (hypoxia). These hypoxic conditions causes growth of the bacteria that also gives salt marshes the sulfurous smell they are often known for. Salt marshes exist around the world and are needed for healthy ecosystems and a healthy economy. They are extremely productive ecosystems and they provide essential services for more than 75 percent of fishery species and protect shorelines from erosion and flooding. There are four physical divisions of the intertidal zone with each one having its distinct characteristics and wildlife. These divisions are the Spray zone, High intertidal zone, Middle Intertidal zone, and Low intertidal zone. The Spray zone is a damp area that is usually only reached by the ocean and submerged only under high tides or storms. The high intertidal zone is submerged at high tide but remains dry for long periods between high tides. 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
ocean debris (termed
rafters). Most prominently, the surface is home to a unique community of free-living organisms, termed
neuston (from the Greek word, υεω, which means both to swim and to float. Floating organisms are also sometimes referred to as
pleuston, though neuston is more commonly used). Despite the diversity and importance of the ocean's surface in connecting disparate habitats, and the risks it faces, not a lot is known about neustonic life. Some peripatetic microorganisms are swept up from terrestrial dust storms, but most originate from
marine microorganisms in
sea spray. In 2018, scientists reported that hundreds of millions of viruses and tens of millions of bacteria are deposited daily on every square meter around the planet.
Deep sea and sea floor The deep sea contains up to 95% of the space occupied by living organisms. Combined with the sea floor (or benthic zone), these two areas have yet to be fully explored and have their organisms documented.
Large marine ecosystems In 1984,
National Oceanic and Atmospheric Administration (NOAA) of the
United States developed the concept of
large marine ecosystems (sometimes abbreviated to LMEs), to identify areas of the oceans for
environmental conservation purposes and to enable collaborative
ecosystem-based management in transnational areas, in a way consistent with the 1982
UN Convention on the Law of the Sea. This name refers to relatively large regions on the order of or greater, characterized by their distinct
bathymetry,
hydrography,
productivity, and
trophically dependent
populations. Such LMEs encompass coastal areas from river basins and
estuaries to the seaward boundaries of
continental shelves and the outer margins of the major
ocean current systems. Altogether, there are 66 LMEs, which contribute an estimated $3 trillion annually. This includes being responsible for 90% of global annual marine fishery
biomass. LME-based conservation is based on recognition that the world's coastal ocean waters are degraded by unsustainable fishing practices,
habitat degradation,
eutrophication, toxic pollution, aerosol contamination, and emerging diseases, and that positive actions to mitigate these threats require coordinated actions by governments and civil society to recover depleted fish populations, restore degraded habitats and reduce coastal pollution. Five modules are considered when assessing LMEs: productivity, fish and fisheries, pollution and
ecosystem health, socioeconomics, and governance. Periodically assessing the state of each module within a marine LME is encouraged to ensure maintained health of the ecosystem and future benefit to managing governments. The Global Environment Facility (GEF) aids in managing LMEs off the coasts of Africa and Asia by creating resource management agreements between environmental, fisheries, energy and tourism ministers of bordering countries. This means participating countries share knowledge and resources pertaining to local LMEs to promote longevity and recovery of fisheries and other industries dependent upon LMEs. Large marine ecosystems include: •
East Bering Sea •
Gulf of Alaska •
California Current •
Gulf of California •
Gulf of Mexico •
Southeast U.S. Continental Shelf •
Northeast U.S. Continental Shelf •
Scotian Shelf •
Newfoundland-Labrador Shelf •
Insular Pacific-Hawaiian •
Pacific Central-American Coastal •
Caribbean Sea •
Humboldt Current •
Patagonian Shelf •
South Brazil Shelf •
East Brazil Shelf •
North Brazil Shelf •
West Greenland Shelf •
East Greenland Shelf •
Barents Sea •
Norwegian Shelf •
North Sea •
Baltic Sea •
Celtic-Biscay Shelf •
Central Arctic •
Iberian Coastal •
Mediterranean Sea •
Canary Current •
Guinea Current •
Benguela Current •
Agulhas Current •
Somali Coastal Current •
Arabian Sea •
Red Sea •
Bay of Bengal •
Gulf of Thailand •
South China Sea •
Sulu-Celebes Sea •
Indonesian Sea •
North Australian Shelf •
Northeast Australian Shelf/Great Barrier Reef •
East-Central Australian Shelf •
Southeast Australian Shelf •
Southwest Australian Shelf •
West-Central Australian Shelf • Northwest Australian Shelf •
New Zealand Shelf •
East China Sea •
Yellow Sea •
Kuroshio Current •
Sea of Japan •
Oyashio Current •
Sea of Okhotsk •
West Bering Sea •
Chukchi Sea •
Beaufort Sea •
East Siberian Sea •
Laptev Sea •
Kara Sea •
Iceland Shelf •
Faroe Plateau •
Antarctica •
Black Sea •
Hudson Bay •
Arctic Ocean •
Greenland Sea == Role in ecosystem services ==