A marine ecoregion is an ecoregion, or ecological region, of the oceans and seas identified and defined based on biogeographic characteristics.
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.” [1]
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. [1] 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. [1]
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 region. [1]
The digital ecoregions layer is available for download as an ArcGIS Shapefile. [2]
The Marine Ecoregions of the World classification defines 232 marine ecoregions (e.g. Adriatic Sea, Cortezian, Ningaloo, Ross Sea) for the coastal and shelf waters of the world.
These marine ecoregions form part of a nested system and are grouped into 62 provinces (e.g. the South China Sea, Mediterranean Sea, Central Indian Ocean Islands).
The provinces in turn, are grouped into 12 major realms. The latter are considered analogous to the eight terrestrial ecozones, represent large regions of the ocean basins:
Other classifications of marine ecoregions or equivalent areas have been widely developed at national and regional levels, as well as a small number of global schemes.
Each of these systems, along with numerous regional biogeographic classifications, was used to inform the MEOW system. The WWF Global 200 work also identifies a number of major habitat types that correspond to the terrestrial biomes: polar, temperate shelves and seas, temperate upwelling, tropical upwelling, tropical coral, pelagic (trades and westerlies), abyssal, and hadal (ocean trench).
One of the most comprehensive early classifications was the system of 53 coastal provinces developed by Briggs in 1974. [3] The near-global system of 64 large marine ecosystems has a partial biogeographic basis.
The World Wildlife Fund—WWF identified 43 priority marine ecoregions, as part of its Global 200 initiative. [4]
A biome is a distinct biogeographical unit consisting of a biological community that has formed in response to a shared regional climate. Biomes may span more than one continent. Biome is a broader term than habitat and can comprise a variety of habitats.
An ecoregion or ecozone is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of flora, fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where the probability of encountering different species and communities at any given point remains relatively constant, within an acceptable range of variation.
Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. The nutrient-rich upwelled water stimulates the growth and reproduction of primary producers such as phytoplankton. Due to the biomass of phytoplankton and presence of cool water in these regions, upwelling zones can be identified by cool sea surface temperatures (SST) and high concentrations of chlorophyll-a.
A biogeographic realm or ecozone is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into ecoregions, which are classified based on their biomes or habitat types.
The Global 200 is the list of ecoregions identified by WWF, the global conservation organization, as priorities for conservation. According to WWF, an ecoregion is defined as a "relatively large unit of land or water containing a characteristic set of natural communities that share a large majority of their species dynamics, and environmental conditions". So, for example, based on their levels of endemism, Madagascar gets multiple listings, ancient Lake Baikal gets one, and the North American Great Lakes get none.
The Tropical Atlantic realm is one of twelve marine realms that cover the world's coastal seas and continental shelves.
The Northwest Shelf Transition, also known as Bonaparte Coast, is a biogeographic region of Australia's continental shelf. It adjoins the Kimberley region of Western Australia and the adjacent coast of the Northern Territory.
The Western Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the eastern and central Indian Ocean. It is part of the larger Indo-Pacific, which includes the tropical Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia. The Western Indo-Pacific may be classified as a marine realm, one of the great biogeographic divisions of the world's ocean basins, or as a subrealm of the Indo-Pacific.
The Central Indo-Pacific is a biogeographic region of Earth's seas, comprising the tropical waters of the western Pacific Ocean, the eastern Indian Ocean, and the connecting seas.
The Temperate Northern Pacific is a biogeographic region of the Earth's seas, comprising the temperate waters of the northern Pacific Ocean.
Marine habitats are habitats that support marine life. Marine life depends in some way on the saltwater that is in the sea. 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.
Temperate Southern Africa is a biogeographic region of the Earth's seas, comprising the temperate waters of southern Africa, where the Atlantic Ocean and Indian Ocean meet. It includes the coast of South Africa and Namibia, and reaches into southern Angola. It also includes the remote islands of Amsterdam and Saint-Paul, to the east in the southern Indian Ocean.
Temperate South America is a biogeographic region of the Earth's seas, comprising the temperate and subtropical waters of South America, including both the Pacific and Atlantic coasts of the continent and adjacent islands. It also includes the remote Gough Island and Tristan da Cunha in the South Atlantic Ocean.
Temperate Australasia is a biogeographic region of the Earth's seas, comprising the temperate and subtropical waters of Australia and New Zealand, including both the Indian Ocean and Pacific coasts of the continent and adjacent islands.
The Eastern Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters around island groups in the central Pacific Ocean. It includes most of Polynesia, except for New Zealand and the Kermadec Islands. It also includes the Marshall Islands and Kiribati from Micronesia. It adjoins the Central Indo-Pacific realm to the west, which encompasses Melanesia and the other island groups of Micronesia.
The Temperate Northern Atlantic is a biogeographic region of the Earth's seas, comprising the temperate and subtropical waters of the North Atlantic Ocean and connecting seas, including the Mediterranean Sea, Black Sea, and northern Gulf of Mexico.
The Magdalena Transition is a marine ecoregion in the eastern Pacific Ocean. It includes the coastal waters along the southwestern Baja California Peninsula, extending from Punta Abreojos in the north to Cabo San Lucas at the peninsula's southern tip.
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