Selection of marine ecoregions

Marine habitats

The distribution of marine biodiversity varies widely throughout ocean basins1). The abundance and diversity of most taxa tends to be highest near continental and island margins that are less than 2,000 meters deep2).
These areas experience nutrient enrichment from upwelling processes and terrestrial runoff3). Areas where significant upwelling occurs are often extraordinarily productive in tropical, temperate, and polar regions. Within major habitat types, species richness and endemism also vary enormously around the globe.

Species endemism tends to be less pronounced in marine ecosystems than in terrestrial or freshwater ecoregions, but several regional centers of endemism are recognized, including the southern coast of Australia, New Caledonia, Lord Howe and Norfolk Islands, the northern coast of South America, the Yellow and East China Seas, the Red Sea, the Mediterranean Sea, the Sea of Cortez, the Great Barrier Reef, and tropical Pacific Islands such as Hawaii, Marquesas, the Tuamotus and Societies, and Easter Island4).

In general, marine ecoregions associated with isolated islands and enclosed seas tend to display higher levels of endemism5).

Select one of the options below to get more information about the specific habitat type.

The marine environment includes a total of 10 major habitat types. However, pelagic (trades and westerlies), abyssal, and hadal major habitat types were not assessed for the Global Ecoregions marine analysis because of the scale of these units compared to other Global Ecoregions, the lack of an accepted classification, and the limited biodiversity information for these ecosystems. Large biogeographic units have been identified for pelagic and abyssal biotas6), but their scale is several orders of magnitude greater than most Global Ecoregions.

These larger units may be biogeographically and dynamically logical for open ocean environments. However, the vast size and dynamic nature of these major habitat types also precluded delineating biogeographic subunits at an appropriate level of resolution for the Global Ecoregions.

Moreover, knowledge of biogeographic boundaries and biodiversity information for these major habitat types is limited at this time. The pelagic major habitat types are characterized by widespread distribution of many species. In contrast, sizable proportions of the ocean trench biotas (hadal) surveyed to date are endemic to single trenches. Our limited knowledge reduces our confidence to undertake comparative analyses.


1) Briggs 1974; Elder & Pernetta 1991; Angel 1992, 1993; Clarke 1992; Kendall & Aschan 1993; Kelleher et al.1995; Groombridge & Jenkins 1996; Ormond et al. 1997.
2) Ray 1991, Johannes & Hatcher 1986, Gray 1997
3) Ray 1988, Norse 1995
4) Robbins 1991, Lieske & Myers 1996, Vernon 1995, Groombridge & Jenkins 1996
5) Kelleher et al.1995, Groombridge & Jenkins 1996
6) e.g., Brinton 1962, Longhurst 1998, Pierrot-Bults 1997, Vinogradova 1997

Click on the map and find out, where the major habitat  types are / ©: WWF
Click on the map and find out, where the major habitat types are.
© WWF

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