Very little is known about marine biodiversity, especially when compared with the information we have on terrestrial ecosystems. Enough data is available, however, to compare the regions in terms of biodiversity.

In its publication The Diversity of the Seas: a regional approach,* WCMC has compiled data from the Regional Seas to produce a comparison of biodiversity as measured by species richness. East Asian Seas and the South Pacific stood out as being particularly rich in species, followed by the Caribbean and North-West pacific.

The East Asian Seas region has the most species overall in the groups covered, with more corals, molluscs, shrimps, lobsters and sharks. The South Pacific has most seagrass species, and the most seabird species.

The most cetacean species are found in the South Pacific and the Upper South-West Atlantic. The Caribbean and North-West Pacific have high numbers of species in most groups, and the Caribbean is particularly rich in endemics. But not always does the highest number of endemics correlate with the highest overall diversity.

Threats

Although threats to biodiversity in the open ocean are increasing, most identified threats relate to coastal and inshore areas. The US National Research council (NRC) Committee on Biological Diversity in Marine Systems identified five major threats to marine biodiversity at genetic, species and ecosystem level:

fisheries operations
chemical pollution and eutrophication
alteration of physical habitat
invasions of exotic species
global climate change

As WCMC points out, "these factors are likely to interact with each other, making the effective long-term management of marine resources one of the major – and most intractable – problems facing humankind."*

Marine biodiversity links:
Mediterranean | Red Sea and Gulf of Aden | Kuwait Region | West and Central Africa | Wider Caribbean | East Asian Seas | South-East Pacific | South Pacific | Eastern Africa | Black Sea | North West Pacific | South Asian Seas | North-East Pacific | Upper South-West Atlantic

*World Conservation Monitoring Centre. 1996. The Diversity of the Seas: a regional approach. Groombridge, B. and Jenkins, M.D. (Eds.) World Conservation Press, Cambridge, UK. 132 pp. Text available from WCMC.