The Atlantic and Eastern Pacific region includes three distinct sub regions: Northern Caribbean   Western Caribbean   Eastern Caribbean and Atlantic. The Atlantic Ocean covers one fifth of the surface area of the planet, second only in size to the Pacific Ocean. It is the world's youngest ocean, only beginning to form around the time of the break-up of the super continent of Panagea about 100 million years ago. It also has the largest drainage basin of any ocean, and the large amounts of sediments entering it from the great rivers of the Amazon, Orinoco, Mississippi, Niger and Congo play a role in inhibiting coral reef development along much of its perimeter.

The only major coral reef development in this entire region is centered around the Caribbean Sea and to the north of Cuba in an area bounded by the Bahamas and Florida. There are smaller reef developments in a few locations in the Gulf of Mexico and around Bermuda in the Northern Atlantic. Brazil too has some reef structures, although in general these are small and intermittent. There are no true reefs on the other oceanic islands or in the Eastern Atlantic. Even in the Caribbean Sea, reef development rarely reaches the extent of reefs in the Indo-Pacific, and there appear to be real physical differences in reef structures between these regions. In all, less than eight percent of the world's coral reefs are found in this region.

In terms of biodiversity the coral reefs of this region are unique. The Atlantic corals now share only seven genera with the Indo-Pacific. There are three clear regions in the Atlantic reef province, with the highest diversity focused in the Caribbean (from Bermuda to Trinidad) but with other small centers of coral diversity in Brazil and the Eastern Atlantic.

In many areas of the Caribbean, including remote localities, there have been dramatic increases in algal cover. While these can sometimes be directly related to human impacts in specific localities, there also appears to have been a regional decline. Many of these can be linked to the widespread die-off of the long-spined sea urchin Diadema antillarum, which occurred in 1983-84. This species was a major algal grazer on the reefs and, in places where over fishing was particularly high, it was often the major herbivore on reefs. The die-off appears to have been pathogenic -caused by bacterial infection - and may have natural or may have been carried to the region in ballast water from ships. At the same time wide areas have been afflicted by coral diseases and once the coral dies, they are rapidly overgrown with algae, especially because of the loss of grazing Diadema, and large areas of reef have now become algae-dominated.

The degree to which these problems are the result of entirely natural processes remains unclear, but this region is also widely affected by many direct human impacts, including sedimentation, nutrient pollution and over fishing. Tourism is probably the most important industry across the wider Caribbean, with most tourists seeking beach based holidays. In many places, coastal development associated with the growing tourism industry has greatly exacerbated the problems facing the reefs of the region. In the 1998 Reefs at Risk analysis, seventy-one percent of the reefs in the Wider Caribbean were described as threatened by human activities. In areas where these problems are most extreme, the rates of recovery of reef systems are certainly being slowed. Efforts to improve reef status and recovery through the implementation of marine protected areas and other coastal management regimes are varied, but include important success stories. At the same time, the indirect nature of many threats means that, even with legal protection, many reefs are still in decline.

The western shores of the Americas are completely separated from the Caribbean Sea and have very different coral reef communities. Although part of the Pacific, this region is quite distinct from the rest of the ocean in terms of its reefs. Much of the continental coastline plunges into relatively deep water as the ocean plates are subducted under the continental plates of North and South America. There are only a few offshore islands lying beyond the continental shelf. Water conditions on the continental shelf fluctuate considerably, with cool water upwellings in most years, occasionally reversed to warm water upwellings during El Nino Southern Oscillation events.

The coral reefs of the Eastern Pacific, because of their isolation from the Central Pacific islands, are highly distinctive communities. Their closest affinities are with the reefs of the Pacific, but they have a much lower diversity of species and many are endemic. The reefs themselves are rarely well developed as physical structures -most are simple coral communities. The few structural reefs are mostly small in overall extent, and consist of only a few meters depth of carbonate deposits. The one exception of this generalization is the Clipperton Atoll, a true atoll administered by  French Polynesia.

Fluctuating oceanographic conditions have a considerable impact on coral reefs. Region wide mass mortalities associated with coral bleaching were linked to a major El Nino events in 1983 and 1997-98. Human impacts on this region are generally low. Most of the reefs are associated with offshore islands and therefore not heavily impacted by shoreline activities. Over fishing is a problem in some areas but there is virtually no tourism, with the exception of highly controlled visits to the Galapagos.

Extracted from The World Atlas of Coral Reefs, by Mark D. Spalding, Corinna Ravilious and Edmund P. Green, published by the University of California Press . For more complete and in-depth coverage of the topics presented in this webpage, I recommend highly purchasing a copy of this beautifully illustrated book. Just click on the University of California Press link above to do so.