THE CARIBBEAN REGION The Caribbean basin comprises over 20 nations and territories, each characterized by unique and wide ranging biodiversity and culture. It is one of the world's greatest centers of biodiversity and endemism, arising from the region's geography and climate: an archipelago of habitat-rich tropical and semi-tropical islands tenuously connected to surrounding continents. Plants and animals arrived from the neighboring continents and islands, and as their descendants spread into new environments they evolved as a result of new ecological opportunities. The region harbors a staggering 12,000 plant species, 1,518 vertebrate species and 3,000 shallow marine species. Of this diverse flora and fauna, many arc endemics tound nowhere else on Earth, some unique to individual islands, or to isolated places within specific islands. Marine The Caribbean tonus the heart of Atlantic marine diversity. Roughly 8 to 35% of species within the major marine taxa arc endemic to this area. The shallow marine environment contains 25 coral genera (62 species sclcractinian coral), 4 mangroves, 7 scagrasscs, 117 sponges, 633 mulluscs, 378 bivalves, 77 stomatopods, 148 echinoderms, over 1400 fishes, 76 sharks, 45 shrimp, 30 cetaceans, 1 sirenia, and 23 seabirds. Only one marine species has gone extinct, the Caribbean Monk Sea, which was last seen in the mid 1950's. The Caribbean contains approximately 10,000 square kilometers ofreef(Spalding, eta!.. 2001; Andretouct eta/., 2005); 22,000 square kilometers of mangrove (amended from Spalding eta/., 1997); and as much as 33,000 square kilometers of scagrass beds (Spalding et a!., 2003). Other unique and interesting carbonate stmcturcs found in the insular Cru·ibbcan include stromatolites, algal ridges, ooid shoals, and blue holes. There is surprisingly little variation in marine species diversity within the Caribbean province in large part because of the high degree of connectivity. The strong and predictable Caribbean Current that meanders through the basin year round transporting larvae between islands and regions. As a result, marine habitats share many of the same marine species and show remarkably low degree of endemism (between marine ccorcgions) in stark contrast to the regions highly endemic terrestrial island biodiversity. Large ranging and highly migratory species such as turtles, whales, sea birds and pelagic fishes, inhabit different portions of the Caribbean basin during different stages of life. Despite this high degree of mixing, there arc significant differences in geology, climate, productivity, and island size all of which influence the relative abundance, extent, intactness, and vulnerability of marine biodiversity in the Caribbean. Three distinct ecosystems arc identified as follows; Tire Ba/wmitm marine ccorcgion encompasses the large shallow bank systems of the Bahamas and Turks and Caicos as well as several smaller banks at the southern terminus owned by the Dominican Republic. This region of the Caribbean is tectonically very stable creating massive build-up of carbonate sediments that make up the banks. The sediments arc almost entirely composed of carbonate grains derived from the shells of living organism that thrive in the warm shallow waters. Islands and small islets number into the thousands and arc all generally low-lying with very limited fi·cshwatcr river outtlows that occur as groundwater discharge. Tides arc larger than in other parts of the Caribbean and have shaped complex coastal landforms of tidal creeks, mud l1ats, and ooid sand shoals. Habitat diversity (beta diversity) is similarly different than other parts of the Caribbean. Reefs tend to be narrow fringing barriers (bank margin reefs) and Holocene biogenic reef islands arc virtually absent. Soft-bottom communities such as scagrass beds arc generally sparser than other parts of the Caribbean while macroalgal biomass on deeper tore reefs is significantly higher. Coral reefs vary in form mainly with respect to exposure to wave energy and generally occur along all of the windward margins of the banks. A number of distinct carbonate structures unique to this part of the Caribbean include an extraordinary number of blue holes, modern stromatolites actively growing in tidal channels, and active ooid sand shoals. 3 -6-