ABSTRACT
Introduction Vast areas of the shallow waters off the Florida Keys are composed of thick accumulations of carbonate sand and mud that, characteristically, are devoid of sea grasses and macroalgae. Typically, these submarine “deserts” occur in areas of strong tidal currents, which produce rapidly shifting sediments that are not conducive to plant growth. As is frequently observed, the open unvegetated softbottom areas are scattered among sea grass beds and mangrove forests, usually in tidal channels, and often intergrade into these other environments in broad ecotonal transition zones (Figure 6.1). In the Florida Keys, two main unvegetated softbottom areas occur, both of which are bathymetrically controlled: the Intertidal Open Carbonate Mudflats, which are found primarily along the intertidal zone of the South Florida Bight sides of the islands; and the Sublittoral Open Carbonate Sand Seafloors, which are found primarily within the deeper waters of the Hawk Channel between the Keys and the offshore reef tract. Each of these soft sediment macrohabitats contains its own resident molluscan assemblage, and those of the Hawk Channel habitats are now known to harbor a large number of endemic species.
