Benthic invertebrates of a modern carbonate ramp: a preliminary survey

A preliminary survey of benthic invertebrates off central west Florida provides documentation of modern epifaunal communities on a low-gradient carbonate slope. Three large-scale biofacies occur in soft-sediment carbonate environments between 200 and 2000 m: an Echinoderm biofacies (200-550 m) dominated by a diverse assemblage of echinoderms, gastropods, and decapod crustaceans; a Penaeid shrimp-conical mound biofacies (550-1200 m) characterized by large bioturbation structures; and a Microbial mat biofacies (1200-2000 m) with only rare epifaunal invertebrates. A fourth, hard-substrate biofacies reflects the presence of localized Miocene and Pleistocene hardgrounds in water depths of 200-600 m. All four biofacies have low population densities. All four biofacies also show biogeographic affinity with other faunas at intermediate depths in the Caribbean region. This biofacies model may provide a modern analogue for faunas of ancient low-gradient slopes such as those of Cretaceous "shelf-sea' chalks of northwestern Europe. -from Authors