Event Name/Location

11th Symposium on the Geology of the Bahamas and other Carbonate Regions

Document Type

Article

Publication Date

2004

Keywords

Carbonates, Bahamas

Abstract

Carbonate mounds found in a broad band from about 325 to 700 m along the western margin of Little Bahama Bank exhibit consistent faunal zonations characterized by assemblages of attached, suspension-feeding macroinvertebrates dominated by sponges, octocorals, crinoids and stylasterid and scleractinian corals. Biozonation on hard substrates appears chiefly dependent on depth (and associated parameters, e.g., temperature) and current flow. Mounds in 325-435 m with up to 30 m vertical relief reveal dense assemblages on gentler up current slopes and flanks, and an almost complete lack of macrofauna on steep downcurrent slopes. Macrofauna include stalked crinoids on upcurrent slopes and crest, octocorals on flanks, and branching ahermatypic corals and basketstars at and near the crest. Within-group taxonomic composition often varies between slopes and crest, and between up- and downslope flanks. In 540-580 m on the southwestern bank margin, mounds with up to 40 m vertical relief support a dense lithistid sponge and ophiacanthid ophiuroid assemblage; limited local biozonation here may be associated with a weaker flow regime. The pronounced zonation reported for lithoherms and adjacent hardgrounds to the north in 500-700 m (Neumann et al 1977, Messing et al 1990) is reviewed. The Caicos Platform island slope supports many of the same macroepibenthic taxa found at similar depths elsewhere in the Bahamas and northern Caribbean. However, because this habitat is a low energy environment relative to those west of Little Bahama Bank under the direct influence of the Florida Current, densities of sessile and sedentary suspension-feeding organisms are substantially lower.

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