DEEP-WATER SINKHOLES AND BIOHERMS OF SOUTH FLORIDA AND THE POURTALÈS TERRACE — HABITAT AND FAUNA

Abstract

Only a small percentage of deep-water reefs have had their benthic and fish resources characterized. This study surveyed eight deep-water, high-relief, hard-bot tom sites off south Florida using human occupied submersibles to characterize habitat and describe the fish and macrobenthic communities: the Naples deep-water sinkhole on the southwest Florida shelf, Jordan and Marathon deep-water sinkholes on the Pourtales Terrace, and five high-relief bioherms on the Pourtales Terrace. These submersible dives were the first to enter and explore any of these features. The up per sinkhole rims ranged from 175 to 461 m in depth and had a maximum relief of 180 m. The Jordan sinkhole may be one of the deepest and largest sinkholes known. The high-relief bioherms occurred at depths of 198–319 m, with a maximum height of 120 m. A total of 26 and 16 fish taxa were identified from the sinkhole and bioherm sites, respectively. Species of potentially commercial importance included tilefish, sharks, speckled hind, yellowedge grouper, warsaw grouper, snowy grouper, blackbelly rosefish, red porgy, drum, scorpionfish, amberjack, and phycid hakes. In total, 66 Porifera taxa were identified and four are possible new species. Twentyone species of Cnidaria included Antipatharia (three spp.), stylasterid hydrocorals (five spp.), octocorals (11 spp.), and one scleractinian. The benthic communities of the Pourtales Terrace bioherms differed from the bioherms along the northeastern Straits of Florida primarily in that the Pourtales Terrace communities lacked the scleractinian coral Lophelia pertusa (Linnaeus, 1758) and stalked crinoids.