Coral mounds on the West Florida slope; unanswered questions regarding the development of deep-water banks

Abstract

Late Pleistocene deep-water coral mounds of 10-15 m relief occur in a20 km linearzone parallel to the 500 m isobath along the West Florida carbonate-ramp slope. These relict mounds were constructed by the densely calcified, ahermatypic framework builder, Lophelia prolifera, and provided habitats for a host of associated invertebrates, including epizoans, epifaunal commensal organisms, nestlers and crevice dwellers, and macroendoliths. Scleractinian diversity and taxonomic composition are congruent with those of other Lophelia buildups in the NorthAtlantic, particularly buildups in the eastern Atlantic. The scleractinians also retain primaty mineralogic, isotopic, and trace-elementgeochemical signatures, indicating relatively little diagenetic alteration, despite dead (>40,000 years b.p.) radiocarbon ages. The small but rapidly expanding global data base on deepwater coral mounds has magnifted two key questions concerning the ecologic and environmental controls on mound nucleation, growth, and death. First, what are the principal ecologic controls on dominance within communities of deep-water framework builders? Second, why are there so many relict and so few living deep-water mounds in the modern ocean? Ecological and paleoecological investigation of these questions would elucidate much about the dynamics of deep-water mound growth.