Composition and Significance of Pteropod Ooze Deposits from Deep-Water Lophelia Reefs, Blake Plateau, NE Florida.

Shelled microinvertebrates preserved in biogenic oozes contribute significantly to the overall structure and function of Deep-Sea Coral Ecosystems (DSCE). However, their composition and distribution, which is directly related to their deposition, remains poorly documented. The Blake Plateau contains a region known as the east Florida Lophelia reef (EFLR), which incorporates a 222 km belt with numerous high relief deep-sea coral mounds. Branching ahermatypic corals baffle pelagic sediment and develop into large bioherms that provide habitat for a countless number of deep-sea organisms. Calcareous ooze was collected in situ from gullies between Lophelia coral reef mounds on the EFLR region at a depth of 792.48 m via the Johnson Sea Link submersible in 2004. Qualitative review of these samples reveals a composition of well-preserved microfossils primarily of holoplanktonic marine mollusks - Euthecosomatous Pteropods. Statistical analysis of ooze samples resulted in the identification of 9 genera and 15 different thecosome pteropod species, with an overall sediment composition consisting of 85.6% pteropods, 8% forams, 3.1% gastropods, 2.3% bryozoan/coral fragments, and less than 1% of other microfossils (heteropods, echinoids, scaphopods, etc.). This unique assemblage of well-preserved microfossils is classified as pteropod ooze (>25% pteropods) with Styliola subula being the most abundant pteropod species comprising 46% of the sediment. Taxonomic analysis of the pteropod ooze deposits in the EFLR region will help characterize the sources and dynamics of sediment supply to the substrate and infrastructure of these critically important DSCE’s.