TEMPORAL DIVERSITY DYNAMICS OF BENTHIC INVERTEBRATES IN A QUATERNARY COLD-WATER CORAL MOUND: ALBORAN SEA (MEDITERRANEAN SEA)

Cold-water coral (CWC) reefs are recognized as biodiversity hotspots in the deep sea worldwide. With sufficient nutrients and a steady sediment supply, CWC reefs may build into CWC mounds over geologic time (hundreds to millions of years). On CWC mounds, living corals thrive near the mound tops where there is the most exposure to currents transporting nutrients. It is hypothesized that corals outcompete other benthic organisms for food and substrate at the mound tops, resulting in low diversity on mound tops and higher diversity downslope. Using a CWC reef sediment core, this project investigates the temporal diversity of benthic invertebrates on a CWC mound in the Alboran Sea (western Mediterranean Sea) over the last ~13,000 years. We have identified 5 primary invertebrate taxonomic groups: barnacles, brachiopods, bryozoans, echinoderms, and solitary corals. The specimens within these groups are being identified to the lowest possible taxonomic level. Overall, the fossil assemblage contains the primary groups of invertebrates with high preservation potential (hard parts) found on living CWC reefs, suggesting that the fossil record is representative of living reefs. Group abundances vary with depth (time) in the core and do not align with patterns of reef growth or the diversity of mollusks (separate study). These findings suggest that the invertebrate assemblages studied here may not be driven by the same ecological factors as mollusks. Smaller sample sizes relative to mollusks and differences in mobility may influence abundance trends. Rank-order correlation analyses indicate that taxa abundances are not significantly correlated with mound aggradation rates, suggesting that abundance patterns are not significantly biased by sedimentation patterns of the CWC mound. Species identifications and assessment of diversity trends will provide further insights and means for comparison between these invertebrates and mollusks.

For more information: trrind@eckerd.edu

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