SPATIAL & TEMPORAL VARIABILITY IN BENTHIC INVERTEBRATE ASSEMBLAGES ACROSS COLD-WATER CORAL REEF HABITATS (MEDITERRANEAN SEA) 

Scleractinian cold-water coral (CWC) reefs are marine biodiversity hotspots, providing feeding, refugia, and nursery grounds for a myriad of benthic species. These dynamic marine ecosystems vary over time, with CWC growth thriving or declining depending on physical environmental conditions and food availability. While modern thriving CWC reefs support high biodiversity, little is known about how coral growth fluctuations affect reef diversity over geologic timescales. This project seeks to assess taxonomic and functional changes in diversity across three CWC reef habitats over the last ~14,000 years. Biogenic materials >2mm were extracted from sediment cores in different reef habitats: mound top (core GeoB13728-2), lower flank (core GeoB1329-1), and upper flank (core GeoB13730-1), collected from the Brittlestar Ridge I coral mound in the Alboran Sea (western Mediterranean Sea). Biogenic materials were organized into taxonomic groups (brachiopods, barnacles, solitary corals, echinoderms), quantified, and compared across cores (habitats). 

Proportional abundances of taxonomic groups varied with depth in each core; however, shifts did not consistently correspond to intervals of thriving CWC growth versus nongrowth. The mound top and upper flank habitats show long intervals of dominance by barnacles and echinoderms, whereas the lower flank habitat is characterized by no prolonged intervals of dominance of any one group.  Intervals of dominance may result from competition for limited, dynamic resources on the CWC reef. These findings align with previous studies, indicating that spatial ecological variability across the reef is more pronounced than temporal changes in CWC growth within individual habitats. These findings improve our understanding of how CWC reefs serve as biodiversity hotspots over time. 

For more information: hkhearsey@eckerd.edu