TEMPORAL AND SPATIAL VARIABILITY IN BENTHIC FORAMINIFERA FOSSIL ASSEMBLAGES ACROSS THE CONTINENTAL SHELF, CHARLESTON, SC

As part of the College of Charleston's Transect Program, sediment grab samples were collected across the continental shelf aboard the R/V Savannah. Eight cross-shelf stations were sampled, in waters with depths ranging from 10 to 100 m. Sediments in the study region consist of a thin veneer of modern and relict sands, underlain by hardground. Between 25 and 39 benthic foraminifera genera (>125 micron size fraction) were identified, with more than 10 “dominant” genera (> 5 % of the genera at any station), including Quinqueloculina, Textularia, Hanzawaia, Cibicidoides, Triloculina, Bigenerina, Bolivina, Eponoides, Amphistegina, and Elphidium. The inner shelf (0-20 m) is dominated by Cibicidoides, whereas the middle-to-outer shelf region (20-50 m) is co-dominated by Cibicidoides, Hanzawaia, Quinqueloculina and Textularia. Cibicidoides dominates again on the shelf-edge where water depth is nearly 100 m and lies beneath the edge of the Gulf Stream. Variations in predominance of foraminifera genera may be due to depth variations across the shelf; proximity to the Gulf Stream; and substrate differences, ranging from coarse sand mega-ripples, to hardground areas surrounded by sediment. ROV-video of the seafloor shows evidence of migrating sand megaripples which may be responsible for seasonal reworking and redistribution of sediments. Comparisons will be presented on foraminiferal assemblage variations and distribution with respect to grain size analyses and video data collected with a remotely operated vehicle. This study is in partial agreement with foraminiferal studies of the South Atlantic Bight and West Florida shelf.