SONAR CHARACTERIZATION OF RELICT MEANDERING RIVER CHANNEL IN THE MID-CONTINENTAL SHELF

During a 2004 College of Charleston Transect cruise aboard the R/V Savannah, a meandering river channel was discovered using sidescan sonar. In November 2006 this site, the Transect River Channel, was surveyed using multibeam sonar aboard the NOAA Ship NANCY FOSTER, to produce a detailed bathymetric map of the area. The relict channel is at least 4 km in length and lies at 20-25 m water depth on the mid-continental shelf off the coast of Charleston, SC. Channel morphology will be investigated for the Swiggle Meander, a segment of the mapped area. Sediment grain size and composition will be used to ground truth backscatter data, and the distribution of hardground and soft-sediment areas for the Swiggle Meander will be analyzed. The southern section of the study site has ROV video data that will be used to further characterize the habitat. Analysis of these data sets will allow for comparison of the Swiggle Meander to adjacent segments of the Transect River Channel as well as to other mid-shelf hardground areas, such as the Gray's Reef National Marine Sanctuary. These studies contribute significantly to the growing body of knowledge of benthic habitats of the southeastern mid-shelf region.