Side Scan Sonar and TV Observations of the Benthic Environment and Megabenthos in the Vicinity of an OCS Exploratory Well in the Middle Atlantic Bight

The benthic megafauna and physical environment around an exploratory well site in the Mid-Atlantic were observed with side-scan sonar and bottom TV prior to, two weeks after, and one year after drilling. Physical alterations (anchor scours, cuttings and debris accumulation) were seen two weeks and one year after drilling. Two weeks after, increases in demersal fish (primarily hake) and decapods (primarily Cancer crabs) were observed. Increases were most evident near the well site and appeared associated with the increased microrelief. Mussel accumulations around the site may also have attracted these species. One year after drilling, hake density was still elevated near the site, but mussels and Cancer densities were not. Decapod densities (particularly galatheid crabs) were lower within 500 meters of the site than beyond, perhaps because of hake predation. Sessile megabenthos (e.g., sea pens) may have been buried by cuttings in the immediate vicinity, but burial effects were not as evident one year later.