SeepC: Preliminary Characterization of Atlantic Margin Seep Ecosystems from Norfolk Canyon to New England Seep Sites.

Wednesday, 16 December 2015
Poster Hall (Moscone South)
Phillip John Turner1, Bernard Ball1, Elijah Cole2, Abigail LaBella3, Jamie Wagner4, Cindy Lee Van Dover5, Adam D Skarke6 and Carolyn D Ruppel7, (1)Duke University Marine Lab, Nicholas School of the Environment, Beaufort, NC, United States, (2)Duke University, Pratt School of Engineering, Durham, NC, United States, (3)Duke University, University Program in Genetics and Genomics, Durham, NC, United States, (4)Duke University, Durham, NC, United States, (5)Duke University Marine Laboratory, Marine Science and Conservation, Beaufort, NC, United States, (6)Mississippi State University, Mississippi State, MS, United States, (7)USGS Coastal and Marine Science Center Woods Hole, Woods Hole, MA, United States
Since 2013, more than 500 seep sites have been located along the continental margin of the eastern US using acoustic signals of gas plumes in the water column. During a July 2015 R/V Atlantis expedition, scientists used the submersible Alvin to explore seep sites at depths of 300 to 1500 m. Study sites ranged from Norfolk Canyon north to New England Seep 2 and included Baltimore, Veatch, and Shallop Canyon sites, as well as new unnamed sites between Norfolk and Baltimore Canyons. Mussels dominated the seep sites (cf ‘’Bathymodiolus’’ childressi) but only small populations (<10s of individuals) were observed at seep sites associated with Shallop Canyon. B. heckerae, the dominant mussel at the Blake Ridge and Cape Fear seep sites (sites associated with salt diapirs off the Carolinas), appear to be present at only one of the Atlantic Margin seeps. At the Norfolk Canyon site, dead B. heckerae shells were observed and live individuals may be within the explored area. The abundant vesicomyid clam of Blake Ridge and Cape Fear sites was absent at the continental margin seeps. Apart from B. childressi, the most conspicuous megafaunal invertebrate species at the newly explored seeps was the red crab, Chaceon sp. and the rock crab, Cancer sp. These crabs are not seep endemic but they were especially abundant at the seeps and were observed to feed and mate on the seep grounds. Molecular tools will be used to explore the genetic structure of mussel populations from Norfolk to New England seeps, and stable isotope methods will be used to test for differences among sites in the source of carbon used by mussels. Alvin video transects and photo-mosaics will be used to collect data on macrofauna associated with seeps and to test the hypothesis that shallow seeps (300-500m) support more diverse assemblages than deep sites (1000-1500m).