39 - Seabed Habitat of a Glaciated Shelf, German Bank, Atlantic Canada

Abstract

German Bank is located off southern Nova Scotia on the Scotian Shelf in the eastern Gulf of Maine and is the offshore extension of the southern Nova Scotia landmass. Much of German Bank is exposed bedrock comprising Cambro–Ordovician metasedimentary rocks intruded by Late Devonian–Carboniferous granitoid plutons. Bedrock has been modified by glacial erosion and is separated by a rugged erosional surface from the discontinuous overlying Quaternary sediments. German Bank can be characterized as bathymetrically smooth glaciated continental shelf, with a regional gradient of less than 1° to the southwest. At distances of tens to hundreds of meters (large scale), geomorphic features are evident in outcropping bedrock and within the overlying glacial and postglacial sediments. High-resolution seafloor imagery was obtained on German Bank using Campod, an instrumented tripod that includes forward- and downward-looking video cameras and a downward-looking 35 mm still camera. The Campod provides a very large-scale (tens of centimeters) view of the seafloor. All visible species of megabenthos were identified to the highest possible taxonomic resolution. Statistical analysis of the relationship between biological factors of megafaunal community data as assessed from large-scale seabed photographs and environmental variables (BioEnv) revealed that the single variable that best explains the distribution of bottom fauna is summer oxygen saturation at the seabed. The best combination of variables related to benthic community composition is water depth, oxygen saturation, seabed cover by cobbles and boulders, and seabed cover by sand.