Bioregionalization of the George V Shelf, East Antarctica

The East Antarctic continental shelf has had very few studies examining the macrobenthos structure or relating biological communities to the abiotic environment. In this study, we apply a hierarchical method of benthic habitat mapping to Geomorphic Unit and Biotope levels at the local (10s of kilometers) scale across the George V Shelf between longitudes 142 degrees E and 146 degrees E. We conducted a multi-disciplinary analysis of seismic profiles, multibeam sonar, oceanographic data and the results of sediment sampling to define geomorphology, surficial sediment and near-seabed water mass boundaries. Geographic information system models of these oceanographic and geophysical features increase the detail of previously known seabed maps and provide new maps of seafloor characteristics. Kriging surface modeling on data includes maps to assess uncertainty within the predicted models. A study of underwater photographs and the results of limited biological sampling provide information to infer the dominant trophic structure of benthic communities within geomorphic features. The study reveals that below the effects of iceberg scour (depths > 500 m) in the basin, broad-scale distribution of macrofauna is largely determined by substrate type, specifically mud content. In waters within the direct influence of glacial ice (depths < 500 m) on the banks, scouring by icebergs is a strong limiting factor in the distribution of macrobenthos. In areas protected from iceberg scour disturbance, such as on the outer shelf banks and slope, the direction and speed of oceanic currents are the likely dominant abiotic factor in the broad-scale distribution of macrofauna. This hierarchical method of benthic habitat mapping could be applied circum-Antarctic for comparison against other geographic areas, and would assist authorities responsible for developing ecosystem-based plans by identifying the different types of marine habitats and their associated biological communities at varying scales on the Antarctic shelf. (c) 2005 Elsevier Ltd. All rights reserved.