Antarctic seafloor geomorphology as a guide to benthic bioregionalisation

Publicly available bathymetry and geophysical data can be used to map geomorphic features of the Antarctic continental margin and adjoining ocean basins at scales of 1:1-5 million. The geomorphic features identified and their properties can be related to major habitat characteristics such as sea floor type (hard versus soft), ice keel scouring, sediment deposition or erosion and current regimes. Where more detailed data are available, shelf geomorphology provides a guide to the distribution of the shelf benthic communities recognised by a number of authors. For areas off the shelf, the relationships between physical environmental parameters and the benthic biota are more poorly known however geomorphic mapping provides insights into major processes that are likely to influence benthic habitats. The geomorphic mapping method presented here rapidly provides a layer to add to benthic bioregionalisation using readily available data and provides useful insights into seabed and oceanographic conditions that influence benthic communities, even in the absence direct measurements. The conclusion from this preliminary study of sea floor geomorphology from the Antarctic is that there is enough data to available already to produce a meaningful benthic bioregionalisation for an area as poorly known as the Antarctic continental margin and surrounding oceans. Studies of shelf biota that have tried to link the physical environment with benthic communities have found links strong enough to suggest that geomorphology is a useful first-pass tool for mapping the distribution of communities. The link between biology and geomorphology is the degree to which sea floor geometry influences oceanographic, biogeochemical and substrate processes to shape the conditions for benthic communities. Additional layers of bed shear stress and sediment characteristics will further refine benthic bioregionalisation when data become available however the results produced by mapping from bathymetry alone are sufficient to justify its use in the first stage of benthic bioregionalisation for CCAMLR waters