Characterization of Benthic Habitat on Northeastern Georges Bank, Canada
Vladimir E. Kostylev, Brian J. Todd, Oddvar Longva, and Page C. Valentine
Abstract. Seafloor habitats of the Canadian part of Georges Bank were assessed and mapped following the habitat template theory (Southwood 1988). The approach considers the primary selective forces (habitat disturbance and adversity of the environment) that have shaped the existing communities of benthic species and that have defined the life history traits of species found in different habitats. The disturbance axis of the template is modeled based on the information on sediment, currents, and bathymetry. The adversity axis is modeled based on chlorophyll concentration, bottom water temperature, salinity, and seasonal variability in temperature. A preliminary sediment map needed for assessment of the natural disturbance rate was developed from high-resolution multibeam backscatter groundtruthed with archive and current sediment sample data. The distribution of megabenthos assemblages identified from underwater photography was found to follow gradients in disturbance and adversity on the bank. We suggest that application of the habitat template theory is useful for ocean managers in defining areas that are more or less likely to suffer from adverse human impacts. If natural rates of habitat disturbance are high, then risk of harmful habitat alteration and degradation is lower than in naturally stable areas. Similarly, if the natural adversity of the environment is high, then adding additional stressors will further reduce the scope for growth of organisms, which makes natural populations in adverse environments less likely to recover than populations in benign environments.