Seasonal variability of epibenthic communities in different areas of the southern North Sea

Between November 2000 and May 2002, epibenthos was sampled monthly with a 2-m beam trawl at three stations along a transect from the southern German Bight towards the northeastern part of the Dogger Bank (North Sea) in order to investigate the seasonal variability of the epibenthic communities. The stations were chosen to reflect a gradient in the hydrigraphic regime, organic matter supply, and fishing effort. The epibenthic community of the southern German Bight was characterized by high biomass and abundance, dominated by Asterias rubens and Ophiura albida. In contrast, at the northern stations in the Oyster Ground and at the Dogger Bank, epibenthic biomass and abundance were substantially lower and the dominant species were mainly crustaceans such as Corystes cassivelaunus, Liocarcinus holsatus, and Pagurus bernhardus. In terms of seasonal variability, mean abundance and biomass in the southern German Bight showed highest values in the summer months and lowest values in the winter months. A similar pattern, but less distinct, was observed in the Oyster Ground. But at the Dogger Bank the pattern was different, with highest abundance and biomass values in the winter months. The differences in spatial and temporal patterns are discussed in relation to differences in temperature, thermal stratification and fishing effort at the three study sites.