ALBERT

Description: For marine invertebrates living at low temperatures of high latitudes Thorson’s rule suggests a comparatively reduced speed of development. Several studies conducted in different climatic zones have revealed the processes involved in the maturation of benthic assemblages. However, the duration and chronology of succession, as well as the influence of environmental impacts on arctic benthic assemblages is only scarcely analysed. Long-term studies are still rare. By analysing species abundances and substrate coverage over an exposure time of one decade the following hypotheses are tested: (i) Exposition time significantly modifies the structure of arctic benthic hard-bottom assemblages, (ii) the macroscopic structure of the substrate surface has a significant influence on the structure of benthic hard-bottom assemblages, and (iii) the succession of benthic hard-bottom assemblages in the Arctic is in general slower compared to the benthic succession in all non-polar climatic zones. In 2002 forty Polyethylene growth panels were installed on an underwater cliff in Kongsfjorden (Svalbard, Norway) in about 20 m water depth. Six of these were grooved to create structural diversity on the panel surface. Once a year the ripening epibenthic assemblages were photographed by scientific divers. Until 2007 annually about eight panels were sampled and replaced, thus creating starting points for succession in different years. Additionally a ground truthing was carried out for reference. The findings of this study indicate a resilience time exceeding a decade. A strong heterogeneity can be observed between the assemblages on different panels, signifying an influence of different starting points. The results are discussed in comparison with results of related studies from this and other cold-water regions.