Distribution of macrozoobenthos in an Arctic estuary (Pechora Bay, SE Barents Sea) during the spring flood period

Pechora Bay, located in the permafrost area of the Russian European Arctic, is characterised by highly variable environments due to its shallowness, complex system of water currents, and extensive freshwater input. The results of several benthic surveys carried out in the 1990s showed the stability of distribution of macrozoobenthos in summer. The aim of this study is to assess the status and distribution of the macrozoobenthos during the spring flood period, when the volume of the Pechora River discharge shows a 5- to 7-fold increase, and to determine the relationship of macrozoobenthos distribution to environmental factors. The intensive river runoff provokes ice scouring of the bottom sediments in shallow areas, causing low species richness, abundance and biomass. It was found that estuarine species spread to the entrance of the bay in flood time but the dominant species in five determined communities remain stable. The strongest driver for species richness and biomass is sediment granulometric composition. Shannon diversity (H′) negatively correlated with the organic matter content of the sediments. Assessing the status of the macrozoobenthos showed that it is slightly disturbed only in the small area close to the Pechora River mouth, influenced both by ice scouring and enormous freshwater discharge.