Some features of the macrobenthos community structure in estuary ecosystems (Kandalaksha Bay, the White Sea)

The main trends of structural changes in macrobenthos communities are described for the estuary ecosystems of the White Sea (Kandalaksha Bay). In the macrobenthos communities, all the major structural parameters (total density, total biomass, and species density) increased longitudinally regarding the growth of water salinity, from the brackish to the marine environment. These parameters of studied communities also increased when moving from the upper littoral to the middle and lower littoral areas (vertically), i.e., in accordance to the tide level zone. The similarity of the species composition increased from the upper to lower littoral, as well as from the brackish to the marine areas. However, the manifestation of these changes and the structural variability between them differed significantly. The number of zones characterized by different water salinity was linked to the number of zones with different species structure and resulted in high total diversity of the community. Both the size of organisms and the ABC-indices increased, from the estuary areas (brackish waters) and disturbed macrobenthos communities to the “normal” communities (pristine marine environment).