The macrobenthos of the lagoon ecosystem of Ermolinskaya bay (Kandalaksha gulf, White Sea): structure, diversity, and dynamics

We studied the specific, spatial, and trophic structure of the macrobenthos of the Ermolinskaya Bay (Kandalaksha Gulf, White Sea) to find out the changes which have occurred since the time of the last study. The most profound changes in the spatial structure of community have occurred at the maregraphic level - from the upper littoral to the middle and the lower littoral zones, and to the sublittoral zone. Four microbenthic communities differing by the species composition, density and the biomass of populations, can be defined in the Bay: (1) the community of the upper littoral zone with the dominating detritophages Hydrobia ulvae, Macoma balthica and the grazer Littorina saxatilis ; (2) the community of the middle littoral zone, which is dominated by detritophages H. ulvae, M. balthica and by sestonophages Mya arenaria, and Mytilus edulis (to the lesser extent); (3) the community of the lower littoral zone with the dominant fitrator M. edulis, detritophages H. ulvae и M. balthica and the grazer L. littorea, and (4) the community of the sublittoral zone with the leading detritophagous M. balthica. Gradual regulation of the Bay by men went to its sitation and the isolation from the open sea, which lead to the dominance of the littoral community in the area of the sublittoral zone. Species, which inhabited the sublittoral zone in 60s of the last century, are now confined to the outlet area of the Bay.