Spatial structure of the macroand meiobenthic communities in homogenous conditions (on the example of the Pechora Sea)

Spatial structure of the macroand meiobenthic communities of the south-eastern Barents Sea (also known as Pechora Sea) was investigated in 2003 during the expedition of the RV «Professor Shtokman». One grid of the stations was used for both benthic size classes. Community dominated by Serripes groenlandicus occupied the most part of the investigated polygon, Astarte borealis dominated the easternmost station. Described communities are in correspondence with historic data. In the meiobenthic communities, nematodes played a leading role, accounting for 86–94% of the total number. Nematode Richtersia inaequalis was dominant on most stations, at the northernmost station the nematodes Cervonema papillatum and Microlaimus affinis dominated. The temperature and the salinity of the near-bottom water layer were homogenous, macroand meiobenthic communities were not influenced by grain size. In contrast to our expectations, communities of the macroand meiobenthos were distributed independently of each other on the mesoscale area (30×11 km).

Benthic habitats in the Tikhaya Bight (the Hooker Island, Franz Josef Land)

Benthic habitats of Tikhaya Bight (Hooker Island, Franz Josef Land, High Arctic) were studied by using SCUBA equipment (diving quantitative method) and Van Veen grabs. Three main communities have been described. A Gammarus setosus-macroalgae community, probably seasonal, developed above 5 meters depth, had a relatively low diversity with biomass 7.6±0.9 g/m2 and abundance 135±40 ind/m2; a mixed bivalves-amphipods-bryozoan community (Serripes groenlandicus, Mya truncata, Haploops laevis, Alcyonidium disciforme) occured in muddy bottoms with some interspersed boulders between 7 and 30 m depth; it included 101 taxons, had a relatively high biomass 152.3±114.2 g/m2 and abundance 1600±940 ind/m2. A bivalve-dominated community with Musculus niger and Yoldia hyperborean inhabited depth of 67–72 m, included 38 taxons and was characterized by high density of abundance and biomass – 670±295 ind/m2 and 356.1±57.1 g/m2, respectively. Comparison with the previous data obtained 20 years ago at the depth 7–30 m, showed that, possibly, the retreat of the glacier under the influence of increasing temperature in the environment and increased runoff of melt water, washes away clay deposits which led to siltation of the bottom in the bay and caused degradation of kelp, which was partially replaced by invertebrate communities inherent in silted soils.