Decadal Changes in Nematoda and Harpacticoida Taxocenes in Blagopoluchiya Bay (the Kara Sea)

— The article describes the results of studies of two main components of meiobenthos—nematodes and harpacticoid copepods—conducted in Blagopoluchiya Bay (Novaya Zemlya, Kara Sea) in 2013 and 2020. The mosaic distribution of these two taxonomic groups was due to high species diversity and low occurrence of most species. Nevertheless, the authors identified patterns in the changes in the species structure of both groups related to the effect of two main environmental gradients (a spatial gradient related to the distance from the bay mouth to the sea and a depth-related gradient), as well as to the patchiness of sediment distribution. In 7 years between the two surveys in Blagopoluchiya Bay the abundance of nematodes increased tenfold, the copepod abundance also increased, but to a much lesser extent. Taxonomic changes in these two groups were observed at both species and family levels, with no differences in the taxa functional structure. The observed changes can be related to changes in abiotic factors and to general changes in the trophic system of the bay due to the establishment of the snow crab Chionoecetes opilio .