M.A. Studenova, I.I. Studenov, D.V. Chupov, A.S. Samodov
Section: Monitoring of natural and anthropogenically disturbed areas
Systematic studies of zoobenthos at the delta of the Severnaya Dvina river begun in 2012. This study contains the most complete information about the taxonomic composition of zoobenthos of the area, the number and frequency of taxons, the number and biomass of each of the taxa. Twenty taxons belonging to 6 types and 11 classes of invertebrates were found in zoobenthos during the whole period of research (2012-2018). The average number of taxons per 1 station during the entire research period was 9, ranging from 5 in the Korabel’ny arm to 16 in the Murmansk arm. Oligochaetes, bivalvia, and chironomidae larvae were found in samples at all stations each year. Isopods, dayflies larvae and beetle larvae were found with lowest occurrence rate. Average value of Shannon ’s zoobenthos index at the delta of the Severnaya Dvina river was 1.21, varying from 0.70 (Maimaxa and Kuznechikha branches) to 1.84 (Murmansk arm). The number of invertebrates over the years varied very widely - from 640 spec/m2 (Korabel’ny arm, 2018) up to 16573 spec/m2 (Murmansk arm, 2014), averaging 5704 spec /m2. Oligochaetes and сhironomidae larvaes were the most numerous. The biomass of invertebrates at the delta of the Severnaya Dvina river varied very widely - from 0.29 g/m2 (Korabel’ny arm, 2017) to 25.3 g/m2 (Murmansk arm, 2014), averaging 6207 mg/m2 for all observation years. The base of biomass was formed by Oligochaetes, their participation in the formation of total biomass reached 94.6%. An average oligochet index was 57.8%. The water condition of the delta of the Severnaya Dvina river was classified as moderately contaminated, according to the values of the oligochet index.
Keywords: Severnaya Dvina river, zoobenthos, taxonomic composition, number, biomass
Article published in number 2 for 2021 DOI: 10.25750/1995-4301-2021-2-060-065