ZOOBENTHOS OF THE SULA ARCTIC RIVER (NORTHERN TIMAN, MALOZEMELSKAYA TUNDRA)

Abstract

For the first time, we studied zoobenthos in the upper reaches of the river Sula located beyond the Arctic Circle. During the study period (July, 2016), the water temperature warmed up to 18-23°С in the river channel and up to 3-5° C in the streams. The zoobenthos of the upper reaches of the river has high quantity but low biomass. Its average abundance was 30.3 thousand individuals per m 2 , and biomass – 2.7 g/m 2 . The highest zoobenthos biomass was founded at the riffles (up to 66.1 thousand individuals per m 2 , and biomass – 6 g/m 2 ) where chironomids and black flies dominated. At the pools, we found low abundance of zoobenthos – 5 thousand individuals per m 2 and 0.3 g/m 2 . Here, in addition to dipterans, a large proportion of leeches and oligochaetes were noted. Near the river banks, 25 groups of hydrobionts were found. Chironomids (40.3%) and ostracods (20.7%) dominated by the number; Ephemeroptera larvae (44.9 %) dominated by biomass. In deeper parts of the river channel, the benthos was poorer; the same groups were numerous as near the banks, and oligochaetes dominated in the biomass (57.9%). The zoobenthos of the streams differed from the riverbed by the greater number of amphipods; its quantitative development was close to that of the river. We found 28 large taxa of zoobenthos in the upper reaches of the river Sula and it tributaries. In the oxbow, we found three more groups: Megaloptera, Heteroptera and Porifera. In general, zoobenthos was dominated by ancient orders of insects: mayflies, stoneflies, caddis flies, and beetles. In addition to dipterans (10 families), 52 species of insects have been recorded: 11 species of mayflies, 10 of stoneflies, 19 species of caddis flies, and 12 species of beetles. In the article, we provide the species list of the zoobenthos. Our research supplemented the fauna of amphibiotic and aquatic insects of theNorthern Timan rivers and emphasized the need to protect the catchment area of this intact region of the Malozemelskaya tundra.