Khamenkova E.V., Teslenko V.A., Tiunova T.M.
Zoologicheskiy zhurnal 2017; 96(4): 400-409
The taxonomic composition of macrobenthos fauna and its distribution in the tributaries and mainstream mid-size salmon Ola River, northern coast of the Sea of Okhotsk were investigated for the first time. In the Ola River basin, 253 taxa of benthic invertebrates belonging to 3 phyla (Plathelminthes, Annelida and Ar-thropoda) and 5 classes (Turbellaria, Clitellata, Crustacea, Arachnida and Insecta) were revealed. Mayflies (Ephemeroptera), stoneflies (Plecoptera), caddisflies (Trichoptera) and Diptera chironomids (Chironomidae) showed the highest species richness and dominated the benthic communities. Most of the fauna (140 species and species groups, or more than 55% of the total) belonged to chironomids. The shares of identified species of mayflies, stoneflies and caddisflies were subequal. An analysis of hydromorphological characteristics and the composition of aquatic insect families revealed that all areas surveyed in the Ola River basin were rhythral while the macrobenthos fauna represented rhythron. Classification obtained through cluster analysis showed spatial heterogeneity in the distribution of benthic fauna along the Ola River run related to changes in temperature, river slope and elevation above sea-level. The heterogeneic fauna distribution and the corresponding change in stable hydromorphological features showed typical epi-, meta- and hyporhythral subzones whose boundaries were difficult to distinguish. However, the rhythral subzones selected were characterized by the habitat selectivity of individual taxa and by peculiar species richness values, thus emphasizing their distinction.
