Zoobenthos Communities of Thermal and Cold Karst Aquatic Ecosystems (Pymvashor Natural Landmark, Bol’shezemel’skaya Tundra)

The summer structure of the zoobenthos in several thermal and low-temperature springs of the Bol’shezemel’skaya Tundra hydroecosystem (Pymvashor Creek) is examined. Compared with cold springs, thermal springs feature a lower diversity of benthic faunal groups but a higher species richness in some of these groups. In terms of abundance, oligochaetes and dipteran (family Chironomidae) larvae prevail in communities of hydrothermal biotopes; while cold karst waters are predominated by dipteran (family Chironomidae) larvae and ostracodes. Mollusks, oligochaetes, or dipterans (family Tipulidae) feature the greatest biomass in thermal springs; in low-temperature springs, chironomids and mollusks predominate in terms of biomass. The fauna consists mainly of widespread eurythermal species, but stenothermal hydrobionts are present as well. No endemic forms typical for thermal waters in other parts of the world were discovered; however, for the first time, representatives of the extrazonal fauna were found in Bol’shezemel’skaya Tundra. Within the studied stretch of Pymvashor Creek, the zoobenthos structure is fairly homogenous regardless of the warming or cooling effects of the springs.