Taxonomic Composition and Biomass of Zoobenthos in Saline Lake Shira: Shifts That Happened in 65 Years

In summer 2016 we studied biomass and species composition of zoobenthos in saline Lake Shira that has large recreational significance for Khakasia and Krasnoyarsk regions. Zoobenthos of the studied lake consisted of 15 species, among those chironomid larvae Glyptotendipes salinus, Chironomus nigrifrons and Chironomus halophilus, and necto-benthic amphipod Gammarus lacustris dominated. Biomass values averaged for the studied summer period (54 days) were 6.8 ± 3.11 g / m2 and 4.4 ± 1.01 g / m2, for Chironomidae and Gammaridae taxa, correspondingly. We found significant difference in dominant species biomass and the total production of chironomids between the littoral and the pelagial parts of the lake. We compared our data with results of the only extensive study of zoobenthos in the lake that was carried out in the early fifties of 20th-century. The amphipod G. lacustris dominated in zoobenthos in that time, like in the contemporary period. In contrast, chironomid species that dominate now were not found in benthic fauna 65 years ago. Meanwhile, biomass values of Chironomidae and G. lacustris decreased in several times compared to zoobenthos values in fifties of the previous century. In general, relatively few number of benthic species in Shira Lake agrees with a common notion that species richness decreases in inland waters with salinity > 15 %%. Averaged biomass of the dominant taxa, Chironomidae family, corresponded to a range of values reported for other saline water bodies.