Non-Biting Midges (Diptera, Chironomidae) in the Benthic Communities of Saline Rivers in the Lake Elton Basin: Diversity, Salinity Tolerance, and Distribution

Abstract

The study presents the results of long-term (2006-2014) research on the non-biting midges (Diptera, Chironomidae) in macrozoobenthic communities of five saline rivers (the Khara, the Lantsug, the Bolshaya Samoroda, the Chernavka, and the Solyanka) flow into hypersaline Lake Elton (Volgograd Province). The rivers have a high mineralization gradient from 4 to 41.4 g/L and diff er in size as well as in the spatial dynamics of hydrological-hydrochemical and hydrophysical parameters. In the mouth reaches, water mineralization in these rivers may exceed 100 g/L. In total, 25 chironomid taxa have been identified, 10 of which were typical of the Solyanka River and Chernavka River where salinity was above 20 g/L. In diff erent years, Chironomus aprilinus Meigen 1838, Ch. salinarius Kieff er, 1915, and Cricotopus salinophilus Zinchenko, Makarchenko et Makarchenko, 2009 were dominant in the Solyanka and Chernavka rivers and so was Tanytarsus kharaensis Zorina et Zinchenko, 2009 in the Khara and Bolshaya Samoroda. The chironomids of the benthic communities of saline rivers are represented by eurybiontic halo-tolerant species. Their distribution and abundance are linked to a complex of hydrological-hydrochemical factors, e.g., the level of overgrowth, water temperature, pH, soil particle size, etc. The chironomid diversity is strongly correlated with mineralization, although there is no clear relationship between chironomid abundance or biomass and mineralization between 6 and 41.4 g/L. The seasonal dynamics of abundance and biomass of chironomid larvae is characterized by spatial heterogeneity due to features of the life cycles of the most numerous multivoltine chironomids.