Distribution of midges (Chironomidae, Diptera) on terrestrial area after their emergence from saline lake Shira
Irina A Vitkovskaya, Elena V Borisova, Nadezhda N Sushchik
Abstract
We studied number and biomass of midges (Chironomidae, Diptera) on terrestrial area where flows of organic matter and essential polyunsaturated fatty acids (PUFA) related with emergence of the amphibiotic insects from saline steppe Lake Shira were dispersed. Records of midge specimen caught by glued terrestrial traps showed that 50 and 95 percentages of the emerged adults of Glyptotendipes and Polypedilum presented within 25-m and 100-m stripes surrounding lakeshore, respectively. The area of these stripes was calculated along with quantification of flows of chironomid biomass and essential PUFA per land area unit that based on data of previously measured export. For 25-m lake-surrounding stripe where 50% of midges swarmed, the annual import of dry biomass and PUFA was 1.5 g m-2 and 15 mg m-2, respectively. In turn, the stripe of 100-m width where 95 % of the midge number were registered got annual flows that were equal to 0.7 g dry mass m-2 year and 7.2 mg PUFA m-2. The calculated values of PUFA export was similar to measurements in some relatively productive landscapes. Number of midges caught at the site that located nearly the most productive lake part was the lowest among all the studied near-lake sites. This site of lakeshore is part of a national reservation where a great number of insectivorous birds live or stop. Lower abundance of swarmed chironomids there were likely related to intensive consumption by terrestrial animals, i.e., birds, for obtaining necessary doses of essential compounds.