Emergence of midges (Chironomidae, Diptera) from a saline lake as a source of organic matter and essential biochemical compounds for arid ecosystems in South Siberia
Elena V. Borisova, Aleksandr P. Tolomeev, Anton V. Drobotov, Nadezhda N. Sushchik
Abstract
Midges (Chironomidae, Diptera) are dominant amphibiotic insects in zoobenthos of large saline Lake Shira that is located in arid landscape of South Siberia. During two vegetation seasons we measured dynamics of chironomid emergence from littoral parts of four stations of the lake. Additionally, during one of the vegetation seasons chironomid emergence from profundal parts (depth of 6 m) of the same stations was measured using original floating traps. Seasonal dynamics of emergence values and their daily means significantly varied among the studied stations and depths and were related to bottom sediment type. The annual export (calculated as the sum all daily values for a vegetation season) of wet biomass was equal to 0.61 g per square meter of water area that included proportional contribution of the areas with various bottom sediments. Based on values of benthic secondary production, we estimated an additional annual export of chironomid biomass from profundal part of the lake as to be equal to approximately 1 g of wet mass × m−2. Meanwhile, summary export of polyunsaturated fatty acids (PUFA) that was calculated using previous data on PUFA content in the studied chironomid taxa, ~ 2 mg × m−2 year−1, appeared to be one of the lowest values when compared to the estimations for chironomids and some other amphibiotic taxa from the similar steppe landscapes.