Fluxes of biomass and essential polyunsaturated fatty acids from water to land through chironomid emergence from a mountain lake

Abstract

Taxonomic composition, seasonal dynamics of biomass of Chironomidae adults that emerged from mountain oligotrophic lake Oiskoe (West Sayan, South Siberia). Value of annual emergence of chironomids averaged for the lake area was 0.42 g of wet weight m−2 and was similar to the value of potential emergence which was calculated from zoobenthos secondary production. For the first time, fatty acid composition and contents of essential omega-3 polyunsaturated fatty acids (PUFA) were compared between larvae and adult stages of chironomids. Content of PUFA per wet weight unit in adult biomass was more than 7-fold higher as compared to that in their larvae. Flux of PUFA per a lake area unit due to chironomid emergence accounted for 1.752 mg  m−2 y−1, and it was in 10 times lower than the global export estimation through amphibiotic insect emergence. Calculations showed that flux of PUFA brought with chironomid emergence per a land unit of the studied mountain territory was very low as compared to that for other landscapes. However, the calculated flux per a land unit within the first 15 m of shoreline was much higher and similar to that in productive landscapes.