Life cycles and habitat selection of two sympatric mayflies under extreme continental climate (River Kharaa, Mongolia)

摘要: Autecologic information of aquatic insects in the river systems under extreme continental climatic conditions is limited. Therefore, objective this study was to analyze life cycles, larval development, densities, microhabitat distribution, and secondary production two sympatric burrowing mayfly species, Ephemera orientalis Ephoron nigridorsum, Kharaa River, Northern Mongolia. Both species were typically distributed within middle reaches focus river, displaying significant different densities across three sites. Four distinct microhabitats for E. nigridorsum identified. The preferred habitats both substrates composed rocks, cobbles, or coarse gravels with variable smaller mineral fractions finer sandy, muddy, organic beside. Based on body size distribution emergence period, it concluded that has a univoltine winter cycle. estimated annual larvae at investigated sites stretch year 2009 1.65 2.25 g DW m � 2 1 . Biomass 294.8 490.3 mg , biomass rate (P/B) 4.5 5.6 respectively. In contrast, displayed summer cycle very likely egg diapause approximately 8 months. Annual estimates 5.27 7.89 281.2 443.2 ; P/B rates 17.9 18.7 reflecting extremely shortened species. We conclude showed difference cycles but no separation habitat selection.