Ecology and biology of Enallagma cyathigerum (Charpentier, 1840) (Odonata) under unstable water conditions in the south of Western Siberia
O. N. POPOVA, A. YU. KHARITONOVI
Institute of Systematics and Ecology of Animals, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Odonata, Enallagma cyathigerum, intrapopulation seasonal groups, abundance, water availability, climate, West Siberian forest steppe
Abstract
As a result of many years of research in the Barabinsk forest-steppe, the peculiarities of ecology and biology of the damselfly Enallagma cyathigerum were revealed. The species lives in all permanent reservoirs - rivers, river channels, lakes and ponds, where its most numerous populations have been identified, and also inhabits temporary reservoirs, surviving in them during periods of drying out due to the egg phase. Biotopic preferences were found in the choice of habitat: the larvae live only in non-reed hydrocenoses, which is associated with the ecological standards of the species. In the last 20 years, there has been a decrease in the number of E. cyathigerum, despite the increase in humidity in the region, which we associate with the consequences of climate warming - weather disasters in the summer, an increase in air temperature and, accordingly, water in reservoirs, leading to a deterioration in the hydrology of reservoirs and suffocation of aquatic organisms. A study of the development of E. cyathigerum on Kargat River and Fadikha Lake in 2004-2006 revealed a one-year life cycle of a species that has a different population structure on a river and lake associated with their different hydrological and temperature regimes. The species population on the Kargat River was unified in all 3 years, on Lake Fadikha in high-water 2004 it was unified, and in low-water 2006 it was divided into 2 seasonal groups - summer with wintering larvae and summer-autumn with wintering eggs. Such a complication of the population structure on Lake Fadikha in 2006 was the result of an increase in water temperature (as a result of an increase in the average daily air temperature and a decrease in the water level in the lake), and is a kind of “adjustment” of the species to the deterioration of habitat conditions in the low-water period: eggs are present in the lake almost all year round (wintering and non-wintering) and the larvae have different ages, and imagoes fly on land from spring to autumn. This adaptive feature of E. cyathigerum may partly explain its relatively high abundance, eurybiont and large range - almost the entire Palearctic.
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