The Distribution of Species of the Genus Diaphanosoma (Crustacea, Cladocera) in Reservoirs of the Volga and Sheksna Rivers: Impact of Environmental Factors

摘要

On the basis of materials that were collected in 2005-2010 in the Sheksna, Ivankovo, Uglich, Rybinsk, Gorky, and Cheboksary reservoirs, the occurrence and abundance of two species, the indigenous Diaphanosoma brachyurum (Lievin) and the recent invader D. orghidani Negrea, are analyzed. These species coexist in all waterbodies. The abundance of alien species is comparable with the abundance of aboriginal species. Over five years, the frequency of D. orghidani has increased 1.5-2 times. The effect of abiotic (water temperature, current, and color) factors, competition with other filter feeders, and predation by invertebrates and fish on the abundance and spatial distribution of the species are discussed.