Analysis of coexistence of the recent invader Diaphanosoma orghidani Negrea with the aboriginal species D. brachyurum (Lievin) (Crustacea, Cladocera) in the Rybinsk reservoir

Abstract

The spatial distribution and long-term dynamics of occurrence and abundance, as well as features of the seasonal life cycle of two species of Cladocera, an alien species D. orghidani and a native species D. brachyurum, were studied in 2005–2011 in the Rybinsk reservoir. It was found that, during a seven-year period, the successful coexistence of the species is favored by the differences in a seasonal cycle, the pattern of distribution in the reservoir area, the predator pressure, and resistance of the alien species to high concentrations of colonial cyanobacteriae and its preference for the parts of the reservoir with running water where the native species is not numerous. Competitive advantages of the invader in the conditions of global warming are discussed.