Distribution of rotifer Kellicottia bostoniensis (Rousselet, 1908) (Rotifera: Brachionidae) in water bodies and watercourses of Nizhny Novgorod oblast

In view of frequent findings of the alien North American rotifer Kellicottia bostoniensis (Rousselet, 1908) in water bodies and watercourses of Russia, the generalization of information about its locations and ecological requirements in particular regions has become an urgent task. The rotifer K. bostoniensis was recorded in 32 water objects (19 watercourses, 13 water bodies) of Nizhny Novgorod oblast from 55° to 56° N and from 42° to 43° E. In most water bodies, we recorded K. bostoniensis for the first time. The invader is widespread in water bodies and watercourses with different morphometry, current velocity, transparency, water color, pH, conductivity, trophic status, and level of anthropogenic pollution. K. bostoniensis dwells in a wide range of water pollution: from quality classes II to VI (clean to extremely polluted) of water. The highest frequency of occurrence and density of the rotifer are mainly recorded in July in ponds of eutrophic streams with slow current, high concentrations of nutrients, and well-developed higher aquatic vegetation. In some water bodies, the invader frequently co-occurred with the aboriginal species Kellicottia longispina (Kellicott, 1879). Only K. bostoniensis was recorded in small streams within the precincts of the city of Nizhny Novgorod. A wide distribution of K. bostoniensis in Nizhny Novgorod oblast and the ability to live in water bodies with different complex of natural factors and degree of anthropogenic impact may indicate high ecological plasticity of the species and the possibility of its further expansion.