ABUNDANCE OF RELATED SPECIES, <i>KELLICOTTIA BOSTONIENSIS</i> (ROUSSELET, 1908) AND <i>K. LONGISPINA</i> (KELLICOTT, 1879) (ROTIFERA: BRACHIONIDAE), IN THE COMMUNITIES OF ZOOPLANKTON OF THE PUSTYNSKAYA LAKE-RIVER SYSTEM (NIZHNY NOVGOROD OBLAST)

Abstract

The article presents the features of the spatial distribution of zooplankton communities in the water area of the Pustynskaya lake-river system. The abundance of two related species of the genus Kellicottia , the alien Kellicottia bostoniensis (Rousselet, 1908) and the indigenous K. longispina (Kellicott, 1879), was analyzed in dedicated communities in 2013-2017. The greatest abundance of the alien species was noted in zooplanktocenoses of mesotrophic water bodies (the Serezha River and Lake Svyato). It was found that after the period of mass development of K. bostoniensis in 2013-2014, which might be due to the initial stage of naturalization of the alien species, its abundance had sharply decreased. In 2013-2014 the abundance of the indigenous species K. longispina (Kellicott, 1879) was significantly lower than that of the alien species. Rotifer K. longispina dominated in the Protoka and Lake Svyato in 2017. The highest density of both species was found in the metalimnion of the mesotrophic Lake Svyato. A statistically significant positive correlation was found between the abundance of K. bostoniensis and the temperature, transparency, and pH of water, as well as the abundance of predatory zooplankton species. The abundance of the native species K. longispina correlated negatively only with the value of water pH.