Impact of heron (Ardea cinerea L. and A. alba L.) habitat on coastal juvenile fish assemblages in Rybinsk Reservoir

Abstract

It has been determined that the stocking density of juvenile fish in an open reservoir shallow-water site in the heronry area in the nesting period is higher than that in the reference site. The juvenile roach Rutilus rutilus L., which is one of the dominant species, in the bird impact zone significantly differs in higher values for both the size–weight characteristics and the body weight-growth rates. The habitat-dependent phenotypic differences in various biotopic assemblages of the juvenile fish are revealed. It has been proven that the environmental impact of the heron-colony life activities on the fish populations in the reservoir shallow-water site is temporary, which is limited by the bird-nesting season.