Ecological and morphological characterization of Dreissena bugensis (Bivalvia, Dreissenidae) from Cheboksary Reservoir (with the description of deep-water ecotype)

Abstract

The bivalve mollusk Dreissena bugensis forms two ecotypes in the Cheboksary Reservoir—typical (shallow) and deep-water ones. This water body is the only place in the European part of the species range where the deep-water morph is found. The two ecotypes differ morphologically (in the ratios of shell height, width, and length; in general outlines and byssus strength) and ecologically (they inhabit parts of the reservoir which differ strongly in environmental conditions). The morphological variability of the deep-water morph is lower than that of the typical one.