Veliger larvae of Dreissena (Bivalvia, Dreissenidae) in the zooplankton of Lake Pleshcheyevo (Yaroslavl Region, Russia)

Abstract

The abundance dynamics, spatial distribution and role of freshwater zebra mussel veligers in the structure of zooplankton were analyzed based on observations in 2012–2016 in Lake Pleshcheyevo (Yaroslavl Region). The mean abundance of larvae in the pelagial of the lake in the peak period (summer) ranged widely (0.05–50.7 thousand individuals/m3 ). The minimal values were shown for 2015 when the mollusks were virtually not reproducing. The densest populations of veligers were observed in the sublittoral and pelagial of the lake. The veligers were mostly concentrated in the upper (0–6 m) water layer. All daily movements of the plankton larvae were restricted to the epilimnion, at a depth of 4–6 m in the daytime at, while in the night they were evenly spread across the upper 6 m of water. In summer the veligers constituted on average 1–38% of the abundance of non-predatory zooplankton.

Keywords

• lakes
• meroplankton
• veligers
• dreissena polymorpha
• distribution
• abundance dynamics