Invasion of Dreissena Polymorpha (Pallas, 1771) to Reservoirs in the Struma River Basin (Aegean Sea Drainage Basin, Southwest Bulgaria)

ABSTRACT

The occurrence of the invasive zebra mussel Dreissena polymorpha was studied in four reservoirs along the Struma River and its tributaries (Aegean Sea basin). It was newly recorded in the reservoirs Izvor, Pchelina and Stoikovtsi. In the Gorna Dikanya Reservoir only shells of the mussel were found. The highest population density was registered in the Stoikovtsi Reservoir (4848 ind./m²) and the highest biomass in the Izvor Reservoir (3753 g/m²). The lowest quantitative parameters were recorded in the Pchelina Reservoir. The potential threats resulting from the species' expansion in the Struma River basin were discussed.

Keywords:

• Abundance
• Aegean Sea basin
• biomass
• Dreissena polymorpha
• reservoirs