Patterns of spread of the zebra mussel (Dreissena polymorpha (Pallas)): The continuing invasion of Belarussian Lakes

The invasion of the freshwaters of Belarus by the zebra mussel, Dreissena polymorpha (Pallas), began at least 200 years ago by the opening of shipping canals linking the Black Sea and Baltic Sea drainage basins. However, zebra mussels have invaded only 93 (16.8%) of 553 studied lakes; at least 20 of these lakes were invaded within in the past 30 years. Zebra mussels were found disproportionately in lakes that were mesotrophic, larger, and had some commercial fishing. Although larger lakes have more intensive fisheries with larger catches, the intensity of the fishery and average catch did not affect the probability of zebra mussel invasion. Zebra mussels were not found in dystrophic lakes (10% of the lakes studied), probably due to their low pH and calcium content. Zebra mussels became locally extinct in one lake due to anthropogenic eutrophication and pollution. Many ecologically suitable lakes have yet to be invaded, which suggests that natural vectors of overland dispersal, e.g., waterfowl, have been ineffective in Belarus. Thus, future spread of this species will continue to depend on human activities such as commercial fishing.