Growth rate and longevity of Dreissena polymorpha (Pallas): A review and recommendations for future study

We review the variety of methods that have been used over the last 50 y in the Former Soviet Union, Eastern and Western Europe, and recently in North America to determine growth rate and longevity in zebra mussels (Dreissena polymorpha [Pallas]). These methods include: counting annual rings, analysis of size-frequency distributions, following growth under experimental conditions and monitoring marked mussels under natural conditions, without removing them from substrate. The last method provides the most reliable data, however this is the least common method used. Dreissena polymorpha growth rates depend on water temperature, season of the year, location in the water column, food availability, oxygen concentrations, water velocity and various other environmental factors. However, it is very difficult to separate the independent effects of each of these factors, especially in natural waterbodies. Several factors may overlap and have additive or synergistic effect that makes it difficult to determine the effects of a single factor. When comparing among studies that used the same methods, we found that zebra mussels grow faster in reservoirs than in lakes. The reported longevity of D. polymorpha varies from 2-19 y and it is not clear to what extent this variation is caused by biological variability and environmental conditions and what amount of the variation is caused by the methods used to assess age and longevity.