HETEROZYGOSITY, SHELL LENGTH AND METABOLISM IN THE EUROPEAN MUSSEL, DREISSENA-POLYMORPHA, FROM A RECENTLY ESTABLISHED POPULATION IN LAKE ERIE

1. Genetic variation at seven polymorphic enzyme loci in a recently established North American population of the European zebra mussel, Dreissena polymorpha, was high, with an average heterozygosity (H) of 0.307, and an average of 3.43 alleles per locus (range 2-6). 2. Mussel shell length was significantly correlated with multiple locus heterozygosity, although heterozygosity at these seven loci explained only 7% of the total variation in shell length. 3. Decreased mass-specific metabolic rate has been proposed as the mechanism whereby heterozygotes grow faster than homozygotes, however, mass-specific oxygen consumption was not significantly correlated with multiple locus heterozygosity. 4. The relationship between body size and heterozygosity is similar in this freshwater bivalve to previous reports for several species of marine molluscs.