Effects of pH, calcium, alkalinity, hardness, and chlorophyll on the survival, growth, and reproductive success of zebra mussel (Dreissena polymorpha) in Ontario lakes

In 1991, field studies were conducted to determine the effects of pH, calcium, alkalinity, hardness, and chlorophyll on the survival, growth, and reproduction of zebra mussel (Dreissena polymorpha). Water from 16 south-central lakes in Ontario was collected and supplied to zebra mussels in a flow-through system. Adult zebra mussel mortality was significantly correlated with calcium and pH. Growth rates of juvenile mussels ranged from -83.3 to 200 µm ·week-1. Water buffer variables (calcium, alkalinity, and total hardness) explained 60-66% of the variation observed in the change in shell length of juvenile zebra mussel (p = 0.001-0.003). There was negative growth at calcium levels less than 8.5 mg Ca · L-1, alkalinity levels less than 17.1 mg CaCO3 · L-1 and total hardness levels less than 31 mg CaCO3 · L-1. Maximum growth occurred at calcium levels of 32 mg Ca ·L-1, alkalinity of 65 mg CaCO3 · L-1, and total hardness of 100 mg CaCO3 · L-1. Positive growth of juvenile zebra mussel only occurred at pH levels greater than 8.3. Only one veliger survived to the settling stage.