Seasonal and Annual Variation in Weight and Biochemical Content of the Zebra Mussel, Dreissena polymorpha, in Lake St. Clair

• Published in: Journal of Great Lakes research 1993, Vol.19 (3), p.541-552
• Main Authors: Nalepa, Thomas F., Cavaletto, Joann F., Ford, Mark, Gordon, Wendy M., Wimmer, Marijo
• Format: Article
• Language: English
• Subjects: carbon; Dreissena polymorpha; Freshwater; Lake St. Clair; Lipids; nitrogen; zebra mussels
• ISSN: 0380-1330
• DOI: 10.1016/S0380-1330(93)71240-X

Zebra mussels, Dreissena polymorpha, were collected monthly from April/May to November in 1990 and 1991 from two sites in Lake St. Clair. The sites were characterized by relatively high and low mussel densities. The following variables were measured: ash-free dry weight (AFDW) per unit shell length (SL), lipid content and classes, carbon content, and nitrogen content. Mussels from the high-density site had a lower AFDW:SL relationship, lower lipid content, and a lower C:N ratio than mussels from the low-density site. Seasonal trends in these variables were consistent between sites and years. AFDW:SL, lipid, and carbon content were highest in the spring and then declined to minimum levels in late summer/fall. The mean seasonal decline in weight from spring to late summer for a standard 15-mm mussel was 60%. This decline was greater than might be expected from gamete release alone and was likely a result of nutritional stress from warm summer temperatures and limited food supplies. Between 1990 and 1991, the mean AFDW of a 15-mm mussel declined 34% and 50% at the high- and low-density site, respectively. However, when C:N ratios and lipid levels in 1990 and 1991 were compared, C:N ratios were only lower in fall 1991 compared to fall 1990, and lipid levels for the 2 years were generally similar.