Oxygen consumption, nitrogenous excretion, and filtration rates of Dreissena polymorpha at acclimation temperatures between 20 and 32 °C

Abstract

Mussels were acclimated to each of four experimental temperatures (20, 24, 28, and 32 °C) for 30 days. Mussels averaged 10.29 mg tissue dry weight. Oxygen consumption rates at 32 °C were 3.65 times larger than consumption rates at 20 °C (p < 0.01). Ammonia excretion rates at 32 °C were 4.9 times greater than those at 20 °C (p < 0.01). O:N ratios were >60 at 20 and 24 °C but declined (p < 0.01) at 28 and 32 °C to <40. Filtration rates, an estimate of feeding rates, were not significantly different at 20 and 24 °C (p > 0.50) but declined at 28 and 32 °C (p < 0.01). Filtration rates at 32 °C were only 27% of the rates at 20 °C. These results indicate that (i) the metabolic expenditure of Dreissena polymorpha rose 265% as the temperature rose from 20 to 32 °C, (ii) metabolism relied more heavily on lipids and carbohydrates at 20 and 24 °C while protein catabolism increased at 28 and 32 °C, and (iii) the potential feeding rates of D. polymorpha declined by 73% as temperature rose from 20 to 32 °C. Above 28 °C D. polymorpha was unable to match energy expenditures with concurrent food intake and forced to rely on stored fuels.