A seasonal energy budget for zebra mussels (Dreissena polymorpha) in western Lake Erie

Abstract

We constructed a balanced energy budget for zebra mussels (Dreissena polymorpha) from the western basin of Lake Erie during the active growth and reproductive season (May-October). We measured metabolic costs (oxygen consumption and ammonia excretion), body mass change, and feces production weekly and marked mussels to quantify shell growth. Costs of reproduction were measured by inducing spawning four times using serotonin and collecting gametes. After conversion to calories, all energy budget components were combined with published length-frequency distributions and mussel densities to estimate population consumption. We estimated that individual zebra mussel consumption averaged 3.16 cal ·day-1 (1 cal = 4.1868 J). Metabolic costs account for >90% of energy consumption. Mussels <15 mm increased in body mass whereas mussels >15 mm allocated energy to reproduction in lieu of somatic growth. Our estimates of population consumption were sensitive to mussel size distribution, with the most abundant size-class responsible for the greatest proportion of population consumption. Based on published estimates for primary production in western Lake Erie, our energy budget estimated that zebra mussels (10 000 - 50 000 mussels ·m-2) potentially consume an equivalent of 10-50% of summer primary production.