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Stoeckmann, A.M. and D.W. Garton, 2001. Flexible Energy Allocation in Zebra Mussels (Dreissena polymorpha) in Response to Different Environmental Conditions, Penn State Worthington Scranton. Reprinted with permission from Journal of the North American Benthological Society (2001) 20(3): 486-500 Flexible Energy Allocation in Zebra Mussels (Dreissena polymorpha) in Response to Different Environmental ConditionsThe ability to adjust physiological parameters in response to environmental conditions while simultaneously maintaining growth and reproduction increases an organism's fitness. We altered energy demands to examine the effect of environmental conditions on energy allocation in zebra mussels (Dreissena polymorpha). We manipulated metabolic costs and ingestion with combinations of 4 temperatures (12, 18, 24, and 30 degreesC), 3 rations, and 2 diet qualities for 7 wk in laboratory experiments. We measured maintenance costs (oxygen consumption and ammonia excretion), somatic tissue mass, shell growth, and reproduction to determine if zebra mussels have flexible energy allocation into tissue mass and reproduction. Increased temperature and ration increased metabolic costs but diet qualities did not. Assimilation efficiency, higher in good diet than poor, decreased with ration. Shell growth, tissue mass, and reproduction responded similarly to temperature and ration. Reproduction was similar, whereas growth and survival differed the most between diets. Good diet mussels reproduced, maintained tissue mass, grew, and survived. Poor diet mussels reproduced but did not grow and died. Diet quality influenced reproductive effort, with lower investment in body mass in the poor diet yielding higher reproductive effort. Thus, zebra mussels are flexible in energy allocation and in stressful conditions, most importantly reduced food quality; reproduce at the expense of maintenance thereby increasing the probability of death. Entire Paper |
