Metabolism and habitat competition in the polychaete Nereis virens

The relationship between lnetabolism and performance during habitat competition in the polychaete Nereis v i r e ~s (Sars) was determined. Twenty palred habitat competition experiments were inltlated between Individuals of similar body mass. The outcome of the competition and the time spent competing for the burrow were noted for each encounter. Protein and lipld contents as well as enzyme activlty (cytochrome C oxidase, lactate dehydrogenase, and pyruvate kinase) were compared between wlnners and losers. There were no significant differences between winners and losers for all parameters. Thc,re was, however, a significant relationship between fight duratlon and enzyme activity for winners. Individuals that won a fight rapidly had more cytochrome C oxidase actlvlty than individuals who fought longer to gain access to the burrow. We conclude that metabolic capacltles are not correlated with the outcome of habitat competition but that aerobic capacity 1s a n Important predictor of fight duration.