Effects of barnacle encrustation on the swimming behaviour, energetics, morphometry, and drag coefficient of the scallop Chlamys hastata
Journal of the Marine Biological Association of the United Kingdom
Barnacle encrustation negatively in£uenced every aspect of swimming in the scallop Chlamys hastata measured in this study. Scallops swam signi¢cantly longer, travelled further and attained greater elevation once epibiotic barnacles had been removed. Shell morphometry of barnacle-encrusted scallops was similar to shells of unencrusted scallops. Speci¢cally, shell length was positively allometric with shell height and shell mass was negatively allometric. However, adductor muscle mass scaled
... le mass scaled isometrically to shell height, in contrast to unencrusted scallops. In the laboratory, the drag coe⁄cient (C d ) of barnacle-encrusted scallops decreased after barnacle removal, in contrast to sponge-encrusted scallops in which no decrease in C d was detected when the sponge was removed from the scallop's valves. Furthermore, scallops swimming with barnacle encrustation required more energy than did unencrusted scallops. Although there was no signi¢cant di¡erence in aerobic energy expenditure between swimming barnacle-encrusted and unencrusted scallops, di¡erences in anaerobic energy expenditure were detected. Speci¢cally, barnacle-encrusted scallops required more arginine phosphate than unencrusted scallops to swim to exhaustion although octopine levels were similar. Thus, barnacle encrustation dramatically decreased a scallop's ability to swim, partly by increasing the drag coe⁄cient experienced by the scallop and the energy required for swimming.