Filtration, Repiration and Assimilation in the Black Mussel Choromytilus meridionalis

Abstract

Filtration rates, respiration rates and assimilation efficiences of C. meridionalis (Kr.) fed on Dunaliella primolecta were examined. No seasonal or tidal changes in filtration rate were recorded. Filtration rates were variable within and between individuals, but were independent of algal concentration over the range 0.4-50 .times. 106 cells l-1. Below 0.4 .times. 106 cells l-1 the filtration rate increased with declining ration. Respiration rate was unaffected by ration level but increased with rising temperature. Assimilation efficiencies were high, averaging 80% between 0.5-8 .times. 106 cells l-1, but declined to zero at 30 .times. 106 cells l-1. The effects of starvation on the filtration rate, respiration rate and assimilation efficiency also were studied. Following starvation, filtration rates increased at all cell concentrations, while the curve for assimilation efficiency showed translation to the left so that efficiency declined to zero at 20 .times. 106 cells l-1 instead of 30 .times. 106 cells l-1. The net result was a shift of the zone of positive scope for growth into a region of lower cell concentrations. C. meridionalis may co-exist with the bivalve Aulacomya ater in the field. Assimilation efficiency and scope for growth were compared in the 2 spp. The greater scope for growth in C. meridionalis may be related to its higher filtration rate; it was more than twice that of A. ater. A. ater obtained a positive scope for growth over a wider range of algal ration levels.