Laboratory Experiments on Pumping and Filtration in 'Mytilus edulis L.using Suspensions of Colloidal Graphite

Abstract

Pumping and filtration of colloidal graphite and shell movements of Mytilus edulis from Carlingford Lough, Northern Ireland, were recorded in the laboratory. Pumping and filtration rates fluctuated widely even in undisturbed animals. Long term recordings demonstrated an inverse relationship between pumping rate and filtration efficiency. The effects of light, tidal cycle, particle concentration, temperature and salinity on pumping rate have been examined. Periods of light and dark did not affect pumping rate nor was there evidence for any intrinsic tidal rhythm in feeding. Pumping increased to a maximum at graphite concentrations of 20-25 mg/l. The rate prior to the addition of graphite influenced the response at certain particle concentrations. Filtration was most efficient at 18.5°C and decreased above 22.5°. Pumping steadily increased to a maximum at 22.5°. Filtration of acclimated mussels was maximal at 25-34‰ whilst feeding ceased at the extreme salinities of 15 and 50‰.