Filter-Feeding in Corbicula fluminea and Its Effect on Seston Removal

Factors affecting filtration rates of the Asiatic clam Corbicula fluminea were studied in controlled laboratory experiments, and the data were then used to illustrate the importance of clam filtering in a North Carolina river. Both temperature and food concentration significantly affected clam filtration rates. Rates measured at winter temperatures were significantly lower than summer rates, while food concentrations and filtration rates were inversely related. Filtration rates were compared among clams collected from several different habitats in North Carolina, and although shell length (SL)-dry flesh weight (DFW) relationships differed between locations, filtration rate-size relationships were not significantly different when SL was used as a measure of clam size. Extrapolation of the above relationships to a population of Corbicula in the upper Chowan River, North Carolina, indicated that the average number of clams in a square meter of river bottom (350) could filter a volume of water equivalent to the overlying water column (mean depth 5.25 m) every 1-1.6 days in summer, depending on seston concentrations.