Filtration rates in the soft clam Mya arenaria:: effects of temperature and body size

The filtration rate of the soft clam Mya arenaria was measured as the volume of water cleared of algal cells (Rhodomonas sp.) in two ways, by means of the clearance method and the suction method. Both methods allow measurements on undisturbed clams buried in the sediment. The filtration rate (F, ml min(-1) individual(-1)) of Mya arenaria as a function of temperature (T, degreesC) could be expressed as: F = 1.78T + 13.35 in the temperature-tolerance interval of 4-22 degreesC where the opening state of the siphons remain unchanged. After a 22 day exposure period to a lower constant temperature of 14 degreesC, the filtration rate was subsequently measured as a function of temperature and expressed as: F = 2.19T + 29.15. Based on the slopes of the regression lines as well as on the observed linear increase in filtration rate during the acclimation period (mainly due to growth), it is concluded that only minor, or possibly no, temperature acclimation may take place in soft clams (and presumably other bivalves). The filtration rate (F, 1 h(-1); 11 degreesC) as a function of dry weight of soft parts (W, g) and shell length (L, mm) could be described by means of the allometric equations: F = 4.76 W-0.71 and F = 0.0007L(2.47).