Suspension feeding and growth of juvenile Manila clam Ruditapes philippinarum reared in the laboratory

Abstract

: Feeding and growth of the Manila clam Ruditapes philippinarum fed on diatom Thalassiosira sp. were examined in the laboratory. The specific clearance rate (CR) relative to soft-body dry weight (w) of clams (shell length: 8–28 mm) followed a power function of w with an exponent of −0.32. The CR for the juvenile clams (shell length: 9–12 mm; w: approx. 10 mg) increased from 8 to 20 L/g per h in the temperature range 12–21°C, and then decreased gradually in the range 21–30°C. Growth rates (G) of juveniles (shell length: 10–12 mm) in terms of ash-free dry weight of the soft body were measured at 9°C and 20°C and increased linearly with weight-specific daily ration (Q) at both temperatures. G values were higher at 9°C than at 20°C when Q was fixed, probably owing to the lower catabolic rate at 9°C. The slope and y-intercept of G against Q gave an assimilation efficiency (0.62) and daily loss of body weight by catabolic processes (1.4%/day) at 20°C.