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.