Temporal dynamics in clearance rate of the Portuguese oyster Crassostrea angulata cultivated in Dapeng Cove, southern China

The oyster Crassostrea angulata is a major species for shellfish aquaculture in southern China. In this study, the in situ biodeposition method was used to estimate the clearance rate (CR) of C. angulata cultivated in Dapeng Cove, southern China, from January 2012 to January 2013. Relationships between CR and the dry tissue weight (DW) of the oyster were estimated for each experimental period. Results indicated that the CR of C. angulata related to DW by allometric relationships (CR = a x DWb) (the a values, representing CR of an oyster with 1 g DW) varied with time. The maximum value (7.678) was observed in November 2012, and the minimum value (0.655) in August 2012, when the oysters were in their reproductive period. The exponent value of b was low when oysters were large, and the minimum (0.215) occurred in August 2012; the b values were all > 0.9 during November and December 2012 when oysters were small. The relationship between the standardized CR (1 g DW; outside the reproductive period) and water temperature (T) can be described by non-linear regression: CRstd = -0.098 T-2 + 4.885 T - 53.476 (n = 6, R-2 = 0.949, p = 0.012), and the CRstd increased with T until a theoretical maximum (7.400 L g(-1) h(-1)) was reached at 24.92 degrees C. No statistically significant relationship was observed between CRstd and other environmental parameters (all p > 0.05). These results may facilitate oyster aquaculture management in southern China.