Effects of food restriction on growth, survival and metamorphosis of Pinctada fucata

In the present study, the effects of food restriction on the growth, survival and metamorphosis of Pinctada fucata were investigated from April 27 to May 25 in 2009 under different feeding conditions. The results showed that the daily growth rate of shell length and shell height in the control group increased gradually but decreased suddenly from day 20, while those in group 1 (feed every other day) and group 2 (feed every 3 days) increased slowly, which significantly differentiated with the case in the control group. It indicated that whether the food was sufficient influenced the growth of P.fucata directly. In the experiment, the survival rate in the control group decreased but the deformity rate of larvae showed no significant difference; the survival rate in group 1 and group 2 were significantly lower than that in the control group, and the deformity rate in group 2 was significantly higher than that in the control group, which indicated that the growth of the larvae was influenced byfood shortage. The larvae in the control group metamorphosed at day 20, and the metamorphosis rate increased gradually. The larvae in group 1 metamorphosed at day 30, but thosein group 2 did not metamorphose throughout the experiment, which showed that the larvae did not have enough nutrition for metamorphosis.