3种无脊椎动物对近江牡蛎Crassostrea ariakensis和熊本牡蛎C. sikamea的捕食研究

捕食是影响牡蛎种群建立和牡蛎礁发育的重要生物因子之一。通过室内受控实验测定了日本蟳（Charybdis japonica）、脉红螺（Rapana venosa）和黄口荔枝螺（Thais luteostoma）对4组规格（W1：壳高10-20mm；W2：壳高20-30mm；W3：壳高30-40mm；W4：壳高>40mm）近江牡蛎（Crassostrea ariakensis）和熊本牡蛎（C.sikamea）的捕食偏好性和捕食效率。双因子方差分析结果表明，日本蟳对2种牡蛎的捕食效率没有显著性差异（P>0.05），但牡蛎规格大小显著影响着日本蟳的捕食效率（P<0.05），即日本蟳对W1组近江牡蛎的捕食效率显著高于W2和W4组（P<0.05），W3组的被捕食效率介于中间（P>0.05）；日本蟳对W1组熊本牡蛎的捕食效率显著高于W2和W3组（P<0.05），W4组的被捕食效率与其他处理组均没有显著性差异（P>0.05）。牡蛎种类（P=0.590）和规格大小（P=0.357）对脉红螺的捕食效率均无显著性影响，不同规格的两种牡蛎均呈现较低的被捕食效率。黄口荔枝螺对2种牡蛎的捕食效率无显著性差异（P=0.917），但牡蛎规格大小显著影响其捕食效率（P=0.035），即对W1组熊本牡蛎捕食效率显著高于其他3个规格组（P<0.05），但其对不同规格近江牡蛎的捕食效率没有显著性差异（P>0.05）。2种牡蛎的壳厚与其壳高之间均存在极显著的正相关关系（P<0.001）。研究结果表明，3种无脊椎动物捕食者对近江牡蛎和熊本牡蛎并未表现出差异性的捕食偏好，但对不同规格牡蛎的捕食效率具有种间差异。

Predation of the sumonie oyster Crassostrea ariakensis and the Kumamoto oyster C. sikamea by three invertebrate species in lab experiments

Predation is one of the most important biotic factors regulating oyster population establishment and oyster reef development. This study examined the predating preference and efficiency of a stone crab (Charybdis japonica) and two oyster drillers (Rapana venosa,Thais luteostoma) on four size class (W1:10-20mm; W2:20-30mm; W3:30-40mm; W4:>40mm) of Crassostrea ariakensis and C. sikamea through lab experiments. The 2-way ANOVA indicated that Charybdis japonica showed no discriminatory predation on C. ariakensis and C. sikamea (P>0.05), while the oyster size significantly influenced the predating efficiency of the stone crab. The stone crab had significantly greater predating efficiency on W1 group of C. ariakensis than W2 and W4 group of the conspecific, and there were intermediate predation efficiency on the W3 group (P>0.05). The W1 group of C. sikamea was predated at significantly greater ratios than W2 and W3 groups of the conspecific, while the W4 group of C. sikamea had similar predating efficiency with the other 3 groups (P>0.05). The driller Rapana venosa had consistently low predating efficiency on the two oyster species (P=0.590) and the four size class of oysters (P=0.357). The driller Thais luteostoma had consistently predating efficiency between C. ariakensis and C. sikamea (P=0.917), but the oyster size significantly affected the predating efficiency of Thais luteostoma (P=0.035). Duncan'' multiple comparison indicated that Thais luteostoma had similar predating efficiency among the four size class of C. ariakensis (P>0.05), but the drillers had greater predating efficiency on W1 group of C. sikamea than the other 3 groups of the conspecific (W2, W3 and W4) (P<0.05). The significantly positive correlations were found between the shell height and the shell thickness for each of C. ariakensis and C. sikamea (P<0.001). It was concluded that the three invertebrates showed no discriminatory predation on C. ariakensis and C. sikamea, while the predating efficiency on different size class of oysters had interspecies variations.