底物中碳酸钙含量对太平洋牡蛎(Crassostrea gigas)幼虫附着的诱导效应

Effect of calcium carbonate content in substrate on spat settlement of Pacific oyster Crassostrea gigas

为探讨底物中钙含量对牡蛎幼虫附着的诱导效应,本研究设计2因子随机区组实验,检验底物碳酸钙含量(4个处理水平:5%、20%、40%和60%)和海水中牡蛎幼虫丰度(低处理组:1 ind·m L^(-1),高处理组:7~8 ind·m L^(-1))对实验底物上太平洋牡蛎(Crassostrea gigas)稚贝附着效果(密度和壳高)的影响。结果表明:钙含量和海水中牡蛎幼虫丰度均显著影响实验底物上附着牡蛎稚贝的密度(P<0.05),钙含量对附着稚贝壳高的影响不显著(P>0.05),幼虫丰度显著影响附着稚贝的壳高(P<0.05);在相同牡蛎浮游幼虫丰度下,20%碳酸钙处理组对牡蛎幼虫附着的诱导能力最大,显著高于60%处理组(P<0.05),5%和40%处理组的诱导能力介于中间;在碳酸钙含量相同情况下,高牡蛎幼虫丰度处理组中实验底物上牡蛎稚贝附着量显著高于低幼虫丰度处理组(P<0.05),而平均壳高却表现为高幼虫丰度处理组<低幼虫丰度处理组(P<0.05)。

To understand whether calcium content in substrate of artificial reefs could affect oyster spat settlement, we designed a twofactor randomized experiment with calcium carbonate in different contents （four treatment levels： 5%, 20%, 40%, 60%） and oyster larvae abundances （low treatment group： 1 ind·mL-1, high treatment group： 7-8 ind·mL-1）. The density and shell height of oyster spats attached onto experimental substrates were measured. The results showed that both calcium content and planktic larvae abundance significantly affected the density of settled oyster spats （P〈0.05）. Planktic larvae abundance in seawater had a significant effect on the shell height of settled oyster spats （P〈0.05）, but calcium content did not significantly affect the shell height of settled oyster spats （P〉0.05）. The substrate with calcium carbonate content of 20% showed the greatest inducing ability to settlement of oyster larvae, and attracted significantly greater oyster settlement than the experimental group of 60% （P〈0.05）. The density of settled oyster spats was greater in the high abundance of oyster larvae than in the low abundance （P〈0.05） regardless of calcium carbonate content, while the contrast result was found for the shell height： high larval abundance treatment 〈 low larval abundance treatment （P〈0.05）.