基于水下摄像的渔山列岛厚壳贻贝资源评估与分析

Survey and resource evaluation of Mytilus coruscus for underwater visual censuses of Yushan Islands

厚壳贻贝是我国东部沿海重要的经济贝类之一,自然环境中栖息范围不甚明确。本文于2014年7月间利用水下摄像的手段,调查和分析了渔山列岛不同断面上厚壳贻贝的自然分布特征。结果表明：渔山列岛潮下带5条断面的生态类型差异显著,不同断面栖息的优势种也不相同;断面间厚壳贻贝的栖息密度均值为37.04~185.80ind/m2,其中断面A的栖息密度最低,断面E的栖息密度最高,断面C和断面D的栖息密度相差不大,但是不同调查样方内厚壳贻贝的栖息密度从0~388.89ind/m2不等;厚壳贻贝主要分布在水深3~9m的水层中,其中以水深5~8m的水层中最为密集,约占总栖息密度的90%以上;在水深8m的区带上,厚壳贻贝的栖息密度为160.19ind/m2,当水深小于1m和大于11m时,厚壳贻贝分布极少;经双因素方差分析表明,厚壳贻贝栖息密度在不同断面（F=57.011,P〈0.01）和不同水层（F=66.495,P〈0.01）中的差异均极显著,断面和水层的交互作用（F=10.483,P〈0.01）对厚壳贻贝的自然分布也有极显著差异;经检验,厚壳贻贝栖息密度（A）的自然分布与水深（D）呈正态分布,可以用高斯方程拟合,R2的取值范围为0.875 3~0.999 7;利用聚类分析发现,调查样方被明显的分为3组,体现了水深在厚壳贻贝自然分布中的显著作用。

Mytilus coruscus, the natural distribution of which was indistinct,is one of the important economic shell-fish of East China Sea. The natural distributions of different sections in Yushan Islands were analyzed by underwa- ter survey in July, 2014. The results showed, the differences of ecological types in five survey sections are signifi- cant,and the dominant species of five sections are different as well. The density of Mytiius coruscus varied from 37.04 ind/m2 to 185.80 ind/m2 in different sections, the density of section A was higher than other sections, the following was section C and section D, the density of section B was the lowest. Furthermore, the density of each survey plot varied from 0 to 388.89 ind/m2. The main natural distribution water depth of Mytilus coruscus was from underwater 9 m to underwater 3 m,but mainly distribution water depth was from underwater 8 m to under- water 5 m, and the total of 90 percent of Mytilus coruscus were recorded in this zone. The highest density of under- water 8 m depth was 160. 19 ind/m2 ,and few mussel were found when the water depth is less than 1 m or exceed 11 m. The density of Mytilus coruscus changed greatly in different sections （F= 57.011, P〈0.01） and water depths （F= 66.495,P〈0.01）,which influenced significantly by section and water depth through double factor va- riance analysis,interaction of survey sections and water depths effected significantly on density of Mytilus coruscus （F= 10. 483 ,P〈0. 01）. The relationship between density （A） and water depth （D） can be represented by the fob lowing Gauss Equation,the valve of equation R2 varied from 0. 875 3 to 0. 999 7. Using hierarchical clustering,the 31 different surveys underwater zones were classified into three groups： the characteristic of first group were blank zone,the characteristic of second group were the water depth from 5 to 8 m,the characteristic of third group was the water depth less than 3 m or exceed than 9 m. The results showed that the water depth is the main factor which influenced the distribution of Mytilus coruscus.