浙江近海春、夏季蟹类群落结构及其与环境因子的关系

根据2015年4月和7月浙江近岸海域单船底拖网调查资料, 分析了春、夏两个季节浙江近岸海域蟹类的种类组成、优势种及资源密度分布, 采用生态多样性指数和丰度/生物量比较曲线(ABC曲线)分析了群落物种多样性及其动态变化, 同时运用典范对应分析(CCA)研究了蟹类群落变化与海洋环境因子的关系。结果表明: 浙江沿岸海域春、夏季共捕获蟹类28种, 隶属于11科19属, 调查海域蟹类主要以暖水性种类占优势; 春季优势种为双斑蟳(Charybdis bimaculata)、三疣梭子蟹(Portunus trituberculatus)和日本蟳(Charybdis japonica), 夏季优势种为三疣梭子蟹和双斑蟳; 两个季节蟹类平均资源密度分别为244.38 和585.60 kg/km2, 中北部海域资源密度高于南部海域; 种类丰富度指数(D)、物种多样性指数(H′)和种类均匀度指数(J′)三种群落多样性指数均不高, 蟹类群落多样性水平处于较低水平; 根据ABC曲线评估干扰对蟹类群落的影响可得: 春、夏季浙江近岸蟹类群落分别处于严重干扰和中等干扰状态; 典范对应分析结果表明: 在进行对应分析的9个环境因子中, 水深为影响研究海域春夏两季蟹类分布的首要环境因子; 盐度(表层和底层)为影响蟹类分布的次要环境因子, 其他环境因子也均在一定程度上影响蟹类群落分布。

COMMUNITY STRUCTURE OF CRABS AND ITS RELATIONSHIP WITH ENVIRONMENTAL FACTORS IN ZHEJIANG COAST AREA IN SPRING AND SUMMER

The coastal waters of Zhejiang Province that contain lots of islands and the water exchange fully in this area were affected by the Yangtze River diluted water, Taiwan warm current, coastal water of Jiangsu Province and the Yellow Sea cold water mass. It was the spawning and feeding grounds of multitudinous crabs because of abundant nutrient salts and food organisms. The crab resources and distribution and community ecology in the East China Sea have been reported since 1990s but mostly concentrated in the sea that was out of the 30 m’s isobath and reported before 2008. Thus, these studies cannot represent the characteristics of crab community in the whole coastal waters of Zhejiang Province due to the small research areas relatively. The current study analyzed the content of coastal crab community including species composition, floristic feature, dominant species, distribution of the resource density, species diversity and the relationship between the community structure and the environmental factors based on the fishery resources in Zhejiang coastal area in 2015 designated survey data using ecosystem diversity indexes, abundance/biomass comparison curve (ABC curve) and canonical correspondence analysis (CCA). The 28 captured crab species were belong to 11 families and 19 genera that were dominated by warm water species with a 78.57%. The dominant species were Charybdis bimaculata, Portunus trituberculatus and Charybdis japonica in spring and Portunus trituberculatus and Charybdis bimaculata in summer. The average resource density was 244.38 and 585.60 kg/km2 in spring and summer respectively, and the density of middle-north Zhejiang coast area was higher than that of the south part. The average values of species abundance index (D), species diversity index (H′) and species evenness index (J′) were not related, indicating a low crab community diversity. According to the abundance/biomass comparison curve (ABC curve), crab community in spring and summer was seriously and moderately disturbed respectively. The result of Canonical Correspondence Analysis (CCA) analysis showed that the depth of water was the primary environmental factor regulating the distribution of crab community in all 9 environmental factors, and the salinity was the secondary environmental factor. These results enrich the basic information of crab species diversity in China’s coastal waters, which hold a useful scientific significance for understanding the dynamic changes of crab diversity in Zhejiang even the East China Sea. At the same time, it can provide reference for the establishment of marine ecological and environmental protection measures in offshore of Zhejiang Province.