三沙湾夏季大型底栖动物群落结构及其和水产养殖活动关系

为了解三沙湾大型底栖动物群落结构以及区域内水产养殖活动对其产生的影响,依据2016年夏季采集的样品数据,分析底栖群落结构、群落与环境因子的相关性以及典型群落参数在不同类型水域(鱼类网箱、海带吊绳、鲍鱼筏式养殖水域和自然水域)间的差异。结果表明,三沙湾共发现大型底栖动物6门75种,群落丰度和生物量均值分别为371.34个·m^-2和21.82 g·m^-2。其中,丝异须虫(Heteromastus filiformis)、不倒翁虫(Sternaspis scutata)、欧努菲虫(Onuphis eremita)、索沙蚕属一种(Lumbrineris sp.)和角海蛹(Ophelina acuminata)等多毛纲动物为数量优势物种,常在鲍鱼筏式和鱼类网箱养殖水域形成较高种群数量。物种数(N)、丰度(S)、生物量(B)和Shannon-Wiener多样性(H′)、Pielou均匀度指数(J′)、Margalef丰富度指数(d)等群落参数在不同水域之间无显著差异(P>0.05)。聚类分析结果显示,区域内群落空间异质性较高,空间差异未反映出水域类型的差别。水深、底层水体温度和盐度、沉积物含水率、粉砂-黏粒比例、总氮含量以及总有机碳含量等环境因子和群落相关性较强。综上,三沙湾底栖群落在群落参数方面与我国沿海温带水域相似,但群落的物种组成和较高的空间异质性较为独特;物种组成可表征网箱养殖活动的底栖生态效应。

Community structure of macrobenthos and its relationship with mariculture in summer of Sansha Bay

For the purpose of investigating the community structure of macrobenthos and its relationships with the potential influences from mariculture in Sansha Bay, a field survey was conducted in the summer of 2016. Typical community indices including number of species(N), abundance(S), biomass(S), Shannon-Wiener diversity index(H1), Pielou index(J1) and Margalef index(d) were calculated and their differences among cage farm, seaweed farm, abalone farm and non-farm waters were detected with nonparametric tests. Community structure of macrobenthos was analyzed using cluster analysis method in Primer 6.0 software. Correlation analysis of community structure and its associated key environmental factors were analyzed with canonical correlation analysis(CCA) method. In the community, a total of 75 species belonging to six orders were identified, the average abundance and biomass was 371.34 ind·m^-2 and 21.82 g·m^-2, respectively. Polychaetes including Heteromastus filiformis, Sternaspis scutata, Onuphis eremita, Lumbrineris sp. and Ophelina acuminata numerically dominated in the community, and the populations usually assemblaged into high densities in abalone raft and finfish cage farm waters. No statistical difference was detected for number of species, abundance, biomass, Shannon-Wiener diversity index, Pielou index and Margalef index among various waters. The structure of macrobenthos community showed remarked spatial heterogeneity in study area. However, spatial differences did not match the discrepancies of studied waters. Depth, temperature and salinity of bottom water, and water content, silt–clay fraction, total nitrogen and total organic matter of sediment were revealed as main factors regulating the benthic community. In summary, macrobenthic community in Sansha Bay was similar with those in temperate waters in Chinese coasts in terms of quantitative aspects of typical community indices. However, it showed a number of unique characteristics, including high spatial heterogeneity. Species composition of community was considered as a reliable indicator for the impacts of mariculture in Sansha Bay.