海陵湾网箱养殖区浮游植物群落结构及其与环境因子的关系

Structure characteristics of phytoplankton community and the relationship with environmental factors in cage fish farming area in Hailing Bay

为研究海陵湾鱼类网箱养殖对浮游植物群落的影响,于2019年1月、4月和11月对海陵湾上、中、下游3个网箱养殖区进行了冬、春、秋3个季节的浮游植物及主要水质因子的调查,共检出浮游植物3门39属96种(含变种),其中硅藻门29属76种、甲藻门8属16种、蓝藻门2属4种。浮游植物细胞丰度为22~3.054×10~5 cells/L,秋季>春季>冬季,湾口处丰度在秋冬两季远大于湾内。冬季优势种主要为细弱海链藻(Thalassiosira subtilis)和佛氏海毛藻(Thalassiothrix frauenfeldii),春季优势种为细弱海链藻和中肋骨条藻(Skeletonema costatum),秋季优势种主要为中肋骨条藻和佛氏海毛藻。冬、春、秋季各采样站多样性指数分别为1.44~4.11、0.66~2.39和1.62~3.10。冗余分析表明,冬季盐度、pH,春季氨氮、pH,秋季硝酸盐、溶解氧对浮游植物优势种影响显著。受河流径流和养殖活动的影响,海陵湾相邻采样站间的浮游植物群落相似性在秋季最高、冬季次之、春季最低。浮游植物群落的相似性差异与调查站位间环境的区域性差异关系密切。

In order to study the impacts to phytoplankton caused by fish cage farming activities,three seasonal investigations(winter,spring and autumn) on phytoplankton community and environmental factors in the Hailing Bay were carried out.In total,171 phytoplankton species were detected,with 76 species of diatom belonging to 29 genera,followed by dinoflagellates represented by 16 taxas(8 genera),blue-green algae by 4 taxa(2 genera).The range ofphytoplankton density was 22-3.054×10~5 cells/L,which ranked as:autumn>spring>winter.In general,the phytoplankton density in the outer bay was higher than that in the inner bay except in spring.Themain dominant species were Thalassiosira subtilis and Thalassiothrix frauenfeldii in winter,T.subtilis and Skeletonema costatum in spring,S.costatum,and T.frauenfeldii in autumn.The range of Shannon-Wiener diversity index(H′)were 1.44-4.11,0.66-2.39 and 1.62-3.10 in winter,spring and autumn.Redundancy analysis suggested that the main variables affecting the dominant species were water salinity and pH in winter,ammonia(NH_(4)-N) and pH in spring,dissolved oxygenand nitrate(NO_(3)-N) in autumn.Under the influence of different runoff and aquaculture activity,most of the phytoplankton communities in autumn were easily clustered into similar communities;however,those in spring tended to be more varied.Close relationshipwas found among the results of cluster analysis of stations on phytoplankton community structures and environmentalfactors.