浙江南部近海春季鱼类群落结构特征及其年际变化

STRUCTURE AND INTERANNUAL VARIATION OF FISH COMMUNITIES IN THE OFFSHORE WATERS OF SOUTHERN ZHEJIANG PROVINCE IN SPRING

根据2016年和2020年5月在浙江南部近海采集的渔业资源调查资料,采用相对重要性指数、Bray-Curtis聚类和相似性百分比SIMPER分析、生物量谱及ABC曲线等方法,分析该水域春季鱼类群落结构特征及其稳定性的年际变化。结果显示:(1)2016年春季共捕获鱼类65种,优势种为带鱼Trichiurus lepturus、七星底灯鱼Benthosema pterotum和鳀Engraulis japonicus,而2020年春季共捕获鱼类30种,优势种为七星底灯鱼和带鱼;(2)通过聚类分析发现,2016和2020年春季鱼类群落空间格局相似,均可划分为南、北群落;(3)通过SIMPER分析,2016年春季南部群落典型种为二长棘鲷Evynnis cardinalis、龙头鱼Harpadon nehereus和鳀,北部群落典型种为龙头鱼,群落间的分歧种为带鱼;2020年南部群落典型种为七星底灯鱼,北部群落典型种为镰鲳Pampus echinogaster和小黄鱼Larimichthys polyactis,群落间的分歧种为带鱼、镰鲳和小黄鱼;(4)基于生物量谱分析,2016年和2020年春季鱼类标准生物量谱的斜率均小于–1,表明生物量均随个体平均体质量的增加而减少;(5)ABC曲线结果表明,2016年春季鱼类群落处于中等干扰状态(W=–0.22),而2020年春季鱼类群落则处于严重干扰状态(W=–0.09);(6)经RDA排序分析,2016年和2020年春季影响鱼类群落分布的主要环境因子均为表层水温、盐度和水深。综上所述,浙江南部近海的鱼类年际变化为鱼类种类显著下降,群落特征种更替明显,群落受外界干扰影响加剧。

Based on the fishery survey data collected in the offshore waters of southern Zhejiang Province in May 2016 and May 2020,the index of relative importance,Bray-Curtis cluster analysis,similarity percentage(SIPMER)analysis,biomass size spectrum,and ABC curves were selected to determine the fish community structure over time.A total of 65 fish species were captured in the spring of 2016,and the dominant species were Trichiurus lepturus,Benthosema pterotum and Engraulis japonicus,while 30 fish species of fish were obtained in the spring of 2020,and the dominant species were B.pterotum and T.lepturus.The cluster analysis revealed similar patterns of fish community in 2016 and 2020,from which the northern and southern communities could be divided.As SIMPER analysis showed,in spring 2016,typical species of the southern community were Parargyrops edita,Harpadon nehereus,and E.japonicus,while in the northern community,H.nehereus was typical;the divergent species between the two communities was T.lepturus.In spring 2020,the typical species of the southern community was B.pterotum,while those in the northern community were Pampus echinogaster and Larimichthys polyactis;the divergent species between communities were T.lepturus,P.echinogaster,and L.polyactis.In addition,as the biomass spectra show,the slopes of normalized biomass spectra were below–1,and the biomass decreased with the increase of average individual weight.The fish community was in a state of moderate disturbance(W=–0.22)in spring of 2016 but seriously disturbed(W=–0.09)in spring 2020 as revealed on the ABC curves.Moreover,surface water temperature,salinity,and water depth were main impact factors on fish community in the two spring seasons.Therefore,the interannual variation of fish community in the offshore waters of southern Zhejiang Province was manifested by significant decline in fish species,obvious change of community characteristic species,and intensification of external disturbance to the local bio-communities.