东海北部鱼类群落多样性及其结构特征的变化

Variation in fi sh community structure and biodiversity in the north of the East China Sea between two periods

根据1991年1月和2004～2006年1月东海北部水域渔业资源底拖网调查资料，从物种和同功能种团两个层面分析了东海北部鱼类群落多样性及其结构组成特征的变化。同功能种团是生态系统中起着相似生态作用、并占据相近或相似生态位的若干物种集合体，本研究结合各鱼种的摄食习性和活动能力差异，将该水域内的鱼类划分为8个同功能种团，分别为浮游动物食性种团、浮游／底栖动物食性种团、底栖动物食性种团、底栖／游泳动物食性种团、杂食性种团、活动能力强的游泳动物食性种团、软骨鱼类种团、活动能力弱的游泳动物食性种团。结果显示，冬季东海北部鱼类群落的物种多样性和同功能种团多样性呈显著线性正相关。经过十余年后，尽管该群落的物种多样性和同功能种团多样性均未发生显著变化，但各同功能种团内的物种数发生了明显变化，物种多样性与同功能种团多样性之间的关系曲线斜率由0．547增加到0．627，群落的生态冗余性有所降低。经相似性分析检验法（ANOSIM）分析，两时段群落间的物种和同功能种团结构组成均发生了显著变化，带鱼、龙头鱼、小黄鱼、黄鲫、灰鲳等物种和软骨鱼类种团、浮游／底栖动物食性种团的相对量的变化是造成其变化的主要因素。结论认为，东海北部鱼类群落结构已显现出向以浮游动物食性和活动能力强的游泳动物食性鱼种为主体的方向发展的变化趋势。[中国水产科学，2008，15（3）：453-459]

The coastal zone of northern East China Sea was the spawning and feeding grounds for many fish species, and was one of the most important fishing regions in China. But with increasely intensified fishing activities and seawater quality deteriorating, the fish community structure changed consequentially during the last half century. Based on the data collected from bottom trawl surveys conducted in January of 1991 and 2004-2006, the temporal changes of fish community structure in the north of the East China Sea in winter were analyzed. The changes were described at two taxonomic levels： one was at species level and the other was at functional group level. A total of eight functional groups were identified within this system, which were based upon trophic levels and adult mobility. They are planktivores, planktivores/benthivores, benthivores, benthivores/piscivores, omnivores, mobile piscivores, elasmobranch and roving piscivores, respectively. The results indicated that there was a significant and positive relationship between species and functional diversity. Species and functional diversity underwent little significant changes through more than ten years, while the slope of the linear model explaining the relationship between species and functional diversity became steeper from 0.547 to 0.627 and the average number of species within most functional group became smaller except planktivores and benthivores. All these indicated that the level of redundancy of the fish assemble in the north of the East China Sea was lower than before. Multivariate analyses indicated that there were significant changes in both species and functional group composition for the fish assemblage between the two periods of 1991 and 2004-2006. The chief discriminating species were Trichiurus japonicus, Harpadon nehereus, Pseudosciaena polyactis, Setipinna taty and Pampus cinereus, while elasmobranch and planktivores/benthivores were the main discriminating functional groups. The percentage of the total catch for planktivores/benthivores, benthivores, benthivores/piscivores, onmivores, elasmobranch and roving piscivores decreased significantly in 2004-2006 compared to that in 1991, while the percentage of the total catch for the two other functional groups obviously increased. In summary, the fish community in the north of the East China Sea underwent structural and functional changes during the last decade. To protect the fishery resources effectively in the area, some measures must be taken as follows： releasing the fishing pressure and reducing environment pollution caused by human activities. [Journal of Fishery Sciences of China, 2008, 15 （3） ： 453-459]