渤海鱼类群落结构关键种

Keystone species of fish community structure in the Bohai Sea

基于2012—2016年每年8月渤海鱼类资源量底拖网调查数据,对鱼类群落进行了CLUSTER聚类分析和MDS标序,根据组间差异种和组内相似种年际贡献率,筛选鱼类群落结构关键种,结果显示:(1)在29.93%~35.69%的相似性水平上,2012—2016年各年度渤海鱼类群落分组情况良好,相应MDS系数都小于0.2。(2)2012—2016年渤海鱼类组间种类组成差异都极显著(P=0.001),贡献组间80%累积差异性,且出现率超过50%的鱼类,4个年度共有的种有鳀(Engraulis japonicus)、3个年度共有的种有黄鲫(Setipinna taty);组间差异性贡献率大于10%,且出现率超过50%的鱼类,3个年度共有种仅有鳀,2个年度共有种仅有黄鲫。(3)贡献2012–2016年渤海鱼类群落组内相似性80%累积贡献率,且出现率超过50%的鱼类,2个年度共有的种有鳀、矛尾虾虎鱼(Chaeturichthys stigmatias)和矛尾复虾虎鱼(Synechogobius hasta);组内相似性贡献率大于10%,且出现率超过50%的鱼类,3个年度共有种有鳀,2个年度共有种有矛尾虾虎鱼和矛尾复虾虎鱼。(4)依据2012—2016年渤海鱼类群落结构相似性与差异性中各鱼种累积贡献率和单贡献率的大小和出现频率,推断鳀是渤海鱼类群落结构的首要关键种,其次为黄鲫,然后是矛尾虾虎鱼和矛尾复虾虎鱼。这4种鱼的站位平均资源量对中上层鱼类及底层鱼类站位平均资源量的比例及相关性和回归性,以及年度的优势度指数也证实上述关键种观点。综上所述,渤海鱼类群落结构首要关键种为鳀,其次为黄鲫,渤海鱼类关键种的研究可为渤海捕捞产业的调整和渔业资源的养护提供科学依据。

This study applied cluster analysis and MDS sequence analysis to catch-rate data of fish species from bottom-trawl surveys in the Bohai Sea in August of 2012 to 2016.We selected keystone species of the fish community in the Bohai Sea,based on the annual contributions of similar species within clusters and different species between various clusters.(1)When the similarity contribution rate ranged from 29.93%to 35.69%,the fish communities in the Bohai Sea were clustered into 7,9,6,5 and 6 groups for 2012–2016 consecutively,with corresponding MDS coefficients equaling 0.16,0.14,0.18,0.15,and 0.17 respectively.(2)There were significant differences(P=0.001)in the species composition of the fish community groups among the five years.The fish species were identified for each year that had cumulatively contributed to about 80%of the difference between community groups and occurred in more than half of the groups.Unfortunately,no common species was identified for all five years.Engraulis japonicus was identified in four years,and Setipinna taty was identified in three years.For species which contributed to more than 10%of the between-groups difference and displayed a more than 50%of occurrence in a year,none occurred in four or five years,only Engraulis japonicas and Setipinna taty occurred in three years.(3)Similarly,the fish species were identified for each year that had cumulatively contributed to about 80%of the difference within groups and occurred in more than half of the groups.No species were common to three or more years.Three species(i.e.Engraulis japonicas,Chaeturichthys stigmatias,and Synechogobius hasta)occurred in two of the five years.For species which had contributed to more than 10%of the within-groups difference and displayed greater than 50%occurrence in a year,no species occurred in more than four years,only Engraulis japonicas occurred in three years,and Chaeturichthys stigmatias and Synechogobius hasta occurred in two years.(4)Based on the annual cumulative or single similarity or difference contribution rates of every fish species to community groups,we conclude that Engraulis japonicas is the primary keystone species in the fish community structure of the Bohai Sea,the Setipinna taty is the second one,which is then followed by Chaeturichthys stigmatias and Synechogobius hasta.This conclusion is supported by the ratio,correlation,and regression of the average catches per station of these four species to that of all the pelagic or demersal species,and the annual dominance indices of these species.Results of this study provide a scientific basis for the adjustment of the fishing industry and the maintenance of fishery resources in the Bohai Sea.