水生态学杂志

为了解杭州湾北部海域鱼类种群组成及结构特点,利用相对重要性指数(IRI)、Cluster聚类和多元统计等方法对该海域鱼类种群结构进行分析。结果显示,春、夏季杭州湾北部海域共出现鱼类22种,隶属8目、12科、19属,鲈形目占比最高,为50.0%,其次为鲽形目和鲱形目,所占比例各为13.6%,生态类型以海洋性鱼类为主。调查共发现6种鱼类优势种,春季优势种为棘头梅童鱼(Collichthys lucidus)、鮸(Miichthys miiuy)和凤鲚(Coilia mystus),夏季优势种为棘头梅童鱼、白姑鱼(Pennahia argentata)、龙头鱼(Harpodon nehereus)、鮸和焦氏舌鰨(Cynoglossus joyneri)。Cluster聚类和非度量多维标度显示,杭州湾北部海域鱼类种群可分为春季组(Ⅰ组)和夏季组(Ⅱ组),春季组由5月站点组成,夏季组由8月站点组成,组间差异系数达到84.17%。ANOSIM分析表明,春季组和夏季组种群结构差异极显著(R=0.554,P<0.01);BIOENV分析表明,春、夏季杭州湾北部鱼类种群结构与温度的相关性最高,相关系数为0.404。研究表明,杭州湾海域仍然是棘头梅童鱼、凤鲚等经济鱼类的产卵场和索饵场,鱼类种群结构的季节变化明显,棘头梅童鱼的生态洄游习性可能是造成种群结构变化的主要原因。

Hangzhou Bay,located in northern Zhejiang Province,is a typical subtropical estuary,supporting the breeding and growth of many fish,shrimp and crab species because of rich food resources. However,coastal industrial pollution and overfishing in recent years has seriously damaged the marine environment and fishery resources in the Hangzhou. The fishery resource is tending toward smaller and younger fish and some economic fish are declining or have disappeared,perhaps leading to collapse of the marine ecosystem. Therefore,information on current fish stocks and the condition of the marine environment in Hangzhou Bay is important for ecological remediation efforts.The fish community structure in northern Hangzhou Bay was characterized,based on a field investigation of fish resources in August of 2012 and May of 2013. The investigation focused on species composition and seasonal variation of the fish community structure in spring and summer. Study methods included the index of relative importance,cluster analysis,and multivariate statistics and the relationship between the fish community and environmental factors was analyzed. Fish were collected at 12 sampling stations by trawling with a 25 m net with an opening of 10 m and net mesh of 20 mm. The trawling was carried out at a speed of 2. 5 knots for 15- 30 min at each station and water temperature,salinity and depth were recorded. A total of 22 fish species were collected during spring and summer sampling,including 19 genera,12 families and 8 orders. Perciformes dominated,accounting for 50% of the total fish species,followed by Pleuronectiformes and Clupeiformes,both accounting for 13. 6%. The ecological groups included marine,estuarine and anadromous fish,with absolute dominance by marine fish( 13 species). Six dominant species were identified: in the spring,Collichthys lucidus,Miichthys miiuy,Coilia mystus; in summer,Collichthys lucidus,Pennahia argentata,Harpodon nehereus,Miichthys miiuy and Cynoglossus joyneri. Cluster analysis and non-metric multidimensional scaling( NMDS) show that the fish assemblage in northern Hangzhou Bay clustered into two groups: Group I,the spring assemblage and Group II,the summer assemblage. Group I consisted of9 stations in May and Group II consisted of 8 stations in August. The dissimilarity between Group I and Group II was as high as 84. 17%. Analysis of similarity( ANOSIM) displayed a highly significant difference in community structure between the two groups( R = 0. 554,P < 0. 01). Using BIOENV,the fish community structure in northern Hangzhou Bay was found to be highly related to water temperature( correlation coefficient,0. 404). Results indicate that Hangzhou Bay is still the spawning and feeding ground for economic fish species such as Collichthys lucidus and Coilia mystus and the significant seasonal variation in fish community structure is mainly caused by the migration of Collichthys lucidus.