To explore the characteristics and diversity of fish communities in the waters south of the Nanri Island,three comprehensive surveys of fishery resources were conducted in the winter of 2009 and the spring and summer of 2010.Bray-Curtis cluster was used to classify the fish communities in the surveyed area,and the number of species,density,ecological groups,and diversity of fish species were analyzed on the basis of the division of fish communities.The effects of the changes in water masses on fish communities' classification and diversity were discussed in detail.The results indicate that in spring,the fish communities comprise two different groups:the northern coastal community and the southern nearshore community.The number of species,density,and the individual diversity index (H') of the northern coastal community were 27 species,7.47 × 103 individuals/km2,and 2.71,respectively,and the corresponding values of the southern nearshore community were 32 species,24.34 × 103individuals/km2,and 1.97,respectively.The number of species and density of warm water species of the southern offshore community were higher than the corresponding values of the northern offshore community.In contrast,the warm temperate species exhibited the opposite scenario-0.In summer,the number of species,density,and H'of the western coastal community were 55 species,329.24 × 103individuals/km2,and 1.97,respectively,while the respective values of the eastern nearshore community were 27 species,106.47 × 103individuals/ km2,and 1.62,respectively.The individual density of both coastal species and nearshore species of the western coastal communities were higher than those of the eastern nearshore community.In winter,the fish communities were divided into northern coastal community and southern nearshore community.The number of species,density,and H'in the northern coastal community were 25,9.96 × 103individuals/km2,and 2.71,whereas the corresponding values in the southern nearshore community were 32 species,28.85 × 103individuals/km2,and 1.97,respectively.The individual density of warm water species and warm temperate species in the southern coastal community were higher than those in the northern nearshore community.In winter and spring,the number of fish species,individual density,and diversity,of the warm water species in the area controlled by the Taiwan Strait warm waters were higher than those of the species dominated in the Fujian -Zhejiang coastal waters.In summer,with the influence of the Taiwan Strait warm water and overland runoff,the corresponding values of the fish community in the western region of the study area were higher than those in the eastern region.We conclude that the demarcation and characteristics of the fish communities were closely related to the seasonal changes of water masses.%为探究南日岛南部水域鱼类群落结构及多样性特征,在2009年冬季,2010年春季与夏季于南日岛南部海域展开了3个航次的渔业资源综合调查.采用Bray-Curtis聚类方法,对南日岛南部海域鱼类群落进行划分,并在此基础上分析了不同群落鱼类种类数、数量密度、生态类群和多样性特征,讨论了水团变化对鱼类群落格局划分及多样性特征的影响.结果显示:春季调查海域的鱼类可划分为北部沿岸群落和南部近海群落,这两个种群种类数分别是27和32种,密度分别为7.47×103尾/km2和24.34×103尾/km2,多样度H'值分别为2.71和1.97,南部近海群落中暖水种数量密度均高于北部沿岸群落,而暖温种相反.与春季不同,夏季由西至东划分为西部沿岸群落和东部近海群落,种类数分别为55和27种,密度分别为329.24× 103尾/km2和106.47×103尾/km2,H'值分别为1.97和1.62,西部沿岸群落中沿岸种和近海种数量密度均高于东部近海群落.冬季调查海域鱼类可划分为北部沿岸群落和南部近海群落,种类数分别为25和32种,密度分别为9.96× 103尾/km2和28.85×103尾/km2,H'值分别为2.45和2.33,南部近海群落暖水种与暖温种数量密度均高于北部沿岸群落.冬、春季时,海峡暖水影响的海域鱼类种类数、数量密度、多样度以及暖水种的数量密度均高于浙闽沿岸水控制的海域;夏季,西部沿岸径流影响的海域鱼类种类数、数量密度、多样度以及暖水种的数量密度均高东部海峡暖水影响的海域.可见鱼类群落分布特征与季节性变化的水团有关.
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