2009年8月至2010年8月每月大潮前后在长江口和杭州湾碎波带的12个站点采集仔稚鱼,共采集到仔稚鱼14907尾,隶属24科74种,主要优势种有刀鲚(Coilia nasus,47.84%)、普氏缰虾虎鱼(Amoya pflaumii,11.58%)、属(Hemiculter spp.,9.12%)、飘鱼属(Pseudolaubuca spp.,6.29%)、多鳞四指马鲅(Eleutheronema rhadinum,5.62%)。分析了碎波带仔稚鱼群聚的时空分布特征与水温、盐度、底质、地形等环境因子的关系。聚类和排序的结果显示,全年仔稚鱼群聚在时间序列上可分为4组,各组间存在明显的种类更替,出现的主要优势种分别是12月–翌年4月的乔氏新银鱼(Neosalanx jordani),5月的中国大银鱼(Protosalanx chinensis)、中国花鲈(Lateolabrax maculatus),6月–9月的刀鲚、普氏缰虾虎鱼、属、飘鱼属、多鳞四指马鲅,以及10月、11月的有明银鱼(Salanx ariakensis)。在空间梯度上可分为长江口碎波带站点和杭州湾碎波带站点两组,两组间相异性贡献度最高的种类是刀鲚和普氏缰虾虎鱼(>10%),多个组内的独有种类显示出不同生态类型鱼类仔稚鱼对碎波带栖息地的生境选择分化。CCA 结果显示,所选的5个环境因子中只有水温和盐度对仔稚鱼群聚整体的时空分布有显著影响,但是对整个时空分布特征的解释度并不算高,意味着还存在其他重要的影响因素,可能包括饵料生物、径流等。对主要种类在单种的尺度上进行了丰度时空分布与环境因子的 GAM 曲线拟合,发现底质和地形对特定种类的仔稚鱼的分布有显著影响。地形开阔平坦、底质为沙质的站点仔稚鱼种类和丰度都相对较多,如优势种中的飘鱼属种类、多鳞四指马鲅、日本须鳎(Paraplagusia japonica)等都倾向选择栖息在开阔平坦的沙质底站点。%The surf zone is an important habitat for larval organisms; in particular, a large amount of research has de-monstrated the utility of the surf zone as a nursery ground for various fish species. In last decade, concerns have arisen in China about this habitat, particularly around the Yangtze River estuary. Species composition, habitat selection, and biodiversity have been previously investigated. This study analyzed the characteristics of the larval fish assemblage in the surf zones of the Yangtze River estuary and Hangzhou Bay and determined the relative influences of various abiotic factors. Fish larvae were collected monthly using a small trawl net (1 m×4 m, 1-mm mesh size) at 12 stations during each spring tide from August 2009 to August 2010. Temperature, salinity, distance from the outermost site (km), land-form, and substratum were simultaneously recorded at each sampling site. All collected specimens were fixed in 5%formalin, after which they were identified to the lowest possible taxonomic division and measured (length, mm). In total, 14 907 individuals were caught by 462 hauls. The dominant species were Coilia nasus (47.84% of the total fish abun-dance), Amoya pflaumii (11.58%), Hemiculter spp. (9.12%), Pseudolaubuca spp. (6.29%), and Eleutheronema rhadi-num (5.62%). Hierarchical clustering grouped the 13 months of sampling into 4 significant clusters(December–April, May, June–September, and October–November), showing clear species replacement among groups. The twelve stations were grouped into 2 groups: the Yangtze River estuary group (ST1–ST7) and the Hangzhou Bay group (ST8–ST12). SIMPER analysis indicated that the species contributing most to dissimilarity among groups were C. nasus and A. pflaumi (>10%), indicating differentiation in habitat selection. Canonical correspondence analysis was performed on the same dissimilarity matrices. Salinity and temperature were significantly related to the distribution of larval and juvenile fishes, but did not significantly explain the total distribution, suggesting latent factors are influencing the assemblage. Generalized additive models were conducted for each primary species to reveal individual influencing environmental factors. The abundance of C. nasus and Pseudolaubuca spp. were positively related to high temperature and sand sub-strata, while Hemiculter spp. were positively related only to high temperature. Two species in the genus Neosalanx showed different environmental preferences. Abundances of P. japonica and A. pflaumi were also positively related to sand substrata. In conclusion, this study revealed that temperature and salinity significantly affected spatiotemporal variation of the entire larval fish assemblages in the surf zones of the Yangtze River estuary and Hangzhou Bay, while substrata and landform had varying influence that differed among species. Habitats with sandy sediment and an open landform may be preferable to most larval fishes in the Yangtze River and Hangzhou Bay surf zones.
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