Characteristics of the Fish Assemblage in the Intertidal Salt Marsh and Mudflat of the Yangtze Estuary

During July 2015 to June 2016, two permanent sampling sites were established in Scirpus mariqueter salt marsh and its adjacent mudflat on the intertidal zone of Chongming-Dongtan in the Yangtze Estuary. Based on monthly trap net surveys of fishes, the characteristics of the fish assemblages in the different subhabitats, including the salt marsh and mudflat, and the monthly variations were analyzed. A total of 19 species of fishes were found belong to 12 Families. The characteristics including the dominant fish species were different in these two subhabitats. 18 species of fish were recorded in the mudflat, of which the dominant species were the Coilia ectenes, Pelteobagrus nitidus and Lateolabrax maculatus. Ten species of fish were recorded in the salt marsh of which the dominant species were the Coilia ectenes, Saurogobio dumerili, Liza haematocheila, Lateolabrax maculatus and Acanthogobius ommaturus. Pelteobagrus nitidus prefers to use the mudflat, while Lateolabrax maculatus and Liza haematocheila prefer to use the salt marsh. There was a significant difference in the monthly variation of fish abundance between the fish abundance of salt marsh and mudflat, while there was no significant difference in fish biomass. The Simpson index of the fish of the mudflat was significantly higher than that of the salt marsh, while the Margalef index and the Pielou index were lower than the salt marsh. The community can be divided into two groups: winter-spring (A) and summer-autumn (B). The abundance of fish in the mudflat and the salt marsh show a very significant correlation with the water temperature (r = 0.773, 0.830, respectively) and a significant correlation with the water salinity(r = 0.654, 0.648, respectively). The abundance of fish in mudflat and salt marsh are both significantly correlated with water temperature and salinity. The abundance of fish of the mudflat (r = 0.470, P > 0.05) is more related to the highest submerged depth than of the salt marsh (r = 0.087, P > 0.05).

中国花鲈在长江口不同亚生境中的栖息特征

为探究中国花鲈(Lateolabrax maculatus)在长江口盐沼湿地不同亚生境的选择利用情况,该研究于春、夏、秋、冬4个季节对九段沙湿地的潮沟、海三棱藨草(Scirpus mariqueter)植被区和光滩3种亚生境进行插网调查采样。结果显示,中国花鲈为长江口盐沼湿地优势种,在春、夏和秋季其空间生态位宽度逐渐减小,而在3种亚生境中的时间生态位宽度依次减小。中国花鲈的数量分布具有明显的时空差异,即春季最多,秋季最少;潮沟中最多,植被区次之,光滩最少。进入长江口盐沼湿地的中国花鲈以幼鱼为主,且集中在春季。潮沟区小规格个体所占比例较高,但光滩和海三棱藨草植被区大规格的个体所占比例高于潮沟。中国花鲈的平均摄食等级在潮沟亚生境呈现从春季到冬季逐渐增大的趋势;在光滩亚生境呈现从春季到秋季逐渐增大而到冬季骤减的趋势;在海三棱藨草亚生境呈现夏季最大,秋、冬季逐渐减小的趋势。中国花鲈平均摄食等级在春、夏、秋季表现为海三棱藨草>潮沟>光滩;而冬季较其他季节特殊,中国花鲈平均摄食等级表现为潮沟>海三棱藨草>光滩。