天津近海鱼类组成和分类学多样性的月变化

Monthly Changes of Fish Assemblages and Taxonomic Diversity in Tianjin Coastal Waters

根据20世纪80年代初天津海域鱼类资源的调查数据,分析了鱼类组成在月份尺度上的变化;计算了该海域鱼类的平均分类差异指数(Δ^+)和分类差异变异指数(Λ^+)。本调查共采捕到鱼类50种,隶属于43属,30科,12目和2纲。其中,软骨鱼仅3种,占总种数的6%。结果显示,天津海域的鱼类组成有明显的月份变化,5-9月的鱼类种类多,群落组成非常相似;并且调查期内每月种类的变化显示出一定的连续性,标序分析的结果为近似首尾相接的环形。计算得到Δ^+指数理论平均值为64,与我国其他海域相比较,处于中等水平;而Λ^+值(130)处于较低的水平。平均分类学差异性指数显示7月份鱼类组成较差,是否和环境污染有关,还有待进一步分析。总结了国内不同海区的相关研究结果,在长江口海域有较高的指数结果;讨论了国内计算鱼类分类学差异性指数时参数不统一对结果影响的问题。

Based on the fish survey in Tianjin coastal waters in early 1980s, changes of fish compositions in monthly scale were analyzed. The average taxonomic distinctness index （△^＋） and the variation in taxonomic distinctness （∧^＋） were also calculated. A total of 50 fish species were captured from March to November, which belonged to 43 genera, 30 families, 12 orders, and 2 classes. There were only three Elasmobranchii species captured during the nine survey months, which was just 60% of the total fish species. The routine PRIMER 6.1 was used to calculate △^＋ and ∧^＋ , as well as to perform the multidimensional scaling （MDS） and RELATE analysis. The compositions of fish in the Tianjin coastal waters indicated an obvious monthly change; fish assemblages from May to September were very similar, but quite different from other months. And the fish assemblage changed in each month indicating the pattern of cyclicity to a certain extent; the result of MDS represented an approximate end-to-end ring. The theoretical value of average taxonomic distinctness was 64, which was in the middle level, compared with other results in China seas. While the variation in taxonomic distinctness was only 130, which was in a lower level among the China seas. Taxonomic distinctness indices showed that the composition of fish in July was not good. The taxonomic diversity studies on the fish in China stretched across large latitudes, from temperate to tropical area. Obviously, the values of △^＋ and ∧^＋ in China Seas did not increase monotonously with the latitude. The higher values appeared near the Changjiang estuary, East China Sea, while the lower values appeared in both lower and higher latitude,especially in the South China Sea. With regards to the calculation of indices, the weight parameter was not consistent in some studies, and it would affect the comparison of results.