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

ZHANG Qingtian; HU Guikun

Abstract：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 6％ 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.