长江口桡足类数量分布与变动

Quantitative analysis of copepods distribution and seasonal variations in the Yangtze River Estuary

于1999年枯水期（2～3月份）、丰水期（8月份）、2000年枯水期（2～3月份）对长江河口浮游动物桡足类采样调查,研究了长江河口桡足类的数量分布与变动。结果表明：1999年枯水期,桡足类在整个长江河口区的平均数量相对不大,为76ind/m^3,但却占同期浮游动物平均数量的95.61%;1999年丰水期桡足类平均数量为254ind/m^3,占同期浮游动物平均数量的84.29%;2000年枯水期桡足类平均数量为97ind/m^3,占同期浮游动物总数量的84.46%。从优势度看,1999、2000年枯水期主要优势种为华哲水蚤（Sinocalanus sinensis）;1999年丰水期主要优势种为火腿许水蚤（Schmackeria poplesia）。虫肢歪水蚤（Tortanus vermiculus）、真刺唇角水蚤（Labidocera euchaeta）则在枯、丰水期均为优势种。从种类数看,桡点类在1999年、2000年枯水期均为14种,1999年丰水期为枯水期的近2倍,达25种。对于长江河口主要桡足类而言,华哲水蚤的季节变化明显,适宜生活在盐度较低水域。虫肢歪水蚤数量年际变化较大,其适盐范围比华哲水蚤较宽、较高。真刺唇角水蚤的适盐范围与虫肢歪水蚤相似且更高一些,但该种在枯水期数量较少,丰水期数量较多,变化显著,更适宜在较高温时生长。火腿许水蚤适盐范围宽,能适应很大范围盐度变化,枯水期数量少,丰水期数量大,较高温度生长良好。

We sampled the Yangtze River Estuary during the dry period（ February-March, 1999 and February-March 2000, respectively） and the flood period （August, 1999） in order to investigate the quantitative distribution and seasonal variations of Copepods. In this study, we found that in the dry period of 1999 the average number of Copepods in the Yangtze River Estuary was 76 ind/m3. This species accounted for 95.61% of all plankton population at the time period; during the flood period of 1999, the average number was 254 ind/m3 , accounting for 84.29% of all plankton population; during the dry period of 2000, the average number was 97 ind/m3 accounting for 84.46% of all plankton population in the Yangtze River Estuary. According to the index of dominance, the dominant species was Sinocalanus sinensis in the dry period of 1999 and 2000 and Schmackeria poplesia in the flood period of 1999 ; whereas Tortanus vermiculus and Labidocera euchaeta were the dominant species in both dry and flood periods. There were 14 Copepods species found in dry period of both 1999 and 2000, and as many as 25 Copepods species found in the flood period of 1999. As the main copepods species in the Yangtze River Estuary, Sinocalanus sinensis abundance varies remarkably with seasonal variation. This study shows that lower salinity suits Sinocalanus sinensis growth. Tortanus vermiculus has rather considerable annual variation in its abundance and can grow in a much wider salinity range than that for Sinocalanus sinensis. The suitable salinity range for Labidocera euchaeta growth is similar to or slightly wider than that for Tortanus vermiculus. Labidocera euchaeta＇s productivity is low in the dry period, but it becomes much high in the flood period. Furthermore, it can grow well in relatively high temperature. Schmackeria poplesia has a wide salinity range suitable for growth and can adapt to significant salinity variation. Its population is low in the dry period, but the population becomes high in the flood period. It can also grow dramatically in relatively high temperature.