中国特有种大型桡足类舌状叶镖水蚤(Phyllodiaptomus tunguidus)在广东水库中的分布特征

Distribution of a Chinese endemic species of calanoids:Phyllodiaptomus tunguidus in middle and large reservoirs,Guangdong Province

舌状叶镖水蚤(Phyllodiaptomus tunguidus)是我国特有的大型哲水蚤,主要分布在我国华南地区.根据2000年对广东省19座典型大中型水库的2次采样和2002年对流溪河水库和新丰江水库的5次采样,重点测定了流溪河水库、新丰江水库和鹤地水库等3座大型水库中舌状叶镖水蚤个体体长及形态参数,分析了广东省大中型水库中舌状叶镖水蚤的种群与个体大小的分布特征.在对19座水库的2次采样中,11座水库发现该种成体,其中5座水库在丰水期没有出现该种的成体,6座水库在丰水期和枯水期都有该种类成体的出现.丰水期与枯水期舌状叶镖水蚤的平均丰度分别为0.465ind./L和0.996ind./L.舌状叶镖水蚤主要出现在大型水库中,特别是贫营养的大型水库,其丰度主要由食物数量、质量与捕食压力所决定.2002年,流溪河水库丰度和新丰江水库舌状叶镖水蚤全年的平均值为1.308ind./L和0.294ind./L,丰水期高于枯水期.在个体大小和形态特征上,2座贫营养水体——流溪河水库、新丰江水库的舌状叶镖水蚤的体长与第一触角长度均大于中营养水体——鹤地水库,这种形态上的差异是由鱼类捕食方式(滤食或选择性捕食)所决定.

Phyllodiaptomus tunguidus, a large calanoids, is Chinese endemic species, and mainly distribute in South China. To understand its population distribution in a large scale, the species was sampled twice in 19 middle and large reservoirs of Goangdong Province in 2000 and five times in two large and oligotrophic waterbodies： Liuxihe Reservoir and Xinfengjiang Reservoir in 2002. Body size and other morphological parameters of P. tunguidus were measured in the Liuxihe Reservoir, Xinfengjiang Reservoir and Hedi Reservoir （large and mesotrophic）. Adult P. tunguidus was found in 11 reservoirs, but only occurred in 6 reservoirs in both flood and dry seasons. P. tunguidus had an average abundance of 0. 465ind./L and 0. 996ind./L in the flood and dry seasons, respectively. In 2002, the average abundance was 1. 308ind./L and 0. 294ind./L in Liuxihe Reservoir and Xinfengjiang Reservoir, respectively. The abundance in the flood season was much higher than that in the dry season. P. tunguidus mainly distributed in larger reservoirs, dominated in large, oligotrophic reservoirs, and its abundance was mainly determined by food concentration, food quality and predation pressure. The first antennule length and body size of the individual adults were longer in oligotrophic waterbodies than that in the mesotrophic waterbody. Predation by filter and planktivory fishes may be the main selection force.