三座南亚热带大型水库敞水区桡足类群落结构比较

于2000-2002年对南亚热带三座大型水库:新丰江水库、公平水库和飞来峡水库敞水区桡足类进行了定性定量采样.三座水库桡足类种类数较少,共检出桡足类4科10属14种,其中8种哲水蚤,5种剑水蚤和1种猛水蚤.主要分布在广东省水库的我国特有种舌状叶镖水蚤(Phyllodiaptomus tunguidus)和广布性种类右突新镖水蚤(Neodiaptomus schmackeri)是出现频率较高的哲水蚤种类,温中剑水蚤(Mesocyclops thermocyclopoides)、台湾温剑水蚤(Thermocyclops taihokuensis)和博平近剑水蚤(Tropocycl opsbopingi)是出现频率较高的剑水蚤种类.水库的流域面积、滞留时间、鱼类捕食和营养状态是影响水库桡足类种类组成和数量的重要因素.三座水库桡足类种类数与水库流域面积大小存在正相关关系.随着水库营养水平的升高,桡足类密度和生物量也相应增加,但是大型哲水蚤的优势度降低,而剑水蚤和桡足类幼体的优势度上升.水力滞留时间很短是引起飞来峡水库桡足类种群波动的主要因素.水库捕食性鱼类对甲壳浮游动物的选择性捕食,对桡足类种类影响较小,对桡足类成体密度影响较大.由于地区差异和鱼类捕食强度等因素的影响,桡足类种类多样性与水体营养状态之间存在不确定性.

Comparative analysis of community structures of planktonic copepods in three large reservoirs, South China

The community structures of copepods in three large reservoirs of South China:Xinfengjiang Reservoir, Feilaixia Reservoir and Gongping Reservoir were investigated from 2000 to 2002. Among the three reservoirs, Xinfengjiang Reservoir is the only oligotrophic water body, Gongping Reservoir is mesotrophic but with higher TSI than Feilaixia Reservoir. In total, 14 species of copepods (8 Calanoida, 5 Cyclopoida and 1 Harpacticoida) were observed. Phyllodiaptomus tunguidus--a Chinese endemic species, and Neodiaptomus schmackeri were common species in Calanoids, while Mesocyclops thermocyclopoides, Thermocyclops taihokuensis and Tropocyclops bopingi were common species in Cyclopoids. Drainage area, water retention time, fish predation and trophic status were the principle factors influencing the species composition, abundance and biomass of copepods. The positive relationship was observed between species richness and the drainage areas of reservoirs. The riverine reservoir-Feilaixia Reservoir with largest catchment contains the highest species richness. Trophic status was associated with the abundance and biomass of copepods. Nutrient-enriched reservoirs support greater abundance and biomass of copepods. However, dominance of Calanoids was lower while dominance of cyclopoids, copepodids and nauplius were much higher in the nutrient-enriched reservoirs. Short water retention time explained the low abundance of copepods in Feilaixia reservoirs. Selective predation of predatory fish can largely reduce the abundance of adult copepods, but doesn't have much influence on species richness of copepods. The relationship between species richness and trophic status were markedly variable because of the difference in watershed background and fish predation among reservoirs.