广东省大中型供水水库营养现状及浮游生物的响应

于2000年调查了广东省18座大中型供水水库的水质现状并探讨了浮游生物对营养水平的响应。总氮、总磷、透明度和叶绿素a分别为0．15～7.15mg／L、0．003～0．387mg／L、0．4～6．3m和0．6～32．3ug／L。总氮、总磷、透明度均与叶绿素a呈较高的相关性。根据这4个因子的综合加权营养状态指数为23．7～55．1，季节差异不大，大多数水库处于中营养状态。金藻在中-富及富营养型水库中没有分布，而蓝藻、绿藻、硅藻和甲藻在调查水库中均有比较广的营养生态位，但它们的密度及相对优势度在各营养型水库中有一定的差异。高营养水平水库有较高的细胞密度和叶绿素a含量。营养水平较低的水库浮游植物以硅藻-甲藻、硅藻-绿藻或金藻-硅藻为主；营养水平较高的水库以蓝藻-硅藻或蓝藻-绿藻为主，并有较高的裸藻密度。浮游动物基本上以桡足类为优势种群，但在中-富营养和富营养型水库中，哲水蚤种类比低营养型水库中少。枝角类优势种类在各营养型水库差别不大。轮虫对水体营养水平的响应相对比较显著。低营养水平水库的轮虫以广营养型、中营养型或寡中营养型种类为主，种类数目比较少；富营养和中-富营养型水库的轮虫以喜在中营养到富营养条件下生长的种类为主，且轮虫种类数目比较多。

Reservoir trophic states and the response of plankton in Guangdong Province

The trophic states of 18 drinking water supply reservoirs and the response of plankton were surveyed in Guangdong Province in 2000. Total nitrogen (TN), total phosphorus (TP) and Secchi disk depth (SD) varied from 0.15 to 7 15mg/L, 0 003 to 0 387mg/L and 0 4 to 6 3m, respectively. They all showed high correlation with chlorophyll a that varied between 0 6 and 32 3mg/m 3. Trophic state indexes (TSI) based on TN, TP, SD and chlorophyll a were between 23 7 and 55 1, without apparent seasonal variation. Among the investigated reservoirs, two were oligotrophic, four oligo mesotrophic, three meso eutrophic, two eutrophic and the others mesotrophic. Reservoirs in the coastal area had higher trophic level, especially in Pearl delta area that is quite developed in Guangdong Province.In the oligotrophic and oligo mesotrophic reservoirs, Chlorophyta and Bacillariophyta were the most important taxa and the proportion of Chrysophyta was distinctly higher than that in the other trophic level reservoirs, while that of Cyanobacteria was low. In the mesotrophic reservoirs, Chlorophyta and Bacillariophyta were also the important taxa, but the proportion of Cyanobacteria increased greatly with the increasing of trophic level. In the meso eutrophic and eutrophic reservoirs, Cyanobacteria was the dominant group, but other groups such as Chlorophyta, Bacillariophyta and Euglenophyta were also well represented. The response of crustacean zooplankton to trophic status was not distinct, for fish played a key role in structuring zooplankton community. Heavy predation from the juvenile and adult of filter feeding fish might result in the relative scarcity of Cladocera and Calanoida, notably the efficient filter feeder Daphnia in most reservoirs. Cladocera were primarily dominated either by Bosmina longirostris, Bosminopsis deitersi, Ceriodaphnia spp. or Diaphanosoma brachyurum, and Copepoda by Cyclopoida. Compared with crustacean zooplankton, rotifer responded to trophic status more distinctly. In the meso eutrophic and eutrophic reservoirs, more rotifer species was found and eutrophic indicators, Brachionus spp., Trichocerca spp., Diurella stylata or Asplanchna priodonta were the dominant groups. In the other trophic level reservoirs, the dominant groups were species with a wide ecological spectrum and oligotrophic indicators.