Abstract: Panjiakou and Daheiting reservoirs (known as Pan-Da Reservoir) serve as the important drinking water source for the Beijing-Tianjin-Hebei area. The status of the reservoir ecosystem is an important indicator to water supply security. Based on field investigations of phytoplankton, zooplankton and macroinvertebrates, we analyzed the community composition and evaluated the status of the aquatic ecosystem and water environment. The results showed that phytoplankton community was dominated by Bacillariophyta and Chlorophyta, while the density was mainly contributed by Chrysophyta and Cyanophyta. The maximum density of phytoplankton in the reservoir was up to 14.45×10⁷ ind·L^-1, showing a algalbloom status. Zooplankton community was mainly composed of Rotifer, Cladocera and Copepoda, and their spatial difference was not identified. Rotifer dominated the community, while Cladocera dominated the density. The Shannon diversity index (H) of zooplankton ranged from 2.31 to 2.50. Macroinvertebrate community was dominated by Chironomidae and Tubificidae. Their densities showed significant difference in spatial distribution; the highest value was up to 14400 ind·m^-2, mainly contributed by Tubificidae indicating severe organic pollution. H of macroinvertebrates of all sites was lower than 0.40, except a value of 0.92 for one site in the most upper reach. Bioassessment of phytoplankton and macroinvertebrates indicated that the reservoir suffered serious pollution in the study period.

Key words: Ganan Plateau., risk perception, adaptation perception, farmer, climate change, adaptation intention