| Overall investigation of physiochemical features and biological factors of reservoir water quality were conducted in Daoguanhe Reservoir from 1999 to 2002. At the basis of these investigations, integrate evaluation of trophic state and environmental status was made. Theoretical base for the reasonable utilization of fishery resource and ecological management of environment were provided using bio-manipulation technique and ecoenergetics means. The main results are as follows:1. The average water depth, water temperature and Secchi degree of four stations in the reservoir was 13.82 m, 17.8℃ and 1.62 m, respectively. Mean pH value was 7.35; the average content of DO was 9.06 mg/L; ALK and Hd were 2.53 mmol/L and 2.26mmol/L, respectively. According to Anekin, the water could be classified to Cm type. The mean concentration of NH4+ (NH3)-N, NO3--N, NO2-N, TIN, and TN were 0.370, 0.086, 0.005, 0.461 and 1.030 mg/L, respectively. The content of PO43--P and TP averaged 0.015 and 0.111 mg/L, respectively. The N:P ratio was 9.4. Total input of TN was 122.38 t and of which 58.88 t was detained in the reservoir; and those of TP were 6.711 and 0.43 t, relatively. Sediment pH value, TOM, TN and TP averaged 4.06, 37.9 g/kg, 2.48 g/kg and 1.17 g/kg, respectively.2. There were 89 species of planktonic algae. The average phytoplankton density was 251.75×104 ind./L; biomass was 5.67 mg/L in wet weight. Biomass was significantly related to the concentrations of TP, ALK and Hd (p<0.05). Phytoplankton was dominated by diatom and blue-green algae according to density and by diatom in light of biomass. Every month there were some obvious predominant species. Many of the dominant species, such as Synedra ulna, Melosira granulata and Cryptomonas erosa, were indication species of organic pollution. Shannon-Wiener, Simpson and Margalef diversity indices averaged as H'= 1.05, D = 6.38 and d=4.24, respectively. The mean content of Chl-a was 7.59μg /L.3. There were 63 species of zooplankton. The average density and biomass of zooplankton were 1391.63 ind./L and 2.27 mg/L, respectively. Most of the predominant species are indicators of eutrophication. There was no pronounced relationship between the standing crops of zooplankton and of phytoplankton (p>0.05); so phytoplankton cannot be well controlled only depending on zooplankton. It was suggested that some correction must be made with respect to the method of transfer of zooplankton density to biomass.4. The community structure and standing crops of periphyton in Chinese reservoir were first reported. Thirty-five genra of periphytic algae were collected using hanging plastic slices. Periphytic algal biomass and Chl-a content averaged 0.2708 mg/cm2 and 1.45μg/cm2, respectively and they had significant linear relationship (p<0.01). Sixty species of peripytic protozoan were found in PFU units.5. There were 17 species of macroinvertebrates. The mean density and biomass of zoobenthos were 142 ind/m2 and 1.03 g/m2, respectively. Among which Tokunagayusurika akamusi and Limnodrilus hoffmeisteri were most predominant and their mean biomass occupied 48.0% and 10.6% of the total, respectively. There was significant negative correlation between the zoobenthos biomass and water depth (p<0.05). Goodnight-Whitley biological index, King biological index, Shannon-Wiener diversity index and Margalef diversity index averaged 13.4, 6.60, 0.48 and 0.37, respectively. It is dependable to apply Goodnight-Whitley, King and Wright index to evaluate trophic state; while Shannon-Wiener and Margalef index, which are widely used in lake are not fit to apply in deep reservoir.6. The density of aquatic bacteria was 3.2×103 cells/mL and ranged from 3.3×102 to 9.0×103 cells/mL. It increased with the increase of the concentrations of N and P; and decreased with the increase of phytoplankton density; and had an inverse variation trend of zooplankton density.7. The annuli on the scale of small scale yellowfin, Xenocyp...
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