Comprehensive Analysis Of Water Quality In Ankang Reservior And The Influence Of Cage Culture Of Fish On The Water Quality

Ankang reservior is important for water source of the Middle Route Project ofSouth-to-North Water Diversion and for regulation and storage capacity. lakes Itswater quality is crucial to the safe operation for the Project. In recent years, The netcage culture in Ying Lake rapidly developed. All attempts to revive the local fishingindustry without water resource protection awareness and ecological concepts couldgradually elicit eutriphication and serious water pollution in Ying Lake, which wouldfinally threaten the safety of water supply of the Middle Route Project ofSouth-to-North Water Diversion.Therefore, the study on water quality for Ying Lakewill favour reasonable fishery program, protection of water quality, rationalexploitation of water resource and ecological management of aquatic environment.In2012,8sampling points for water and phytoplankton were set up in somesections of lower reaches of the Ying Lake. The chemical and physical indicatorsincluding nitrogen, phosphorus, chemical oxygen demand (COD), dissolved oxygen,chlorophyll, and transparency in water samples were analyzed. The phytoplanktonwas detected and analyzed. Three sediment sampling sites were set up for analysis ofmineral salts. The main results of this research are as follows.1) The annual variation of the physical and chemical indicators of the water ofthe Ying Lake showed that the water quality had the annual fluctuation of high levelin spring and winter and low level in summer and autumn with generally lowerlevel all the year round.2) After a qualitative and quantitative observation for phytoplankton in somesections of Ying Lake in2012,110genera of phytoplankton were identified to belongto seven phylums. Among them,29genera belong to Bacillariophyta. Five generabelong to Pyrrhophyta. Four genera belong to Chysophyta. Twenty-four generabelong to Cyanophyta. Four genera belong to Euglenophyta., Forty-two genera belongto Chlorophyta. And two genera belong to Cryptophyta. The main dominant generacontain Peridinium from Pyrrhophyta, Synedra Ehrenberg and Melosira from Bacillariophyta, Chlorella from Cyanophyta, Cryptomonas and Chroomonas fromCryptophyta, Euglena from Euglenophyta, and Microcystis from Cyanophyta.3) Netcage culture had negative effects on the trophic level of Ying Lake. It increasedeutriphication and decreased the biodiversity of phytoplankton in some sections ofwater area.4) Net cage culture negatively impacted the deposition of nitrogen andphosphorus, which related to the culture scale and the amount of feed for net cageculture.In general, the water quality of that the detected sections of Ying Lake is good.However some sections are somewhat polluted. The net cage culture has adverseeffects on water quality of Ying Lake Large-scale net cage culture has a significantnegative influence on the deposition of nitrogen and phosphorus in the sediment andthe culture scale and the amount of feed fed in net cage culture should be controlled.