An investigation on microbial ecosystems and physical chemical factors was conducted in the water and water pipe of a reservoir power station at East Fujian Province.It was found that the abundant reproduction of sheathed bacteria might be the main cause for the plugging of the water pipe at the station.The results showed:①Iron bacteria in this hydropower station were identified as sheathed bacteria.②The water temperature and the total Fe concentration had singnificant effects on the numbers of sheathed ba...