Abstract:

Based on data collected at four stations in Daning River in the spring of 2004 and 2005,phytoplankton community structure,vertical distribution，abundance,biomass,C contents,diversity index,richness index and evenness index were studied.The causes of eutrophication and water blooms in Daning River were analysed and control measures were then put forward.The dominant species were 〖WTBX〗Asterionella formosa,Cryptomonas ovata,Cyclotella caspia,Stephanodiscus neoastraea〖WTBZ〗 in the spring of 2004 and those were 〖WTBX〗Pandorina morum,Eudorina elegans,Cyclotella caspia,Cryptomonas ovata〖WTBZ〗 in the spring of 2005.Average cell densities,biomass,C contents in the spring of 2004 and 2005 were 171.1×105 cells/L,12.2 mg/L,1 732.2 μg C/L and 113.1×105 cells/L,10.1 mg/L,1 395.9 μg C/L,respectively.Algal bioassay of filtered water at panda′s cave stations revealed that phosphorus was the limiting factor of algal blooms.Reducing life sewage input and controlling surface runoff were key points controlling eutrophication and water blooms in Daning River.

Key words: Daning River, waterquality evaluation, algal bioassay, water blooms