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| Short-term Effects of Abamectin on Water Quality and Community Structure of Plankton in Freshwater Aquaculture Ponds |
| DONG Jiasha,HE Xugang,DENG Min,YOU Xin,LIU Quansheng,QIN Ya,CHEN Rong |
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Abstract T he short‐term effects of abamectin (0 .0375 mL/m3 ) on plankton community structure and water quality parameters were evaluated in three ponds with grass carp (Ctenopharyngodon idellus) as dominant species in Chonghu Lake (Gong’an ,Hubei) .The nitrate level was decreased significantly , whereas nitrate nitrogen ,ammonium nitrogen and total nitrogen were increased significantly .There were no significant differences in levels of phosphorus ,and soluble phosphate and in pH value .The microscopic examination showed 6 phyla with 80 species of phytoplankton ,32 genera with 41 species of zooplankton before abamectin administration ,and 7 phyla with 94 species of phytoplankton ,38 genera with 48 species of zooplankton after abamectin administration .Among them ,10 species of protozoa ,5 species rotifers ,9 species Chlorophyta ,1 species Bacillariophyta and 2 species Euglenophyta were only found before the application of abamectin;9 species protozoa ,10 species rotifers ,3 species adult copepods ,10 species Chlorophyta ,8 species Bacillariophyta , 7 species Euglenophyta , 1 species Pyrrophyta and 1 kind of Chrysophyte were only found after the application of abamectin .The dominant species of phytoplankton and zooplankton were changed significantly , and miniaturization species increased after the abamectin administration .The density and biomass of protozoa and cladocera were decreased significantly , the number of copepods increased significantly ,whereas the density and biomass of rotifers did not change much .Abamectin might result in drastic fluctuations in the density and biomass of phytoplankton such as Euglenophyta ,Cyanobacteria and Pyrrophyta .The application of abamectin in pond might easily lead to euglena blooms .The findings suggested that abamectin should be used with caution .
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Received: 25 September 2015
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