光合细菌强化对精养鱼塘藻类群落结构的影响

通过定期向池塘投加光合细菌,研究了有益微生物强化对精养鱼塘浮游藻类群落结构的影响。结果显示:光合细菌强化塘(试验塘)藻类组成以绿藻、硅藻为主,养殖前期(5—6月初),以针杆藻、直链藻等占优势,中后期(7—9月)则以绿球藻、栅藻、盘星藻、小环藻、菱形藻等为优势种,水色呈淡绿、黄褐色等良好状态;而对照塘藻类组成在前期与试验塘没有明显差异,但在中后期出现明显变化,以微囊藻、颤藻、鱼腥藻、席藻等蓝藻占优势。试验塘藻类生物量显著低于对照塘(P<0.05),且对照塘生物量波动变化大,蓝藻数量所占比例可高达77.6%,远高于试验塘蓝藻比例(均值低于25.0%);此外,藻类Shannon-Wiener指数、Pielou指数试验塘均大于对照塘。结果表明:光合细菌的定期添加有效控制了蓝藻增值,保持了藻类多样性,使精养鱼塘藻相趋于稳定,有利池塘养殖。

Effects of photosynthetic bacteria strengthen on phyplankton community structure in intensive fish ponds

Effects of beneficial microorganism strengthen on phytoplankton community structure in intensive fish ponds were studied through adding photosynthetic bacteria into the fish ponds regularly.The results showed that main species were Chlorophyta and Bacillariophyta in the PSB strengthened(experimental)ponds,Synedra.sp,Melosira.sp were dominant species in early stages of aquaculture(May and early June),while Chlorococcus.sp,Scenedesmus.sp,Pediastrum.sp,Cyclotalia sp,Nietzsche sp were dominant species at middle and later culture stages(July to September).Water color was in good condition such as light green,brown.There were no significant difference on the phytoplankton community structure of both system in early period,However,significant changes appeared at middle and later culture stage in the control pond,Microcystis.sp,Oscillatoria.sp,Anabaena.sp,Phormidium.sp of Cyanophyta were dominant species.The biomass of algae in the experimental ponds was significantly lower than that in the control pond(P<0.05)and algae varied greatly in control pond.The proportion of the Cyanophyta increased to 77.6%,which was much higher than those in experimental ponds(less than 25.0%).Besides,the Shannon-Wiener index and the Pielou evenness index of algae in the control pond were lower than those in experimental pond.It was concluded that photosynthetic bacteria maintained phytonplankton diversity in the ponds by effectively restricting the growth of Cyanophyta.It is promising to use photosynthetic bacteria to keep a stable phytonplankton in fish ponds.