鲤鱼种和鲢鳙对池塘浮游生物的影响

IMPACTS OF CARP FINGERLING AND SILVER AND BIGHEAD CARP ON POND PLANKTON

本文根据1990年4—9月对9个鱼池的研究,报道鲤鱼种和鲢鳙对浮游生物的影响。结果表明:鲤鱼种使浮游植物和浮游动物生物量增加,浮游植物大型化,浮游动物小型化,并使浮游植物多样性增加,浮游动物多样性下降;鲢鳙密度增加,浮游生物小型化明显,微型藻类和超微型藻类在浮游植物中所占比重显著增加,小型浮游动物(原生动物和轮虫)在浮游动物中比重也明显增加;鲢鳙密度对浮游生物多样性和浮游生物量的影响具有阶段性,当鲢鳙密度低时,增加鲢鳙密度,浮游植物多样性和生物量增加,浮游动物多样性和生物量下降;当鲢鳙达到一定密度后,鲢鳙密度对浮游植物和浮游动物多样性影响不大,而浮游植物量随鲢鳙密度的增加反而有不同程度的下降,浮游动物量则随鲢鳙密度的增加而略有上升。

This paper reports the results of the effect of filter-feeder fish on plankton in nine fish ponds from April to September, 1990. The main results obtained are as fellows:1. Larger algae are become the dominant with stocking fingerling due to the cladocerans decreased by fish capture.2. Stocking fingerling stabilize phytoplankton community, phytoplankton community fluctuates little with fingerling but much without fingerling.3. Phytoplankton biomass, zooplankton biomass and production in stocking fingerling ponds are much more than those in control ponds.4. The plankton size is becoming smaller with the increase in density of slver and bighead carp. Both of the percentage of nanoalgae and picoalgae in phytoplankton and the percentage of protozoa and rotifera in zooplankton are increasing.5. When the density of silver and bighead carp gets some level,the change in diversity index of plankton is littie with the density increasing, the biomass and production of phytoplankton are not increasing but little decreasing,and the, biomass and production of zooplankton are not decreasing but little increasing with density increase.