放养鲢鱼(Hypophthalmichys molitrix C et V)对水库围隔浮游生物群落的影响

本文研究在水库围隔实验生态系统中鲢鱼对浮游生物群落的影响。结果表明,放养鲢鱼后,浮游动物生物量、浮游植物生物量、叶绿素a和浮游植物毛产量分别下降了58.7％、63.6％、52.5％和65.0％;透明度、浮游植物群落多样性指数分别提高了18.2％、32.5％;铜绿微囊藻数量减少了90.6％“水华”得到明显抑制。但小型绿藻(<20μm)数量未出现显著变化,因而其在藻类生物量中所占比例反而提高了82.3％。围隔内可被鲢鱼滤食的大型藻类(硅藻、甲藻、隐藻和绿藻(>20μm))占藻类生物量的85.8％,因此鲢鱼的存在能明显限制浮游植物的生物量。此外,放养鲢鱼还显著降低了水体中的COD,TP,DO和pH值,这表明鲢鱼对水质有净化作用。

INFLUENCE OF SILVER CARP (HYPOPHTH-ALMICHTHYSMOLITRIX C ET V) ON PLANKTON COMMUNITYIN RESERVOIR ENCLOSURES

The ineluence of silver carp on plankton community was studied in controlled experimental enclosures in a reservoir. The results indicated that zoo-plarkton biomass, phytoplankton biomass, chlorophyll-a concentration and gross primary production were reduced by 58.7%, 63.6%, 52.5%, and 65.0% respectively, water transparency and Shannon-Weiner's diversity index of phytoplankton community were increased by 18.2% and 32.5%, when silver carp were stocked in the enclosures. In the meantime, The number of Mic-rncystis aeruginnsa were reduced by 90.6% by silver carp versus controls,and water blooms caused by the algae were significantly inhibited. Filter-feeding of silver carp resulted in an ircreaee in the percentage of the minor green algae (<20nm) in total algal biomass. Biomass of net-phytoplankton that could be efficiently fed by silver carp amounts to 85.8% of the total algal biomass, therefore silver carp was able to control algal biomass.Silver carp significantly decreased COD, TP, DO and pH as well. This fact suggests that silver carp can improve water quality.