The hypertrophic subtropic Donghu Lake’s dense water bloom(of mainly Microcystis Anaabaena andOscillatoria)that occurred annually from the beginning of the 1970s, has disappeared since 1985. The infiuenceof planktivo...The hypertrophic subtropic Donghu Lake’s dense water bloom(of mainly Microcystis Anaabaena andOscillatoria)that occurred annually from the beginning of the 1970s, has disappeared since 1985. The infiuenceof planktivorous fishes (silver and bighead carps) on the water bloom was studied for three years usingthe enclosure method. The enclosures stocked densely with bighead and/or silver carp were free of waterbloom during the experimental period. The water bloom that appeared in the fish-free enclosures was completelyeliminated in 10-20 days by introduction of silver and/or bighead carp(grass carp was not effectivein controlling water bloom).This study showed clearly that grazing pressure by planktivorous fishes is a keyfactor in eliminating water bloom from the lake.展开更多
In order to clarify whether the planktivorous silver carp and bighead carp can collect phytoplanktonas small as Cyclotella(【20μm)in Donghu Lake,studies on phytoplankton in their gut contents and feceswere made in 19...In order to clarify whether the planktivorous silver carp and bighead carp can collect phytoplanktonas small as Cyclotella(【20μm)in Donghu Lake,studies on phytoplankton in their gut contents and feceswere made in 1990.The fish were cultured in both net cage in Donghu Lake and aquaria with the lakewater.Past the intestine,the average valve diameter of Cyclotella changed little.The average ratio of emptyfrustule of Cyclotella to total Cyclotella in the foregut contents of the fishes were 1.8—1.9 times higherthan that in the lake water,but changed little from foregut to feces.The aquarium experiment showedthat both carps could collect particles as small as 8-10μm, which was obviously narrower than the dis-tance between their gill rakers.Probably,secretion of mucus plays an important role in collecting suchsmall展开更多
基金This work was supported by FEBL(State Key Laboratory for Freshwater Ecology and Biotechnology of China)fundsNational Natural Science Foundation of China (Grant NO.3937014)
文摘The hypertrophic subtropic Donghu Lake’s dense water bloom(of mainly Microcystis Anaabaena andOscillatoria)that occurred annually from the beginning of the 1970s, has disappeared since 1985. The infiuenceof planktivorous fishes (silver and bighead carps) on the water bloom was studied for three years usingthe enclosure method. The enclosures stocked densely with bighead and/or silver carp were free of waterbloom during the experimental period. The water bloom that appeared in the fish-free enclosures was completelyeliminated in 10-20 days by introduction of silver and/or bighead carp(grass carp was not effectivein controlling water bloom).This study showed clearly that grazing pressure by planktivorous fishes is a keyfactor in eliminating water bloom from the lake.
文摘In order to clarify whether the planktivorous silver carp and bighead carp can collect phytoplanktonas small as Cyclotella(【20μm)in Donghu Lake,studies on phytoplankton in their gut contents and feceswere made in 1990.The fish were cultured in both net cage in Donghu Lake and aquaria with the lakewater.Past the intestine,the average valve diameter of Cyclotella changed little.The average ratio of emptyfrustule of Cyclotella to total Cyclotella in the foregut contents of the fishes were 1.8—1.9 times higherthan that in the lake water,but changed little from foregut to feces.The aquarium experiment showedthat both carps could collect particles as small as 8-10μm, which was obviously narrower than the dis-tance between their gill rakers.Probably,secretion of mucus plays an important role in collecting suchsmall
