武汉东湖微囊藻水华形成及消失原因的探讨——围圈放养实验

STUDIES ON THE CAUSES OF RESUMPTION AND DISAPPEARANCE OF MICROCYSTIS BLOOM IN DONGHU LAKE (WUHAN, CHINA) :STOCKING EXPERIMENTS IN ENCLOSURES

采用围圈试验的方法,将东湖微囊藻水华的形成和消失过程重现。根据有关生物调控(Biomanipulation)的原理,我们设计了鲢鳙草鱼的放养试验。实验结果表明:放养鲢鳙的围圈,水华在很短时间(约15天)内消失,放养草鱼的围圈,水华几乎不受影响,而没有放养的围圈,其水华日趋浓厚。这一结果显示出滤食性鱼类对围圈内浮游生物群落结构的影响是巨大的。在实验过程中通过测定碳、氮、磷等营养元素的变化,重点探讨了它们对微囊藻水华形成与消失过程的影响。

By using enclosure method, the Microcyatis bloom which disappeared after 1985 in Donghu Lake (Wuhan, China) was successfully recovered , and some causal factors of the resumption and disappearance of the summer Microcy at is bloom were dealt with. According to the biomanipulation theory, the authors designed a series of stocking experiments in which three domestic fishes-silver carp, bighead carp and grass carp were introduced. The results show that in the silver carp and bighead carp stocking enclosures, the bloom vanished in a short period (15 days), and no change took place in the grass carp stocking enclosures, whereas in the fish-free enclosures, the bloom was even more abundant. It is concluded that planktivorous fish have great effects on the plankton community structure of the enclosures where Microcy stis bloom occurred. Also, the fluctuation of various forms of carbon, nitrogen and phosphorus were fully discussed in order to show some implications of their effects on Microcy slis bloom.