揭开武汉东湖蓝藻水华消失之谜

水华（亦称湖靛）是湖泊富营养化最恶劣的表征之一。武汉东湖７０年代至１９８４年间每年夏季出现蓝藻水华，１９８５年起突然消失，至今已有１４年没有重现，原因何在？通过三次设在湖里的围隔试验，证明鲢鳙的大量放养，是水华消失的决定性因素。

UNRAVELING THE ENIGMA OF THE DISAPPEARANCE OF WATER BLOOM FROM THE EAST LAKE (LAKE DONGHU) OF WUHAN

Cyanobacterial water bloom is one of the most obnoxious characteristics of eutrophication in tropical and subtropical lakes. In the East Lake (Lake Donghu) of Wuhan,there was outbreak of such water bloom every summer from the 1970s up to the year 1984. In 1985, it ceased to recur for the first time, and has vanished from the lake for 14 years now. The reason for its disappearance was not clear. Through in situ enclosure experiments in the lake for three years, it has been disclosed that the intense stocking of the filter feeding fishes silver carp (Hypophthalmichthys molitrix) and bighead carp ( Aristichthys nobilis) plays a decisive role in the elimination of water bloom from the lake, and that the present status of water chemistry in the lake is still vulnerable to the outbreak of Microcystis bloom. The paper epitomizes the layout and the results of these enclosure experiments. Integrated with the echo sounding records of fish biomass and the fishery production of the lake over the years, the authors assert that the recurrence of water bloom can be prevented so long as the biomass of silver carp plus bighead carp in the lake maintains at or exceeds the level of 50 g per cubic meter of lake water, as reflected in the lake's fishery production (1 015 t) in 1985. The authors also make comments on the current theory and practice of biomanipulation for the control of eutrophication.