Study on the Spatial and Temporal Distribution of Blue Algae in Lake Dianshan in Summer

To understand the spatial and temporal variation characteristics of blue algae in summer in Lake Dianshan,the phytoplankton in Lake Dianshan from June to September in 2009 was surveyed. It found 11 genera and 28 species blue algae in total. Microcystis,Oscillatoria and Chroococcus were the main composition communities of blue algae in Lake Dianshan in summer. In the survey period,the average density of blue algae in Lake Dianshan was 16.48×106 cells/L which changed during 1.01×106-59.76×106 cells/L. The characteristics were:September > July > August > June. The mass propagation and aggregation of Microcystis in September caused that the water blooms phenomenon in the partial water areas was serious. In the space,the average density of blue algae in the west and southwest parts of Lake Dianshan was bigger than in the east and southeast. When the nutritive matter was sufficient,the temperature was the main factor which affected the generation and disappearance of blue algae water blooms. The wind direction was also an important factor which affected the distribution of blue algae.

General Thinkingon the Management of Blue Algae Outbreak in the Taihu Lake,the Chaohu Lake and the Dianchi Lake

Among the Chinese lakes with the problem of eutrophication, the Taihu Lake, the Chaohu Lake and the Dianchi Lake have the worst cases of blue algae outbreak, which happen every year. Other lakes also have problems of blue algae outbreak at various degrees. However, some lakes don＇t have such problems. Practices have shown that through comprehensive management, the problem can be basically eliminated or significantly alleviated. ＂Water bloom＂ and blue algae outbreak have different connotation. The major factors affecting blue algae outbreak are sources of pollutants and ecological environment. Experiences are summed up and a new thinking on its management is developed： resolving the problem of blue algae is fundamental to lake management and development goals should be clearly set forth so as to eventually build a healthy aquatic ecosys- tem. The problem of blue algae can＇t be fully tackled by solely relying on the management of eutrophication but only by combining efforts of reducing the amount of blue algae and the management of eutrophication. The number of reduced blue algae should be larger than that of naturally prolifera- ted algae so as to alleviate and eliminate the problem of blue algae outbreak. Various engineering and technical measures and relevant protective procedures should be carried out in a scientific and proper manner. The total amount of nitrogen and phosphorous entering the lake either from point-source or non-point source pollution should be substantially reduced. Controlling the source of pollution and intercepting pollutants are the bas- ic measures. Wastewater treatment plant is the largest point source pollution in the future and adequate plants should be built with improved emission standards. Meanwhile, other measures including fishing out blue algae, diverting water, dredging, ecological restoration and expanding reed zone, should be implemented to alleviate the problem of eutrophication and eventually eliminate the problem of blue algae outbreak.

Genotoxic effects of microcystins mediated by nitric oxide and mitochondria

Microcystins are potent toxins,produced naturally by cyanobacteria（blue green algae）,and they present significant threats to human and animal health（WHO,1999;Chorus,2001;Carmichael et al.,2001;Falconer,2005;IARC,2010;Ma et al.,2015）.