Algae and trophic status of Donghu Lake (Wuhan) with reference to their changes during the past 40 years

Abstract

对东湖9个湖区藻类的群落结构、生长潜力、初级生产力和营养状况进行了比较研究。结果表明,9个湖区藻类的种类组成无明显差异,绿藻为主,蓝藻和硅藻次之;藻类的生长潜力和初级生产力各湖区差异较大,均以茶港湾重污染区最高和牛巢湖最低。根据各项指标综合分析,9个湖区水质优劣的顺序是:牛巢湖、汤林湖、后湖、郭郑湖、菱角湖、筲箕湖、庙湖、喻家湖和茶港湾重污染区。对东湖的大水面郭郑湖40年来藻类的有关参数进行比较发现,藻类个体数量的峰值40年内增加了百倍以上,而藻类的属数却比50年代减少了一半,藻类多样性下降,种类小型化现象明显;初级生产力也有较明显增长,60年代和90年代的水柱口产氧量分别为1.6和4.60O₂8/(m²·d)。到目前为止,东湖的污染在继续发展,富营养化仍在加重。;Donghu Lake> located at the northeastern part of Wuhan city, is a shallow lake with an area of 32 km². It is a hyper-eutrophic lake polluted by domestic sewage and industrial waste. The community structure, growth potential (AGP), cell density, chlorophylLa and primary production of algae in nine areas of the lake were investigated in 1991~1993. Green algae is the most important component and blue-green algae as well as diatoms are subdominant groups in the lake areas. The dense bloom of blue-green algae has vanished since 1985. The maximum AGP and primary production were found in Chagang area and the minimum in Niuchaohu area. According to the parameters concerning trophic level obtained in this study, the descending order of water quality of the nine lake areas is Niuchaohu area, Tanglinghu eirea, Houhu area, Guozhenghu area, Lingjiaohu area, Shaojihu area, Miaohu area, Yujiahu area and Chagang area. As compared with the algal data from Guozhenghu area (a typical sublake) after the 1950s, the decadal peak value of algal individuals increased over one hundred times in the past 40 years. However, the genera of algae in the sublake were reduced by 54% during the same period. The results clearly demonstrate that the eutrophication of Donghu Lake has not yet been controlled. The features of degenerated lake ecosystem are quite obvious in this lake.