Feng Sheng

Variability of bacterioplankton in the north zone of Lake Taihu

Bacterioplankton are not only decomposers of organic material but also secondary producers in water ecosystems. They are abundant and dynamic members of remobilization of organic carbon and regeneration of inorganic nutrients in water environments. This paper presents the seasonal variation in the abundance of bacterioplankton and the difference in different zone, the relationship between the environmental factors and the abundance of bacterioplankton in the North Lake Taihu from January to December in 2003 ,the results showed that the number of bacte-rioplankton changes with the seasons. With the increase of water temperature, the number of bacterioplanklon in the water increases, the smallest value in winter, and the largest value in summer. The number of baclerioplankton was closely correlated with the concentration of chlorophyll a ( r2 = 0. 8301 ,n = 12, P 0.01 ) and water temperature (r2 =0. 463 , n = 12, P 0. 01 ) respectively, but has no correlation with the nutriment. The results indicate that the nutrimental substance is very high in Lake Taihu, and is not be the limiting factrs for bacterioplankton ; the DOC is an important source for bacterioplankton which comes from the phytoplankton.