Abstract：2 sub-lakes in Donghu Lake: Guozheng Lake and Miaohu Lake were chosen, and sampled seperately in winter and summer. g23 gene of T4 virioplankton was amplified, randomly sequenced certain clones. 46 sequences were got. Phylogenetic analysis showed that these sequences fell into 6 independent groups and exihibited high diversity. The phylogenetic analysis also suggests that: 1) the eutrophication level and season change have something to do with the structure of virioplankton community; 2) only part of the sequences are closely related to marine T4 virioplankton, so the others may represent eutrophicated freshwater virioplankton; 3) anthropogenic forcing can obviously influence the genetic diversity of T4 virioplankton in certain freshwaters.
