Comparison of recruitment from sediments with pelagic growth of cyanobacteria in Lake Taihu,China

Cyanobaeteria recruitment from sediments is an important seed bank for their pelagic abundance. We estimated cyanobacteria recruitment from sediments with migration traps in Lake Taihu from March to June 2005, measured in situ growth rate of cyanobacteria in the water column in specially designed chambers, and compared the siy.es of both processes. Meanwhile the effect of zooplankton grazing on cyanobacteria growth rate was also measured. Cyanobacteria recruitment increased with some degree of fluctuation from March to June, peaking in April; in situ growth rate of cyanobacteria also showed a general increase at the same time, only reached maximum in early May. No obvious effect of zooplankton grazing was observed on the in situ cyanobacteria growth rate. Cyanobacteria recruitment only accounted for a small portion of the pelagic growth ( 2.5% ) thereby suggesting that future research on cyanobacteria bloom development be focused on the pelagic populations in water column.