Mechanical mixing (when appropriate) was performed by hand, immediately after changing the water by up-ending each container several times until all the sediment was suspended in the water.The second experiment was conducted using the samples collected in May 2006. Two benthic populations of Microcystis originating from the blooms of 2005(the same population as in the first experiment, but which had spent a further 6 months in the sediment) and of 2003 were collected, pooled by year and homogenized before being distributed into glass containers. The procedure described above for the first experiment was used again.However, the highest temperature of 17C was not used here.The experiment lasted 14 day, and the sampling days were as follows:day 1,2,5,7,9,12 and 14