Experimental Simulation of Microcystis Bloom Formation from Natural Phytoplankton Communities

An experiment with easy, repeatable management was carried out to demonstrate Microcystis bloom formation from natural phytoplankton communities. This was achieved in warm season by putting eutrophic, high chl a content water with a natural phytoplankton assemblage (no cyanobacteria bloom) containing Microcystis into colorless transparent glass jars outdoors for a few days and then with nutrients enrichment. In the experiment, water of 3.5-4.5 mg/L TN, 0.3-0.4 mg/L TP and 120-160 colong/L planktonic chl a from a pond was put into two jars on 12 June 2007. On 25 June, net addition of 3.1 mg/L NO3-N and 0.45 mg/L PO4-P was put into one jar, and by 4 July, a Microcystis bloom had occurred on the surface water of the enriched jar, but not in the other. On 5 July, the nutrients addition was repeated, and subsequently the Microcystis bloom became more significant. On 8 July, the same concentration of nutrients was added to the remaining jar, and by 10 July, a Microcystis bloom had also occurred in the second jar. The nutrients enrichment provides a chance for the Microcystis out-competing the other algae from natural eutrophic water rich of phytoplankton. The experiment demonstrates an easy and repeatable method of achieving a Microcystis bloom from natural phytoplankton communities, which may be useful for the further study of bloom mechanisms.