SCUM - SIMULATION OF CYANOBACTERIAL UNDERWATER MOVEMENT

This paper describes the initial development of a computer simulation model of the vertical and lateral movement of a cyanobacterial bloom. Cyanobacteria actively regulate their position vertically within a wat er column by changing their buoyancy state in response to changing pho tosynthetic rates. Additionally the cyanobacteria are liable to latera l movement due to wind-induced currents and turbulence in the surface layers. The model may be applied to a range of water-bodies under diff erent wind environments. Initial results predict that periods of sever e lake mixing encourages overbuoyancy in Microcystis, resulting in the rapid formation of surface scums. Oscillatoria respond slower to chan ges in near-surface mixing and are liable to become entrained quickly within weak and turbulent currents. The model results agree well with published field studies.