ENVIRONMENTAL-CONTROL OF PHYTOPLANKTON PRODUCTIVITY IN TURBULENT TURBID SYSTEMS

Factors affecting phytoplankton productivity are analysed in turbid sy stems, such as shallow lakes and rivers. When resuspension from the se diment or loading from the catchment significantly increases inorganic (non-algal) turbidity and hence light attenuation potentials for high production are not realised. Energy available for phytoplankton growt h is strongly regulated by underwater light availability which depends on the critical mixing depth, fluctuating light intensities and algal circulation patterns. Higher production rates in shallow waters are o ften compensated by greater algal respiration due to higher water temp eratures when compared to deeper lakes. Total daily integral productio n of turbulent, turbid environments can be predicted from a combinatio n of easily measured Variables such as maximum photosynthetic rates, a lgal biomass, surface irradiance and some measure of underwater light attenuation.