Combined effects of organic pollution and eutrophication in the South Para reservoirs, South Australia

Preliminary results of a comparative limnological study of three Mediterranean reservoirs in South Australia from August 1995 until March 1996 are presented. The reservoirs are characterised by meso- to eutrophic and dystrophic conditions. Dynamics and interactions between DOC, SRP and phytoplankton biomass were investigated regarding differences in mixing conditions, water levels and catchment links of the reservoirs. A scenario analysis was conducted to predict effects of artificial aeration and DOC removal in the Barossa reservoir. Results indicate positive and negative feedbacks between organic pollution and eutrophication such as nutrient limitation by organic complexation of phosphorus, light limitation of phytoplankton growth by water colour and DOC release after phytoplankton breakdowns. Orientation of further research and management options are discussed.