Ecological and water quality experts from Water Technology and Monash University joined forces to assess the water quality and ecological processes of the Gippsland Lakes.
The Lakes have suffered recurrent summer toxic blooms of cyanobacterium Nodularia spumigena since 1985. Diatoms and dinoflagellates also commonly form blooms in the Lakes. Nodularia has the ability fix free nitrogen and is typically found during periods of low freshwater inflows in brackish waters near the inflowing rivers. Growth of Nodularia is controlled by a combination of biological, chemical and physical drivers which are impossible to simultaneously assess through physical experiments.
Whilst the key drivers of the growth of Nodularia (intermediate salinity, stratification, bottom water hypoxia and sediment phosphorus release) are well understood, there was a lack of quantitative tools to predict bloom formation and assess management options to mitigate them.
A 3-D fully coupled hydrodynamic biological ecological model was used to explore the interaction between the physical and biogeochemical controls over Nodularia blooms. The hydrodynamic model included turbulent mixing within the water column, whilst the ecological component of the model contained over 40 state variables and 200+ processes, parameterised by 176 constants to describe the biological/ecological and chemical reactions occurring in the water column and sediment compartments.