Shifts in natural nutrient flux pathways in a catchment-estuarine system and their implications for eutrophication of coastal waters
In a catchment system there are many processes controlling nutrient fate and transport and in a natural systems these exist in equilibrium. However, the rapid pace of catchment development, coupled with the threat of a rapidly changing climate, perturbs the system from its natural condition often causing severe water quality problems. The aim of this research is to understand how nutrients are transported through and transformed within a catchment-estuarine system and how the natural pathways have changed in response to changes in flows, hydrodynamic conditions and nutrient loads resulting from alteration in catchment land use. To study this, the case of Peel-Harvey estuary in Australia will be considered. This site has historically experienced eutrophication pressures due to an excess of fertilizer application on the sandy soils of its catchment. Costly remedial measures have been implemented but it remains unclear how the system processes nitrogen and phosphorus. This project will evaluate the fate of the nutrients and their pathways before and after the remedial measures and analyse the response of the system under different hydro-climatological conditions.
Eutrophication is considered a severe worldwide water pollution problem because its consequences transect environmental, economic and social problems. For example, in Australia, it has been estimated that algal blooms in freshwaters cost the community between AUD 180 and 240 million every year (more if estuaries and coastal waters and considered) and this costs are incurred by different stakeholders including farmers (Atech, 2000 in David 2006). Therefore it is of interest to natural resource managers to be able to quantify and predict how exogenous nutrients that reach the water courses are transported, transformed and finally available to be converted into algal biomass. As well, it is relevant to understand the link with different land uses and climate variability and how future changes are likely to manifest. This research will provide useful information about the whole system (catchment-water body), its absorbing capacity and will consequently contribute to innovative management strategies.