MANAGING THE AQUATIC ENVIRONMENT

The primary objective for managing eutrophic waterbodies must be to reduce the level of available nutrients. However, where diffuse agricultural runoff is the principal source of nutrients, this is slow and difficult to achieve. In the meantime symptoms - principally the excessive growth of algae - must be managed in the interests of nearby human populations and of the ecosystems themselves. The management measures currently employed in large coastal waterbodies in southwestern Australia are mainly mechanical collection and disposal of algal accumulations. These do not significantly reduce nutrient levels. However, removal of the algae allows smothered seagrasses to regenerate and prevents the release of nutrients from anoxic surface sediments under decaying algal masses. Other measures appropriate to smaller water bodies include the use of algicides, chemical treatment, and dredging. The channel from Harvey Estuary to the sea (under construction) has the potential to significantly reduce nutrients and algal growth in Peel-Harvey estuary by increasing exchange with the sea.