Algal blooms in Lake Burley Griffin are an example of a system crossing a threshold of concern. The desired state is one in which the water is clean and algae are a small component of the life forms in the lake. When phosphorus levels reach a certain critical level, in combination with particular environmental conditions, the lake system can shift rapidly into a state where toxic blue–green algae flourish. This renders the lake a significant health hazard to people, and impairs aesthetic and recreational values.
The resilience of the lake is its ability to absorb phosphorus and cope with environmental shocks and still remain clear and clean. That resilience is not just ecological – it also includes the factors that affect the ability of decision-makers to anticipate an algal bloom and take action early to avoid it.
Algal Bloom, Lake Burley Griffin Photo: Colleen Petch, Canberra Times