The primary goal of marine protected areas (MPA) is the conservation and protection of marine biodiversity. This is achieved by preventing or reducing pressures such as fishing and coastal development. Over time ecological theory predicts that these areas return to a more natural state with improved resilience and ability to recover from disturbance. The harmful algal bloom in South Australia is the single biggest threat to marine biodiversity in the state’s history. MPAs may be our most effective tool to facilitate recovery from this unprecedented event. South Australia has a network of 19 marine parks and 85 sanctuary zones and a suite of long-term monitoring sites designed to monitor the effectiveness of the network. These long monitoring sites have been invaluable in enabling the assessment om HAB impacts across space and species groups but more importantly will allow us to track recovery and evaluate the importance of MPAs at supporting recovery.