Cumulative impacts and ecosystem resilience

Understanding the cumulative impacts of global and local pressures on tropical marine ecosystems

Tropical marine ecosystems are under pressure from rapidly changing environmental conditions. Global pressures include warming seawater, ocean acidification and more intense floods, droughts and cyclones. Local and regional pressures include commercial and recreational fishing, and degraded water quality caused by sediment, nutrient and pesticide run-off from agriculture and coastal development.

While global pressures are difficult to manage locally, there is hope that the resilience of local marine ecosystems can be enhanced by reducing local pressures. Our multi-disciplinary teams are using field research, SeaSim experiments and modelling to understand the cumulative and interacting impacts of local pressures, and critical thresholds.

For example, AIMS monitoring documented a 50 per cent loss of coral cover on the Great Barrier Reef in 1985─2012 due to the combined effects cyclone damage, crown-of-thorns starfish and bleaching. We’ve also found that corals in low nutrient waters have a greater temperature tolerance than those exposed to sediments, fertiliser-derived nitrogen and phosphorus, and pesticides. On the other hand, AIMS experiments have shown that, contrary to earlier concerns, ocean acidification does not seem to weaken the temperature tolerance of corals.

New knowledge provided by AIMS supports initiatives such as the Reef 2050 Long-Term Sustainability Plan and Reef Water Quality Protection Plan for the Great Barrier Reef. It will enable mapping of predicted resilience across the Great Barrier Reef World Heritage Area, and contribute to risk assessment and decision support systems. These tools will help industries and environmental managers to reduce pressures and plan long-term management and remediation associated with coastal development, including ports.