Cumulative impacts and ecosystem resilience

Tropical marine ecosystems are being affected by human activities at global, regional and local scales. Our research seeks to understand the cumulative impact of these pressures, develop models to predict changes in ecosystem resilience and monitor the health of the reef.

Tropical marine ecosystems are currently subject to a range of pressures including climate change (warming seawater, ocean acidification and more intense cyclones); the effects of degraded water quality (both direct: sediment, nutrient and pesticide loads; and indirect: crown-of-thorns starfish outbreaks, disease); coastal development; and recreational and commercial fishing. We know, with variable levels of certainty, how each of these pressures affects reefs and key coastal ecosystems. A detailed understanding of the cumulative impact of these pressures is essential for environmental managers and industry seeking to reduce impacts through regulation and better practice. AIMS research in the field of resilience – the ability of ecosystems and biological communities to resist and recover from impacts – is providing essential information the development of long-term management and remediation plans.

Achievements

  • Our long-term study of the Great Barrier Reef revealed a 50 per cent decline in coral cover over 27 years due to cyclone damage, crown-of-thorns starfish and bleaching.
  • We discovered that the speed of coral death rose alarmingly if colonies were flooded with sediment containing high levels of nitrogen and phosphorus, such as fertilisers.
  • Using core sediments recording 2000 years of river inputs, we revealed how increased agricultural run-off has affected inshore reefs after European settlement of north-east Australia in 1860.
  • AIMS has played an integral role in the development of the Reef Water Quality Protection Plan and continues to be an important part of the Marine Monitoring Program, which assesses water quality of the Great Barrier Reef inshore lagoon and the status of inshore coral reefs.

Future Directions

  • Develop and test predictive models of reef resilience and cumulative impacts based on observational datasets and process studies.
  • Develop risk assessments and models of cumulative impacts associated with coastal development, including ports.
  • Map areas of predicted vulnerability and resilience and develop decision-support tools to optimise management, reduce risks and improve the state of the Great Barrier Reef World Heritage Area.
  • Develop ecosystem function-based approaches to identify and document the cumulative impacts of human activity on the health and resilience of coastal ecosystems
  • Determine the short- and long-term impacts of known and emerging contaminants entering the Great Barrier Reef World Heritage Area and coastal systems in north-west Australia.
  • Integrate our inshore and shelf reef monitoring data with the outputs from catchment and coastal sediment models to develop potential impact scenarios
  • Develop new technology and autonomous systems to cost-effectively expand our monitoring of water quality and ecosystem responses.