At the scale of the Great Barrier Reef ecosystem, most habitats or species groups are in good condition; however there have been declines in species that play key ecological roles. These declines have been mainly due to direct use of the ecosystem, land management practices in the catchment, or declining environmental variables because of climate change.

There are concerns about aspects of the ecosystem’s health. Sea temperature, sea level and sedimentation are all expected to increase because of climate change and catchment runoff, causing deterioration to the ecosystem. Changes in the chemical processes of ocean acidity, nutrient cycling and pesticides now affect large areas of the ecosystem. At the same time, reductions in some predator and herbivore populations may have already affected ecological processes, although the specific effects remain unknown. Outbreaks of diseases appear to be becoming more frequent and more serious.

The vulnerabilities of the ecosystem to climate change, coastal development, catchment runoff and some aspects of fishing mean that recovery of already depleted species and habitats requires the management of many factors. In some instances, the ecosystem’s ability to recover from disturbances is already being compromised with either reduced population growth or no evidence of recovery.

The independent assessment of existing protection and management found that management is most challenging for those topics which are broad in scale (often well beyond the boundaries of the Great Barrier Reef) and complex. For example addressing climate change impacts requires global responses; coastal development and water quality require coordinated actions throughout the catchment. The management of fishing is socially and biophysically complex. The assessment indicated that addressing cumulative impacts is one of the least effective areas of management.

Notwithstanding these challenges, many of the management measures employed in the Great Barrier Reef Region and beyond are making positive contributions to resilience (as evidenced by recovery of some species and habitats). The Zoning Plans for both the Great Barrier Reef Marine Park and the adjacent Great Barrier Reef Coast Marine Park that were introduced in 2004 are the most significant action taken to enhance biodiversity protection. They provide a robust framework for management and are already demonstrating positive results. Compliance with and public support for these and other measures is a critical factor in building the resilience of the ecosystem.

Taken together, available information indicates that the overall resilience of the Great Barrier Reef ecosystem is being reduced. Given the effectiveness of existing protection and management in addressing the most significant pressures on the ecosystem (principally arising from outside the Region), this trend is expected to continue.

• Factors that affect resilience

• Comparison with other reef ecosystems 

• Case studies of recovery after disturbance
  

• Assessment summary