Great Barrier Reef

Emma Knezevic and Bill McCormick, Science, Technology, Environment and Resources

Key Issue
Threats to the Great Barrier Reef from poor water quality and climate change urgently need to be addressed to maintain its natural values and ensure long term sustainable uses of the park.

The Great Barrier Reef (GBR) extends 2,300km along the coast of Queensland (see Figure 1) and is the world’s largest system of coral reefs. With great diversity of species and habitats, the GBR is one of the richest and most complex natural ecosystems on earth. It was inscribed on the World Heritage List in 1981. The reef is visited by more than two million people each year and the catchment region generates a value-added economic contribution of $5.7 billion annually.

Managing and conserving the GBR and its unique values is a challenge, and both the Australian and Queensland Governments have specific responsibilities.

The Great Barrier Reef Marine Park Authority (GBRMPA), a Commonwealth authority, manages the Great Barrier Reef Marine Park, as established by the Great Barrier Reef Marine Park Act 1975 (Cth). GBRMPA’s regulatory tools include zoning, plans of management, permits and policies.

The Queensland Government, through the Queensland Parks and Wildlife Service and Fisheries Queensland, works with the Commonwealth in managing adjacent state marine parks and islands.

Successive state and Commonwealth governments have referred to the GBR as the ‘best managed reef in the world’. They highlight GBRMPA’s multiple-use approach to balancing fishing, tourism and recreation, as well as maritime and transport access.

Figure 1: Great Barrier Reef and adjacent catchments

Great Barrier Reef and adjacent catchments

Source: Reef Plan Report Card Summary

Threats to the GBR

Threats to reef health include coral bleaching due to elevated sea temperatures, ocean acidification, outbreaks of Crown of Thorns Starfish (COTS), and cyclones. Threats also arise from coastal development, agriculture and industrial activities on adjacent land and the associated catchment run-off from these activities. As such, land and water management within or adjacent to the GBR contributes to cumulative impacts on the reef ecosystem.

A 2012 study, published by the National Academy of Sciences (NAS), found that coral cover had declined by around 50% since 1985. Tropical cyclones, predation by COTS and coral bleaching accounted for 48%, 42% and 10% of the estimated loss, respectively. The authors concluded that tropical cyclones and coral bleaching can be linked to climate change and mitigation measures are unlikely to be effective in the short term.

Water quality and reef management

In 2003, the Queensland and Australian Governments released the Reef Water Quality Protection Plan (Reef Plan) to address the issues of run-off from land. This plan was updated in 2009 and 2013.

Funding to implement the plan was sourced from the Natural Heritage Trust, Caring for our Country and Reef Rescue programs. The Reef Plan website states that, in 2013, the Australian and Queensland Governments collectively allocated $375 million over five years to its implementation. In 2015 a further $100 million was committed by each government.

The GBR Outlook Report 2014, prepared by GBRMPA, explains that run-off into the GBR from adjacent land carries increased nutrients found in fertilisers such as nitrogen and phosphorus, as well as pesticides and herbicides used in agriculture. Water quality is further reduced by sediments.

The impact of run-off is uneven across the GBR, and depends on pollutants and their concentrations, catchment sources and distance of reefs from the coast. Similarly, the effects of coral bleaching and COTS outbreaks vary by location and timing. The 2012 NAS study (above) reported that the remote northern region had relatively low mortality from COTS and cyclones, and coral cover was stable with the exception of a slight decline due to bleaching from 1998 to 2003. In contrast, a 2016 bleaching event has most severely impacted the northern region.

Crown-of-Thorns Starfish (COTS)

Occasional COTS outbreaks are considered natural, but outbreak frequency and intensity have increased as a result of reduced water quality. In particular, increased nutrient levels as a result of catchment run-off encourage plankton blooms, increasing the food available to COTS larvae. During COTS outbreaks, the starfish eat coral faster than it can re-grow, leading to a decline in coral cover.

In addition to intensive efforts to manually control COTS during outbreaks, improving the water quality is expected to reduce the likelihood of COTS outbreaks.

Coral bleaching

Coral bleaching is caused by heat stress when water temperatures rise for prolonged periods. Coral bleaching is the term used when tiny marine algae that live in coral (zooxanthellae) are expelled. The coral tissue then appears transparent, revealing the white skeleton. 

Significant coral bleaching outbreaks occurred on the GBR in 1998 and 2002. However, 2016 has seen the most extensive bleaching event with reports of up to 90% of some reefs affected to some degree. Impacts from this event are still unfolding, but coral mortality (at June 2016) is 22% across the GBR, with the most affected sites observed in the northern section. The Australian Institute for Marine Science explains:

Between February and May, the GBR experienced record warm sea surface temperatures. Extensive field surveys and aerial surveys found bleaching was the most widespread and severe in the Far Northern management area, between Cape York and Port Douglas. Here, bleaching intensity was ‘Severe’ (more than 60% community bleaching). Bleaching intensity decreased along a southerly gradient. While most reefs exhibited some degree of bleaching, this bleaching varied in intensity (from less than 10% to over 90% community bleaching) and was patchy throughout most of the management area. (View the GBRMPA map for more information.)

World Heritage in danger?

Since 2005, the World Heritage Committee has repeatedly warned Australia that the GBR was under consideration for inclusion on the List of World Heritage In Danger. ‘In danger’ listings are designed to:

...inform the international community of conditions which threaten the very characteristics for which a property was inscribed on the World Heritage List, and to encourage corrective action.

The World Heritage Committee’s decisions relating to the GBR in recent years have raised concerns about proposed and existing developments in and near the World Heritage Area, water quality issues (including sediment and agricultural nutrient run-off), and climate change.

The Australian and Queensland governments have responded to these concerns in a number of ways, to ensure the GBR is not placed on the ‘in Danger’ list. A key part of this response is the Reef 2050 Long-Term Sustainability Plan, which was informed by a strategic assessment of the impacts on the reef. This Plan aims to put in place a long-term, comprehensive approach to improve the condition of the GBR. The Implementation Strategy identifies priority actions in the implementation of the Reef 2050 Plan.

Controversy arose in May 2016 when the Australian Government’s Department of the Environment successfully requested the removal of references to Australian sites, including the GBR, in a United Nations report, World Heritage and Tourism in a Changing Climate. The Department was reportedly seeking to avoid confusion over terminology.

Proposed Reef Fund

The Coalition’s 2016 Election policy proposes the creation of a $1 billion Reef Fund to finance clean energy projects in the GBR catchment region. The Clean Energy Finance Corporation will manage the Fund. It is unclear how the Reef Fund will directly benefit the health of the GBR in the short to medium term. It will not fund projects primarily designed to improve water quality, although improvements to water quality may arise as a secondary benefit from some of the clean energy projects.

The policy cites examples of projects that will be funded such as:

  • solar panels to substitute for diesel on a farm and
  • more energy efficient pesticide sprayers and fertiliser application systems.

Further reading

GBRMPA, Great Barrier Reef Outlook Report 2014, 2014

Australian and Queensland Governments, Reef 2050 Long-term Sustainability Plan, 2015


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