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The Decline of the Great Barrier Reef and Plans for Its Restoration

Ashley Carver

The Great Barrier Reef (GBR) is the world’s largest coral reef system, consisting of 400 types of coral, 1,500 fish species, and 4,000 mollusc species. Historically, the GBR has not suffered serious degradation due to its strong legal protection as well as its distance from human populations. There has been little effect on the reef by local disturbances such as fishing, industrial and urban pollution, tourism, oil spills, and other anthropogenic factors. However, the GBR has been experiencing mass coral bleaching and declining coral growth rates. These disturbances are a result of terrestrial runoff, tropical cyclones, coral diseases, and the overall increasing seawater temperatures. Additionally, the GBR has seen population outbreaks of coral-eating crown-of-thorns starfish (COTS), and these outbreaks are likely to become more frequent as human activities continue to harm coral reefs.

Since 1995, the GBR has lost more than half of its corals as a consequence of warming seas. Evidence suggests that this loss is not directed towards certain coral types; rather, all types of corals within the GBR had experienced a decline. While all corals had diminished, this reduction was more prominent in branching and table-shaped corals— large, structural corals that provide habitats for fish and other marine life. Essentially, with the loss of structural corals comes the loss of marine life habitats.

A leading threat to corals in the GBR is coral bleaching, a process in which stressed corals release zooxanthellae, microscopic algae that grows within their tissues that also acts as corals’ source of food. As corals release more algae, their tissues become increasingly transparent, therefore exposing their white skeletons and making them more vulnerable to starvation and disease. Drivers of coral bleaching include rising ocean temperatures, changes in water quality, increased exposure to sunlight, and extreme low tides. Corals are especially susceptible to temperature rises, as bleaching can occur if there is a one degree Celsius rise in temperature for only four weeks. If water temperatures remain high for eight weeks or longer, the corals will start to die off.

Considering climate change is the main source of ocean and land temperature rises, it is pivotal that not only urgent action be taken to reduce global emissions, but also to protect and restore the world’s reefs. Countless organizations, including the Australian Institute of Marine Science (AIMS), are involved in the Reef Restoration and Adaptation Program (RRAP) – a program that “brings together some of the best minds in marine science, technology, and engineering, to create a toolkit of effective, at-scale Reef interventions that are feasible, safe, acceptable and affordable.” As climate change is the world’s unfortunate reality, the first stage of the RRAP works towards the protection, restoration, as well as reef adaptation to warmer climates.

AIMS lead the way in kick starting the program by conducting an investigation revolving medium and large scale reef intervention. The study was 18 months long and constituted over 150 scientists from over 20 global organizations. Results of the study suggested that there is possibility for successful intervention on the world’s reefs, and that doing so would bring benefits to both the GBR and Australians living in a broad span of climates. Currently, the RRAP is in a ‘research and development phase’ in which intervention methods are undergoing tests for feasibility and risk assessments. This is being done with the hopes of creating a balance between minimizing risk and maximizing benefits and opportunities for the GBR.


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  2. BBC. (2020, October 14). Great Barrier Reef has lost half of its corals since 1995. BBC News. Retrieved April 24, 2023, from

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  5. Reef restoration and adaptation program. AIMS. (2023). Retrieved April 24, 2023, from

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