Thursday, December 1, 2022

The official student newspaper of Methodist Ladies' College, est. 2020

Coral Bleaching: The Express Train to Extinction

This article was written by Rachael Beckwith on behalf of the MLC Green Team.

The Great Barrier Reef is one of the most biodiverse ecosystems on the planet- “home to more than 1625 species of fish, 411 types of hard coral, one-third of the world’s soft corals, 133 species of sharks and rays, six of the world’s seven species of threatened marine turtles, and more than 30 species of whales and dolphins, including the vulnerable dugong” [1]. With a total length of over 2300km, so long that it can be seen from space[2], the reef is one of the most unique places in Australia.

Like all coral, the coral found in the Great Barrier Reef receives its colour from the zooxanthellae algae, a single celled organism that lives inside coral polyps. These two species have a symbiotic relationship whereby the zooxanthellae is provided with a safe, protected environment as well as nutrients to carry out photosynthesis; the coral has a reliable source of food through products of photosynthesis from the algae[3]. When environmental conditions change drastically due to extreme  temperatures, sunlight exposure, or pollution, this coral becomes stressed, expelling the algae from its cells. Not only does this response cause the coral to lose its vivid colour, but also renders it without a food source, placing the coral at risk of disease and even death[4].

This phenomenon is termed ‘coral bleaching’ and is one of the many threats to marine life that have arisen due to climate change. Without coral to support the reefs, thousands of unique species are at risk of endangerment and the reef ecosystem itself may even collapse.

In addition to being of tremendous concern for the reef’s prolonged survival and the existence of resident species, coral bleaching also creates uncertainty to the livelihoods of communities that rely upon the reef for income. The Great Barrier Reef has historically been a major tourist destination in Australia. In 2015-2016 alone, the reef is estimated to have contributed 6.4 billion dollars to the Australian economy, both directly and indirectly, creating over 64,000 jobs[5]. Yet with the coral now bleached white, its aesthetic appeal is lost, and the habitat of many aquatic species is also destroyed. The reef can no longer supply pharmaceutical compounds or resources to the community at significant rates, which may also create a negative impact on the surrounding cultures of tropical island communities[6].

So how did this happen?

The primary source of coral bleaching in the Great Barrier Reef is the increase in ocean temperature as a result of climate change, mining, and pollution. Carbon emissions are a large contributor to the greenhouse gas effect, which has caused average global temperatures to rise 1 degree since pre-industrial times[7]. These emissions can be attributed to the burning of fossil fuels for power, including the mining and usage of coal, which accounts for around 46% of global CO2 emissions[8]. Additionally, “when oil and gas is extracted, the voids fill with water, which is a less effective insulator. This means more heat from the Earth’s interior can be conducted to the surface, causing the land and the ocean to warm”7.

To combat the catastrophic changes to the environment in the Great Barrier Reef, the Australian Government has implemented legislation to protect the longevity of the reef. This includes the Environmental Protection and Biodiversity Conservation Act 1999, the Great Barrier Reef Marine Park Act 1975, the Great Barrier Reef Marine Park Amendment Act 2007, as well as the Great Barrier Reef Marine Park and Other Legislation Amendment Act 2008[9]. While its aims are to primarily protect and conserve reef wildlife, the government is most heavily focused on park usage and the courses of action following breaches, rather than environmental regulation. The effectiveness of these legislations, however, is highly contentious as the reef saw a 30% coral death in 2016, and a further 20% in 2017[10]. As described by Lauren E. James, half of the Great Barrier Reef has been bleached to death since 2016. A bleaching event in 2016 was so severe that predicted limits of the Great Barrier Reef’s coral endurance had to be overhauled completely, and the future of the reef is still uncertain[11].

As the reef continues to struggle under environmental pressures caused by climate change, species and biodiversity loss remains an issue that is becoming increasingly difficult to control. Even though efforts have been made to restore the reef to its original state, the events of 2016 and 2017 suggest the current plan involving marine parks has not accounted for the reef’s immense fragility. The loss of this iconic natural landmark would be truly devastating to Australia, both in terms of biodiversity and economic activity; regardless, it is beyond paramount that we do what we can to save the reef.

[1] The Reef, Great Barrier Reef Marine Park Authority,3000%20species%20of%20molluscs%20(shells)

[2] Fight for our Reef,to%20Townsville%20%E2%80%93%20covering%201%2C500%20km.

[3] Zooxanthellae … what’s that?, National Ocean Service,need%20to%20carry%20out%20photosynthesis.

[4] What is coral bleaching? National Ocean Service,and%20are%20subject%20to%20mortality.

[5] The Value, Great Barrier Reef Foundation,16%20(direct%20and%20indirect).

[6] Bleaching Impacts, The Nature Conservatory,the%20livelihoods%20of%20local%20communities.

[7] Fossil fuel extraction could be contributing to climate change by heating Earth from within, The Conversation

[8] Climate Change,,emissions%20from%20the%20electricity%20sector.&text=This%20means%20that%20the%20age,soon%20come%20to%20an%20end.

[9]Managing and protecting the Great Barrier Reef, Australian Government,Protective%20legislation,complementary%20pieces%20of%20federal%20legislation%3A&text=Australia’s%20key%20national%20environment%20law,World%20and%20National%20Heritage%20areas.

[10]Lorin Hancock. Everything You Need to Know about Coral Bleaching—And How We Can Stop It, WWF

[11]Lauren E. James, 2018. Half of the Great Barrier Reef Is Dead, National Geographic


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