The Great Barrier Reef: A Shrinking Oasis

Located in the Coral Sea off the Coast of Queensland, Australia, the Great Barrier Reef is the largest structure created by living organisms on the planet. The reef itself consists of 2,900 individual reefs and 900 islands, and stretches over 1,400 miles in length. The structure is so large, that it can even be seen from space. The reef supports an incredible array of plants and animals, and has historically been an integral resource to the region proving to be a valuable source of tourism, it was even classified as a World Heritage Site in 1981. 

Aerial view of the Great Barrier Reef, which is so long it could cover the entire U.S. West Coast. Photo by ShutterStock

However since 1995, more than 50% of this highly delicate ecosystem has been completely wiped out. Massive swaths of reef have been completely destroyed, largely due to events known as “coral bleaching” due to increased surface water temperatures caused by human influenced climate change. These bleaching events are caused when coral polyps expel their zooxanthellae, symbiotic dinoflagellates which reside in the arms of each polyp. This photosynthetic, single-celled algae gives corals their distinctive colors and are highly susceptible to changes in their environment. When a warming event occurs, the corals physically expel their zooxanthellae, leaving them a stark white in contrast to their traditionally more vibrant selves. While this even doesn’t necessarily kill the corals themselves, it does render the coral highly susceptible to disease or other outside factors. The reef’s decline is largely due to the fact that no corals are immune or resistant to these bleaching events, affecting both large and small, and young and old specimens and colonies. 

Coral Bleaching events in the Great Barrier Reef have occurred in 1998, 2001, and 2006. When human activities, such as greenhouse gas emissions failed to be curbed, these events became exacerbated as time moved on, occurring across 2008-2009 and 2010-2011, with further mass bleaching events continued to occur in 2016 and 2017, and continue to occur in sporadic fashions to this day. These mass bleaching events are due to increased surface water temperatures and can be triggered by as little as a 1.5° Celsius change. Tropical corals are very delicate creatures and can only thrive at highly specific water temperature ranges, these natural limiting factors allow corals to create veritable oases on the seafloor, however it is this same specific needs that make them highly susceptible to environmental changes. These temperature events are only expected to increase in frequency so long as human influenced climate change is allowed to continue unchecked. And while relatively short periods of increased temperatures may only produce minor damage to the corals themselves, prolonged exposure can produce irreparable damage across massive swaths of swaths of ecosystems, frequently targeting more susceptible coral species such as elkhorn or soft-bodied corals. Some organisms can recover from these events depending on the severity of the damage, however this recovery can take upwards of 10 years among less damaged individuals. This issue is especially severe amongst larger, older species which often are too easily susceptible to these events and can therefore not replenish the younger populations due to the reduced numbers of older, breeding aged adults. 

To curb the further damage to the reef’s ecosystem, the Australian and Queensland governments formed a plan, in 2015, for the protection and preservation of the reef’s universal heritage until 2050. This 35 year plan, titled “Reef 2050 Plan” is a document proposing possible measures for the long-term management of pollution, climate change and other issues that threaten the life span and value of this global heritage. The plan consists of elements for measurement and improvements, plans for sustainability, water quality improvement, and investment for the protection and preservation of The Reef until 2050.