Impact of Climate Change on the Great Barrier Reef

One of the biggest issues which are facing us today is that of climate change. As climate change has commonly been determined to be the result of increased levels of carbon dioxide in the atmosphere, as a result of a rise in usage of fossil fuels (Karl et al, 2003). While climate change can have many harmful effects, one main negative impact is that of its results in coral reefs, such as the Great Barrier Reef. The coral provides the algae with a safe place to live, and the algae provide oxygen and remove waste substances from the coral (Stimson et al, 2002). The Great Barrier Reef is on the coast of Queensland, Australia, and it is the largest coral reef in the world. The reef is made up of more than 2900 reefs and covers 344,400 square kilometres of the coast (The Great Barrier Reef Foundation, 2019) . However, there are several different events that has caused by climate change, which has negatively impacted the Great Barrier Reef. These incidents include rise in water levels, increase in water temperatures, coral bleaching and changes to fish populations.

As global temperatures increase, this leads to an increase in the level of water throughout the Great Barrier Reef. This increase in water quantities can have a major impact on the reefs where most of the coast line is at a low depth. As the water levels keep increasing, this can also assist the growth of the turbidity of the water leading to a smothering of reefs, causing them to die. Normally corals do not grow at depths more than 50 meters, as the level growth this could impact the areas in which it is able to grow (Knowlton, 2018). Nonetheless, based on recent estimates most professionals trust that out of all the other issues which will appear as a result of climate change, this factor is the least concerning (Lutjeharms et al, 1991).

The next main issue is the increase in water temperatures. Corals can only survive within a precise temperature range. Typically corals grow in water temperatures that are between 20C to 32C, outside these temperatures the corals will most likely die. After the temperature of the water increases, the corals then become stressed and it forces the symbiotic algae to leave (Stimson et al, 2002). When is occurs, corals turn white. After the coral has changed colour it will starve and feed on themselves. If the water temperatures change back to its normal state, the corals can be able to recover. Even though climate change is always altering the temperature, the bleaching corals may never recover and will die (Lesser, 1997).

During the 2016 marine heatwave, which killed immense amounts of coral, has also impacted on the significantly on the sea life that live in the Great Barrier Reef. Due to the decrease in corals, many fish species lose their source of food, this can cause fish communities to move elsewhere. Many fish species were impacted by the loss of their homes, even in some places where the corals weren’t affected the fish populations responded negatively to the rise of water temperatures. One species of fish, parrotfishes, were severely were negatively affected by the rise in intense sea temperatures. Parrotfishes play a vital role on the wellbeing of coral reefs, where their grazing helps control algae that compete with corals for habitation space. Though, this fish population have chance to come back as cooler temperature return to the Great Barrier Reef. Experts say they can save the corals from climate change, but they cannot help the fishes that are impacted from the rise of sea temperatures (Stuart-Smith et al, 2018)

Furthermore, other research is required to control exactly what is causing the death of corals. For example a new study showed that it was the mixture of acidification and increased temperatures that leads to the decreased existence after coral bleaching (Anlauf et al, 2011). Therefore, additional research is needed to establish if there is a way to  prevent the occurrence of these two situations. By working together it is possible to avoid the disappearance of corals.

Reference:

• Karl, T, Trenberth, K, 2003, Modern Global Climate Change, Science Mag, 15th August 2019, <https://www.agro.uba.ar/users/fernande/Karl%26Trenberth2003.pdf>
• Stimson, J, Sakai, K, Sembali, H, 2002, Interspecific comparison of the symbiotic relationship in corals with high and low rates of bleaching-induced mortality, Coral Reefs, 15th August 2019, < https://link.springer.com/content/pdf/10.1007%2Fs00338-002-0264-3.pdf >
• The Great Barrier Reef Foundation, 2019, The Facts, Barrier Reef, 15^th August 2019, < https://www.barrierreef.org/the-reef/the-facts >
• Knowlton, N, 2018,Corals and Coral Reefs, Smithsonian, 15^th August 2019, < https://ocean.si.edu/ocean-life/invertebrates/corals-and-coral-reefs >
• Lutjeharms, J.R.E, Valentine, H.R, 1991, Sea-level changes: consequences for the southern hemisphere, Department of Oceanography, 15^th August 2019, <https://link.springer.com/content/pdf/10.1007%2FBF00139004.pdf >
• Lesser, M.P, 1996, Oxidative stress causes coral bleaching during exposure to elevated temperatures, Department of Zoology and Center for Marine Biology, 15^th August 2019, < https://link.springer.com/content/pdf/10.1007%2Fs003380050073.pdf >
• Anluf, H, D’Croz, L, O’Dea, A, 2011, A corrosive concoction: The combined effects of ocean warming and acidification on the early growth of a stony coral are multiplicative, Science Direct, 15th August 2019, < https://www.sciencedirect.com/science/article/pii/S0022098110004570 >