What is Ocean Acidification?

Ocean acidification is the lowering of the pH value of the world’s oceans from  absorbing carbon dioxide molecules, the reaction is as follows; CO2 + H2O + CO3−2→ 2HCO3. The heightened absorption of carbon dioxide into the ocean in the past century is mainly caused by anthropogenic impacts such as heavy industry and vehicle use.

Récif corallien (Acropora) (Ile de la Réunion)

Ocean acidification is currently a very highly studied area with several organisations with large impacts on research within the field such as the European Project on Ocean Acidification (EPOCA), the U.K. Ocean Acidification Research Programme (UKOA) and the U.S Ocean Carbon and Biochemistry Programme (OCB) being interested in researching the levels of acidification as well as the effects it can have on both our environment and ocean communities. Ocean acidification has a particularly strong effect on marine communities containing calcifying organisms i.e. Coral Reefs, as the corals that make up the foundations for these habitats are especially effected by the lower pH due there skeletons being made from calcium carbonate which dissolves easily in lower pH levels.

What effect does Temperature have on Corals?

Global warming is a well known problem throughout all natural sciences but it has a profound effect on the tropical coral reefs of our planet. Global warming effects most if not all hard coral species due to there symbiotic relationship with their zooxanthellate algae of which provide vital food for the coral through photosynthesis, temperature fluctuations of around three to four degrees Celsius causes the zooxanthellae to leave the calcium carbonate skeleton leaving a bleached white skeleton behind. the Zooxanthellae leaving the coral skeleton in these raised temperatures is because of there inability to cope with the heightened temperatures on a chemical level within their tissues, vital enzymes and proteins in which the organism needs to survive denature and are no longer any use to the organism. this results in the Zooxanthellae having to leave the skeleton for survival.

The Double Edged Sword:

Both of these massive problems go very much hand in hand as with the elevated temperatures the ocean is able to absorb more carbon dioxide into the ocean, further lowering the pH and increasing acidification of the coral reefs but not only do these two problems go hand in hand, it also increases their vulnerability to other stressors such as disease and direct impact from natural storms and human interference including stress from the aquarium trade, tourism (snorkelling, diving etc) and fishing that can devastate corals through trawling and dynamite fishing.

The Take Home Message:

the take home message that should be taken from this article, is to save our coral reefs which are a vital and important ecosystem to the whole planet, we must control and monitor the effects of both global warming and acidification through anthropocentric inputs, in doing this we would see a decrease in corals being affected by other factors such as natural phenomena and disease.


References; Further Reading

Anthony, K., Kline, D., Diaz-Pulido, G., Dove, S. and Hoegh-Guldberg, O., 2008. Ocean acidification causes bleaching and productivity loss in coral reef builders. Proceedings of the National Academy of Sciences, 105 (45), 17442-17446.

Doney, S., Fabry, V., Feely, R. and Kleypas, J., 2009. Ocean Acidification: The Other CO2 Problem. Annual Review of Marine Science, 1 (1), 169-192.

Fabry, V., Seibel, B., Feely, R. and Orr, J., 2008. Impacts of ocean acidification on marine fauna and ecosystem processes. ICES Journal of Marine Science, 65 (3), 414-432.

Hoegh-Guldberg, O., Mumby, P., Hooten, A., Steneck, R., Greenfield, P., Gomez, E., Harvell, C., Sale, P., Edwards, A., Caldeira, K., Knowlton, N., Eakin, C., Iglesias-Prieto, R., Muthiga, N., Bradbury, R., Dubi, A. and Hatziolos, M., 2007. Coral Reefs Under Rapid Climate Change and Ocean Acidification. Science, 318 (5857), 1737-1742.

Jokiel, P., Rodgers, K., Kuffner, I., Andersson, A., Cox, E. and Mackenzie, F. (2008). Ocean acidification and calcifying reef organisms: a mesocosm investigation. Coral Reefs, 27(3), pp.473-483.

Jokiel, P. and Coles, S. (1990). Response of Hawaiian and other Indo-Pacific reef corals to elevated temperature. Coral Reefs, 8(4), pp.155-162.


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