Monday, November 23, 2015

Human Impact Pt 4

Coral bleaching, when corals expel the symbiotic algae, zooxanthellae, due to changes in the environment, is another human impact that is threatening the Great Barrier Reef. It is caused by ocean temperatures above 91℉, runoff and pollution, overexposure to sunlight, and extreme low tides. The previously stated events cause the coral to be stressed and turn completely white as the algae that causes its color leaves. If the bleaching is not severe, some coral can recover and reproduce more zooxanthellae; however, if the amount of algae lost is too high or the time it’s gone is too long, the coral is more susceptible to diseases or even death (14). As we experience increased climate change, coral bleaching is only getting worse. There has been two mass bleaching events in the Great Barrier Reef. The first was in 1988 where 50% of all reefs in the world suffered bleaching due to the highest sea temperatures that has ever been recorded. The second was in 2002 where 60% of the reefs were affected. After both these events, 5% of the corals reefs in the Great Barrier Reef was severely damaged (8). 
Bleached Coral
Source: http://climatecommission.angrygoats.net/wp-content/uploads/Coral-reefs.jpg

Coral Bleaching Process
Source: http://www.gbrmpa.gov.au/__data/assets/image/0017/10556/What-is-coral-beaching_with-photos_v1-02.jpg

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