Coral Bleaching: Current Event

            On June 3rd, 2014, Science Daily reported findings that were conducted by researchers at the University of Georgia in terms of what really happens to corals during periods of unusually high oceanic temperatures. The details of the study were published in the journal Limnology and Oceanography. Specifically, the researchers focused in incredible detail on an instance of coral bleaching that had occurred in the Caribbean, as well as how this instance had negatively affected the algae that surrounded the coral.

            Single-celled algae that lives in, on, and around coral reefs serves as the corals’ source of nourishment. The algae is also responsible for maintaining the corals’ color, which is stripped away from the organism during the process of coral bleaching. The article states, “many species of these algae are highly sensitive to temperature, and are unable to survive as ocean waters warm. The coral can expel these algae when the water temperature grows too high, a phenomenon known as coral bleaching” (University of Georgia, 2014). In essence, when algae are exposed to the unusually high water temperatures, they die out and lose their function, thereby negatively affecting the lives of the corals that they inhabit.

            Since the year 2007, Dustin Kemp, “a postdoctoral associate in the UGA Odum School of Ecology,” studied the occurrence of coral bleaching by routinely examining samples “from six colonies of Orbicella faveolata, also known as mountainous star coral, and their associated symbiotic algae” (University of Georgia, 2014). The studies lead by Kemp occurred progressively over the course of two years, during which he and his team took samples from corals found in all six of the aforementioned colonies. The researchers took samples from corals that had both retained their color as well as those that looked as though they had undergone coral bleaching. Because the studies went on for two years, the researchers were able to observe and analyze coral samples from organisms before bleaching, during the bleaching process, and after the bleaching process was over (University of Georgia, 2014).

            The results of the study showed that, during the process of coral bleaching, the heat-sensitive algae had died out, while the heat-tolerant algae remained consistent in number. Two months later, the “heat-tolerant algae had taken over the parts of the coral formerly occupied by the heat-sensitive algae” (University of Georgia, 2014). Kemp noted that the corals eventually recovered from the bleaching event, but that “there could be potential trade-offs associated with the shift to heat-tolerant algae,” such as the possibility that “some heat-tolerant algae may provide less food than those they might replace” (University of Georgia, 2014). However, the article suggests that the researchers are conducting further research in order to learn more about these potential trade-offs. Specifically, it notes, “Kemp is currently conducting research at reefs in the Caribbean and Pacific, looking at how heat-tolerant algae affect corals in areas where corals have been documented to have stable, long-term associations with heat-tolerant algae” (University of Georgia, 2014).

Referenced Link: http://www.sciencedaily.com/releases/2014/06/140603135827.htm