Fun with Science Club®


			Are east side or west side pieces of coral tougher? Carrie Straight 05.25.01 Increasing solar radiation and increasing sea temperatures can bleach coral. The breakdown of pigments and algae cause this “bleaching”. Scientists from the United Kingdom wanted to learn how susceptible a coral (Goniastrea aspera) is to radiation and increasing temperatures. In Phuket, Thailand, researchers located a coral colony that had temperature-induced bleaching, but Goniastrea aspera colonies only bleached on their east-facing surfaces. When solar radiation bleached Goniastrea aspera colonies only the west-facing surfaces bleached. These scientists wanted to know if this species of coral only bleached on the east side because of the temperature. They hypothesized three reasons why the east side would be more susceptible to bleaching: 1) Maybe different types of algae hung out on the east and west sides of the coral. The algae might be differentially susceptible to bleaching. 2) Maybe the east and west side of the coral got different levels of solar radiation. Or, 3) maybe the different sides could handle temperature changes better. The scientists tested these ideas. They identified the algae from the two sides , but found no differences in the types of algae on the east and west sides. They measured the amount of solar radiation hitting the sides, but found no differences in solar radiation at the time when the bleaching occurred. To test the third prediction, they took samples from the east and west side of the coral and put them into tanks at different temperatures but using the same amount of radiation. They found out that the west side pieces of coral were more tolerant of the combined temperature and radiation. Next the scientists might study why the west sides are more tolerant.


			Brown, B. E., R. P. Dunne, M. S. Goodson, and A. E. Douglas. 2000. Bleaching patterns in reef corals. Nature 404: 142-143.