The picture below is a satellite generated image of sea surface temperature (SST) taken on June 22, 2011. Coral reefs are generally found in shallow, coastal waters that have temperatures ranging from 18-30°C. In these areas, the coral's symbiotic algae can still receive light.

Corals are acclimated to the average temperature in the area where they live. Temperatures of as little as 1°C above the average monthly maximum have been shown to cause heat stress.

In the summer of 2010, the second highest recorded global ocean surface temperatures occurred. Watch the coral bleaching video to see how this affected coral reefs in the Caribbean.

After watching the video answer the following questions:

• What happens to corals when higher than average temperature is prolonged?
• If global ocean temperatures increase as expected, the number of prolonged periods of high temperature will increase. How do you think this will impact coral reefs?