Coral Bleaching in the Caribbean

Coral bleaching, U.S. Virgin Islands, October 2005

Image courtesy CCMA Biogeography Team

Students will use authentic satellite data to determine when the sea surface temperature meets the criteria to induce coral bleaching.
Grade Level: 5 – 12
Estimated Time for Completing Activity: 50 minutes
Learning Outcomes:
  • Students will practice analyzing images, maps and graphs from Internet-based educational resources.
  • Students will explore the correlation between sea surface temperature and coral bleaching.
  • Computer with Internet access
  • Computer Printer
  • Atlas or Map
  • Colored Pencils
  • Ruler
AP Environmental Science Topics
  • Global water problems
  • Impacts and consequences of global warming
  • Interactions among species
Lesson Links:

Coral reefs are collections of tiny marine creatures that live inside limestone skeletons attached to rocks on shallow ocean floors. Corals feed on algae that thrive in the sunlit water surrounding the reef. However, when water temperatures get too warm, the algae food source dies and corals turn a whitish color. The coral creatures may die, too, if the warm water conditions remain for an extended period of time.

Although the threshold for coral bleaching varies by region and coral type, scientific observation has determined that coral bleaching may occur when sea surface temperature (SST) exceeds 30C or 86F for a week or longer. During late 2005, a major coral bleaching event occurred when these conditions existed in the Caribbean Sea. In this lesson, you will collect SST data from the MY NASA DATA Live Access Server to explore this event.

The SST data are provided by the U.S. Naval Oceanographic Office (NAVOCEANO), using several sources of data-collection by buoys, ships, aircraft, and satellites. More information and pictures of coral bleaching may be found at the NOAA Center for Coastal Monitoring and Assessment (CCMA) Web site (links above).


1. Click on the lesson link to the Live Access Server.
2. Click on the Choose Dataset tab, located above the blue global reference map.
3. From the list, select Oceans.
4. Select the radio button for Daily Sea Surface Temperature (GHRSST).
5. Using an atlas or map, select a latitude-longitude position in the Caribbean coastal water where you would expect coral reefs (for example, 18 N 65 W).
6. Enter the latitude and longitude in the compass rose boxes located under the blue global reference map. (For example, enter 18 N in the north and south positions, and enter 65 W in the east and west positions.)
7. Under Line Plots, select Time Series.
8. In the drop-down menu for the Date Range, select Sep 5, 2005 as the beginning date, and October 31, 2005 as the ending date.
9. Click on the Update Plot tab, located above the blue global reference map.
10. A line-plot should appear. Confirm that the plot is for the dates and location you selected. Line breaks or unreasonable data-points may occur for missing data.
11. Save or print your graph for later use.


1. On the temperature graph you created for your location, use your ruler and a blue colored pencil to draw a horizontal line at 30C. Did the sea surface temperature exceed 30C at any time during your time series? Using a red colored pencil, carefully shade the area between the red SST line and the blue line you drew.

2. The blue line represents the observed temperature criteria for coral bleaching to occur. Examine your red-shaded areas. For what period of time was the SST equal to or higher than the bleaching threshold? Was it long enough to cause coral bleaching? Do you think it was long enough to cause massive coral die off?


Read the Extension Activity News Article in Lesson Links and answer the questions below.

1. Increased sea surface temperature increases both the intensity of hurricanes and coral reef bleaching. Then how can hurricanes reduce the risks of coral bleaching?

2. How will global warming affect sea surface temperatures, hurricane intensity and coral bleaching?

Read and discuss the information on the lesson link ‘Things You Can Do To Protect Coral Reefs’.

Lesson plan contributed by Rex Roettger, Aguadilla, Puerto Rico

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