EarthLabs > Corals > Lab 6: Using Data to Identify Hot Spots and Predict Bleaching Events > 6B: Bleaching Hot Spots

Using Data to Identify Hot Spots and Predict Bleaching Events

Part B: Bleaching Hot Spots

Bleaching hot spot map for North America on April 17, 2008. Image source: NOAA.

Scientists have found that corals begin to get stressed when the sea surface temperature (SST) gets just 1 °C warmer than the highest expected temperature for the warmest month of the year. This temperature is called the bleaching threshold. SST can be monitored using Earth-orbiting satellites, which are able to keep a continuous watch on the state of the oceans around the globe. Data from these satellites are vital for predicting and fighting coral bleaching.

  1. To identify areas at risk for bleaching, start by looking for places where SSTs are warmer than normal. Go to NOAA's Coral Reef Watch home page. Click on the HotSpot icon in the left-hand navigation bar to access the most up-to-date bleaching hot spot data. The Coral Reef Watch HotSpot maps highlight those areas around the world where sea surface temperatures are above the maximum monthly mean (MMM).
  2. Find the cell in the table with the most current data. Click on the Global link for that date to open up a global map of current hot spot data.
  3. Examine the map to familiarize yourself with how the data are reported.
    • light blue areas are at or below the MMM temperature
    • light purple areas are above the MMM, but still below the bleaching threshold
    • yellow to red areas are above the bleaching threshold (HotSpot: SST = 1 °C greater than the maximum expected summer time temperature), meaning that corals in those areas are experiencing thermal stress
    • numeric values show the number of °C the temperature is above the MMM

    Checking In

    Answer the following questions about the HotSpot map.

    • Using the dotted line grid as a way of dividing the map into smaller regions, how many regions were experiencing thermal stress?

    Stop and Think

    1: Were any areas above the bleaching threshold? Explain.

  4. Use your browser's back button to return to the main HotSpot map page. Click on the lower Animations (90d) link 45ns for a view of hot spot progression over the last 3 months.

  5. Watch the animation at least once all the way through, noting which months appear to have more or less thermal stress than is seen in the most current data.

    Checking In

    Answer the following question about thermal stress over the last 6 months.

    • How do the current levels of thermal stress compare to those over the last 6 months?
    • Do certain regions appear to experience thermal stress more often than others?