Coral Cam Web Site

WHAT IF THE REEF DIES?                                   Gail Swenson

OBJECTIVE: This lesson will provide opportunities to model, using simple laboratory
                            materials, some aspects of reef ecology.  In addition, student conclusions
                            drawn from the activities will be referenced to known data.   Finally,
                            students will be asked to consider what they can do to insure reef survival.

AGE GROUP:   Suitable for students ages 10 and beyond 


Coral reefs are sensitive living structures found in warm marine waters around the world.  Bermuda's reef is unique for it is the northern most latitude in which true coral formations are found.  Several forces are acting on reefs and scientists are learning more about the contribution reefs make to the immediate ecosystem as well as to the larger biosphere. 


PURPOSE: How might sewage discharge affect a marine ecosystem?  Powdered milk will
                    represent the sewage.  The more milk, the more sewage present.  Yeast will
                    represent plants growing in the marine ecosystem.  The amount of plant growth will
                    be determined by the length of time it takes for the Bromthymol blue color to


Bakers yeast                                 Powdered milk ( to represent the sewage)   

Bromthymol blue solution              Timer (watch or clock)

Thermometer                                Graduated cylinder (10, 25, or 50ml)

Test tubes and rack                       Measuring spoons or gram balance


1.  Place 3 test tubes in a rack, and label tubes 1 and 2 as "sewage", label # 3 as a
2.  Place  tsp. (1.0 g) powdered milk  into  #1 test tube.
3.  Place 2 tsp (4.0 g) powdered milk into a #2 test tube.
4.  Add tsp  (1.0g) yeast to all 3 test tubes.
5.  Add  15 ml of water to each tube.  MIX WELL.
6.  Add 20 drops Bromthymol blue solution to tube #  1, RECORD THE EXACT TIME,
     AND MIX.
7.  Add 20 drops of Bromthymol blue to tube # 2 , RECORD THE EXACT TIME, AND
8.  Repeat for tube #3.
9.  Observe tubes 1,2,3 and NOTE THE EXACT TIME WHEN THE BLUE COLOR

Processing the results

    1.Create a data table to display your results.
    2.Create a line graph of your results.
    3.Predict what would happen if you used 1 tsp. of powdered milk in this experiment.
    4.How might sewage discharge near a coral reef affect the health of a reef system?
    5.Refer to to research your answer to question # 4.  Were you
    correct based on data collected from reef sites?  Explain.


PURPOSE: To learn how substances that dissolve in water can be changed into substances
                    that do not dissolve in water. Coral animals do this chemistry when they build their
                    calcium carbonate exoskeletons by bringing together calcium ions and carbonate ions.


Lime water (make by mixing 5 grams of ordinary lime in 1 liter of water.  Mix well and filter) Use the filtered solution. Cover tightly to store for the activity.
Soda straw
Test tube or Erlenmeyer flask (any transparent container.)


1.Place a small amount of limewater into a test tube or Erlenmeyer flask.

2.Place the soda straw into the limewater and slowly exhale for several breaths.

3.Observe what happens.

Processing the results

1. Calcium ions are released when minerals, such as lime, dissolve in water.  How is a calcium
    ion different from a calcium atom?
2. Carbonate ions are created when carbon dioxide, a gas in our atmosphere, mixes with water. 
    A carbonate ion is called polyatomic because it contains several atoms yet has an ionic charge.
    Use a chemical handbook or a chemistry text to learn about the solubility of calcium
3  If coral reefs were to die, what do you predict would happen to the amount of carbon dioxide
    in the air above the coral reef? Explain.
4. Refer to to learn more about this topic.
      a) Graph the ten warmest years of the century. What does this indicate about impact humans
          are having on global warming?
      b) What has happened to the sea level in the past 100 years?
      c) How does a change in sea level affect coastlines?

ACTIVITY 3  Barrier to Erosion

Throughout the world barrier beaches and reefs protect shorelines from the ceaseless action of waves and storms.  Bermuda's coral reefs nearly encircle the island and act to maintain the land area by absorbing the force of waves and by providing coral sands that accumulate along the shore.

PURPOSE:  To demonstrate effects of wave action with and without a barrier reef


Large, shallow tray (baking pan, plastic container)

Sand                      Rocks                     Water                 Board to make the waves

A coral reef (any solid structure that will be just below the water level)


1. Place the rocks and sand on one end of the tray to create the mainland area.
2. Elevate the end of the tray that has the land area.
3. Position the coral reef a distance from the land area.
4. Slowly add water until the reef is submerged and the land area is above water level.
5. Put the board in the water near the low end of the tray and push back and forth to create
6. Observe what happens to the land.
7. Now remove the coral reef and repeat the wave action, observing what changes occur to
    the land.

Processing the results

1.Sketch the land before and after the wave action with the barrier beach in place.
2.Sketch the land before and after the wave action WITHOUT the coral reef.
3.Predict what would happen to Bermuda if large sections of the coral reef were to die.


PURPOSE:  To learn what happens to a coral reef when fish are removed from the habitat.


Use the web site to research how these reef organisms obtain their nutrition: coral polyps, phyoplankton, zooplankton, parrot fishand algae.

Processing the results

1. Which organisms are in competition for living space on the reef? Explain your answer.
2. What will happen when over fishing depletes the parrot fish  population? Explain.
3. Sketch a coral reef habitat as it would look after the parrot fish had been removed.

Which organisms would have a growth in population and which would have a decline?  Explain.

Summarize the changes would occur in the Bermuda area if a coral reef died.

Use this web site, to  learn about things you can do to save the reef.

BBSR and TCOE Coral Web Site Team 1999
Funded by a grant from the Goldman Foundation