Coral Reefs: A Chance Of Success
OverviewCoral reefs are certainly one of our planet’s greatest natural attractions. During this activity, students will understand the three main environmental factors that corals need to survive and thrive on. Students will appreciate how fortunate we are in American Samoa to have all three important environmental factors in order for corals to survive. They will also learn how vitally important corals are, and what they need to do to protect these resources.
Students will be able to:
1. Identify the three essential environmental components needed by corals to survive.
2. Identify the physical factors that limits where coral reefs develop.
Coral reefs are some of the most diverse ecosystems in the world. Corals (amu) are actually colonies of tiny animals living together on the reef. The individual animals that build the reef are called “coral polyps”. Within the body of the coral polyp live small, single celled algae known as “zooxanthellae.” These tiny plantlike cells photosynthesize in the coral’s body. Just like terrestrial plants, they make food using sunlight and nutrients. Photosynthesis uses sunlight to convert carbon dioxide and water into food and oxygen. They contain some of the most colorful and varied forms of life on earth. Thousands of living organisms rely on coral reefs for survival. For corals to really survive and thrive they need to have these three factors, the right temperature, the right depth, and strong enough wave action to bring in nutrients. Temperatures must not be too hot or too cold. Water temperatures must range from 62 degrees Fahrenheit to 90 degrees Fahrenheit for corals to survive. Depths must be shallow enough for corals to have enough sunlight to begin the process of photosynthesis. When depths exceed three hundred feet, sunlight will not have enough energy to begin photosynthesize. Wave action must be strong enough to bring in nutrients for corals.
American Samoa is one of the most privileged places in the world because all three of these environmental components exist here. The coral reefs of the Samoan Archipelago are biologically diverse. Over 250 species of corals have been reported in the archipelago. More than half of all the coral species known in the entire Indo-Pacific region, which stretches from East Africa to the islands of Polynesia, are found here. In addition, approximately over 950 near shore fish species in the waters of the archipelago, compared with only 460 nearshore fish species in Hawai’i. With global warming and climate change already affecting the growth of our corals, it is critical that humans must take action to preserve these precious resources.
For each group:
Handouts & Worksheets
Introduce Inquiry Questions?
What are three essential environmental components needed for corals to survive?
Ask: Can coral reefs develop anywhere in the ocean? If yes, explain why coral reefs are able to grow anywhere. If not, why? Lead students in a discussion about what things might limit where coral reefs develop. Ask them to name some of the conditions that corals need to survive such as water temperature; clear shallow water; strong wave action to bring in nutrients. Write these on the board. Explain to students that an area must meet these criteria for a reef to successfully establish and thrive.
Activity 1: Growing Planula
Have students sit in a group of six; distribute one scorecard, one die, and one chart for every group. Show students the die and explain that they will be playing a game and pretend to be coral planula (immature coral polyp) in search of a settling area. Each student will roll the die three times, once for each survival factor. Explain that to survive, they must roll one of these numbers when casting the die for that condition: Temperature = 2,3,4,5 (1 too cold, 6 too hot) Depth = 1,2,3,4 (5, 6, too deep) Wave action = 4,5,6 (1,2,3, too weak to bring in nutrients). Let each student keep score of what number will appear on the die for each condition. Be sure to state what factor they’re rolling for each time. If they get a healthy number for all three rolls of the die they qualify for the next round.
Gather the qualifying planulas in front of the class for the final round. Ask each student the following questions:
1. What are coral temperature requirements and why?
2. What are depth requirements?
3. Why do corals need strong wave action?
The students that answer these questions are the winning polyps.
Conclusion with Inquiry Question
What are the three essential environmental components needed for corals to survive?