Coral Reef Conservation

Coral reefs are complex ecosystems that are endangered by human activity.

Introduction

Coral reefs are some of the most colorful and diverse ecosystems on Earth. The structures of reefs are large and impressive, but the reefbuilding organisms are small invertebrates that are related to anemones and jellyfish, all members of the family Cnidaria. Coral animals rarely live alone. They form big groups called colonies in which the animals connect to each (see Figure 1).

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Figure 1 Coral colony

Corals can be divided into two major types: soft and hard. Soft corals have flexible skeletons made of gorgonin, a tough protein. Scattered throughout the gorgonin are sharp spicules of calcium carbonate. Hard corals build a cup-shaped home of calcium carbonate. If threatened by predators, the animals pull themselves inside their protective skeletons. When hard corals die, their skeletons are left behind and become the base on which other corals build. Millions of coral skeletons form a reef.

Under ideal environmental conditions, coral reefs grow at the rate of about 3.9 inches (in.) (10 centimeters [cm.]) each year. For such growth to occur, the water must be clear so that light can penetrate. In addition, temperatures must range from 73.4 to 84.2 degrees Fahrenheit (°F) (23 to 29 degrees Celsius [°C]). The creation of a large reef can take thousands of years. Reefs around the world are having trouble surviving because of damage to the environment. In this activity, you will conduct research on coral reefs and learn how to help conserve these unique ecosystems.

Time Required

55 minutes for part A

55 minutes for part B

Materials

access to the Internet

colored pencils or markers

science notebook

Please review and follow the safety guidelines at the beginning of this volume.

Procedure, Part A

1. Access the following Web site: URL: http://oceanservice.noaa.gov/education/kits/corals/welcome.html.

2. Read through the Web site, using the “→” button to navigate forward. As you read, answer the Analysis questions.

3. Click on the image of a coral polyp to show a detailed, labeled diagram. Draw this diagram in your science notebook. Include all the labels.

4. Click on the image of a nematocyst to show a detailed, labeled diagram. Draw this diagram in your science notebook. Include all the labels.

5. Click on the image of a coral reef to show an enlarged diagram. Draw this diagram in your science notebook. Include all the labels.

Procedure, Part B

1. Many of the troubles facing coral reefs are caused by human activity. As you completed Part 1, you read about some of the problems. Select a problem and search the Internet for sites that suggest solutions to the problem. Read these sites and take notes in your science notebook. Write a 500-word paper on the problem and solution.

Analysis

1. What are three basic types of coral?

2. What is a coral polyp?

3. Why are corals described as colonial organisms?

4. How does a coral organism take in food? How does it get rid of wastes?

5. How do corals use nematocysts to capture their food?

6. Explain the mutualistic relationship between zooxanthellae and corals.

7. What is coral bleaching?

8. Why do coral require clear, nutrient-poor water?

9. How does a coral reef form?

10. Match the shapes of corals to their descriptions.

have large, flattened branches

have wide plates that create whorllike patterns

resemble fingers

grow in thin layers on the substrate

a. encrusting coral

b. elkhorn coral

c. foliase coral

d. digitate coral

11. How do coral reefs get started?

12. What are three types of coral reefs?

13. How long does it take for barrier reefs to fully form?

14. What type of environment is best for reef-building corals?

15. Why are adult corals described as sessile?

16. Explain asexual reproduction in coral.

17. How do coral reproduce sexually?

18. Why are coral reefs considered valuable ecosystems?

19. What happened to coral reefs during the 1997 to 1998 El Niño season?

20. List some threats to corals reefs caused by humans.

21. Name at least four sources of pollution that damage coral reefs.

22. Why are coral diseases occurring more frequently than in the past?

23. Why should coral reefs be protected?

Coral reefs, some of the most productive places on Earth, are critically important marine ecosystems. One-fourth of all marine species and half of the fish caught commercially live on or around reefs. Reefs are also valuable resources for humans. Because coral reefs support so many different kinds of organisms, they are natural places for scientists tom search for new drugs.

Hundreds of medications, including the drug AZT which is used to treat HIV, have been derived from organisms on the reefs. In addition, reefs are natural barriers against incoming waves that protect the coast from damage during storms. Tourism in regions adjacent to reefs generates incomes for thousands of individuals.

Reefs are damaged by natural storms and fluctuations in weather, but their most serious threats are anthropogenic, related to humans. A list of specific and widely spread threats has been compiled by the Coral Reef Task Force. The top seven problems are the following:

1. Pollution, including sediments and chemicals that drain into the water from nearby landmasses

2. Overfishing, both commercially and for recreation

3. Destructive fishing practices, such as using cyanide or dynamite to kill or stun catches

4. Dredging and changes to the shoreline, primarily to ease the movement of ships

5. Grounding of ships and damage caused by ship anchors

6. Outbreaks of coral diseases

7. Changes in global climate that have unnaturally increased ocean temperature, frequency of storms, and rises in ocean levels

Connections

Coral reefs are primarily found in tropical oceans where waters are clear and temperatures and pH are ideal. Most of the U.S. coral reefs are in the western Pacific (Hawaii, Guam, American Samoa, and Commonwealth of Northern Mariana Islands). The remainder are off the coasts of Florida, Texas, Puerto Rica, and the U.S. Virgin Islands. These reefs are shown as orange dots in the map in Figure 2. Like reefs around the world, U.S. coral reefs are in danger because they are very sensitive to changes in the environment.

Figure 2 U.S. coral reefs

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One of the biggest threats to coral reefs is related to global climate change. Levels of carbon dioxide in the air are at an all-time high due to combustion of fossil fuels for production of electricity and to power vehicles. At the interface of air and ocean, some of this carbon dioxide dissolves in the water, increasing its acidity. Corals are not able to build their skeletons when ocean water is acidic.

Carbon dioxide in air also increases the thickness of the greenhouse gases, causing Earth’s surface temperature to rise. If temperatures exceed 84.2°F (29°C), corals expel the algae that live with them. The solution to both problems sounds simple: reduce the output of carbon dioxide. However ways to implement this solution are difficult to find. The situation is serious, but well worth pursuing. With a little help, damaged reefs can survive and bounce back.

 

 


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