Coral reefs the world over are threatened by pollution, rising ocean temperatures, and overfishing. In Cuba, however, reefs are flourishing. This video from NATURE follows a marine biologist as he explores the variety of corals, fish and other wildlife in Cuba’s tropical waters, and considers why Cuba’s reefs are so healthy in comparison with those in the the rest of the world.
- Observe and note the different shapes of coral present in the ocean reefs. Why do you think coral grows in these various shapes?
- Why are Cuba’s coral reefs thriving?
- How might different countries and environmental groups around the world address the threats facing coral reefs today?
- Why is elkhorn coral so special to Cuba’s coral reefs, and the Caribbean region?
Even though at first appearance corals may look like plants or even rocks, they are in fact animals, related to sea anemones and jellyfish. Corals live in colonies of genetically identical, multicellular organisms called polyps. The polyps secrete skeletons of calcium carbonate that form the hard structure we recognize as large corals and coral reefs (and so often mistake for rocks). Corals are usually found at shallow depths in tropical waters, and depend on sunlight to survive. They feed on small organisms including plankton and tiny fish, and many corals are dependent on a specific type of algae which helps produce energy as well as assisting with calcification of the corals’ skeleton. Coral structures can grow in many different shapes, some resembling brains, cabbages, table tops, antlers, wire strands, or pillars.
Coral reefs, the large structures built out of millions and millions of coral skeletons over time, are extremely diverse ecosystems that are home to thousands of species. It is estimated that 25% of all marine species live in and around coral reefs, including over 4,000 species of fish, 700 types of coral, and thousands of other plant and animal species. The most common type of coral reef is called a fringing reef, found near coastlines of islands and continents, separated from the mainland by a small channel or lagoon. These are the types of coral reefs found in and around Cuba. Other types of coral reefs include barrier reefs, atolls, and patch reefs.
Cuba is home to large fringing coral reefs at Archipelago de los Colorados along the northwest coast, and the Jardines de la Reina in the south. These reefs are home to the largest fish populations in Cuba – possibly even in the entire Caribbean! However, these fish populations are consistently sought out by local, touring, and commercial fishermen, and overfishing is the main threat currently facing Cuba’s coral reefs. As a result, fishing is banned in the area, specifically a 386-square mile area surrounding the Jardines de la Reina, now set aside as a marine reserve area.
Coral reefs are extremely sensitive to environmental changes, and depend on clear, clean saltwater to survive. Pollution and agricultural runoff can have a huge impact on the health of a coral reef. In this sense, Cuba’s Communist government may have inadvertently helped protect the Cuban reefs for many years, by preventing the flow of fresh water to the sea as well as strictly limiting the availability and use of fertilizer and pesticides. However, as Cuba begins to open its doors to the rest of the world, increased commercialism and tourism is once again increasing levels of pollution, sedimentation, and development in coastal area, which creates a negative effect on the corals.
Content Standard C
THE INTERDEPENDENCE OF ORGANISMS
Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years.
Human beings live within the world’s ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected.