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Unformatted text preview: PROJECT OCEANOGRAPHY SPRING 2000 23 CORAL REEFS Unit 1 Lesson 3: Corals, Forams, and Reef Health Lesson Objectives: Students will understand the plight of coral reefs, and the diseases and factors responsible for their decline. Vocabulary: coral bleaching, zooxanthellae, ozone, carbon dioxide, coralline, foraminifera, symbiotic Source and co-author: Dr. Pamela Hallock Muller, University of South Florida Corals and Forams Coral reefs are in trouble worldwide. According to a 1998 study by the World Resources Institute, 60% of the world’s coral reefs are threatened. Threats to coral reefs can be classified as local, regional and global. Forams are small organisms that live on the coral reef. They are subject to bleaching and may die if the environment is not favorable. Ultraviolet radiation, carbon dioxide and other factors affect them. Local Threats Local threats include runoff of sediments and nutrients from land, overfishing and destructive fishing, dredging and careless boat operation, including grounding of large ships on coral reefs. Many “local” threats are so widespread, they are actually regional or even global in extent. For example, the World Resources Institute report concluded that there are virtually no reefs in the entire world, with the exception of some protected areas on Australia’s Great Barrier Reef, that are not overfished. Pipe Coral PROJECT OCEANOGRAPHY SPRING 2000 24 CORAL REEFS Regional Threats Regional threats include new diseases that sweep through populations of organisms living on the reefs. For example, in 1983, an unknown disease, possibly a virus , is believed to have come through the Panama Canal from the Pacific Ocean. This disease killed most of the spiny sea urchin population, first in Panama then throughout the Caribbean and to the Western Atlantic reefs of the Florida Keys and Bahamas. More than 99% of the spiny sea urchins were killed. The virus seems to still be present, because spiny sea urchins are now uncommon on Caribbean reefs. The consequence of the die-off of the spiny sea urchin has been unlimited growth of algae on coral reefs. The spiny sea urchin population fed on the algae populations found on the coral reefs. For example, in the early 1980’s, coral covered more than 60% of the reefs in Jamaica. Now, coral covers less than 10% of the reef. Algae are taking over the reefs everywhere. Another disease swept through the coral reefs of the Caribbean and western Atlantic in the 1980’s – white-band disease . This disease, which looks like a white band of death as it attacks a coral colony, wiped out most of the branching coral ( Acropora palmata and Acropora cervicornis ) throughout the Caribbean....
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- Spring '11