Assignment 3:
Question: If the coral is bleached, this means that:

a) The fish will turn white trying to mimic the environment.
b)  Zooxanthellae are no longer welcome in the coral soft tissues
c) The diver could sustain severe eye damage because of high clorox concentration in the vicinity of affected coral

Bio 394a HN
CORAL REEF DISEASE NOTES
Dusıan Palic´
A coral reef is both a physical structure and a highly productive ecosystem. The physical structure is built over centuries by the piling up of skeletons deposited by reef-building corals, which are colonies of tiny animals. Each animal within the colony is known as a polyp and has a simple tubular body with a ring of stinging tentacles around a central mouth. Within these polyps are even smaller single-celled plants (zooxanthellae). Corals filter food from the water using their tentacles, but they also rely heavily on their zooxanthellae, which use the sun’s energy to synthesize sugars, some of which are taken up and used by the polyps. These corals, then, must have sunlight to grow, reproduce, and build their limestone (calcium carbonate) skeletons. Of the roughly 800 species of reef-building (Scleractinian or stony) corals that have been described worldwide, about 65 are found in the Caribbean. Although these species are the great architects of the coral reef, their numbers are dwarfed by a great diversity of other life forms—turtles, fish, crustaceans, mollusks, urchins, sponges, and others—which make coral reef ecosystems the most diverse on Earth.
The Caribbean region possesses about 26,000 sq km of shallow coral reefs, about 7 percent of the global total. Reefs dominate shallow marine habitats over wide areas of the Caribbean, especially around islands. They are more sparsely distributed through the Gulf of Mexico. Far out in the Atlantic, the coral reefs of Bermuda are the most northerly in the world.
The Caribbean encompasses 35 countries and territories bordering the Gulf of Mexico and Caribbean Sea, including the oceanic island of Bermuda.
The nearly 7.8 million sq km of land that drains into the Caribbean stretches from the Upper Mississippi Basin in southern Canada to the Orinoco Basin of Colombia and Venezuela. The total population within this drainage area was estimated at 290 million in 2000, of whom some 41 million people lived within 10 km of the coastline. Average population density within this coastal strip increased by 14 percent between 1990 and 2000.
Over the last three decades, tourism has surpassed fishing as the most important economic activity for many coastal localities. In 2000, more than 40 million people visited the region (excluding the United States), generating over US$25 billion in revenue.
Perhaps the most profound and widespread changes in Caribbean coral reefs in the past 30 years have been caused by diseases of corals and other organisms. In recent decades, an unprecedented array of new diseases has emerged, severely affecting coral reefs. Most observations of coral reef disease reported across the globe have come from the Caribbean region.
Prominent among these reports have been the Caribbean-wide die-off of the long-spined black sea urchin Diadema antillarum; widespread losses of major reef-building corals (staghorn and elkhorn) due to white band disease; the current widespread occurrence of aspergillosis, a fungal disease that attacks some species of gorgonians (sea fans); and numerous outbreaks of white plague.
The Global Coral Disease Database includes 23 differently named diseases and syndromes affecting corals alone in the Caribbean. Three of these diseases—black band disease, white band disease, and white plague—account for two-thirds of the reports in the database and affect at least 38 species of corals across the Caribbean The impact of coral disease varies according to a variety of factors; a disease can cause different levels of mortality in different years at the same location.
The reasons for this sudden emergence and rapid spread of reef diseases throughout the Caribbean are not well understood. Diseases have been observed all across the Caribbean, even on the most remote coral reefs, far from human stresses. Almost nothing is known about the causal agents; indeed, pathogens have been identified for only three of the 23 diseases observed in the region. Linkages to other sources of stress to reefs (e.g., sedimentation or pollution) are poorly understood and the role of human activities in bringing these diseases into the region is also unclear. At least one pathogen seems related to desertification in Africa, blown with dust across the Atlantic, while the pathogen responsible for the die-off of the long-spined sea urchin may have been transported into the region via the Panama Canal in ballast water from ships. More research and integrated environmental monitoring are needed to better understand and help predict this major, widespread threat to coral reefs.Threats to coral reefs in Western Caribbean
The Western Caribbean subregion includes one of the longest reef systems in the region. The Mesoamerican Reef stretches from the Mexican Caribbean coast of the Yucatan Peninsula to the Bay Islands off the coast of Honduras. This reef system includes a near continuous barrier reef, which runs for 220 km off the coast of Belize.
Overfishing is the most pervasive threat to reefs in the Mesoamerican reef. Off Mexico's Yucatan Peninsula, the Caribbean reefs have been subject to intense artisanal fishing since the 1960s, when this formerly underdeveloped and isolated coast was opened to the pressures of modern development. In Belize, there is evidence of overfishing by small-scale local fishers and industrial fishing fleets. Intensive fishing in Honduras has affected the reef populations around the Bay Islands, and fishers also travel to remote offshore banks instead of fishing the heavily exploited fringing reefs.
Coastal development is rapid, with tourism burgeoning in many coastal areas. Sedimentation is a problem for reefs near the coasts, particularly off southern Belize and continental Honduras, where the intensification of agriculture and logging over the last few decades has resulted in increased erosion. Nutrient pollution is also a problem due to runoff of fertilizer from banana and citrus plantations, from southern Belize down through Guatemala and Honduras. However, standards for minimizing the environmental impact of banana cultivation are being encouraged through initiatives such as the Better Banana Project.
Reefs in the Mesoamerican reef, particularly near Belize, were severely damaged by two large-scale, natural disturbances in 1998. A bleaching event, coinciding with high sea-surface temperatures, was followed by Hurricane Mitch, a Category 5 storm. Bleaching caused catastrophic coral loss in the lagoonal reefs of Belize, while the hurricane caused widespread coral destruction in fore reefs and outer atoll reefs. The full consequences of these events will take years to emerge.

List of most common coral diseases:
Hard Corals
• Black-band Disease
• Bleaching
• Dark Spots Disease
• Rapid Wasting
• Red-band Disease
• Tumors and Skeletal Anomalies
• White-band Disease
• White Plague
• White Pox
• Yellow-blotch or Yellow-band Disease
Coralline Algae
• Coralline Lethal Disease
• Coralline Lethal Orange Disease
Sea Fans
• Aspergillosis
• Red-band Disease
Additional information may be found at:
http://www.coris.noaa.gov/about/diseases/
http://ourworld.compuserve.com/homepages/mccarty_and_peters/coraldis.htm
http://marine.wri.org/pubs_content.cfm?PubID=3944
http://www.coralreef.noaa.gov/welcome.html