Step 1 - Read Information and look at the Infographic
Corals are animals that build coral reefs. Coral reefs are home to many species of animals – fish, sharks, sea turtles, and anemones all use corals for habitat! Corals are white, but they look brown and green because certain types of small plants, called algae, live inside them. The algae produce food for the corals so they can grow big, and the corals provide the algae a safe home. The algae and corals form a mutualism, or a relationship between two species where both partners benefit each other and do better together than they would alone.
Coral reefs are one of the most biologically productive ecosystems on Earth. Most people have seen images of brightly colored fishes and other reef-dwelling organisms, yet many do not understand why these systems are personally important. Programs and articles about coral reefs typically point out benefits that include protecting shorelines from erosion and storm damage, supplying foods that are important to many coastal communities, and providing recreational and economic opportunities. These benefits are obviously important to people who live near reefs, but there is another aspect of coral reefs that can benefit everyone: the highly diverse biological communities are new sources of powerful antibiotic, anti-cancer and anti-inflammatory drugs
Despite their numerous benefits to humans, many coral reefs are threatened by human activities. Sewage and chemical pollution can cause overgrowth of algae, oxygen depletion, and poisoning. Fishing with heavy trawls and explosives damages the physical structure of reefs as well as the coral animals that build them. Careless tourists and boat anchors also cause mechanical damage. Thermal pollution from power plants and global warming cause physiological stress that kills coral animals and leaves the reef structure vulnerable to erosion. Many of these impacts are the result of ignorance; people simply aren’t aware of the importance of coral reefs or the consequences of their actions, but the damage and threats to reefs continues to increase on a global scale. Some of the most severe damage appears to be caused by thermal stress.
Shallow-water reef-building corals live primarily in tropical latitudes (less than 30° north or south of the equator). These corals live near the upper limit of their thermal tolerance. Abnormally high temperatures result in thermal stress, and many corals respond by expelling the symbiotic algae (zooxanthellae) that live in the corals’ tissues. Since the zooxanthellae are responsible for most of the corals’ color; corals that have expelled their algal symbionts appear to be bleached. Because zooxanthellae provide a significant portion of the corals’ food and are involved with growth processes, expelling these symbionts can have significant impacts on the corals’ health. In some cases, corals are able to survive a “bleaching” event and eventually recover. When the level of environmental stress is high and sustained, however, the corals may die.
Prior to the 1980s, coral bleaching events were isolated and appeared to be the result of short-term events such as major storms, severe tidal exposures, sedimentation, pollution, or thermal shock. Over the past twenty years, though, these events have become more widespread, and many laboratory studies have shown a direct relationship between bleaching and water temperature stress. In general, coral bleaching occurs where water temperature increases by 1° C. (1°C is roughly equal to 34°F)
A healthy reef
Step 2 - Watch video "Study of Coral Reefs"
Step 3 - Parts of the world that are dealing with Coral Bleaching
Take a look at these maps and see where most of the problems are...