Coral Reefs Coral reefs are warm clear shallow

Coral Reefs

Coral reefs are warm, clear, shallow ocean habitats that are rich in life n The reef's massive structure is formed from coral polyps, tiny animals that live in colonies; when coral polyps die, they leave behind a hard, stony, branching structure made of limestone. n Coral reefs develop in shallow, warm water, usually near land, and mostly in the tropics; coral prefer temperatures between 70 and 85 ° F (21 - 30 °C).

Types of Reefs: 1. Fringing reefs are reefs that form along a coastline. They grow on the continental shelf in shallow water. 2. Barrier reefs grow parallel to shorelines, but farther out, usually separated from the land by a deep lagoon. They are called barrier reefs because they form a barrier between the lagoon and the seas, impeding navigation. 3. Coral Atolls are rings of coral that grow on top of old, sunken volcanoes in the ocean. They begin as fringe reefs surrounding a volcanic island; then, as the volcano sinks, the reef continues to grow, and eventually only the reef remains.

1. Fringing Reef: Polynesian island of Mooréa

2. Barrier Reef

The Great Barrier Reef (off the coast of NE Australia) is the largest coral reef in the world. It is over 1, 257 miles (2000 km) long.

3. Tuanake Atoll in French Polynesia

What are coral polyps? n n Coral polyps are small marine invertebrate animals. Most polyps live in large colonies. There are two types of corals: n Hard corals: secrete calcium carbonate skeleton (forms the reef when the coral polyp dies) n Soft corals

Great Star Coral: each polyp is about 1 cm in diameter

1). The mouth is surrounded by tentacles armed with stinging cells for capturing plankton. During the day these tentacles are folded in the digestive sac. 2). Microscopic single-celled algae that give the coral its green, blue or brown colour are located in the tissue of the living coral. (3). These symbiotic algae (Zooxanthellea) process the wastes produced by the polyps. Through photosynthesis they generate oxygen and organic compounds which the polyps themselves can use. They may also help the polyp lay down calcium carbonate.

Corals are carnivorous!! n Corals are carnivores that eat zooplankton (like copepods and tiny marine larvae). They catch food using tentacles that surround the mouth; the tentacles have poisonous stingers (called nematocysts) n Zooplankton: Small animals that generally have limited or no swimming ability and are transported through the water by currents and tides examples: amphipods, shrimp, fish larvae, copepods, invertebrate larvae, protozoans and rotifers

Coral reproduction: n Corals reproduce either asexually (the polyp grows another polyp out of its side) or sexually (polyps can be male, female, or male and female)

Predators Corals are eaten by the crown-of-thorns (a large starfish that eats coral polyps), parrotfish, and other animals.

Threats to Coral Reefs: 1. Human Contact: Touching Reefs, even slightly, can harm them. Boats and dropped anchors can cause severe damage to these fragile ecosystems. Frequent human contact kills the reefs over time. 2. Runoff Water: Silt from eroded soil in runoff water can block sunlight. Without sunlight, photosynthesis does not occur and reefs gradually die. 3. Sewage: Untreated or improperly treated sewage promotes the growth of algae, which harms coral reefs. 4. Cyanide Fishing: Some fishermen stun fish by squirting cyanide, a very toxic poison, into reef areas where fish seek refuge. The poison does not kill, but disorients the fish in the coral where they hide. The fisherman then rip apart the reefs with crowbars to capture the fish. In addition, cyanide kills coral polyps and the symbiotic algae and other small organisms necessary for healthy reefs. Cyanide fishing is common in the South Pacific and Southeast Asia.

5. 6. 7. Fertilizers & Pollution: Fertilizer runoff, pesticides and other chemicals can poison reefs. Blast Fishing: Shock waves from blast fishing can destroy coral reefs. Increased UV rays: causes coral bleaching (when the zooxanthellae die and leave the coral white.

Coral reefs: importance Tropical coral reefs are very productive ecosystems. n Not only are do they support enormous biodiversity, they are also of immense value to humankind. n Latest estimates suggest coral reefs provide close to $30 billion each year in goods and services n

Coral reefs: importance 1. Fisheries: Coral reefs are vital to the world’s fisheries. They form the nurseries for about a quarter of the ocean's fish, and thus provide revenue for local communities as well as national and international fishing fleets. An estimated one billion people have some dependence on coral reefs for food and income from fishing. If properly managed, reefs can yield around 15 tonnes of fish and other seafood per square kilometre each year. 2. Tourism: Tourism revenues generated by coral reefs are also significant. For example, according to a report by the Key West chamber of commerce, tourists visiting the Florida Keys in the US generate at least US$3 billion dollars in annual income, while Australia’s Great Barrier Reef generates well over US$1 billion per year. Sustainably manged coral reefbased tourism can also provide significant alternative or additional sources of income to poorer coastal communities in developing countries.

Coral reefs: importance 3. Coastal protection: Coral reefs break the power of the waves during storms, hurricanes, typhoons, and even tsumanis. By helping to prevent coastal erosion, flooding, and loss of property on the shore, the reefs save billions of dollars each year in terms of reduced insurance and reconstruction costs and reduced need to build costly coastal defences - not to mention the reduced human cost of destruction and displacement.

Coral reefs: importance 4. Source of medical advances: We can also expect coral reef species to contribute to future medical advances. Already coral reef organisms are being used in treatments for diseases like cancer and HIV. Just as with tropical forests, we may continue to find the answers to medical problems in the coral reefs - so long as we can keep them healthy. 5. Intrinsic value: For many coastal societies around the world, coral reefs and their inhabitants are intricately woven into cultural tradtions. For these people - as well as for those who have floated with a mask and snorkel, immersed themselves in the three dimensional wonderland of a scuba dive, or experienced these habitats through media and books - a world without coral reefs would be an infinitely poorer place.

Reef Diversity n http: //www. enchantedlearning. com/biomes/coralreef/coralree f. shtml

Video content n n Nat Geo-coral reef Nat Geo Great Barrier Reef

Blue Planet: Coral Seas n Video Link: https: //www. dailymotion. com/video/x 7768 j 9