Coral reefs are the base for many marine life ecosystems, and they are the most diverse ecosystems.  Coral reefs are complex ecosystems that are often referred to as the “rainforests” of the ocean.  Reefs are found in mostly warm, shallow waters, but are occasionally found in cold, deep waters. Coral reefs are dying at a fast rate, but can be preserved.  Coral reefs are scuba diving attractions and consist of many bright colors.
Overview of reefs
Coral reefs provide shelter and food to many marine life including jellyfish, shellfish, fungi, sponges, sea urchins, turtles, and many more.  They are home to 25 percent of the species in the ocean.  Coral reefs are not only a sightseeing attraction, but they also protect coastlines from waves and storms, provide food for millions of organisms, and provide habitat. 
What is coral?
A coral is a colony of coral polyps living close together.  Corals have calcium carbonate skeletons that protect them. Corals work together with plant-like cells called zooxanthellae, which is a type of algae.  Corals and algae are interdependent because corals depend on algae for nutrients, and algae depend on coral for shelter.  Zooxanthellae take in carbon dioxide, then through photosynthesis, gives off oxygen and other important nutrients.  A lack of algae leads to bleaching and evidently, the death of corals.
Where are coral reefs found?
As mentioned before, coral reefs are found in shallow waters as well as deep waters. They are found in the Pacific and Indian Oceans, the Caribbean and Red Seas, the Arabian Gulf. They are mostly found near the equator, in warm waters. A very well known coral reef is located in Australia and is named the Great Barrier Reef.  The Great Barrier Reef is the largest reef in the world, stretching to over 2,300 kilometers.  This reef in particular is in danger.
Coral reefs are dying at a very fast rate, and there are no signs of it slowing down.  Global warming is among one of the main causes for the dying of coral reefs. The rise in ocean temperature causes coral bleaching.  Overfishing and pollution are two other main threats to coral reefs. Ocean acidification is yet another factor, which raises carbon dioxide levels. A rise in carbon dioxide levels is harmful because it makes it difficult for marine life to build shells and skeletons.  The loss of coral reefs will hurt developing countries who depend on reefs for tourism. Many reefs in Australia, including the Great Barrier Reef, are in danger because of the building of ports. Ports block sunlight from getting to the coral and they dirty the water, which causes the coral to become ill. 
Global warming is one cause of coral bleaching. Coral bleaching is the term used to describe what happens to coral when it loses its vibrant color and turn white. The coral ejects the algae living within it. Coral relies on algae for floor, and bleaching occurs when there is a lack of that algae.  Thirty-to-forty percent of reefs around the world have been killed because of coral bleaching.  The growth and reproduction of coral is slowed down due to bleaching.
There are many ways to help save coral reefs. The average person can do a number of things that will help the reefs. They can refrain from using lawn fertilizers and washing their cars with soap, this will reduce the amount of chemicals that run off into the ocean.  People can also be sure to not walk on coral reefs, and boaters can make sure they are not dropping their anchors on reefs. Reducing carbon dioxide levels is vital to the preservation of coral reefs. A recent finding explains that by injecting vinegar, a common household item, into harmful starfish, corals can be saved. However, this is only a short-term solution. 
Other closely related articles in this wiki include:
- Coral Reef Ecosystems | Reef Relief. Accessed November 20, 2015, from http://www.reefrelief.org/learn/coral-reef-ecosystem/
- van Sebille, E. (2015, October 10). Coral reefs are not just pretty – they are vital to life. The Guardian. Accessed November 9, 2015, from http://www.theguardian.com/commentisfree/2015/oct/11/threat-to-coral-reefs-climate-change
- Harvey, F. (2012, September 15). Coral Reefs of the Caribbean Facing Collapse. Accessed November 9, 2015, from http://www.climatecentral.org/news/caribbean-coral-reefs-face-collapse-14983
- Wassener, B. (2012, July 9). How to Rescue the World’s Reefs? Accessed November 9, 2015, from http://green.blogs.nytimes.com/2012/07/09/how-to-rescue-the-worlds-reefs/
- Bedolfe, S. (2012, August 6). Blue Zoo: Stony Corals. Retrieved November 9, 2015, from http://www.oneworldoneocean.com/blog/entry/blue-zoo-stony-corals
- Lee, J. J., & 2014, N. G. P. W. J. 16 11:05:00 E. (2014, July 16). Digging Up the Seafloor Makes Coral Reefs Sick. Accessed November 9, 2015, from http://news.nationalgeographic.com/news/2014/07/140716-australia-coral-reef-dredging-sediment-disease-environment-ocean/
- Dirscherl, R. (2015, November 16). Can corals survive in warmer seas? Accessed November 20, 2015, from https://cosmosmagazine.com/earth-sciences/can-corals-survive-warmer-seas
- Sullivan, K. (2015, September 13). Scientist fear mass death for Hawaii’s coral reef. Accessed November 9, 2015, from http://www.morningticker.com/2015/09/scientist-fear-mass-death-for-hawaiis-coral-reef/
- Clemens, D. (2015, September 23). Vinegar Could Save Australia’s Great Barrier Reef : Discovery News. Accessed November 9, 2015, from http://news.discovery.com/animals/vinegar-could-save-australias-great-barrier-reef-150923.htm
- NOAA Coral Reef - by NOAA Coral Reef Conservation Program
- Coral Reef - by Encyclopedia of Earth
- Great Barrier Reef - by National Geographic
- Coral Reef 101 - by Coral Reef Alliance
- Corals and Coral Reefs - by Smithsonian National Museum of Natural History Ocean Portal
- Coral Reef Information System - by NOAA CoRIS