Coral Reefs

Credit: Chuck Savall http://www.coral.org

Corals are in fact animals, even though they may exhibit some of the characteristics of plants and are often mistaken for rocks. In scientific classification, corals fall under the phylum Cnidaria and the class Anthozoa. They are relatives of jellyfish and anemones.

Coral reefs are the most diverse and beautiful of all marine habitats. Coral Reefs are the "Rainforests" of the ocean. Reefs are ecologically important ecosystems and have a high biodiversity that serves as a storage bank of rich genetic resources. They are a source of food and medicine, and they protect the coast from wave erosion.

Credit:http://www.coral.org

Coral reefs benefit a healthy world by providing:

Habitat: Home to more than 1 million diverse aquatic species, including thousands of fish species
Income: Billions of dollars and millions of jobs in more than 100 countries around the world
Food: For commercial fishing enterprises and for people living near coral reefs, especially on small islands
Protection: A natural barrier protecting coastal cities, communities, and beaches
Medicine: Potential treatments for many of the world's most prevalent and dangerous illnesses and diseases

Corals are marine animals related to jellyfish and anemones. Both colonial and solitary corals catch plankton (microscopic plants and animals) and other suspended food particles with arm-like tentacles, which feed a centrally located mouth. Most hard corals also host symbiotic algae, a long-standing and successful partnership. These algae provide them with an additional food source through photosynthesis. Coral reefs are formed by corals that secrete hard calcareous (aragonite) exoskeletons, giving them structural rigidity. These colonial “hard corals” form elaborate finger-shaped, branching, or moundshaped structures and can create masses of limestone that stretch for tens or even hundreds of miles. 

Clean, clear water is essential to their health. Once coral larvae settle on a hard substrate and become established, colonies can arise if conditions are suitable for growth. Given enough time, coral colonies become thickets. As coral thickets build upward on the skeletal remains of older colonies, a reef is established. Today, richly diverse coral reefs are found in the tropics along coastlines, on the margins of volcanic islands, and as isolated coral atolls.

There are two distinct regions in which tropical coral reefs are primarily distributed: the Wider Caribbean (Atlantic Ocean) and the Indo-Pacific (from East Africa and the Red Sea to the Central Pacific Ocean).

• The diversity of coral is far greater in the Indo-Pacific, particularly around Indonesia, the Philippines, and Papua New Guinea. Many other groups of marine fauna show similar patterns, with a much greater diversity in the Indo-Pacific region.

• Although they possess a smaller number of species the corals of the Atlantic are still unique, with few common species between the two regions .

Coral reefs are found in about 100 countries. Coral Reefs are home to over 25 percent of all marine life and are among the world's most fragile and endangered ecosystems. In the last few decades over 35 million acres of Coral Reefs have been obliterated. Reefs off of 93 countries have been damaged . When corals are stressed by high temperature, ultraviolet light or other environmental changes, they lose their symbiotic algal cells, and appear white (the white skeleton is actually visible through the transparent tissue). Depending on the intensity and duration of the stress, the corals may recover or die. 

If the present rate of destruction continues, 70% of the world's coral reefs will be destroyed within the next few decades.

Climate change will destroy the world's great coral reefs within a century, according to a report by German and Australian marine scientists.Researchers say governments must take action now to reduce the emissions of gases such as carbon dioxide, which are thought to be behind a rise in average global temperatures.

A slight rise in temperature can bleach coral like this

The scientists combined their coral expertise with the latest climate models to project what is likely to happen to the world's greatest reefs if global warming remains unchecked. Their study suggests the unique marine environments will increasingly become victim to a process known as coral bleaching.

A slight rise in maximum water temperatures - only one to two degrees - can stress the corals. This causes them to expel the microscopic organisms, known as zooxanthellae, which color their tissues and provide them with essential nutrients.

If the zooxanthellae do not return, the corals will die. In 1998 every reef system in the world's tropical oceans were affected by some degree of bleaching. The report says the frequency and intensity of bleaching is set to rise.

The report's lead author is Professor Ove Hoegh-Guldberg, an expert on coral bleaching at Sydney University. Coral reefs could be eliminated from most areas of the world by 2100, Even the world's largest reef - the Great Barrier Reef off Australia - could be dead within 30 years unless measures are taken now to slow climate change.