In many parts of the world, the coral population has undergone a massive reduction due to various human factors. The health of the coral reefs has been steadily declining over the past few decades. Environmental pollution and rampant destructive fishing practices damage the delicate corals. Nutrients seeping into the sea from agricultural areas cause the algae in the sea to increase in volume. This causes smothering of the corals and leads to decrease in size of coral reefs. Quite recently, the decrease in the coral populations has been attributed to a dozen or more deceases that attack corals. Many of these diseases were unknown until recently.
Coral reefs have also been affected by bleaching. Bleaching is the discoloration or loss of symbiotic zooxanthellae. In 1979 and 1980, several incidents of coral bleaching occurred at reefs around Okinawa, Easter Island, northeast Australia, and the Caribbean Sea. Outbreaks of bleaching also occurred in 1982 and 1983, including reefs off east Africa, Indonesia, and the west coast of Central and South America, and from 1986 to 1988 in areas such as Taiwan, Hawaii, Fiji, Mayotte Island, and the entire length of the Great Barrier Reef. The most extensive bleaching episode ever documented occurred in 1998 and affected reefs in the Indian Ocean, Pacific Ocean, Red Sea, Persian Gulf, and Caribbean Sea. In some areas 100 percent of the corals were bleached and more than 70 percent of the corals died. (Smith 2003)
Taking the rapidly declining coral population and the vulnerability of corals various measure are being taken in many countries to prevent further damage to the corals. Some of these steps include strict vigilance on fishing practices, artificial plantation of corals etc. Methods of coral community rehabilitation included coral transplantation and translocation, reattachment of coral fragments, providing artificial substrata, coral cultivation, prevention measures, and mitigation of damaged coral reefs. (Yeemin No