1. Why coral reef bleaches and decrease
What is a white part of corals? It is a bone. When algae which corals have are lost we can see bones through corals’ transparent tissue. Stresses cause coral bleaching ―high or low temperature of seawater, strong light, ultraviolet rays, low density of salt, and so on. They prevent algae from photosynthesizing and a surplus of sunlight energy injures algae more. The effect is dying of algae, and corals die too because they get nutrients from algae. Anyway, acanthasters are famous as natural enemies. Actually, they do not eat algae of coral but they eat corals directly. Certainly they decrease …show more content…
Effect of decreasing of coral reef
Why coral bleaching is bad? There are three main reasons. First, coral reefs are places which many animals live. Microbes and crustaceans eat mucus. Fish use corals as safe houses. For example, there are many kinds of animals in Okinawa’s coral reef: damselfish family, threadsail filefish family, sea-cucumber, sea-urchin, starfish, and so on. Moreover, coral reef hold only 600,000km2 that is 0.1% of the surface of the earth but over 90,000 kinds of living thing are in there. That is about 5.3% of animals in the earth.
Second, coral reefs are natural embankments. Corals grow well in the place which waves are strong. Therefore lands are protected from being eroded.
Third, coral reefs absorb CO2 in the air and release O2 by photosynthetic which algae do in the coral surface. A volume of CO2 which coral reefs decrease exceeds volume which forests on the lands do and corals absorb CO2 to form their bones. Therefore coral reefs are called “forests in the