Why do corals compete for space on the reefs.

Corals and big coral reefs are well known in the world. They are seen as exotic and for many people something they want to see. They are associated with clear and warm water in the tropics. Divers that are in closest contact with reefs can see that there is a lot going on there e.g. fish moving around and the quiet competition between corals. The corals always compete on the reefs, with both indirect and direct competition. “what do they compete about?” Light, temperature and clear water.

Light is the main factor that corals compete about. Corals are living in a mutualism relationship with the zooxanthellae (a form of plankton). Zooxanthellae uses photosynthesis to create energy and this energy is used by the coral that gives the zooxanthellae protection. This relationship is the reason that the corals need to compete. Zooxxanthellae can be free living in the ocean, but when they leave the coral, the coral bleach. This bleaching occurs when the water temperature is 1 degree colder or warmer than the corals can handle. if this happens for less than a week the zooxanthellae can come back to the corals, but if longer the coral will die. What can also affect the corals is the turbulence of the water and how much sediment there is in it to block out the light from the corals.

All of these factors is more or less natural, but humans have increased them in past century. What corals are competing for is the living space they need to survive. One new problem that has been seen the last 10 years for the corals are acidification that we spoke about a few weeks ago.