Coral Reef

Sprawling apartments has been phenomenal in the growth and development of Ranchi. Similarly in the marine waters, growing coral reefs are apartments to diverse animals. Do you know what a coral reef is? Well, it is a ridge or elevated part of a relatively shallow area of the sea floor approaching the surface of the sea.

Coral reefs are massive wave resistant structures built largely by coral and consisting of skeletal and chemically precipitated material. These are made by polyps i.e. animals belonging to the Coelenterata.

There are basically three types of coral reefs: Fringing reefs, Barrier reefs and Atoll. 

The fringing reefs develop along the shoreline and from the shoreline and form a channel or lagoon between the reef and the shore. The atolls are island made of corals.

Lakshadweep is called a ‘coral island’. Do you know why it is called so? Well, because the whole landmass has been generated by piling up of dead polyps, layer by layer and the formation has taken many years!

The coral reefs are most complex ecosystems found on the planet. 

These are found in great concentrations between 4 degrees north and south latitudes in western portions of all major oceans. They generally extend to about 30 degrees north and south of equator. They develop at a temperature not less than 20 degrees Celsius. This is the reason why they are not found in very cold seas.

Coral reefs are very important as they are home to many sea dwelling creatures like colourful fishes, conch, squids, octopuses, crabs etc. Coral reefs form important ecosystems. They also provide food to different animals like star fish. These support fish production up to 2.5 lakh tonnes per year.

Coral reefs control the concentrations of carbon dioxide in the lower atmosphere and in the sea water. Coral reefs check sea waves against going towards sea coasts by reducing their speed.  They are helpful in controlling Greenhouse Effect as they absorb carbon dioxide.

Not only do the reefs help in maintaining ecological balance in the marine waters, they also provide different types of raw materials for industries. Coral is used in making jewelry, in repairing bones.

Coral Reef is an example of symbiosis between animals and plants. Many algae grow in the corals, algae provide food to them and they provide shelter. The algae- zooxanthellae and the coelenterates exchange gases. To reach for light corals grow to occupy vast expanses in the oceans and seas. Coral reef is the largest living structure visible from the space!

The multiplying coelenterates lead to the increase in the mass of the coral reef. But in doing so, the coral reef is exposed to physiological stress. The stress is caused by conditions such as light, temperature of water and non-availability of nutrients.

When exposed to stress corals expel the algae out and turn white. This is called coral bleaching.  It is not that only warm water causes coral bleaching cold water also has the same effect. Coral bleaching is evidence that the corals are experiencing stress and if they are further stressed, they can die. It is matter of great concern worldwide.