Although coral reef ecosystem covers very less geographical area of world oceans, it shelters and supports vast diversity of marine organisms including fishes, crabs, molluscs, lobsters, etc. On the basis of structure and place, coral reef can be classified as fringing, barrier, and atol reefs. But, the formation, as well as existence of these limestone landforms depends on the certain determinants that I am going to explain in this blog, “Types of coral reefs and it’s determinants”.
Major determinants for coral reef development
Here are some essential conditions that are instrumental in determining the growth and development of coral reefs.
•Temperature of sea water-
Average water temperature is highly essential for the sustainable growth of coral polyps. It should neither be too low too high. For certainty, around twenty degree Celsius is ideal for better growth.
In case of higher or lower tempraure, the algae Zooxanthellae will abandon symbiotic relationship. And finally, polyps will die.
Therefore, such marine organisms only survive in the tropical and sub-tropical regions of the world oceanic.
•Depth of the sea water
Though the polyps are benthos, they can’t thrive in the deep water. For the photosynthesis process, sunlight is prerequisite condition. Hence, beyond the 180 feet, the chances of survival are negligible.
Most importantly, these organisms cannot survive even in the absence of adequate water. That’s why these polyps are called too delicate to survive.
As I mentioned earlier that coral polyps are instrumental in absorbing calcium from sea water. So, calcium is necessary to make protective calcareous skeleton for themselves.
For this, certain degree of salinity is utmost important. Obviously, Coral polyps cannot thrive in fresh water nor in mere brackish. You know that sea water salinity is 35 practical salinity units. And, for coral, it should be between 32 to 40 practical salinity units. Then, it is found in the areas of tropical and sub-tropical, away from riverine drainages.
•Sediment free water
Sediments can cause clogging effect on polyps. In the turbidity, Coral might not survive. For this reason, sediments free oxygenated clear water facilitates the ideal growth of colonies of tiny marine organisms.
Considering these conditions, the location may be somewhere in the tropical or sub-tropical regions, away from riverine drainages. Strictly speaking, the continental shelf and islands are generally preferred.
Major types of coral reefs
On the basis of above discussed conditions, Coral reefs are generally classified as fringing, barrier and atol reefs. Let’s see the detailed description of these types one of one.
You might have heard about “The Great Barrier Reef of Australia.” It is the largest barrier reef of the world. It is formed in the proximity of coast. A comparatively deeper lagoon separates barrier reef from the coast.
Fringing reef is much closer to the coast compare to barrier. It is also gets separated by lagoon but less deeper.
•Unlike earlier two, it is found in the archipelago regions. These landforms are circular in shape but similar in structure. We know that continental shelf region is rich in marine ecology. And, these landforms are also part of this region.
Thse are main types of coral reefs generally found various part of the world oceans. But, nowadays, these topographical feature are facing existential threat due to oceanic acidification and coral bleaching. This is enough to get insight of types of coral reefs and it’s determinants. In the next blog, I will discuss the coral bleaching and oceanic acidification…