Coral reef ecosystems


“Oceanic ecosystem manifests unique way of functioning across the vast fathomless water masses. It is the best epitome of beauty of nature… “

Structure of marine ecosystem with plankton, Nekton, and Benthos
Nature offers a lot of surprises for enthusiastic spectators…

Coral reef ecosystems are the storehouse of the most diverse, luxuriant marine biodiversity which is widely known as rainforest of the sea.

These landforms are formed by the variety of lime secreting and shell forming animals and plants. Such animals are called coral polyps which are marine invertebrates with calcareous skeleton.

With other creatures and plants, delicate coral polyps are instrumental to form calcareous marine landforms that shelter variety of species.

Unfortunately, nowadays, these  coral reef ecosystems are on the verge of degradation amidst the ocean acidification and rampant pollution.

In this piece of writing, “Coral reef ecosystems” I going to reveal the true state of greatest living treasure on the earth.

What are coral polyps

Coral polyps are tiny marine animals. They live in a colonies with millions of numbers. For more specific understanding, such oceanic creatures belong to class “Anthozoa” of phylum “Cnidaria.”

Anatomically, these animals have hard calcareous skeleton to protect themselves. Unlike other marine creatures, they  receive energy through symbiotic relationship with photosynthetic algae known as “Zooxanthellae.”

Zooxanthellae is a single celled microscopic organism with autotrophic abilities. Hence, polyps thrive as long as the Zooxanthellae is in symbiotic relationship. Otherwise, polyps will not survive.

Such tiny benthos are better known for theirs abilities to absorb dissolved  calcium from from sea water and form calcareous skeleton to protect themselves.

This is the most important ability to absorb and secret calcium, label them as  reef builder. In addition, they are instrumental in maintaining the calcium cycle in the oceans.

What is mean by coral reefs

Coral reefs are typical type of marine landforms formed by the lime secreting polyps over a period of time. But, to forms such marine landforms, certain conditions are need to be fulfilled.

As the polyps are too susceptible to adverse conditions, they thrive in the certain locations in the oceanic topography. We know that these carbonated structure become a shelter for millions of precious maritime species. In this way, Coral reef ecosystems are labeled as the “rainforest of the ocean.”

Pre-conditions for coral survival and growth of coral polyps

•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.

•Salinity level

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. Most strictly, the continental shelf and islands are generally preferred.

Different forms of coral reefs

On the basis of above discussed conditions, Coral reefs are classified in the following way:-

•Barrier reefs

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 reefs

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.

It means that these marine landforms are the greatest storehouse of the varied species, sheltered in the coral reefs. This indicates the degree of importance of coral reefs. As per the statistics, these reefs shelters around 30 percent of marine species.

Impacts of global warming on coral reefs

Global warming is the gradual process of increasing tempraure of our planet. It is happening due to constant concentration of greenhouse gases.

Global warming is facilitated by the  excessive  use of fossil fuels for power plants and automobiles are attributed to the emissions of greenhouse gases. It is causing multiple negative impacts on the environment as a whole.

Temperature rise and coral bleaching

Temperature induced coral bleaching is the most common that the coral ecosystems facing today. It is more impactful than the coral diseases. As per the various studies, sea tempraure has been rising since last second half of the twentieth century. Even rise in 1-1.5 degrees Celsius, Coral ecosystems will face challenge of survival.

Simply, Coral bleaching means loss of single celled microscopic organism “Zooxanthellae.” It becomes lifeless and colourless in case of rise in 1-1.5 degrees of temperature. In this situation, the coral polyps will not survive because of symbiotic relationship.

So far, there are various cases of coral bleaching and consequent depletion have been surfaced in the leading jounels and research papers. The news about the greatest Australian reef is also alarming.

Ocean acidification a potential threat for coral existence

As I discussed earlier that the level of carbon dioxide  has been continuously rising in the atmosphere. The excessive carbon dioxide is getting dissolved into the sea water, making it more acidic.

For the technical purpose, when the carbon dioxide dissolved in the water, the result will be the carbonic acid. Carbonic acid converts calcium carbonate into calcium bicarbonate which is easily dissolvable in the water.

And, we know that coral polyps absorbs calcium to form calcareous skeleton for protection. In this situation when the degree of carbonic is constantly growing, the fragile coral polyps becomes exposed to the adverse forces of climate.

Apart from this, rampant coastal urbanization, pollution, and  plastic waste is another problem that is directly threatening the very survival of one of the most fragile organisms.

Tourism and improper fishing activities are no less responsible for the loss of reef ecosystems. Despite laws, conventions, and protocols, it is still continue even faster than earlier. Not only does it causing the damage for the marine biodiversity, but it is also threatening the livelihood of millions of people in the coastal regions. Unquestionably, due corrective measures should deserve priority to ensure enduring balance.

Equatorial natural region

Learning present continuous tense

Would have for missed opportunity

Understanding adjective clause

Deforestation and soil erosion

Biodiversity of ocean

Corrective measures for bleeding biodiversity

Relations between India and Pakistan

Export driven economic growth

Understanding no sooner than

Conditional sentences