It is said that there is a ‘completely different world’ under the sea which is almost like a ‘parallel universe’. It is hard not to be mesmerized by the beauty of the marine kingdom. Among the life that thrives underwater, the coral reefs definitely stand out for all the right reasons. Most tourism companies project eye-catching images of huge coral reefs. They are not only aesthetically pleasing but also ecologically and commercially important. They are also termed as ‘Rainforests of the Seas’ as they support wide variety of aquatic life including fish and other invertebrates.
What exactly are Corals and where are they found?
Corals are actually large group of invertebrate animals belonging to class Cnidaria. An individual coral is called a ‘polyp’ and many individuals come together to form a colony. Their body parts consist of a stomach that has one open end and tentacles which are defensive in function. They feed on zooplanktons, fish and food particles.
Generally, the corals are slow growers. Over the course of time, the polyps secrete calcium carbonate (CaCo3) skeletons. The coral reefs are formed from these secreted skeletons of millions of polyps. The reefs come in different shapes and sizes. Some have primary secondary branches, finger-like structures while others have ball-like structures/mushroom-like structures. Highly evolved form of symbiosis is exhibited by coral reefs.
The presence of corals is not restricted to any particular area and they are found throughout the world in shallow as well as deep waters. The reefs which are found in shallow and tropical waters have algae which prefer 22-29°C temperature. On the other hand, the deep-sea corals are found at the depth up to 20,000 feet.
The ecological and commercial importance of corals
Safeguarding of coastal life – Coral reefs are the best aquatic ecosystem to support marine species. Despite the fact that they take up less than 1% of the oceanic floor, they shelter 25% of aquatic life. The Australian great barrier reef accommodates close to 9000 marine life forms. According to scientific community, there are still many undiscovered species living in vicinity of the reefs.
One of the biggest roles corals play in nature is the protection of coasts from erosion and big storms. These structures aid in mitigating the loss of property and lives due to waves and flooding. Degradation of these ecosystem can adversely affect the coastlines.
Food requirements – Many populations in developing and island countries, depend on reefs for getting food. 10 % of fish caught around the world are found in areas with coral reefs. This industry is worth billions of dollars. Additionally, the polyps which make up the reefs are rich in protein. The reef ecosystem is also a home for many molluscs and crustaceans.
Economic benefits – Because of its aesthetic value, reefs are crucial to boost tourism and recreation activities. Fishing, sea diving and snorkeling are the most sought-after activities in this region. Hence, Reef tourism pumps billions of dollars and makes up thousands of employment opportunities.
Medicinal properties – Scientific community also takes great interest in corals due to their medicinal properties. It can be beneficial for treating cancer and can also be used in bone regeneration. More studies can also reveal pharmaceutical applications. Moreover, these species are culturally significant for indigenous population.
The Rainforests of the Seas are in Distress
Just like any other ecosystem, coral reefs are vulnerable to certain anthropological factors. According to Global Coral Reef Monitoring Network (GCRMN), there was a loss of 14% of coral reefs worldwide. The biggest challenge to the health of coral reefs is coral bleaching. Simply put, coral bleaching happens when the pretty colours of corals are lost and they turn white.
The biggest contributors to coral bleaching are climate change and change in chemistry of ocean. When there is a rise in atmospheric temperature, the sea water temperature also increases. The zooxanthellae, which is algae living in symbiotic relationship with corals is expelled by the corals when the temperature rises. When the algae leave, the colour of coral fades and it gets bleached. Even an increase of 2 degrees Fahrenheit can make the coral expel the algae. If the temperature doesn’t decrease then the algae stay out of the corals, leading to the death of corals. Few algae form a protective neon covering around them when they start to bleach. Extended period of bleaching can be a recipe for disaster as the entire ecosystem collapses.
Photo credit: Henry Wolcott/Marine Photobank.
The concentration of atmospheric CO2 is directly proportional to the concentration of CO2 in ocean water. Increased CO2 in sea water results in more carbonic acid, which in turn changes the basic chemistry of oceans. This decrease in the pH lowers the quantity of dissolved salts and ions which are crucial for corals.
The aftermath of coral bleaching
As corals start to bleach, the algal population starts to swell. There has been almost 20 % rise in the number of algae on coral reefs. When the algae take over, there is a deterioration of the reef ecosystem and biodiversity. Reduction in the number of corals, affects the reproductive ability of the ecosystem. Several reports suggest that in future the incidents of bleaching will only increase and the degradation will be irreversible. Organisms like jellyfish, starfish, crabs and shrimps depend on coral ecosystem for habitation, safety and spawning. So, when there are such disruptions in ecosystems and food-webs, these species are exposed to risk of extinction
The story does not end here. This phenomenon has many consequences on the livelihoods of fishing communities as there is depletion in population of marine creatures. The tourism and other associated industries will also take a hit due to coral bleaching.
The silver lining for the Rainforests of the Seas
Despite these depressive facts, corals can be saved and rejuvenated with proper measures. Even if we take notes from the past events like 1998 coral bleaching episode, the corals did bounce back to the original levels in a matter of few years. According to 2019 estimate, there was a 2% surge in the number of coral reefs.
Corals are quite resilient and with time can return to their original glory. Researchers have conducted studies in different countries and found out more resilient reefs in India, Kenya, Australia and Malaysia. The bright future of the coral ecosystem resides in these safe houses.
We can contribute to the conservation of reefs by reducing the use of harmful chemicals and fertilizer runoff. Additionally, heavy metal discharge, oil spills, accumulation of microplastics and mining activities pose threats to the marine diversity. Stringent actions should be taken by authorities against such practices.
Furthermore, there is an urgent requirement to find solutions to global warming and take concrete actions to alleviate its effect. Awareness programmes about the preservation of coral reefs should be conducted for the common public as well as other stakeholders. More investments should be done for conservation of reefs worldwide. Humans should not be ignorant and leave the corals to their fate.
In conclusion it can be said that, global unity and rigorous efforts must be taken for protection of these ‘underwater kingdoms’.
Conclusion
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Written by: Rajashri Nene