Corals are animals and are a type of polyp which is a group of organisms. Corals reef is calcium carbonate and a bit of rock.
Corals house just 0.1 percent of the ocean floor, and residence of 25 percent of the ocean family. Yet this small portion is exquisitely colorful, vivid and beautiful, but corals are sad as they are losing their friends and family.
What are Corals Anyways?
To clear a very basic doubt, corals are not Flora. They are living organisms. Corals are animals and are a type of polyp which is a group of organisms that have a single stomach, mouth which is ringed with tentacles.
There are two coral types: hard and soft corals. It is the hard corals that form the corals reef and what is that? Corals reef are reefs formed by corals. Reefs are any base or a rock and corals reef is calcium carbonate and a bit of rock.
How are Corals Reef Formed?
Coral larvae keep moving freely in the waters. Sometime later, they attach to a hard surface at island edges or submerged rock surface to form their houses and then coral polyp (the adult-form of coral larvae) uses the calcium and carbonate ions from water to make a calcium carbonate skeleton for themselves. When they die, they leave behind their skeleton and new polyps use it as a foundation and form their own. Hence, layers of CaCO3 keep on forming and forming and the coral polyp, of course, stays at the top layer. And this is how coral reefs are formed! Many coral polyps come and go, the reef becomes bigger and makes a colony!
What Do Corals Eat, and How??
Coral polyps have algae called zooxanthellae. These algae have a symbiotic relationship with coral polyps. And what is that relation? In a symbiotic relationship, an organism uses the other organism as a host and uses that host’s organism’s resources for its own self.
But in corals the case is a tiny bit different.
The coral polyp gives out carbon dioxide and, by the way, oceans take upto 22 million tons of CO2 a day, which is very high now (climatic change, you see) but the oceans usually have a great amount of CO2. So these coral polyps give CO2 to zooxanthellae, who then photosynthesis and make their own food and also that food is so much that it also becomes enough for the coral polyp.
Coral polyps do catch and eat plankton and other microorganisms via their tentacles, but it does not usually do much. Ninety percent of the corals’ food comes from their dear algae. Also, this algae is responsible for those magical colors that corals have-blue, green, orangish red, pale yellow and so many, like a colour book! Believe me, in just one square metre of the coral polyp cell, millions of these algae (zooxanthellae) reside!
Do Corals Help Us?
Corals are hella useful. They are at times mined for making medicines for arthritis, heart problems, etc.
They are tourist spots! I mean just two years ago my friend was in a scuba costume watching those corals underwater!
They are very good for reef fishing. Coral reefs are an ecosystem just like a tropical forest is. It has fishes, sponges, sea turtles, starfish and many more, so they are good for fishing.
What Problems are Corals Facing Today?
The corals reef have lost their families due to pollution, excessive nutrients, overfishing and mining, tourism and oh our dear global warming-climate change.
Corals of the Great Barrier Reef saw a bleaching event in the years 1980, 1982, 1992, 1994, 1998, 2002, 2006, 2016 and 2017. It has lost 90% of its corals.
Also, The Great Barrier Reef is the largest reef in the whole world and is located in the Coral Sea, Australia!
Now, what is bleaching. See, corals can live in 23°-27°C of water approximately. When the heat rises, they cannot bear it. The coral polyps stress so much because of the heat that they blow off their algae (you should watch some bleaching videos, it will look as if the corals are puffing out toxic air trapped in them!) or some corals lose it slowly.
As this zooxanthellae algae goes away from the coral polyps, the coral polyps then have a shortage of food as most of their food comes from the algae and they also start losing their colour. The corals turn white and now the difficult span of corals becoming white is called bleaching. White corals are not dead, but if we don’t maintain the temperature they do die.
Too much CO2 in the oceans causes coral polyps to take in less CaCO3 from the waters and it slows and impairs their growth. Additionally, CO2 makes oceans acidic and if there is bleaching and the oceans are too acidic, it becomes tougher for corals to recover.
Now, deforestation leads to loosening of soil and, ultimately the sediments flow into the ocean. Sediments become a curse for the coral reef because one of their conditions to survive in waters is that they should have no sediments to be there in the water. Why? This is because sediments actually block the sunlight and kind of get stuck on the corals. Now those algae inside the coral polyp need sun for photosynthesis, but when the sun isn’t reaching, the algae can’t function because of which the coral cannot either.
Also, too much nutrient pollution in waters causes a different type of algae to form on the water surface (you probably might have seen its pictures in your science textbook-that pale yellow-green algae on the water surface!) Hence, they block sunlight from entering the waters, causing the same problem to the corals!
The 2016 coral bleaching event of the Great Barrier Reef, Australia was kind of less severe.
And the reason is the nature is a protector of its family. A cyclone named Winston hit in 2016 in Fiji and had further gone to Vanuatu, Tonga and Queensland. The Great Barrier Reef is located off the coast of Queensland. Now, during that year, the bleaching started taking place in the great barrier because the heat had brought water at high temperatures and was becoming a hell of a wreck.
The cyclone had hit the south of the coral sea (the coral sea is where the great barrier reef is located) and because of the cyclone, the southern waters of the coral sea had cooled down a bit. And because of this, the portion of the great barrier which was located in these southern waters, had bleached very little as the high temperature water had been cooled down by the cyclone! Whereas the northern portion of the Great Barrier Reef has seen the worst bleaching. It is weird to say, but a cyclone saved corals’ lives.
What is being done to Protect Corals?
Well, a new technique called coral microfragmentation is used. In this, a very tiny portion of the coral or a single polyp is fragmented and made to grow. If we take a huge portion and make it grow, the coral takes years and years to form. But if we use microfragmentation, then the same coral will become a three year old in just weeks or months! This technique was extremely helpful, is used in 26 species of coral and the team that found it had taken 25,000 such fragments and from them planted 10,000 back in the sea!
As Kristen Marhaver said, ‘The best time to save corals was fifty years ago but the second best time is now‘.
Thank you and please, if you can stop spilling acrylics in your basin and plastics and pollution in rivers, then do so. You will save coral houses!