Why should we care about coral reefs disappearing?


They are such a beautiful, rich source of life and biodiversity.


How are they even related to me? I care more about the jobs and the economy.

Certainly, the “Pro” argument will not cut any ice with any person struggling with holding onto their jobs or finding a new job. Corals are remote, otherworldly, mysterious. You neither know or are likely to care about how your life and the corals are related.

But they are. And if you live near the coast, they are very closely connected.

And even if you live farther away, they are connected. The truth is, we get a lot more from coral reefs than we are aware of.

This makes understanding them, and the reasons behind their disappearance, relevant for us.

(this article earlier appeared in Firstpost)


Imagine you were the king of a medieval country. Your country is a fortified city and there are barbarians at the gate. What would you do first?

Yes, that’s right. Ensure that your wall is in good order.

Travel to today. The past weeks have seen us being bombarded either directly by floods, or by storm surges around the world.

And we have been chipping away at our “proverbial” walls. You see, the walls protecting our coastlines are the coral reefs and the mangroves. And they are being devastated.


Figure 1: The barrier reef seen from the sky; Picture by the author.

Fourteen years ago, I first swam in the Great Barrier Reef. It was an underground world of heart-stopping beauty. So beautiful, that some would have wanted to stay forever. Purple, orange, green, yellow, pink – the reef appeared a living tapestry spun from Nature high on weed. There is life – such life – fish darting in and out of the crevices, giant clams, fish in schools, turtles, sharks and then the corals themselves – fan shaped, fern shaped or branched. There is no comparison between sterilely seeing it on a TV screen and actually being in the waters. The cool embrace of the sea, the sound of one’s breath in one’s ears and having the fish in touching distance only to dart away as we extend our fingers.

Services provided by the corals

Such beauty makes you forget the astounding importance of the reefs, and trick you into thinking this is just Nature’s frothy exuberance. Coral reefs occupy about 0.2% of marine surface area but hold about a third of marine species. They are an ecosystem, where, as in a play, each character plays a role (sometimes more than one) on which the entire play is balanced. The corals provide support and a home for algae and nooks for fish to hide from predators and grow. The algae in turn produces food for the coral.  Herbivorous fish eat the algae and keep them from overwhelming the corals. Predators, like sharks and barracuda, keep the fish numbers in check. Everything is in a beautiful balance resulting in a garden of jewels under the sea.


Figure 2: The corals reefs – an underwater paradise with an unpleasant reminder – the bleached coral at the bottom left (Picture by the author)

Reefs provide so much for humanity.

Reefs protect the shorelines from erosion and storm surges. They are the outer ring beyond the mangrove defence.


Figure 3: A shark in the Great Barrier Reef is a sign of a healthy reef. However, that did not make us feel safer when actually in the water with the shark. (Picture by the author)

Animals and plants from the reef are a rich source of molecules to combat threats to our health. The National Ocean Service calls the reefs the medicine cabinet of the 21st century holding key molecules to treat Alzheimer’s and Cancer.

In an age where “jobs” are at risk, coral reefs provide jobs – the Great Barrier Reef in Australia contributes AUD$5.8 Billion in primarily tourism, creating over 68000 jobs in the process.

Globally, 275 million people live within 30 km of a reef, and depend on it for some part of their sustenance. In poorer countries, this means food and protein from the fish in the reefs, which cannot be supplanted from outside.

There is one more unsettling service the coral reefs provide.

Corals have been around for hundreds of millions of years, although the origins of the present reefs are more recent. They have also gone extinct a few times before. Interestingly or disturbingly, depending on your view, coral reef extinctions coincide with mass marine extinctions throughout the geological records. This makes the reefs an ideal canary in the global-warming coal mine, if you will. Long ago, coal mines did not have ventilation channels to allow toxic gases such as Carbon monoxide to escape. To ensure their safety, coal miners carried a canary in a cage with them into the tunnels. In the mines, the bird would sing, only stopping when it died as the gas concentration got too high for it, but not yet too toxic for the humans. It was an effective, if inhumane, early warning system.

Coral reefs can be thought of as our early warning system of life on the planet.

Chipping away at the wall

Last month I swam again amidst the reefs. The colours were on mute. Bleaching was easily visible. Even in the carefully “tourist-designated” scenic spots, algae-defeating-coral was visible. It was seeing “Through a glass, darkly”.


Figure 4: Coral that has been overwhelmed by algae (picture by the author)

In the millions of years of their existence, corals have never faced such a combined onslaught of stressors at such a pace as they do today.

Corals consist of a hard skeleton and a softer part, called the polyps. These polyps form symbiotic relationship with a single-celled creature called zooxanthellae. Like a good marriage, each brings something to the relationship, and each gets something essential from it. The corals provide the zooxanthellae with protection, a home and some nutrients. The zooxanthellae in return give the corals over 90% of the food they require, along with their lovely colouring. The problem begins when the temperatures rise. The zooxanthellae produce food by photosynthesis; several studies show that increased temperatures damage this process. The marriage is broken, and the zooxanthellae is chucked out by the coral. Only problem is, there is no one to make food. The coral is left bleached and weakened. The term “bleaching” refers to the loss of colour as the corals lose their symbiotic partners. If the bleaching is minor, the coral often recovers, finding other zooxanthellae partners. But in prolonged warming or mass bleaching, the coral dies. Recent and repeated warming has resulted in mass bleaching, where entire colonies of coral have died out. This is more serious, and harder to recover from.

The problem is compounded by the pace of warming. Corals are genetically very diverse – and in that diversity, there exist corals that can thrive in warmer temperatures. But the current warming is faster than anything the corals have had to cope with in the past.

Warming is not the only threat. Before the industrial revolution too place, the carbon cycle of the planet was thought to be in equilibrium. But today, humanity puts out about 33 billion tonnes of carbon dioxide each year into the atmosphere. A quarter of this is taken up by the oceans by converting the carbon dioxide into carbonic acid, which acidifies the waters. Corals need a material called argonite to form their bones. Typically, shallower water have plentiful quantities of argonite for corals to thrive. But as the ocean acidifies, argonite concentrations drop. This weakens the corals. In 40 years or so, concentrations may drop too low for the corals to form their skeletons.

Apart from these two serious global threats, there are the local hazards of overfishing, pollution (both sewage and runoff), storms and predators. Overfishing, especially of herbivorous fish, leaves the coral vulnerable to be overwhelmed by rising levels of microalgae. Pollution weakens all constituents of the ecosystem while sediments from sewage lowers the amount of sunlight reaching the corals – essentially starving them. Corals, weakened from the heat, acidification, sewage, pollution, become susceptible to disease and decay.

One of the most robust conclusions of climate science is that the coral reefs, unless something drastic changes, are doomed. The International Panel for climate change puts it thus: “Warming and acidification will lead to coral bleaching, mortality, and decreased constructional ability (high confidence), making coral reefs the most vulnerable marine ecosystem with little scope for adaptation.” That’s scientist-speak for “Sorry, you’re screwed”.

Next Steps

This is a tragedy.

But is there hope?

India has reefs mainly in the Andaman and Nicobar Islands, Lakshadweep, in the Gulf of Mannar and the Gulf of Kutch.

Dr E. Vivekanandan, Retired Scientist from the Central Marine Fisheries Research Institute says, “Hope is very remote”. Remote does not mean absent. One big victory has already been won: mining for coral has stopped. The corals of the Gulf of Mannar – one of the largest reef system in mainland India –  suffered from overfishing and coral mining. Until 2005, coral was mined first to build houses (we visited an old house in Tuticorin made from coral), and then to supply the appetites of the lime industry. Then two changes came about: First, in 2001, corals were added to the Schedule 1 of Wildlife Protection Act. Then, during the 2004 Tsunami, the villages shielded by the coral reefs did not have the property damage or the death toll of the unshielded villages. That is when the value of the coral reefs as effective bio shields was realised by their most effective guardians – the local villagers. This enabled the second change, the 2005 ban on mining coral, to have bite – because the villagers subscribed to it.

Another story of hope came from the Lakshadweep islands. During the monster 1998 El Nino, the reefs in these islands were badly bleached, as were reefs across the world. But the recovery in Lakshadweep was much faster than expected. What was going on? What was so special about these corals?

Nothing, it turned out. The specialness was that the fishermen of the islands mainly fished tuna farther away from the coast. The herbivorous fish in the reefs were not overfished here. These fish devoured the algae and allowed the corals to recoup.

As Dr Madhusudhan from the Nature Conservation Foundation says, “The threat [to the reefs] is from global causes, but resilience has to be built through local actions.”

Other ways of building resilience include ensuring sewage is not dumped into the reefs as in the Gulf of Mannar. The second is to expand the area under a Marine Protected Reserve. This will allow the fish populations to increase and spill over to non-protected zones in an acceptable way to fishermen.

But underlying all of this is to increase the perceived value of reefs. “We have to put a value to it.” says Dr Vivekanandan.

The Great Barrier Reef provides billions of dollars and thousands of jobs to the Australian Economy. It therefore has clout. Indian reefs are mutely suffering their many blows because they are perceived to have little value.

Eco-tourism, that can generate local jobs and engage public interest, is one promising idea. This must be very carefully done with a full engagement of the local population. Done wrong, it can damage the reef further. But done right, it can engage public interest and create a more sustainable stream of income for the locals, while helping build coral reef resilience.  The tiger reserves are packed attractions to Indian travellers. It’s time we stuck our head under the water.

The underground canary is beginning to stop her song. Can the World hear her silence?




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