Sri Lanka’s endangered coral reefs

By Madushka Balasuriya

Sri Lankans often enjoy relating the now mythological story of how the leader of the then still-to-blossom Singapore once voiced, in complete sincerity, their goal of one day attaining the lofty standards of progress set by Sri Lanka.

Sri Lankans often share this story in the same way your middle-age, overweight uncle speaks of that one glorious summer spent bowling to Aravinda de Silva in the nets in school. It’s at once both a boast and wistful nostalgia, the ultimate what-could-have-been. It is also something we are all susceptible to, and Nishan Perera is no exception.

“When you consider what they were like before 1998, the reefs nowadays don’t even compare. They don’t even have 10% of the coral cover that they used to have at that time,” marine biologist Perera opined, as he presented a public lecture on the impact of climate change on coral reefs. 

“The entire structure of the reef system in our region was completely changed in the 1998 event. Some reefs like the Bar Reef in Kalpitiya were very badly affected but recovered, before eventually dying again last year. Basically it changed the entire reef system across the Indian and Pacific Oceans, parts of the Great Barrier Reef, and parts of Indonesia. The Maldives and Seychelles were also very badly affected.”

Sri Lanka is at present home to some 212 species of coral, but that number is fast reducing due to a combination of both direct and indirect actions by human beings. One of the most pressing manifestations of these actions is a phenomena called ‘coral bleaching’.

The ‘1998 event’ Perera – co-founder of marine research and consultancy firm Blue Resources Trust – spoke of is one of the most devastating ‘bleaching’ events to ever affect Sri Lanka – and much of the world. If you’ve never heard of the term though, fret not, Perera himself admitted it was not the “sexiest” topic, however when given a freehand to present on a subject matter of his choosing at the monthly Wildlife and Nature Protection Society of Sri Lanka (WNPSSL) lecture, he knew there were very few topics more important in the Sri Lankan context.

Coral bleaching

To gain a complete understanding of ‘coral bleaching’ it is important to first appreciate that corals are living creatures. Found in the living tissue of corals is a symbiotic algae. The photosynthesis conducted by the algae produces food for itself, while the excess food it produces creates a vital food source for corals. This algae is also what provides colour to the corals.

Coral bleaching occurs when this symbiotic algae is no longer present on the coral. The exact reason for this – whether the algae leaves or is expelled, or whether there is a chemical change – is still unknown, however what is known is that when corals are subjected to a certain level of stress this reaction occurs.

“Stress can be many things. It can be temperature, it can be pollution, it can be sediment or an increase in mud in the water. It can be disease or changes in salinity. It can be caused by multiple factors, but temperature related stress is the most commonly observed phenomena now.”

There have been gradual increases in sea surface temperature in the shallow waters of the ocean over the last few decades, as a result instances of bleaching have become more frequent. Even an increase of 1-2 degrees in the surface temperature of the ocean will put undue stress on corals. In Sri Lanka water temperatures average about 28-29 degrees, however at times last year it was at 30-31 degrees, noted Perera.

“Coral bleaching has been happening as long as there have been corals. Events of bleaching have been recorded throughout history. However what’s happening now is that there has been an increase in frequency and magnitude. 

“We call these mass coral bleaching, or global mass coral bleaching events, where right across the world in large areas or extensive ocean systems corals are being stressed at the same time. As a result the ability of corals to recover from this is being compromised, and it is only expected to get worse as temperatures rise.”

Increased frequency in mass bleaching events

As touched upon earlier, arguably the biggest mass bleaching event took place in 1998, while the first of its kind was recorded in the early 1980s, which was when people started understanding this as “a major threat to coral reefs,” explained Perera. 

“There were sporadic bleaching events in areas, but not a mass, global level bleaching event. Not until 1998. Sri Lanka was very badly affected and a lot of the reefs on the South Coast have never recovered from that.”

Before the 1998 bleaching event, the Bar Reef in Kalpitiya was considered one of the healthiest coral reefs in Sri Lanka. In terms of coral cover, 80% of the bottom of sea bed was covered in live healthy coral – a very high percentage – which according to Perera made it one of the best in the world. However in 1998 almost all of the corals died. The reef was bleached in April/May 1998, and by October 1998 it was a complete algal reef. 

“It was like a meadow of algae, very few fish. It was completely destroyed,” recalled Perera.

However going in the Bar Reef’s favour was the fact that there were very few people going into the reef, (due to the war there was very little fishing pressure and almost no tourism). This resulted in the reef recovering naturally. In 2009 February there was almost 80% coral cover again.

“The reef had recovered significantly, it was almost back to pre-bleaching levels. The species composition had changed and the diversity had decreased, but in terms of overall reef health it was quite good.”

Sadly, the last bleaching event in 2016 has resulted in the entire reef dying. Perera though is keen to look at the positives. “What it shows is that reefs do recover, the Bar Reef can be resilient. Nature is resilient, but of course these stresses are increasing. What we don’t know is what the Bar Reef will be in 2025.”

There was a smaller but global event in between in 2002 as well, however the one last year was certainly the most worrying; it lasted for a much longer period. Beginning in 2015, it continued up until mid-2016.

“It went across the ocean, affecting coral reefs across the world and ended basically around August 2016. So it was a longer duration, the frequency was shorter and the scale was much bigger.”

Research consolidation 

However, despite the threat alert for the event being put up in 2015, Perera said, for anyone privy to the relevant data it was far from a surprise. At the start of 2016 “everyone here was expecting the reefs in the Indian Ocean to be affected by bleaching,” he said, that was despite temperatures being normal in January and February. “Everyone was predicting that in May and June the temperature would go up and the corals would be heavily affected.”

This ability to predict and map changing temperatures in the ocean, he believes, is key in combating a seemingly insurmountable adversary.

“If you know there is a bleaching event coming, you can predict that a certain area will have reduced fish stocks. This will mean that fishermen move to another area, so you can already predict that there is going to be increased stress on another reef and put regulations in place ahead of time, rather than just wait till they get there and start destroying the reef before stepping in.”

To do this, Perera urges, that all available data and research information be consolidated into a central, easily accessible database, while also calling for collaboration among researchers to collect more long-term data.

“Research is really important, and this is something that Sri Lanka is often lacking. In the marine sector it’s worse than in the terrestrial sector. We don’t have enough coverage or data to see if a reef dying is down to a particular type of stress. There is a need for long-term data. 

“A lot of the work done is in sporadic surveys, it’s not connecting into one long-term data set. So you need what you call time series data to look at patterns over a 10-20 year cycle. You need to have a little more collaboration as amongst researchers to do this, not just individual research projects but research that contributes to a national database.”

Holistic conservation approach

While indisputable evidence now exists in supporting the notion of global warming being a result of human activity, that is still an indirect human impact on coral reefs. More pertinent to Sri Lanka are the direct consequences of actions taken by its population.

Illegal and destructive fishing methods such as dynamite fishing, bottom trawling and the use of Lyla nets, are destroying the country’s marine life, while overfishing is reducing stocks of herbivorous fish near coral reef systems. 

According to Perera, the growth of algae on a reef is extremely high, but this is kept in check by herbivores. If left unchecked the algae would overwhelm the reef, and the corals would die.

“What happens is there are so many herbivores that they are basically cropping the algae. There are so many herbivores eating the algae that you don’t even see the algae. Even on a healthy reef there are very high growth rates of algae. As soon as you overfish the herbivores then there is no cropping of the algae, and it basically outgrows the coral. 

“The reef then goes from a coral system to an algal system. It has been proved scientifically, where then the reef dies in a month.”

Controlling these factors, Perera says, requires the Government to take an active part in nurturing the resistance to degradation of coral reefs and its habitats.

“We can help reefs increase their resistance to these events by eliminating some of the stresses. Human stresses are very easy to stop, like overfishing, pollution, coastal development. By reducing these stresses you can make the reef more resistant, basically boost its immune system.”

However Perera notes that it is crucial that entire ecosystems are protected, not just a select few. This he says is major problem in Sri Lanka, calling on the Government to pay more attention to habitat connectivity. Perera also believes the Government needs to be more proactive in the conservation, instead of just only doing so only in popular tourist destinations.

“You need to have a network of protected areas, even if they are small protected areas. The push should be to establish a few large ecosystem-based protected areas rather than 10-20 small protected areas. 

“This is one of the biggest problems in Sri Lanka. We are protecting isolated reefs, basically because of public pressure or somebody goes there and takes a picture, we basically go and protect Pigeon Island or Hikkaduwa or one isolated reef in Galle. But there is no connectivity of habitats, there is no large ecosystem protection. So you need to have a more long-term approach to this and look at how we encompass all the different habitats.”

Never too late

Indeed, Sri Lanka does have four protected marine areas as assigned by the Department of Wildlife Conservation, however little is being done to implement the existing regulations.

At the start of his presentation, Perera offered a telling quote encapsulating the difficulty he faces in his research and getting across his message. “It’s been great fun the hours spent in the ocean, but there is also the frustration of trying to do something against the odds at times,” he said, before adding the qualifier that it was ultimately reward in itself to do work that you love.

In Sri Lanka it is an unwelcome truth that that work at the moment is primarily being conducted by individuals like Perera, whose passion it is, and not necessarily by those whose job it is. If that does not change any time soon, Singapore’s visit to Sri Lanka will no longer be the only story spoken of with a hint of pride amidst wistful nostalgia. We’ll also have our once great marine life to recall fondly.

-Pix by Upul Abayasekera