While climate breakdown destroys one of the ocean’s most important ecosystems, a new study shows there may be some hope

Support us and go ad-free

Back-to-back heatwaves in the central Indian Ocean killed more than two-thirds of corals in two years, a study has shown. But research by the Zoological Society of London (ZSL) suggests some corals were more resilient to the high sea temperatures, which could provide hope for the important habitat as the planet warms.

Heatwave statistics

Scientists studied reefs in the remote Chagos Archipelago of the British Indian Ocean Territory (BIOT) before and after two ocean heatwaves. They brought unusually high sea temperatures and came 12 months apart. The study said that surveying of the sea floor between 2015 and 2017 found high sea temperatures led to the loss of nearly 70% of hard corals.

In 2015, seawater temperatures around reefs in the territory were unusually high for nearly eight weeks. Sea floor surveys before and after the heatwave saw live healthy coral cover fall by 60%. But before the corals could recover, another ocean heatwave that lasted four months hit in 2016. Although researchers were unable to assess the impact of the second heatwave across all the islands of the archipelago, data from the Peros Banhos Atoll show 68% of the remaining corals were bleached and 29% died. This suggests the heatwaves together killed around 70% of hard corals between 2015 and 2017.

Underwater forests

Read on...

Support us and go ad-free

The study said its findings are significant beyond just the Chagos Islands because:

Coral reef futures now predominantly depend on how [they] respond to repeated warming events, and if they can adapt to altered climatic conditions.

And ZSL said the study was important because the BIOT has remained “largely uninhabited” by humans since the 1970s. This provided an opportunity to study the impact of climate breakdown on coral reefs “relatively undisturbed” by direct human activity.

Coral reefs are one of the planet’s most important ecosystems. As the World Wide Fund for Nature (WWF) points out, coral accounts for just 0.1% of ocean area but supports 25% of its life. Its biodiversity “rivals that of the tropical forests of the Amazon or New Guinea”.

Survivor resilience

There was some good news, though. While the second heatwave lasted longer, it killed fewer of the surviving coral. Researchers suggest the remaining corals are more resilient to rising temperatures. Their ability to survive may be key to protecting reefs from rises in sea temperatures driven by global warming.

Dr Catherine Head of ZSL, lead author on the study, said:

It is encouraging that reefs may have some degree of natural resilience, though further research is needed to understand the mechanisms by which some corals are able to protect themselves. This may be our best hope to save these vital habitats from the catastrophic effects of climate change.

However, the study pointed out that this is threatened by “increasingly frequent and severe thermal anomalies predicted as a consequence of accelerating global climate change”.

“There is hope”

Helen Pitman, director of the Chagos Conservation Trust, told The Canary:

While it is a great disappointment to hear the news that a large per cent of coral in the central Indian Ocean has suffered from the devastating effects of back to back extreme sea warming it is encouraging to see that there is hope for many reefs. Building resilience to the effects of climate change is key to the survival of the world’s coral reefs. The [BIOT] Marine Protected Area is a vital living laboratory that can hopefully help answer some of the questions around how and why some corals still survive against the odds. This will not only help secure corals’ future in the Territory but also across the world.

We must adapt

Many Chagossians, their supporters, and international rights organisations have condemned the UK’s ongoing colonial control of the islands. In 2011, the Guardian reported on conflict between environmentalists and human rights advocates over British marine protection policies in the Chagos Islands. It’s crucial that we bring this to any discussion of ecological issues in the area.

Nonetheless, the latest study reveals for the first time just how deeply industrial society is impacting coral reefs. But it also shows how adaptable some species can be to problems that we have created. And they are also teaching us something important: it’s time for us to be adaptable to their needs.

Additional reporting by PA

Support us and go ad-free

We need your help to keep speaking the truth

Every story that you have come to us with; each injustice you have asked us to investigate; every campaign we have fought; each of your unheard voices we amplified; we do this for you. We are making a difference on your behalf.

Our fight is your fight. You’ve supported our collective struggle every time you gave us a like; and every time you shared our work across social media. Now we need you to support us with a monthly donation.

We have published nearly 2,000 articles and over 50 films in 2021. And we want to do this and more in 2022 but we don’t have enough money to go on at this pace. So, if you value our work and want us to continue then please join us and be part of The Canary family.

In return, you get:

* Advert free reading experience
* Quarterly group video call with the Editor-in-Chief
* Behind the scenes monthly e-newsletter
* 20% discount in our shop

Almost all of our spending goes to the people who make The Canary’s content. So your contribution directly supports our writers and enables us to continue to do what we do: speaking truth, powered by you. We have weathered many attempts to shut us down and silence our vital opposition to an increasingly fascist government and right-wing mainstream media.

With your help we can continue:

* Holding political and state power to account
* Advocating for the people the system marginalises
* Being a media outlet that upholds the highest standards
* Campaigning on the issues others won’t
* Putting your lives central to everything we do

We are a drop of truth in an ocean of deceit. But we can’t do this without your support. So please, can you help us continue the fight?

The Canary Support us