Colours of a Catastrophe

by Shreya Yadav

 

I am swimming in the unusually warm waters of Kalpeni in the Lakshadweep, overwhelmed by the bizarre colours of this catastrophe. Muted pastel shades have turned violently psychedelic. A branching colony of brown Pocillopora is now lavender, sky-blue fingers of Acropora a radiant white, grey sheets of Montipora fluoresce green and pink. Before the final loss of colour there is a heightened luminosity – stressed corals eject their symbiotic algae and for a brief while, starvation looks stunning. It is like swimming over the canvas of some hallucinating artist. From the surface, the reef is pockmarked with colour, like a tree trunk covered in spots of glowing lichen. I can’t help but think this is beautiful. But what it really indicates is the end of an ancient symbiosis with algae. The colours are just different shades of stress.



A reef in Kalpeni starts to bleach
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Pale and bleaching coral colonies (left) 
that were healthy just a few months previously (right)

The first few months of 2016 have been the hottest on record since 1880. A particularly strong El Niño resulted in extreme weather across the globe – floods when it shouldn’t have been raining, droughts where it should have, unexpected snowstorms and very hot seas. In the Indian Ocean, sea surface temperatures were higher than what they have been in the last 15 years. In the Lakshadweep atolls off the west coast of India, we were recording 31 degrees even at 20 meters below the surface of the water. Already, large parts of the Great Barrier Reef in Australia had bleached and the coral was beginning to die. NOAA’s monthly updates on global sea surface temperatures predicted abnormally hot waters for the Lakshadweep in May. So were we surprised when the reefs began to turn white? Not really. This had been predicted and expected and so we were ready for it, quadrat and camera in hand.

But I had only read about corals bleaching “en masse”, never really seen it happen. Now, as we swim over some of our favourite reefs, everything is pale or glowing white, even species that we expected to stay more protected in deeper, cooler waters. Just a few months ago we had dived these same sites and marvelled at how well some of them seemed to be recovering from the coral bleaching mortality of 2010. Now, decade-old coral boulders stick out from the reef like fragile snow castles.

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The bleaching was severe across several species of coral

We are doing short, rapid assessments of as much reef area as we can survey before the weather turns. There is hardly enough time to think underwater – the quadrat is mechanically laid on to the reef, a photograph taken, and the process repeated a few meters away. But the few times I peek into a bone-white colony, I see how exposed some of the animals have become. The stonefish and Pocilloporid crab, usually so well camouflaged, now stand out like bright red cherries on a porcelain plate. Hawkfish still perch on the branches of bleached coral but look dangerously visible. A leopard blenny looks unnaturally bright against its paling host. Where will these animals go when the coral dies? How quickly do these relationships begin to unravel?



Coral-associated and dependent species become starkly visible during a bleaching event

Here in Kalpeni, one of the southernmost islands in the chain, the damage is most visible. I am diving with Gafoor, a Divemaster with the Department of Tourism. He too is shocked by how fast the coral is bleaching. It has gotten worse this week, he says. A lot of the stressed coral is already covered in algae. This is the final stage of death – once a coral colony bleaches and is overgrown by macroalgae, it cannot recover. Their skeletons will slowly crumble and accumulate in piles of rubble on the reef. In some areas, these broken pieces will be cleared away by the force of monsoon storms, potentially freeing up space for a new batch of coral juveniles. On other reefs, these rubble piles never move, becoming more and more overgrown by different kinds of algae. But in both scenarios, mature adult coral are necessary to seed the reef again. Diving these waters now, I wonder how much reproductive coral is going to remain after this warming event. Everywhere, vast fields of bare coral skeleton stretch out before us. Even giant clams, usually a bright purple because of the algae they house in them, have turned pale.

Pocillopora with algae on tips

The tips of this colony of bleached Pocillopora are beginning to be covered in algae
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Giant clams, usually an electric blue because of the algae they house in them, 
also bleach during warming events

When we surface from the dive in the lagoon, Gafoor looks visibly worried. Where will we take the tourists? he asks. This was our most popular site. I tell him there’s a chance not all of this will die – especially if the rains come soon and cool the water down. Corals can live for a little while without their algal symbionts, and are very often able to recover from stress if water temperatures drop back to normal levels after a short period. Not all bleached coral will necessarily die.

Recovering reef

An example of a recovering reef, after the coral mortality of 2010

But the sky is clear and the water is calm. Our boat cuts through the lagoon, blurring the white reef below us. Gafoor and I watch the ripples in silence.

 

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2 thoughts on “Colours of a Catastrophe

  1. Spectacular post. While the story itself is tragic, the narration is brilliant. Hopefully the recovery that you are hoping for will happen.

    1. Thank you for reading Badri. I hope too that the damage is not as bad as we think it might be.

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