In hot water

Updated

How the hidden menace of coral bleaching is going global.

The emerald waters of Kane'ohe Bay on the north eastern coast of O'ahu in Hawaii appear to be a picture of environmental perfection.

But below the surface a natural catastrophe is spreading — coral bleaching.

With the oceans already heated from climate change, the onset of a severe El Nino has forced the declaration a global bleaching event.

The unfolding catastrophe could hit the Great Barrier Reef by early next year and Australian government scientists and universities are readying a national taskforce to study mass coral bleaching should it occur.

But all is not lost — while Hawaii has been the epicentre of the problem, its scientists could also hold the solution — with researchers breeding "super coral" resistant to bleaching.

They are also wheeling out high-tech equipment to track the bleaching in never-before-seen detail.

Coral graveyards

The devastation of large swathes of coral is unfolding on the front doorstep for Rusty Brainard, chief of the National Oceanic and Atmospheric Administration's (NOAA) Coral Reef Ecosystem Division in Hawaii.

"[A few weeks ago] I went out and it was a calm morning, the sun had just come up and I was stand-up paddle boarding and it was beautiful," he said.

"When it's glassy you can look right down to the reef and at one end of the bay... all of the coral that I could see was white or significantly bleached and it just stands out so much against the background.

"Here in Hawaii this is only the third time that this has ever happened — 1996, last year and this year — and this year is by far the worst we've ever seen here."

When oceans warm, the colourful organisms that live inside the coral flee, turning it fluorescent white.

It leaves the coral severely stressed, vulnerable to disease and if the warming is prolonged it will eventually kill the coral.

Satellite monitoring and underwater thermometers have observed water temperatures reaching 30 degrees Celsius around Hawaii this year.

Dr Brainard, who is studying the global bleaching event, warned that the world needed to "hope for the best and prepare for the worst".

"Twenty per cent of the corals globally died during [the 1998 global bleaching] event," he said.

"If this event is of similar scale — which the early signs are — that is a huge catastrophe for corals.

"But there could be lots of changes between what happens with this event and what happened 17 years ago."

Further afield on the island of Maui NOAA scientists investigating the bleaching declared some areas a "coral graveyard".

"They covered a stretch on Maui where there was already extreme mortality, they characterised it as devastation," Dr Brainard said.

High-tech fight

In a bid to understand and even fight back against the bleaching, the teams in Hawaii are turning to increasingly high-tech tools.

Cameras and microscopes are being used to monitor the reef in incredible detail to capture how the coral changes over time.

Called a photomosaic, the 150 square metre, high-resolution image is part of a project run by Emily Kelly from the SCRIPPS Institution of Oceanography.

"You can look at both the large scale actions as well as small scale interactions," Dr Kelly said.

"We can even see the little coral recruits, which means the little babies that have just landed by the larvae that are floating in the water column and they land on the bottom and they start out as one polyp - that's smaller than a fingernail and we can see that."

Andy Mullen's hand-built underwater microscope takes that a step even further.

It can capture images one-tenth of the size of a single hair.

Many of the ocean's most important biological processes occur at microscopic scales, but when samples are brought back to a lab much of this information is lost.

"People have made instruments to look at plankton free floating organisms in the water at micro scales but never able to look at the seafloor," the Jaffe Laboratory for Underwater Imaging researcher said.

"We were looking at interactions between [turf] algae and corals as well as the zooxanthellaes, which are the symbiotic [organisms] which live inside [and feed] the coral.

This current bleaching event is an opportunity for scientists to get a better understanding of those interactions according to Dr Kelly.

"For many corals that are able to recover we will be able to understand a little more about how they recover," she said.

"Then in the future we'll know some of the things that may have been more stressful to the corals that resulted in mortality.

"There are a lot of things we can do locally to protect our reefs and even though there are these global issues like climate change, we'll be able to understand what some of those local solutions could be.

"A lot of those come from managing the fish on the reef… and managing the pollution coming off the land."

Breeding super coral

Tucked away off Hawaii's main island of O'ahu is Coconut Island.

It is most well known because that is where the opening scenes of Gilligan's Island were filmed.

But it is now the home to the Hawaii Institute of Marine Biology, where some of the most cutting edge coral reef science is being conducted.

Here — led by the Institute's Director Ruth Gates — they are breeding and training super coral.

It is put through its paces in warm and acidic water.

"We're looking for the best environmental performers, the super corals, the ones that seem unaffected by disturbances that are killing the ones right next door," Dr Gates said.

"We bring them into the lab, we put them into what we call environmental treadmills - this is conditions of the future, and we expose them to stresses, we run them in this environment but we don't kill them obviously.

"We're basically giving them a challenge."

With the Institute's offices surrounded by more than 50 patch reefs — many of which have already bleached — it is quick and easy to return the "super" coral and observe whether it has survived.

"We had one experiment where we transplanted corals onto the reef and we subsequently had conditions on the reef that induced bleaching - none of the corals that had been in our experiments had bleached.

"That's a very exciting thing."

Dr Gates and her team are working in conjunction with Australian Institute of Science Researcher Madeleine van Oppen to assist the evolution of corals.

This includes the training of super corals and then selectively breeding them.

"We know that those individuals that are offspring from selectively bred super corals will have greater ability to withstand future climate conditions," Ruth Gates said.

She said it was not genetic modification of corals, just helping speed up what nature does over time.

"We've never done anything like this before… but that doesn't mean that we shouldn't.

"We're at a pivot point in our understanding of what's going on in our reefs.

"We can sit back and say it is too dangerous, we are doing too much intervention and risk losing all your reefs worldwide - what would that mean to us?

"Billions of people would be affected by the loss of reefs - it is extremely important to our food security, our coastal security and many many many island economies so what are they implications of waiting to see what nature does?"

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Topics: oceans-and-reefs, environment, environmental-impact, environmental-management, great-barrier-reef, climate-change, hawaii, united-states

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