Coral Bleaching & The Great Barrier Reef

In April 2016 I submitted an article to The Marine Professional - a publication of the Institute of Marine Engineering, Science & Technology (IMarEST) focusing on the mass bleaching event that had hit the Great Barrier Reef at the time.  In their September 2016 issue, The Marine Professional featured a comment from a reader, in which he stated that he shared the article with Dr. Russell Reichelt - chair of the Great Barrier Reef Marine Park Authority.  The reader alleged that  Dr Reichlet told him that the article "contains some accurate things mixed with half truths and alarmism". A number of  coral reef, marine biology, and climate scientists have been in touch to express their concern about Dr Reichelt's alleged comments on my article.  After liaising with Dr Reichelt's office*, I am pleased to be able to set the record straight on what he did - or rather did not say.

*I did contact Dr Reichelt directly, but he replied via his office not directly.

After corresponding with Dr Reichelt's office to determine where the "half truths and alarmism" were in the article, I have been informed that, whilst Dr Reichelt recalls the article being brought to his attention, he never made any such comments about the article.  In fact, he hadn't even seen the article to comment on in the first place.  He has since read the piece and agrees that it is factual.

I have not attempted to contact the reader to find outwhere his comment came from.

Below is a copy of the article I submitted to The Marine Professional.   For those who want to see the article after it has been through their editorial process, please see the June 2016 edition of The Marine Professional.

The Article

The Great Barrier Reef “is one of the most spectacular, complex, but fragile ecosystems in the world”, Sir David Attenborough remarked in the landmark documentary ‘The Great Barrier Reef with David Attenborough’.  When filming began in 2014, no one could predict just how poignant the timing of the first broadcast – December 2015 in the UK and April 2016 in Australia, would be.   2016 has seen the worst bleaching event every recorded on the Great Barrier Reef.  As of 20th April the National Coral Bleaching Taskforce, convened by Professor Terry Hughes, reported that only 7% of individual reefs that make up the Great Barrier Reef are unbleached.  Coral mortality rates around 50% are reported in the northern section of The Reef were waters are warmest, and is expected to increase.  In mid-April, scientists from University of Technology Sydney and Macquarie University reported bleaching inside Sydney harbour – some 1,300 km from the southern tip of the Great Barrier Reef.  The proximate cause of the bleaching - a strong El Niño and warming sea surface temperatures which has stressed the corals.  The ultimate culprit – us.

Coral polyps form a symbiotic relationship with zooxanthellae – microscopic unicellular algae that reside inside the coral.  In return for supplying carbohydrates and other organic products of photosynthesis, the corals provide zooxanthellae with a safe environment and compounds (the coral’s metabolic waste) for photosynthesis.  As waters warm, zooxanthellae metabolic rates increase.  Combined with sunlight, increasing photosynthesis means more oxygen production, even to levels toxic to the corals, at which point the corals eject the zooxanthellae.  Since zooxanthellae also provide coral with colours, their ejection also means the coral turns white – just like they have been bleached.  As long as warming isn’t prolonged, corals can recover if they regain zooxanthellae, albeit with reduced growth and reproductive output.  If corals stay bleached for a long time, the corals run the risk of starvation, disease, and death.

Covering an area around 344,400 km2 – an area larger than the United Kingdom, Holland, and Switzerland combined, the Reef supports over 3,000 species of mollusc, 1,635 fish species, 600 soft and hard coral species, 133 species of sharks, and over 30 species of whales and dolphins - and a wealth of social and economic human values.  The 2013 Deloitte’s Access Economics report indicates that The Reef raises an estimated A$7 billion per annum in direct expenditure.  Most of this (A$6.7 billion) comes from domestic recreational and domestic/international tourism activities.  Commercial fishing and aquaculture bring in A$193 million in direct expenditure, and reef science – ranging from study of The Reef itself to pharmaceutical developments, contribute approximately A$106 million.  The 2 million visitors per year to the Great Barrier Reef Marine Park pay an Environmental Management Charge vital for the management of the Park.  The potential loss of visitor revenue would have severe impacts for the Marine Park, and Queensland’s tourism industry.  Throughout April, both the Marine Park and Tourism Tropical North Queensland have used social media to encourage people to continue to visit the reef, stressing that there are still some corals to see.  Meanwhile scientists, exacerbated with the lack of coverage in the Queensland’s largest newspaper the Courier Mail, have paid for a one page open letter outlining how the current bleaching event is the worst in The Reef’s history, and that climate change driven by greenhouse gas emissions is the primary cause. The total social and economic impacts of this bleaching event may not be fully realised for years to come.

In the search for solutions, there are no quick answers.  Once a bleaching event starts, we cannot stop it.  All we can do is monitor, learn, and hope that the damage is not long lasting.   Research on these events is helping managers to explore ways in which severity of future bleaching events might be reduced.

Research lead by Dr. Tracy Ainsorth from James Cook University’s ARC Centre of Excellence for Coral Reef Studies and published in April suggests that corals may be more resilient to bleaching if they are exposed to a “practice run” – a gradual increase in temperature.  These “practice runs” have been observed in different areas of the Reef in around 75% of the stress events over the past 30 years – including a number of corals affected by the present bleaching event.  However, as sea surface temperatures continue to increase, bleaching events will become more frequent – and the practice runs opportunities will decline, meaning an increasing risk of coral mortality.  The work does suggest that reducing other stressors such as pollution and agricultural runoff on reefs that show a propensity to increase coral resilience could help increase survival, though in the absence of meaningful emission reductions, this is not a long-lasting solution.

Others are looking to more complex approaches to help The Reef survive both climate change and ocean acidification impacts.  A joint project between the Australian Institute of Marine Science and Hawaii Institute of Marine Biology is looking at “assisted evolution” - accelerating the rate of evolution to help corals adapt to the rapidly changing environmental conditions.  The five year project is exploring four different approaches that may prove viable in producing more resilient corals – selective breeding such as cross-breeding coral from the colder, southern part of the reef with those from the central section; manipulating the microbial communities associated with corals; assisting the evolution of microbes so they become more resistant to stress; and pre-conditioning ‘pregnant’ corals with the aim of producing offspring that are more tolerant to stress (epigenetics).  Whilst concerns have been raised about the potential loss of genetic diversity from such projects, the scientists involved feel the risk of losing The Reef is greater.

If assisted evolution seems an unconventional suggestion, a 2012 paper lead by University of California’s Dr. Greg Rau, outlines some arguably stranger ones.  Experimental shading of corals with anchored, floating material has been shown reduce heat stress, whilst applying low-voltage electrical current could stimulate coral growth after bleaching events.  The scale at which coverage could be applied for these techniques means that in reality they could only act as triage for the most at risk and, due to the costs of implementation, likely most valuable reefs.

Ultimately, meaningful action for the Great Barrier Reef – and indeed all corals, means tackling climate change.  Unfortunately, even if we were to completely stop our greenhouse gas emissions today, we would not see a climatic response in our lifetime. Through ‘committed warming’, temperatures will still rise for some time after emissions cease, though the earlier we take action, the more likely we are to avoid some of the worst predicted impacts of continuing  emissions. One does not need to look too far from The Reef to find one of those greenhouse gas producers – the coal industry.

Australia’s seeming love affair with “big coal”, Professor John Quiggin (University of Queensland) has argued, comes from the idea that the country depends on the industry which does not necessarily hold true.  About 2% of the Australian workforce are employed directly or indirectly by coal, and the A$6 billion per year generated in salaries represents less than 5% of Australia’s total earnings.  In terms of taxation, the industry provides around 1% of the total revenue per year.  Although committing to reduce emissions by 26%- 28% by 2030 at the Paris Climate Change Conference, investment in the coal industry continues whilst renewable energy investment lags.  Commenting on recently approved leases for the Carmichael coal mine and rail project in Queensland, Federal MP for Dawson (Queensland) George Christensen argues that since the coal will be burned overseas, Australia carbon dioxide emissions will not be increasing.  Unfortunately for the Great Barrier Reef, the climate doesn’t differentiate between carbon emitted from Australia or elsewhere in the world – it all adds to climate change and it all impacts The Reef.

Unsurprisingly approval for the Carmichael project has been met with frustration from scientists and NGOs concerned with the health of The Reef.  Referring to Australia’s governments as “behaving like a mob of drunken sailors” in an interview with Australian broadcaster ABC News, world-leading coral researcher Dr Charlie Veron fears that both Australian federal and state governments are not doing enough to deal with climate change or protect the Great Barrier Reef.  Indeed Australia’s pledges made at the Paris Conference – to reduce emissions by 26% - 28% by 2030 based on 2005 levels is far below the 40% - 60% reduction recommended by independent Australian government advisors The Climate Change Authority.  Recently announced cuts to federal government climate science research at CSIRO have done little to bolster faith in Australia’s ability to play its role in reducing climate impacts – and in turn, help The Reef.


Pop-Out Boxes

Two 'pop-out' boxes were also submitted.  They are as follows:

Box 1: The impact of bleaching on the damselfish, banded humbug.

Coral reefs provide habitat for a wealth of other organisms.  Consequently, reef degradation has implications for more than the coral polyps themselves.  Dr. Darren Coker (King Abdullah University of Science and Technology) has researched the movement of the damselfish Dascyllus aruanus – commonly known as the banded humbug living around Lizard Island in the northern section of the Great Barrier Reef following experimental bleaching of branching corals Seriatopora hystrix.  The fish stayed with the bleached coral until it died, after which around 67% of the fish left to live on healthy coral colonies.  Whilst the fish preferentially chose to relocate to coral colonies with other damselfish, competition and aggressiveness of conspecifics already resident on alternative colonies appears to be the primary reason why not all individuals left the dead coral.  When these remaining fish were offered alternatives that had no competitive resident fish, they all relocated.  The work suggests that as long as alterative healthy corals are available, the damselfish will be able to survive.  However where bleaching mortality is widespread, like in the 2016 bleaching event, competition for suitable habitat is likely to become more intense, and perhaps not even reachable if distances are too great.


Box 2: Hyperspectral satellites could identify coral bleaching

Earth-observing satellites have been used by the National Oceanic and Atmospheric Administration (NOAA)’s Coral Reef Watch to provide long-term, near real-time monitoring of the world’s coral reefs for over a decade.  As well as identifying areas at risk of bleaching, the modelling allows forecasting of potential bleaching months in advance.  More recently, the National Aeronautics and Space Administration (NASA) have been trialling hyperspectral instruments that could detect variation in reef colour – meaning it may be possible to see when corals bleach.  The Hyperion hyperspectral instrument attached to the Earth-Observing-1 (EO-1) ‘proof-of-concept’ mission, is able to offer a 30-meter resolution.  This is not the first time hyperspectral imaging has been attempted by NASA.  The Hyperspectral Imager for the Coastal Ocean (HICO) was the first imaging spectrometer specifically designed to sample the Earth’s coastal oceans.  In 2014 after 5 years of operation, the HICO computer suffered a severe radiation hit during a solar storm, from which it never recovered.



Image:  Agincourt Reef, Great Barrier Reef, Queensland, Australia.  Credit: Robert Linsdell/Flickr (CC BY 2.0)