Some corals do well in warmer waters – researchers ask how

From the National Oceanography Centre, Southampton (UK)

This shows Acropora coral from the Persian/Arabian Gulf bleached during summer 2012. Credit: Coral Reef Laboratory

How do corals survive in the hottest reefs on the planet?

Coral reefs are predicted to decline under the pressure of global warming. However, a number of coral species can survive at seawater temperatures even higher than predicted for the tropics during the next century. How they survive, while most species cannot, is being investigated by researchers at the National Oceanography Centre, Southampton (NOCS) and New York University Abu Dhabi (NYUAD).

We tend to associate coral reefs with tropical seas of around 28 degrees, where even slight warming can have devastating effects on corals. But in the Arabian/Persian Gulf, corals survive seawater temperatures of up to 36 degrees Celsius every summer, heat levels that would kill corals elsewhere.

In their study, the NOCS team worked closely with NYUAD researchers to select and characterise model corals from the Arabian/Persian Gulf, which will facilitate future molecular-scale investigations into why they can tolerate heat stress.

“We have established successful laboratory cultures of Gulf corals,” said Dr Jörg Wiedenmann, Head of the Coral Reef Laboratory and Senior Lecturer at University of Southampton Ocean and Earth Science, both of which are based at NOCS. “This will greatly accelerate the progress of unravelling the mechanisms that underlie their surprising heat resistance.”

Reefs are made up of many species of coral, each of which have a mutually beneficial, or “symbiotic”, relationship with algae living in their tissue. These algae supply vital nutrition to the host but are sensitive to environmental changes including increases in seawater temperature.

Even a temperature rise of just one degree Celsius can harm the symbiotic algae, which in turn can increase mortality in corals. The associated loss of symbiotic algae is known as “coral bleaching” because the white skeletons of the corals become visible through the tissue depleted from the algal pigments.

“In Gulf corals, both the coral host and the associated algal partners need to withstand the high seawater temperatures,” said Dr Wiedenmann who led the study.

But the scientists were surprised to discover that the algae in Gulf corals belong to a group not known for its thermal tolerance.

“We see that the algae are indeed special but in a way that we did not expect,” said Dr Wiedenmann. “The algae that we found in most of the corals in Abu Dhabi reefs were previously described as a ‘generalist strain’ that is usually not found in corals exposed to high levels of heat stress.”

“The system seems to be more complex than it is commonly thought but now we are in an excellent position to tackle these important questions.”

The Natural Environment Research Council (NERC) has recently granted funding to Dr Wiedenmann and the Coral Reef Laboratory, so that the team can do just that. The researchers will build on their previous findings and use their model corals to investigate the molecular mechanisms that allow corals to thrive at extreme temperatures.

Already around 30 per cent of coral reefs are severely damaged and more than half of coral reefs worldwide may be lost within the near future because of global warming. A better understanding of how corals respond to rising sea temperatures is important for predicting the fate of coral reefs and to optimise reef conservation.

“Gulf corals are living at the limit of their tolerance,” said co-author Professor John Burt from the New York University Abu Dhabi. “We have observed an increased frequency of coral bleaching events in this area, and we need to act now to protect and understand these ecosystems that hold the answers to many important climate change related questions.”

The study was published in the journal Marine Pollution Bulletin as part of a special issue on coral ecosystems of the Gulf that was initiated during the first NYUAD “Coral Reefs of the Gulf” conference in 2012.

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The paper – Hume B., D’Angelo C., Burt J., Baker A.C., Riegl B. and Wiedenmann J. (2013) Corals from the Persian/Arabian Gulf as models for thermotolerant reef-builders: Prevalence of clade C3 Symbiodinium, host fluorescence and ex situ temperature tolerance – is available online at http://dx.doi.org/10.1016/j.marpolbul.2012.11.032.

Reference: B. Hume, C. D’Angelo, J. Burt, A.C. Baker, B. Riegl, J. Wiedenmann, Corals from the Persian/Arabian Gulf as models for thermotolerant reef-builders: Prevalence of clade C3 Symbiodinium, host fluorescence and ex situ temperature tolerance, Marine Pollution Bulletin, doi: 10.1016/j.marpolbul.2012.11.032.

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27 thoughts on “Some corals do well in warmer waters – researchers ask how

  1. Always wondered why Scientists assumed Coral reefs wouldn’t cope with temperature rises.

    Coral has survived through much warmer periods than now. I just assumed that the coral that couldn’t cope with warmer temperatures would decline, whilst those that could would take over. And vice versa for colder temperatures.

  2. “We have observed an increased frequency of coral bleaching events in this area, and we need to act now to protect and understand these ecosystems that hold the answers to many important climate change related questions.”

    Maybe it is the increase of shallow water by the created islands in the gulf that increase the temperature so it is AGW (Anthropogenic gulf warming )

  3. Just for point of reference, humans and all of their various parasites, bacteria, viruses, fungi, etc. all survive perfectly at 37C, with occasional forays into even higher temps (which can assist the body in killing off some of the more delicate invaders). It’s difficult to imagine that ocean life can’t either survive at similar temperatures, or that some other well adapted life can’t fill the niche currently occupied by life forms that favor lower temperatures.

    Sometimes I wonder how someone can be smart and/or intelligent and/or educated and yet still miss the glaringly blindingly obvious.

    “Gulf corals are living at the limit of their tolerance,” said co-author Professor John Burt from the New York University Abu Dhabi. “We have observed an increased frequency of coral bleaching events in this area, and we need to act now to protect and understand…

    How, exactly, do we “act now”? What course of action will “act now” involve? Because if it involves reducing CO2 emissions, I’m not buying it. Maybe, just maybe, consider that if something unusual is happening at those reefs, some OTHER agent is responsible, such as actual pollution… like a surplus or shortage of some nutrients or chemicals.

  4. On another thread we are discussing human interaction with animals and to a lesser extent plants. The coral has figured out how to survive heat. But these men don’t know how it can. We need to study this more they cry. Which translates to, “give us money so we can save the planet”. Meanwhile the coral are doing okay. Which species is arrogant and foolishly wasting resources and which is motoring along just fine? Yes humans and plants and animals are different. The differences do not always flatter humans.

  5. “How do corals survive in the hottest reefs on the planet?”

    I believe the term is ‘Natural Selection’.
    H/T to Charles Dawin.

  6. Well, it would appear that as always, our wise and learned scientists are forever “surprised” when their “modeling” of something doesn’t fit the reality. If science went back to the “scientific method” instead of “assuming and modeling,” perhaps we would finally start to get a handle on our world and how we actually interact with it. Looks like, in the case of the coral, different algae populations build up in the coral to nurse the coral through temperature changes. Funny, really. I never thought that everything in the world was so “temperature change intolerant” as what our “scientists” seem to believe.

  7. A fundamental assumption that narrows western science potential for analysis and understanding is that change is gradually over long periods of time. From this comes the alarmist claim that plants and animals will not cope with the temperature changes anticipated by the IPCC. A brief look at the record shows a remarkable range of adaptive capability and also built in recovery mechanisms. Of course there are upper and lower temperature limits, but they are much wider than generally applied.

  8. I thought corals were supposed to be at risk not from warmer temperatures directly but ocean ‘acidification’.

  9. ‘We tend to associate coral reefs with tropical seas of around 28 degrees, where even slight warming can have devastating effects on corals. But in the Arabian/Persian Gulf, corals survive seawater temperatures of up to 36 degrees Celsius every summer, heat levels that would kill corals elsewhere’

    Anybody ever hear of an obscure theory in an old book ‘The Origin of Species’ by an guy with a beard called ‘Charles Darwin’? I think he called it evolution or something….but it never caught on.

    Might be worth taking another look though……

  10. Tim Ball says:
    February 6, 2013 at 6:54 am
    A fundamental assumption that narrows western science potential for analysis and understanding is that change is gradually over long periods of time. From this comes the alarmist claim that plants and animals will not cope with the temperature changes anticipated by the IPCC.
    ======================================================
    See also : summer, winter

  11. However, a number of coral species can survive at seawater temperatures even higher than predicted for the tropics during the next century. How they survive, while most species cannot, is being investigated
    ===================
    We already know this….they have different zoox

  12. Did they say 30 percent of coral reefs are severely damaged …. due to global warming??? Seems that that ‘fact’ has already been shown tenuous.

  13. Oi! We dove these bloody reefs 6 months ago, and would ya look at that! It’s bleached!
    The reefs we dove after that are bleached, and the next reef and the next. It’s GOT to be that pesky global warming wot done it!

    Never mind the corals we didn’t dive in the same area aren’t bleached, it’s the warming!

  14. “Coral reefs are predicted to decline under the pressure of global warming. However, a number of coral species can survive at seawater temperatures even higher than predicted for the tropics during the next century. How they survive, while most species cannot,”

    These predictions are wishful thinking by the warmists, as they had to have everything going bad with warming. However, calcium carbonate is less soluble in warm water than cold and warmer is thus better. Furthermore, coral metabolism simply increases and lays down more base; they grow faster. Rapid warming or cooling can kill corals, but there has been no rapid warming by their standards. And, as we are currently actually cooling, the current “warming” is truly not a threat.

    Coral bleaching from temperature changes is a normal thing. Go back a few months later anf the corals are all good again. They bleach to switch their symbiotic photosynthetic organisms to those better suited to the new temperature. They are changing their clothes. Warmists love to report bleaching but never go back later to find that the bleaching is gone.

    It is cooling that threatens coral ranges as the CaCO3 solubility increases with cooling.

    As they buy into the claimed warming in the next century and the “threatened” corals, these bozos are not marine biologists. Even the higher CO2 is a boon for corals as they have more food from which to build structure. pH changes are little to none due to CO2, particularly as photosynthesis is an alkalizing process that can RAISE the pH by 2–3 whole units during daytime. A bit of acidification might be a good thing, but carbonic acid is a non-starter in the complex buffer of sea water.

  15. It is ingenuous of them to pretend that they are surprised that life is so resilient. Corals have been around sooooo much longer then us and have been through many temperature changes. Millions of years of glaciations and inter glacials. Just like the polar bear, they have been there before—been there, done that.

    Their assumption that corals are fragile in the face of normal climate changes belies a poor education or one that was biased by the needs of the global warming agenda.

  16. The most important fact gleaned from this “paper” is that they do NOT know why…

    This is the usual human condition and not terribly surprising, eh ? Keep that fact in mind for 90% of climate science and it will serve you well.

  17. higley7 says:
    February 6, 2013 at 10:29 am
    It is ingenuous of them to pretend that they are surprised that life is so resilient. Corals have been around sooooo much longer then us and have been through many temperature changes
    ====================
    higley, the argument is “rapid” change……but then they can’t explain why bleaching is a normal response to rapid changes…so bleaching has become the new coral death….even though bleaching is perfectly normal and the way corals have adapted to rapid change…..

    Then ask them how corals are packed and shipped all over the world for the aquarium hobby…if corals are so delicate

    switch their symbiotic photosynthetic organisms = zooxanthellae = dinoflagellates = at least nine clades
    so they more or less have a choice of nine different ones and more than one at the same time…….
    They can also reduce or increase the amount of one clade or more than one and not technically bleach at all.

  18. I love these guys. For years I’ve been saying the corals wouldn’t die from a degree or so of warming, or they’d have been dead for eons. And for years the mantra has been that no, I was an idiot because it was well understood about coral, the science was settled … and now this guy says:

    “The system seems to be more complex than it is commonly thought but now we are in an excellent position to tackle these important questions.”

    At least they’ve gotten to where the first half of their sentences are true … and the gradual climbdown continues …

    w.

  19. As a personal observation in the Maldives over the past 20 years, I have seen that is is generally the coral in the shallow lagoons (highest temp) that grows back first after a bleaching event. Bleaching also occurs in the deeper areas where there are upwellings of colder water that never reach such high temperatures. As many seem to have recognised, there is far more to this than temperature. There seems to have been a blinkered approach that it must be “Global Warming” yet, as others have pointed out above, there have been warmer periods & strangely, we still have coral. Still, maybe now that the “Experts” have caught up with us lay people, there may be progress. I live in hope!

  20. Don’t these idiots every take ONE course in Geology????

    The whole blasted lot of them need to go back to school and learn REAL SCIENCE… OH Wait… link

  21. How much coral bleaching & other damage is caused by sbf50 or other degrees of sunblock worn by the divers checking this?
    DaveE.

  22. Corals in the Gulf (1) withstand summer temperatures up to 10°C higher than corals elsewhere and have recovered from extreme temperature events in 10years or less. This heat-tolerance of Gulf corals has positive implications for the world’s coral populations to adapt to increasing water temperatures. However, survival of Gulf corals has been severely tested by 35-37°C temperatures five times in the last 15years, each time causing extensive coral bleaching and mortality. Anticipated future temperature increases may therefore challenge survival of already highly stressed Gulf corals. Previously proposed translocation of Gulf corals to introduce temperature-adapted corals outside of the Gulf is assessed and determined to be problematical, and to be considered a tool of last resort. Coral culture and transplantation within the Gulf is feasible for helping maintain coral species populations and preserving genomes and adaptive capacities of Gulf corals that are endangered by future thermal stress events.

  23. IIRC, coral evolved during much warmer times and climes. Somehow they managed to adapt to our chilly conditions. I’m sure they’ll be happy to get back to normal.

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