New Study Shows Some Corals Might Adapt to Climate Changes

UM Rosenstiel School-led study exposes two threatened corals to future climate change conditions

MIAMI—New research shows that not all corals respond the same to changes in climate. The University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science-led study looked at the sensitivity of two types of corals found in Florida and the Caribbean and found that one of them—mountainous star coral—possesses an adaptation that allows it to survive under high temperatures and acidity conditions.

“Stressful periods of high temperature and increasingly acidic conditions are becoming more frequent and longer lasting in Florida waters,” said Chris Langdon, marine biology and ecology professor and lead author on the new study. “However, we found that not all coral species are equally sensitive to climate change and there’s hope that some species that seemed doomed may yet develop adaptations that will allow them to survive as well.”

The researchers exposed two threatened Caribbean reef-building coral species, staghorn coral (Acropora cervicornis) and mountainous star coral(Orbicella faveolata), were exposed to combinations of normal (26 degrees Celsius) and elevated temperature (32 degrees Celsius) and increased carbon dioxide levels (pH 7.8/800 ppm) for nine weeks. Genetic and physiological data such as skeletal growth was then collected on the corals to determine if stress events are recorded in a coral’s skeletal history.

At the end of the nine weeks any corals that were still surviving were recovered at the cool temperature and normal pH to determine the capacity of these corals to bounce back once environmental conditions became more hospitable as naturally occurs as summer transitions into fall.

The researchers found that the staghorn coral was more sensitive to heat stress. It experienced 100 percent mortality after 25 days at the elevated temperature of 1.5 degrees Celsius above the historical maximum monthly mean temperature for the Florida Keys.  South Florida waters could begin to experience hot spells of this intensity and duration once every five years by 2035, which according to the researchers suggests that the species could become increasingly rare within 20 years.

The mountainous star coral survived 62 days at the elevated temperature and quickly recovered when temperature was reduced at the end of the experiment. Reduced pH did not affect survival but did significantly impact growth under normal temperatures.

“Based on these results we predict that mountainous star coral will very conservatively be able to tolerate any warming the Florida Keys is likely to experience now until 2060 and very possibly to the end of the century,” said Langdon. “This optimistic prediction needs to be qualified by the fact that decreasing pH will impact the reproductive potential of this species. While the decreasing pH won’t kill the corals outright it will mean that fewer baby corals will be produced to replace adult corals that die of natural or unnatural causes.”

Coral reefs are especially vulnerable to climate change because they are easily affected by warm water. When ocean temperatures rise, the algae that give coral its bright colors leave their host, causing it to look white, a condition known as ‘coral bleaching’. The loss of algae, which provide coral with much of its energy, make corals vulnerable to starvation and disease.

The mountainous star coral had special algae, called D symbionts, which the researchers believe made it able to adapt to the experimental climate change conditions.

Rapidly warming oceans are resulting in more frequent and severe mass bleaching events, while the uptake of CO2by the surface ocean is driving down the pH making it more difficult for corals and other organisms to build their skeleton and shells.

The study allows researchers to better understand how corals respond to heat stress and ocean acidification, which is important since these conditions are expected to affect corals in coming decades and to understand how these stressors are recorded in coral skeletons.

The study, titled “Two threatened Caribbean coral species have contrasting responses to combined temperature and acidification stress,” was published on July 31, 2018 in the journal Limnology and Oceanography, DOI: 10.1002/Ino.10952.

91 thoughts on “New Study Shows Some Corals Might Adapt to Climate Changes

  1. What remarkable science.
    They discovered this adaptable nature of at least some corals, without considering that climate has changed continuously over the past millions of years, while corals have also adapted to those changes.

    • Oh come on Alan. You seriously think that ocean temperatures have varied as much as 1.5 degrees in the past five hundred million years that coral have been around? /sarc

    • Indeed – imagine the changes that coral the entire world over had to deal with as we came out of the last glaciation period and headed towards the Holocene; temps at the polar regions suddenly rose some 8-9 C, and sea level, globally rose some 400 feet (at a rate of 45 mm/yr. during some long periods of time (100’s of yrs))

      • GaryH845

        “Twelve Invisible Eco-Catastrophes and Threats of Doom That are Actually Fake”

        “Ocean “Acidification” will kill all the coral reefs and shellfish in the world”

        “Once again, invisible CO2 will wreck havoc by so drastically lowering the pH of the oceans it will make it impossible for the out-of-sight corals and shellfish to produce their calcareous shells, thus undermining the entire food chain in the sea and destroying fisheries worldwide. This story was invented around 2004; co-incident with the beginning of the 20-year “pause” in global warming that began around 1998. The fact is coral reefs evolved when CO2 was at least 10 times higher than today and corals have survived and thrived for hundreds of millions of years since then. It is also a fact that the Humboldt Current off Peru, which has the highest CO2 and lowest pH in the world’s oceans, produces 20 percent of the world’s fish catch. In other words more CO2 is good for growth in the sea in the same way it is on land. It doesn’t take much research to conclude that ocean “acidification” is one big fabrication.”

        Former Greenpeace activist, founder and Director Patrick Moore.

          • A very colourful homepage. The articles look to be excellent and would keep one busy for weeks reading through them.

            From the article you linked to:
            “In the deep oceans, the CO2 concentration increases as sinking organic matter from biological production (which varies seasonally) is decomposed. These additions of CO2 to the deep oceans cause its pH to decrease … When this CO2-rich deep water upwells to the surface, it creates regions with lower pH in the surface waters”

            I’m not convinced this is true. The map looks to be inconsistent with major river outflows, shallow regions, hot/cold regions, or anything else I can come up with. From undersea ocean current maps that I’ve seen, it also doesn’t appear to match.

            It would be most interesting if someone could do a WUWT article based on a map like this and try to explain it.

          • Greg

            An admirable desire but frankly, no one can really make sense of what you’re asking.

            Much like an understanding of a disease, we can only piece one part of our understanding of anything into the jigsaw puzzle of everything one piece at a time.

            I despair at science sometimes, but take faith in its single irrefutable truth, it is more often wrong than it is right. Without that single human vulnerability, there would be no need for science and the 97% concencus would indeed be correct.

            But it can’t possibly be correct because I believe all scientists would agree that there must be more failures than successes in scientific endeavour. There would be no need for experiments otherwise.

            It appears climate scientists can assure humanity of the future yet they can’t predict the success or failure of GM crops, they can guess at an infants health prior to birth and debate the effects of . They can’t accurately anticipate anything really, because science, to my mind at least, is a constantly evolving observation.

            Science has no answers, only questions.

      • Well, it’s easy-peasy to adjust to temperature and sea-level changes when the CO2 level is constant! It’s that changing CO2 level that chokes the life out of everything, dontchyaknow?

    • “What remarkable science.”…yes
      TDS takes another victim….slowly starting to turn around

      amazing what science can do…..when it’s not being paid to promote one way

  2. It is noted in passing that these same corals survived the ice age, the Minoan Warming Period, the Roman Warming Period, the Medieval Warming period, the Little Ice Age and the Modern Warming Period. I dare say they will adapt to the cooling of the 21st century.

    • Let’s also note that corals live in the Persian Gulf where summer water temperatures reach 36C. The symbiont algae that they host is adapted to warmer waters. It is very likely that in any given population there is a distribution of individuals that are better adapted to warmer or colder temperatures, and that the biggest cohort is adapted to current temperatures. As ambient temperatures change, conditions will favor a shift in the distribution with the best-adapted individuals reproducing more and gradually becoming dominant.

      Despite the fact that ocean oscillation effects like El Niño likely cause sudden temperature shifts far exceeding the long-term shift in average temperature, the alarmists would have us believe that the poor helpless coral critters will not be able to cope and adapt fast enough.

      Another interesting point is that many coral species live in deep, dark water apparently as cold as 4C where they obviously cannot benefit from symbiont algae.

      Reality is always much more complicated than the warmists want us to believe. But I am sure we should be alarmed, because a species with a 500,000,000 year history is obviously very fragile and could be wiped out at any minute.

    • They kept the corals in large salt water aquariums so they could monkey around with the environment. If only corals has claws and teeth….

    • They add CO2 until they deplete the buffer/alkalinity….then the pH will drop
      Alkalinity is more important to corals than calcium….low alkalinity, carbonate/bicarbonate will kill them, when it’s low they will pull carbonate back out of their skeleton and die

      They are assuming, without saying so, that an increase in CO2 will deplete alkalinity….it will not

      also, in their “experiment” the corals were not able to recruit new symbionts…which is what would normally happen….if their zoox were not adapted to the higher temps, the corals simply starved to death

    • Would you support that statement with some facts? You have made me instantly and honestly curious about your assertion.

  3. Just look at the geologic history of coral. Coral evolved during periods of much higher CO2. BTW, Coral are living organisms that exhale CO2 lowing the pH around them to levels lower than the general sea water. Your exhale has CO2 between 20,000 and 40,000 ppm, the atmosphere has CO2 of 400 ppm.

    Isolating the Impact of CO2 on Atmospheric Temperatures; Conclusion is CO2 has No Measurable Impact

  4. Heat is probably the last thing these corals must deal with in Florida waters. They are more likely to catch a chill during the coming Grand Solar Minimum. As with so many other plants and animals that live in and around Florida, they are at the farthest limit of their range. A slight drop in temperature can spell the end for them. Witness the difficulties that manatees go through every winter. RSMAS does it again, perverting would could have been a useful paper on temperature tolerance of local corals into a celebration of Warmists nonsense.

  5. So they take the coral out of normal (26 degrees Celsius) water, and suddenly plop it into elevated temperature (32 degrees Celsius) – and do the same with the Ph change. Ah – shock treatment.

    Now folks – try slowly raising the temp of the water from 26 to 32 C – over several year’s time, and report back to us.

    That’s the issue with el Nino’s sudden warming – shocking the coral.

    PS – coral doesn’t like sudden drops in temperature either. Take the same coral and suddenly plop it into 20 C water, and see how it does.

    Here’s a report (10 yr-long study) that finds that coral – out of the reach of human contact and direct human induced pollution, etc.,. is pristine in many places in the world.

    • Here’s the experiment that I would recommend. Maybe somebody can get me grant money?

      Collect samples of coral from a range of habitats where the ambient water temperature ranges are cooler to warmer. Initially keep them in tanks at their normally-accustomed temperatures. Now put the coolest-temperature group into a test tank together with the next warmer cohort and with the test tank water temperature ideal for the coldest water corals. Next, gradually warm the water to the optimum for the second cohort and add the third cohort of still-warmer-water corals to the tank. Once again gradually raise the water temperature to the optimum for the third cohort. Continue doing this until all of the corals are in the tank and the temperature is at the optimum for the warmest-water corals.

      I would predict that all of the colonies will survive and end up hosting the type of symbiont algae found in the warmest water samples.

      The same experiment could then be performed in reverse, starting with the warmest-water corals at their accustomed temperature and adding the next cooler-water sample, then gradually cooling the water to the temperature optimal for the second-to-last cohort, etc. The difference in the second experiment should be that in the end, all of the corals have symbionts that were originally only in the coldest-temperature coral colony.

  6. My understanding is that the algae do not “leave” but are expelled by the coral to allow a better suited variety to colonize. In an artificial, controlled lab environment alternatives may not be available.

    • Yes, I think that is correct Steven. That’s a key defect of their study. They have a closed system where the only available symbionts are the ones that are not adapted to the warmer water. In the experiment that I proposed above, if there is a range of symbiont algae in the environment, my theory is that the coral colonies will all end up hosting the best-adapted symbionts (and a few less-well-adapted variants will of course continue to exist to the extent that they can survive the new conditions).

  7. “The researchers exposed two threatened Caribbean reef-building coral species, staghorn coral (Acropora cervicornis) and mountainous star coral(Orbicella faveolata), were exposed to combinations of normal (26 degrees Celsius) and elevated temperature (32 degrees Celsius) and increased carbon dioxide levels (pH 7.8/800 ppm) for nine weeks. ”

    Did they gradually raise those levels over the same time period it is theorized it would take for them to change naturally?

    • of course not…nor did they allow them to change out their dinoflagellates/zoox like they would normally do
      20 something days…the corals probably just starved to death

  8. Did they give any thought to looking at the taxa lists for coral reefs in really warm environments like the Red Sea and Persian Gulf?

  9. ‘New Study Shows Some Corals Might Adapt to Climate Changes’ If wishes were horses beggars MIGHT ride….

  10. Ours is a planet of unrelenting change. Every living species present today is here because they are unrelenting in their genetic abilities to Survive, Adapt, and Thrive! Why would we expect anything else?

  11. “…increasingly acidic conditions…” that are not close to being acidic conditions at all.

      • They were specifically referencing current conditions, lol…

        “…increasingly acidic conditions are becoming more frequent and longer lasting in Florida waters…”

    • Fake science, I do not know, but absence of it, I can see. Sorry WUWT, but it has been rather warm in the Northern hemisphere lately -hot, actually, in many parts-. Your absence from the debate has been obvious.

      • “Sorry WUWT, but it has been rather warm in the Northern hemisphere lately -hot, actually, in many parts”

        .. Psssst…..It is called “Summer” !!!!

        And guess what… it gets rather cool in the Northern hemisphere in winter -cold, actually, in most parts !!

        • I thought I had mentioned that I was talking about about a slightly warmer situation than the usual, I also thought that anybody but a stupid asshole would have noticed that.

          • “rather warm in the Northern hemisphere lately -hot, actually”.. does not equal “a slightly warmer situation than the usual”….

          • In the N hemisphere, some regions have been cooler than usual, while others have been warmer than usual.

            Personally, I hope they ban you for that sort of vitriol.

          • Hey Francois, how are those Northern Hemisphere sea temps? You know…the ones so cool that there’s been hardly any Atlantic hurricane activity and the reason why the rest of the hurricane season is projected to be abnormally quiet?

            What does a warmer-than-average Northern Hemisphere have to do with the topic of the thread? Anybody but a stupid asshole would notice that it is about coral adapting to temperature and pH.

  12. The problem with this type of aquarium experiment is that the corals adapt to changed temperatures by changing their symbiotic zooxanthellae. In the ocean there are many strains around, in aquariums not so much.

  13. The idea that there are “increasingly acidic conditions” in the ocean is simply not true. The ocean is growing increasingly NEUTRAL … but that doesn’t sound sufficiently terrifying.

    It does, however, provide an easy way to determine if something about the ocean is hype—if they talk about “acidifying”, it’s hype.


    • Dear Sir, up to a point, your endless ranting about “increasingly acidic” conditions, or “less basal” conditions are not indicating anything about the real ocean we are talking about. The hype is yours, you are not talking about real things, just conjecturing on your dreams.

      • Frenchy: No one is going to listen to you without you providing some sort of explanation or clarity.

      • Francois, anybody but a stupid asshole would know that “increasingly acidic conditions” was intentionally selected and used for its rhetorical impact. The “real oceans” are not in the midst of acidic conditions. It’s akin to saying that a billionaire is experiencing “increasingly impoverished conditions” whenever he spends some money.

        • Michael Jankowski
          ….It’s akin to saying that a billionaire is experiencing “increasingly impoverished conditions” whenever he spends some money.

          Perfect analogy!

      • Francois.

        It is scientifically correct to say that some parts of seas or oceans are becoming slightly less basic (not basal), if that indeed be happening, which on an ocean-wide basis has not been demonstrated and can’t be.

        It should be obvious that “increasingly acidic” is simply a propagandistic phrase, without scientific basis.

      • François writes

        The hype is yours, you are not talking about real things, just conjecturing on your dreams.

        Neither are the purveyors of “acidic effects” when they equate how life copes with an equilibrium change vs how an inanimate object reacts chemically.

      • they do fine…even when it rains..those corals were way over 90 degrees
        Live corals are shipped dry….just shake them off and drop in a bag
        …all anemones are rung out and shipped dry too

  14. Oh, yeah, I wanted to point out that most of the world’s coral is found in what is called the “coral triangle“. Why is this of note?

    It’s because the water in the Coral Triangle is the warmest ocean water of the planet. Now, given that corals grow where the water is warmest, do you really believe that warming waters endanger the Caribbean or Australian coral reefs, all of which are growing in much cooler water?


    • Indeed. I’ve been wondering if there is any body of sea water on the planet that isn’t hypersaline or somesuch that is simply too warm for corals. I suspect not and that once acclimated, tropical reef corals can probably survive any temperatures that sea water can reasonably reach without the help of volcanic vents or molten lava

      Not to mention that if the oceans actually warmed significantly, tropical reef corals would surely expand poleward of their current limit.

      • Since corals thrive in the hottest seawater on the planet, the answer is no. Many species do live in deep, cold water, but they’re not subject to bleaching.

        No point in having a photosynthetic symbiont if you live where the sun doesn’t shine.

  15. Mod

    Is there a problem with the WUWT blog?

    It’s desperately slow and unresponsive. Copy and paste is a waiting game.

    Or is it my end that’s the problem?


  16. “Over half of all known coral species are found in deep, dark waters where temperatures range from 4-12° C. For this reason, we call these corals the “cold-water” or “deep-sea” corals. They are found all over the world.”

    • Note that these corals have a completely different biology from the hermatypic (=reef building) corals that only live in warm shallow water. For one thing they don’t have any zooxanthellae (no light = no photosynthesis).

      • Yes, that’s true. The corals in shallow tropical waters have evolved to depend on their symbionts and that makes them less robust in the face of climate change but also makes them able to grow faster when conditions are conducive. There has always been climate change and they have always adapted. It’s absurd to say that the current minor warming is worse than any changes that they have experienced over the past 500 million years.

  17. Reading the abstract, they make predictions about the studied species chances of surviving past 2035, based on immediately raising either the temperature or the CO2 concentrations to extreme levels.

    Not only is it incredibly unlikely that either condition will occur by 2035 (or during the rest of the century), it discounts the fact that the corals would have decades in which to adapt.

    These people are not scientists.

  18. “there’s hope that some species that seemed doomed may yet develop adaptations”

    One possible translation: We told you 20 years ago that the coral reefs would all disappear in 5-10 years. This is why it didn’t happen.

  19. I don’t see any mention of this in the comments, so perhaps that indicates some of you are not familiar with the Bikini Atoll. That was the site of a series of high-yield thermonuclear tests from 1946 to 1954. Testing was done in the coral reefs, seabed, waters, and airspace. Unimaginable heat. Tremendous shockwaves and craters. Radiation that remains too high for human habitats to this day.

    No idea how it changed the pH of the water, but odds are great it changed radically for a while. Note, too, that these were instantaneous changes, not a slow evolution.

    The coral reef? It’s fine.

    Corals will survive longer than Man, imo.

    • Yeah but what about the poor coral polyps that were there when the bomb went off? Think of the children!

      • Don’t know the effects the bombs had on the polyps, but polyps in carbon dioxide infused water are a good thing. If you are old enough, you will remember, “Polyp, polyp, fizz, fizz, oh what a relief it is.”

        (Sorry. Couldn’t resist.)

  20. “Stressful periods of high temperature and increasingly acidic conditions are becoming more frequent and longer lasting in Florida waters,” said Chris Langdon, ”

    Say no more. Get the kids outa the water now.
    (Sarc. coz the protocol requires it)

  21. A few years ago I watched a pro-AGW IMAX film on coral reefs, which focused on The Great Barrier Reef. In the narration, they slipped up be revealing that reef sits on the fossilized remains of a dozen other reefs. Instantly I realized that meant that the reef had been completely killed off in other epochs, yet there it is today in all it’s glory. It also means that there is some survival mechanism that allows the reef to completely restore itself in the same place after total destruction.

    There have been many articles here at WUWT that have dealt with false representations of how much the reef has been damaged by CAWG or other man-made supposed catastrophes. The use of the word “acidified” causes me to instantly discount an article or post as propaganda. Man has initiated processes that have made a dent in killing The Great Barrier Reef. Despite that, 95 percent of the reef remains a massive living thing. Reading about it before writing this post, I was surprised to learn that not all of it has been explored yet.

    It must have been an imposing sight during the last ice age rising like a dead tower out of the ocean. Yet there it is, one of the most beautiful things to explore underwater on our planet.

  22. Having a little bit of knowledge about the Florida Keys environment it is hard for me to believe that 32 degrees C (89.6 degrees F) is not been a relatively common occurrence in the Keys. Yet it would be interesting to know exactly where they got their temperature data from “the wild.” The Florida Keys, especially the reef system is an extremely dynamic place, most especially the outer edges of the reef that are influenced by the Florida Current. And the Florida Current doesn’t exactly stay in one place for very long.

    Corals are difficult to keep in captivity. Some species do not do well even if you match what you might believe are optimum conditions. I have known only a couple of people that kept more than a couple of species successfully. Interestingly the folks I knew that kept corals really well were not degreed scientists.

  23. Coral reefs that have survived for millions of years. I am totally surprised they can adapt of climate change. Next someone will work out that polar bears, turtles and crocodiles maybe able to adapt as well.

  24. Corals are a non issue. They just move around on the currents to wherever is best for them. The GBR is older than the current series of ice ages, when sea levels drop 100 metres and you can walk from Cairns to the GBR most of the time… Coarls are not endangered, they are prolific and regenerate wherever conditions are appropraiate. When the reefs move, which natural change ensures, the tourist hence research money moves with them. But very slowly, there is a difference between regional weather cycles and sea level change, cyclonic damage recovery, and any effect from much smaller and slower actual global climate change, which is almost imperceptible in comparison. Nothing to sea hear.

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