Marine biology: Acidified oceans may corrode shark scales

Prolonged exposure to high carbon dioxide (acidified) seawater may corrode tooth-like scales (denticles) covering the skin of puffadder shysharks, a study in Scientific Reports suggests. As ocean CO2 concentrations increase due to human activity, oceans are becoming more acidic, with potential implications for marine wildlife. Although the effects of acidified water have been studied in several species, this is the first observed instance of denticle corrosion as a result of long-term exposure.

Lutz Auerswald and colleagues investigated the effects of exposure to acidified seawater in puffadder shysharks. The authors found that in three sharks housed in acidified seawater for nine weeks, 25% of denticles on average were damaged, compared to 9.2% of denticles in a control group of three sharks that had been housed in non-acidic water. They suggest that such corrosion may impair the sharks’ skin protection and open-water sharks’ ability to swim, as denticle surface affects their swimming speed. They also speculate that similar corrosion may occur in sharks’ teeth (which have the same structure and composition as denticles), which may negatively impact their feeding.

However, the authors also found that although exposure was linked with increased carbon dioxide concentrations in blood taken from a total of 36 sharks housed in acidified seawater for different periods of time, concentrations of carbonate also increased. This prevented the blood from becoming more acidic, suggesting that these sharks may be able to adjust to high CO2 conditions during periods of exposure.

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Article and author details

Acid-base adjustments and first evidence of denticle corrosion caused by ocean acidification conditions in a demersal shark species

Corresponding author:

Lutz Auerswald
Department of Environment, Forestry and Fisheries and Stellenbosch University, Stellenbosch, South Africa

DOI

10.1038/s41598-019-54795-7

Online paper

https://www.nature.com/articles/s41598-019-54795-7

From EurekAlert!

~cr comment.  PH of 7.3 expected in the year 2300, probably under RCP 8.5

118 thoughts on “Marine biology: Acidified oceans may corrode shark scales

  1. The oceans are not acidic, and never will be. Even if reduced to Ph 7.3, which is unlkely, the ocean is alkaline.
    The way this article is written is highly misleading.

  2. “3 per replicate for hypercapnic treatment, 2 or 3 for normocapnic treatment.”

    So normocapnic sharks were less handled than treated sharks. They found more damage to hypercapnia treated sharks. Could the extra damage have been caused by extra handling? Did they always sample the same area of the sharks? They don’t say.

    • Pretty sad that some sharks were “sacrificed using ethylene glycol monophenyl ether (C8H10C2, 0.8 ml l−1)” for something that is unlikely to happen in another 300 years from now.

  3. It says that these sharks adapt to a highly variable environment: possibly being stuck in a tank with an abnormal ph does not allow for adaptation.

  4. pH of 7.3 = basic. Whenever a “scientists” talks about a basic liquid (e.g. sea water) as being acidic, that is the first clue that there is no science being done. Just advocacy.

    • Yes, the water would be nearly neutral. How in anything but a deranged bureaucratic so-called scientist’s head can this be “acidic”? They FLUNK, FAIL, and are demoted to janitors based on their knowledge of chemistry. Never allowed to publish again. It is so absolutely frustrating how ignorant or dishonest these people are. I’m leaning toward absolute pathological liars at this point.

      There is no emissions scenario under which the ocean is actual acidic—NONE. Less alkali or neutral at the most. None of them have ever heard of buffering, either.

      • Then again Sheri. Most janitors I’ve known know the difference between what is acidic and what is more like lye or ammonia. Their language addresses acid but expresses base as anything that acts like lye or ammonia.

        However in my Chemical Engineering days I use to run into engineers, scientists and M.D.’s who had no clue about chemistry. It seems that many here on WUWT have a healthy amount of applied knowledge and are willing to reconsider what they know when things fail to add up in their experience. I feel blessed to be able to read that they contribute. You are one such contributor also.

        Practicality is a powerful tool for waking a person up to what works and what doesn’t, as I am sure you know. I always enjoy your posts. Thank you. Merry Christmas to you and yours.

    • Well I read the paper, the authors don’t use that terminology, they use the term hypercapnic. Whoever wrote the article was the one who used the term “non-acidic water” the authors referred to it as “normocapnic treatment”.

    • “The ocean is not acidic.”
      He didn’t say it was. He spoke of acidified seawater, and defined his terms:
      “high carbon dioxide (acidified) seawater”.

      The endless claims here that you can’t talk of acidity until pH is below 7 are just ignorant. You can increase the acidity of any environment (or reduce it). Just as you can heat it, regardless of its temperature.

      There are conditions that acidify your blood, causing acidosis. Blood pH is normally 7.3. You’ll be gone before it gets to 7. No use insisting your blood is still basic.

      • The Science News article (see below) said “After nine weeks of exposure to seawater doctored to mimic projected acidic levels in 2300” and “the average pH of oceans will dip from 8.1 today to 7.3 by 2300.”

        Still alkaline. I’d be happy with “less alkaline,” I think acerbic thoughts when I hear that pH 7.3 is acidic.

        • Acidification is the act of making a solution acidic. Going from pH 8.1 to 7.3 is more like neutralization than acidification (Is pH 7.3 is predicted according to RCP 8.5? If anyone is familiar with the reference: “Stocker, T.F., et al., Eds., IPCC (2013) Climate Change 2013: The Physical Science Basis” please let us know.)

        • The trouble is that alkalinity in sea water isn’t defined by pH, it is the sum of all the bases present including borates, silicates, phosphates, carbonate, bicarbonate etc. so ‘less alkaline’ isn’t appropriate.

      • Medical terminology (acidosis) does not define chemical usage, Nick.

        In Chemistry, one can’t talk of acidity until pH is below 7. Supposing not is just ignorant.

        One can reduce alkalinity until pH 7, and then go on to increase acidity.

        Reducing marine pH from 7.9 to 7.3 is not increasing acidity, because pH 7.3 is not acidic. It is alkaline.

        The transition from pH 7.9 to 7.3 is a reduction in alkalinity. It is not an increase acidity, despite it is an increase in [H3O+], because the solution neither began nor finished as acidic.

        Calling less alkaline marine water acidified is a dishonest confusion of terms; typical of the hyper-politicized pseudo-science that is AGW consensus climatology.

        Pseudo-science that you hotly defend, Nick.

        • “In Chemistry, one can’t talk of acidity until pH is below 7. Supposing not is just ignorant.”
          The term here is acidification. But I think your claim is just ignorant, and I’d invite you to cite authority for it. Acidity is relative to some buffer system. In water, or with titrations of strong acid/strong alkali, where the H⁺/OH⁻ system is the nearest thing to a buffer, pH 7 is the neutral point. But other buffers have different points. The bicarb/CO₂ settles to pH 7.3, and anything on the acid side of that has consequences. So does shifting the pH of sea water.

          • Nick – Why don’t you check the dictionary definition of acidification and neutralization. I’m a Chem Eng. and I also did check the dictionary definition. Acidification is a misuse of the word which is just one more reason it’s so easy to be a skeptic these days.

          • “Why don’t you check”
            Let’s have some actual quoted, preferably scientific, authority for the claim that you can’t speak of acidifying a solution until the pH is below 7?

          • What you think is mere opinion, Nick. You’re untrained.

            I’m a PhD professional experimental chemist. On this question, I am an authority.

            Reducing pH from 7.9 to 7.3 is not acidification. If anything, it’s dealkalization; an awkward terminology that is not used.

            If someone said they acidified a pH 7.9 solution, the expectation would be that the final pH is less than 7.

            The usual way of describing pH 7.9 to pH 7.3 change would be, ‘reduction of alkalinity.’

            But those charlatans use “acidification” to garner attention and angle for grant money.

            the H⁺/OH⁻ system” is not a buffer. Pure water is unbuffered.

            Buffers do not have neutral points. They have equivalence points where the Brønsted acid and base forms are of equal concentration.

            You don’t know what you’re talking about, Nick. You just defend the lurid usage of CO2 demonology; using your education to deliberately mislead. For reasons only you know.

          • Some examples:

            Acidification: the process of becoming acid or being converted into an acid (The Free Dictionary)

            Acidification: The act or process of acidifying, or changing into an acid. (Websters 2013)

            Acidify: to convert into or become acid (Collings)

          • Nick, “actual quoted, preferably scientific, authority

            That’s me, Nick. 30+ years an experimental physical methods chemist.

          • Come on, Nick Stokes. You know why climate change alarmists like to bandy around the term “ocean acidification”. Why defend them? How dare you!

          • “I am an authority.”
            You’re not a great respecter of mathematical authority. But let’s hear an independent authority.

            ““the H⁺/OH⁻ system” is not a buffer.”
            Yes, it is. It’s just that the pH range is wide. But if you put in a stronger acid, say HCl, or a stronger base, say NaNH₂ , they react with the counterpart H⁺/OH⁻, just as in any buffer system. OK, you could say that they react with water – it’s the three -way system, like CO₃⁻/HCO₃⁻/CO₂ .

            It’s true that it isn’t a pH buffer.

            “Buffers do not have neutral points. They have equivalence points”
            If you prefer that term.

          • Stokes doing a Stokes Defense as usual and redefining everything, why do you guys waste your time with the old troll.

          • Nick, “You’re not a great respecter of mathematical authority.

            Supposing you mean yourself, Nick, you’re not a mathematical authority. Because you’re an opportunistic mathematical obfuscater. As an non-honest broker, you’re not a viable authority on anything.

            Has it ever occurred to you that your propensity to mislead betrays the pedagogical integrity of the people who trained you in mathematics? Did they indulge your tendency, you’d have been betrayed. But they were honest.

            But let’s hear an independent authority.

            What’s the substantive difference? You’d not know who’s correct. You’d only know who you prefer to believe. Like someone who chooses the cleric whose preachments are agreeable.

            
“Yes, [the H⁺/OH⁻ system” is a buffer]. It’s just that the pH range is wide.

            pH is defined as the negative log of the hydrogen ion concentration in water, Nick. Water cannot be a buffer in water. Outside of water, pH has no strict analytical meaning.

            But if you put in a stronger acid, say HCl, or a stronger base, say NaNH₂ , they react with the counterpart H⁺/OH⁻, just as in any buffer system.

            No, they do not. Both of them react with H2O. The NaNH2 reacts irreversibly.
            NH2(-) + H2O -> NH3 + OH(-).

            The buffer partner of NaNH2 is NH3. The buffer partner of HCl is NaCl (or the equivalent salt).

            The buffer ion in aqueous HCl is chloride, not OH(-).

            OK, you could say that they react with water – it’s the three -way system, like CO₃⁻/HCO₃⁻/CO₂ .

            Neither HCl nor NH2(-) is anything like the carbonate system, except they all have something to do with hydrogen.

            It’s true that it isn’t a pH buffer.

            Buffer pH only has meaning with respect to [H+] in water. One can use the term buffer for other systems, such as redox buffers used to maintain a certain emf.

            But equivocating the definition of “buffer” won’t make you right.

            If you prefer that term.

            Equivalence points are not neutral points. Equivalence point has a very specific meaning. That term is not equivocal and it does not mean neutral.

          • “The buffer partner of NaNH2 is NH3. The buffer partner of HCl is NaCl (or the equivalent salt).”
            For a PhD professional chemist, you’re pretty hazy on this stuff. NaNH₂ cannot be a buffer partner in aqueous solution, because it is a stronger base than OH⁻. The buffer partners are always the weakest base present, and the weakest acid. Chloride cannot be a conjugate base, because it cannot accept a proton in aqueous solution; the water would accept it first.

            “Neither HCl nor NH2(-) is anything like the carbonate system”
            I didn’t say it was. The analogy is with the OH⁻/H₂O/H₃O⁺ system. The most basic component can accept two protons. So if you add H⁺ to sea water, it will be accepted by CO₃⁻⁻, if abundant, or HCO₃⁻, in a more acid environment. Likewise HCl will give a proton to OH⁻, if abundant, or H₂O if not.

          • Nick Stokes, December 20, 2019 at 8:39 pm , “NaNH₂ cannot be a buffer partner in aqueous solution, because it is a stronger base than OH⁻

            Nick Stokes, December 20, 2019 at 6:21 pm , “… say NaNH₂ , they react with the counterpart H⁺/OH⁻, just as in any buffer system. (my bold)”

            Nick Stokes, shifting his ground.

            Chloride cannot be a conjugate base …

            Chloride is the conjugate base of HCl

            I didn’t say it was.

            Yes you did. You wrote, “But if you put in a stronger acid, say HCl, or a stronger base, say NaNH₂ , they react with the counterpart H⁺/OH⁻, just as in any buffer system.OK, you could say that they react with water – it’s the three -way system, like CO₃⁻/HCO₃⁻/CO₂ .

            That’s you supposing that HCl or NaNH2 is like the carbonate system.

            And you’re wrong to suppose that a shift in pH from 7.9 to 7.3 is acidification.

            So are Jacqueline Dziergwa, Christopher R. Bridges, Sarika Singh, Sven E. Kerwath, Joachim Enax and Lutz Auerswald.

          • Two can play at this game!

            To paraphrase:

            The term here is caustification. Causticization is relative to some buffer system. In water, or with titrations of strong acid/strong alkali, where the H⁺/OH⁻ system is the nearest thing to a buffer, pH 7 is the neutral point and anything on the caustic side of that has consequences. So does shifting the pH of sea water.

          • Acidification refers to reducing the pH below 7, and always has, whatever the Great Stokes decrees.

            It’s not just Nick. The CAGW cult is like a bunch of Nell’s…

            https://youtu.be/UJtbgI0YsLM

            They have spent all their lives huddled together in their safe space echo chambers, refusing to interact with others, and they have developed their own unique language which they wish us to adopt. They get angry when you question their special language.

        • From either direction (acid or base) if you reduce either toward pH 7 you are neutralizing it.

          If you go from base to acid (pass below pH 7) then you could say you are acidifying it, becasue you are making it acid.

          So acidifying a base solution to make it less strong should be “weakening” or reducing the strength of the solution since it stays base.

          QED Acidifying is not what is going on since it does not go below pH 7. Hence it is to scare people.

          • Graemethecat December 21, 2019 at 6:41 am
            Acidification refers to reducing the pH below 7, and always has, whatever the Great Stokes decrees.

            No, acidification refers to the process of increasing the hydrogen ion concentration in a solution and is frequently used in experimental instructions, such as “acidify the solution by adding 0.1M HCl solution until a pH of 7.5 is reached”.

            Bill T December 21, 2019 at 4:52 am
            From either direction (acid or base) if you reduce either toward pH 7 you are neutralizing it.

            Only if you stop when you reach neutral conditions, i.e. pH 7.0.

        • “In Chemistry, one can’t talk of acidity until pH is below 7. Supposing not is just ignorant.”
          The term here is acidification.

          Then why not say the oceans are becoming “less caustic”? (That is, moving away the high pH of, say, caustic soda.)
          It’s just as “accurate” as “acidification”.
          Not scary enough?

      • “There are conditions that acidify your blood, causing acidosis. Blood pH is normally 7.3. You’ll be gone before it gets to 7. No use insisting your blood is still basic. – Nick Stokes”

        No, that is completely misleading and just plain wrong!

        Blood is normally slightly basic, with a normal pH range of 7.35 to 7.45. Usually the body maintains the pH close to 7.40. At the normal pH of 7.40, the ratio of bicarbonate to carbonic acid buffer is 20:1. Metabolic acidosis** (pH below 7.35) is a condition called primary bicarbonate deficiency.

        A person with a blood pH below 7.35 is considered to be in “physiological acidosis” only, “because blood is not truly acidic until its pH drops below 7.” And while a a continuous blood pH below 7.0 – acidic – can be fatal a pH above 7.8 – ‘caustic*’ – definitely is!

        While respiratory acidosis IS due to an excess of carbonic acid, resulting from too much CO2 in the blood and it is characterised as overly acidic it is never literally acidic!

        Again, this is another deliberate abuse of language and terminology driven by politics.

        *I think the use of caustic as the true opposite of acidic – particularly in this day and age – is fair, appropriate, completely justified and very revealing!

        **Acidosis is not a reference to the acidity of the blood itself it but to a wide variety of disorders that cause an imbalance in the production of acids or bases. Acidosis and alkalosis are categorised depending on their primary cause; metabolic or respiratory. Metabolic acidosis and metabolic alkalosis are caused by an imbalance in the production of acids or bases and their excretion by the kidneys. Respiratory acidosis and respiratory alkalosis are caused by changes in carbon dioxide exhalation due to lung or breathing disorders.

      • Nick,
        Surely the term “acidification” refers to water becoming more acid. For water to necome more acid, it must first be acid. If it is alkaline then it is not acid.
        Water with a ph of greater than 7 is not acid, it is alkiline. Therefore water which is alkaline cannot undergo acidification. The only scientifically correct phrase to describe it would be “reduction of alkalinity”. But of course that’s not scary enough.
        By the way, calling people you don’t agree with “ignorant” does you no favours.
        Your analogy with temperature is completely false. That’s because – provided the temperature is in the range 0 to 100 degrees C – there is no point at which the nature of the water changes, apart from getting warmer. There is no equivalent of a ph of 7.
        Chris

      • Nick the comment “becoming more acidic” was claimed and is false for reasons already explained .

      • A problem that I see is that some use an authority that others do not accept. This is hardly new or surprising of course and the result is further separation into tribes whose linguistic authorities do not overlap.

        It is similar to titration (https://www.quora.com/What-is-titration-What-are-its-types-Provide-4-examples) where one is adding acid to an alkaline solution until it is neutralized. The goal is neutralization, not acidification. I have not been able to find whether anyone calls the substance being tested “acidified” but it seems unlikely, not in that realm anyway.

        The problem as I see it is that “acid rain” is actually acidic and will dissolve minerals. “Acidic oceans” aren’t acidic. The result is dismissal of expertise and at best chasing squirrels and arguing over these things.

      • “The endless claims here that you can’t talk of acidity until pH is below 7 are just ignorant.”

        Just as claims that you can’t talk about helium liquefaction until its temperature is below 4.22 K are ignorant. Even though 5 K helium is still a gas, if you reduce the temperature by 0.1 K, you’re liquefying it…right? Even though, uh, it’s still a gas.

        It’s a deliberately misleading and completely grammatically, logically wrong use of the language.

  5. The oceans are a buffered alkaline solution, they can’t become much less alkaline than they already are. So it doesn’t matter what experiments in unrealistic settings show, because in the real world it’s a non problem.

    • “The oceans are a buffered alkaline solution, they can’t become much less alkaline than they already are.”
      In fact, the pH, stabilised or not, is irrelevant. The problem is that each added CO₂ converts one CO₃⁻⁻ to HCO₃⁻. It is the loss of carbonate that is the issue.

      • Not really. In actual fact, the biota of the ocean simply say, “ooh, yum, more calcium carbonate for my shell, skeleton, etc”. And return the oceans back to the original alkaline solution.

        More importantly, how did the ‘researchers’ create this ‘acidified’ environment? Without actually reading the article, would I be right in assuming that they added acid to the water?

        • “And return the oceans back to the original alkaline solution.”
          No, they don’t. Removing carbonate makes the oceans more acidic. But the point is that it is harder for them to build with calcium carbonate if the carbonate in solution is lowered. Solubility equilibrium.

          “Without actually reading the article”
          Just read the first sentence here
          “Prolonged exposure to high carbon dioxide (acidified) seawater”

          • ==> Pat Frank

            I’ve worked this out semantically!

            Since the globalist left have betrayed the logic of the neutral, we just need to start using the word caustic in opposition to acidic!

            i.e. Any acid approaching neutrality is causticization!

            Now, when the globe starts cooling, “ocean caustification” would have a very nice ring to it! 😉

        • All that will happen is that a tiny amount of the calcium carbonate rock under the oceans or in solution will be converted to calcium hydrogencarbonate. The change in pH will be absolutely negligible.

          As usual, the Great Stokes reveals his complete ignorance of Physical Chemistry.

        • More importantly, how did the ‘researchers’ create this ‘acidified’ environment? Without actually reading the article, would I be right in assuming that they added acid to the water?
          Yes they added acid in the form of CO2:
          “Filtered seawater for the system was provided by the main water storage tank of the research aquarium. It supplied each replicate via a header (mixing) tank. In two of the header tanks, pH was adjusted by its own CO2 supply for hypercapnic treatment. This was accomplished by using a pH controller (7074/2, TUNZE, Germany) containing a solenoid valve (7074.111) and a pH electrode (7070.110) attached to a 9 kg CO2 bottle (technical).”

          • No, again that is deliberately misleading!

            CO2 is not an acid!

            It is only in the presence of water that CO2 can combine* with H2O and form the weak acid known as carbonic!

            To give some realistic balance, every time it has rained fresh water from the clouds since the dawn of time it has been in the form of carbonic acid!!

            *Also of course depending on the temperature of the water and the partial pressure of the gas.

          • Scott W Bennett December 24, 2019 at 4:09 am
            No, again that is deliberately misleading!

            No it’s accurate, as you yourself noted adding CO2 to water creates carbonic acid in situ.

            To give some realistic balance, every time it has rained fresh water from the clouds since the dawn of time it has been in the form of carbonic acid!!

            And that carbonic acid has a pH around 5.5.

            The description I included showed that the researchers adjusted the pH in the same way it would change due to increased CO2 in the atmosphere. That was a direct answer to the previous poster’s question (Hivemind). Sorry if it contradicts your propaganda.

  6. Acidified oceans may cause Bigfoot’s feet to shrink.

    Acidified oceans may cause alien abductions to increase.

    Acidified oceans may cause the Loch Ness Monster to develop acne.

    Acidified oceans may cause pigs to fly.

    Grant checks please!

  7. In defence of the paper with regards to referring to the oceans becoming acidic. Acidosis, is where the blood becomes more acidic whilst remaining alkaline, with the pH going below the normal minimum (7.35) whilst remaining >7.0. Alkalosis is the opposite with pH being above 7.45.

      • Orange juice works the same way and it won’t dissolve fully. So, no OJ, no vinegar, no lemon juice, etc if one worries about acids as some very insane dentists seem to (again, a group that leans toward the idea humans are too defective to survive without their services, though we did….) destroy your teeth. The tooth won’t dissolve overnight.

        Your stomach secretes HCl. Why don’t people find that alarming? 🙂

        • Your stomach secretes HCl. Why don’t people find that alarming?

          Those who suffer from acid reflux do find it alarming.

  8. I like how they chose to use the word “corrosion.” Sounds awful.

    I like how they hypothesized pH=7.3 water could “corrode” shark teeth similar to carbonated soda (pH=3 to 4) “corroding” human teeth. After all, soda is another evil.

    What I liked best is that the authors note that pH can drop to near these levels and even worse already (“…Frequent upwelling events in austral summer cause periodic episodes of hypercapnia [pH levels 7.4–7.6] which can even reach pH 6.6 for several days during low oxygen events in autumn…”). Then they later state that while a baseline pH=7.3 is not “expected” until 2300, it could arrive sooner because pH=6.6 is already observed. Huh?

      • I’ve put deionized water (zero alkalinity) with a magnetic stirrer on our pH meter in the lab at work. It starts out with a pH around 7.00. Over time it drops to around that range or lower as it absorbs CO2.
        A few drops of tap water (alkalinity between 30 and 40 mg/l) and the pH comes right back up.

  9. > This prevented the blood from becoming more acidic, suggesting that these sharks may be able to adjust to high CO2 conditions during periods of exposure.

    It’s almost as if sharks have existed for hundreds of millions of years, including many ages where CO2 levels were much higher than present ones.

  10. Shark placoid scales are similar to our teeth, with a “vascular core of dentine capped by a thin layer of enamel.” Not sure how much this has been studied but they are probably variable. Teeth, which are replaced continually, are modified scales. These did seem to have a very minor amount of erosion although I always have to wonder about calling a pH of 7.3 hypercapnic, certainly not severe, but it’s a long time since I had physiology. Considering what shark skin deals with this did not seem to be structural damage based on their photos. As they incompletely note this has long been known as a highly productive area with upwelling. Bull sharks stay in that low of a pH longer than the 60 days studied. If they are predicting to 2300 they might want to study the situation a little longer and put their hand in the stomach of a recently killed shark.

    “ Our results however suggest that chronic exposure to severe hypercapnic (pH 7.3) conditions causes the dissolution of fluorapatite and in turn corrosion and weakening of the denticle surface….. In H. edwardsii, however, the response shown after acute exposure was maintained for a period of more than 60 days. In both treatments, plasma pH levels were very similar and there was no acidosis as could be expected if compensatory mechanisms cannot be maintained for prolonged periods….. Our results however suggest that chronic exposure to severe hypercapnic (pH 7.3) conditions causes the dissolution of fluorapatite and in turn corrosion and weakening of the denticle surface. ”

  11. “They also speculate that similar corrosion may occur in sharks’ teeth (which have the same structure and composition as denticles), which may negatively impact their feeding.”

    Teeth that they frequently lose, and are promptly replaced! Thus, while in their mouths, they are exposed to ‘challenging’ pH levels for a fraction of the animals lifespan. After being lost, the teeth commonly survive in bottom sands for millions of years, showing no effects of corrosion.

    Once again, the operative word here is “may,” with no estimate of probability.

  12. Their article says, “… housed in non-acidic water.” How can that be when they are implicitly defining acidity as a continuum of pH 0 through 14? That is, clueless researchers like these refer to a lowering of pH as “becoming more acidic.” Their attempt at political correctness results in a paper that is imprecise and contradictory.

      • Phil
        You are right. It appears that EurekaAlert decided to use the “acidic” and “non-acidic” terminology. However, the authors of the article do explicitly endorse the acidity continuum concept when they say, “… leading to a lowered pH – a process known as ocean acidification.”

        Interestingly, the authors pessimistically predict “As a result of climate change, upwelling events in eastern boundary current systems, and in turn hypercapnic episodes, are predicted to become longer, more frequent and severe in the near future.” Coastal areas with strong upwelling are usually the richest fishing areas in the world because of the nutrients that are brought up. As claimed by Salvettci (2018), “This high productivity is promoted by the upwelling of subsurface nutrient‐rich water driven by the effect of the winds over the ocean surface.” Thus, one might reasonably expect fisheries to thrive in the future. Yet, the authors only see the negative effects.

        https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL080634

  13. The first sharks appear in the fossil record in the Silurian period when atmospheric CO2 levels ran from abot 4,000 down to 3,000 ppm. Yet modern sharks cannot withstand even 400 ppm? Guess they just don’t make em like they used to.

  14. Current ocean pH runs about 8.1 to 8.3. Since pH is a logarithmic scale, increasing pH by one unit increases alkalinity by a factor of 10, so that “acidified” (less alkaline) water at pH 7.3 is 6 to 10 times more acid (or less alkaline) than current sea water. The amount of CO2 that would have to be dissolved in the oceans to reach pH 7.3 is much greater than could be generated by burning all the world’s known fossil fuel reserves, without accounting for conversion by photosynthesis.

    But if less alkaline water really does cause sharks to swim more slowly, that would be beneficial to the smaller fish normally eaten by the sharks. So let’s just keep burning fossil fuels, so that we have more fish to eat and less fish fed to the sharks!

  15. Science News scooped WUWT!

    I added at their FB page:

    As for CO2 chemistry and biochemistry, there’s a lot I don’t know about bicarbonate buffering and the formation of limestone and chalk which took out a huge amount of CO2 from our ancient atmosphere by critters that are still around.

    We have a lot to learn, and that learning may not [include] the destruction of the biosphere or whatever you’re concerned about.

    Here’s the result of growing conches at 2,850 ppm CO2. (Gee, my house had two unvented propane space heaters until a couple weeks ago, I have direct experience with that level of CO2!)

    https://www.whoi.edu/oceanus/feature/ocean-acidification-a-risky-shell-game/

    <bExcerpt:

    While a postdoctoral scholar at the Woods Hole Oceanographic Institution (WHOI), Ries worked with WHOI scientists Anne Cohen and Dan McCorkle. In tanks filled with seawater, they raised 18 species of marine organisms that build calcium carbonate shells or skeletons. The scientists exposed the tanks to air containing CO2 at today’s level (400 parts per million, or ppm), at levels that climate models forecast for 100 years from now (600 ppm) and 200 years from now (900 ppm), and at a level (2,850 ppm) that should cause the types of calcium carbonate in shells (aragonite and high-magnesium calcite) to dissolve in seawater.

    “The wide range of responses among organisms to higher CO2—from extremely positive to extremely negative—is the truly striking thing here,” Ries said.

    As expected, in the highest CO2 used, the shells of some species, such as conchs—large, sturdy Caribbean snails—noticeably deteriorated. The spines of tropical pencil urchins dissolved away to nubs. And clams, oysters, and scallops built less and less shell as CO2 levels increased.

    However, two species of calcifying algae actually did better at 600 ppm (predicted for the year 2100) than at present-day CO2 levels, but then they fared worse again at even higher CO2 levels. Temperate (cool-water) sea urchins, unlike their tropical relatives, grew best at 900 ppm, as did a temperate limpet.

    Crustaceans provided the biggest surprise. All three species tested—the blue crab, American lobster, and a large prawn—defied expectations and grew heavier shells as CO2 swelled to higher levels.

    “We were surprised that some organisms didn’t behave in the way we expected under elevated CO2,” said Anne Cohen, second author on the Geology paper. “Some organisms were very sensitive [to CO2 levels], but there were a couple [of species] that didn’t respond ’til it was sky-high—about 2,800 parts per million. We’re not expecting to see that [CO2 level] any time soon.”

    • Ric
      I suspect the explanation for the observations is that different species have an optimum pH that corresponds to the pH at the time they first evolved. By the expenditure of energy, they can exist above and below the optimal pH. So, as the pH is manipulated in the experiment, some species do better and others do poorer, depending on what their optimal pH range is.

      • Interesting experiment, but it ignores adaptation over time, making it relatively useless for any real world application. Almost all of the life science papers about climate change do not include the remarkable adaptation ability of life, making almost all of them useless and irrelevant.

        • It also ignores the fact that the oceans cannot change nearly as rapidly as conditions in a tank. Coral reefs have vast quantities of dead coral which effectively form the surrounding lithology. This will slowly dissolve to counteract increasing levels of CO2, thus maintaining local buffering and probably negating much, if not all, of the effects.

          It’s another experiment which does not adequately represent real life, but produces what the researchers wanted to find.

          • This paper is about an ecosystem where the conditions do change rapidly:
            “Frequent upwelling events in austral summer cause periodic episodes of hypercapnia (pH levels 7.4–7.6) which can even reach pH 6.6 for several days during low oxygen events in autumn. Upwelling takes place in 3–10 day cycles in spring and summer, moving cold (~10 °C), hypercapnic water (pH 7.4–7.6) closer to the surface”.

    • “Crustaceans provided the biggest surprise.” No surprise there, big old literature on blue crab physiology. As to Science News—-
      https://www.sciencenews.org/article/ocean-acidification-could-degrade-sharks-tough-skin
      “Shark denticles are made from dentin, which we know from human dentistry is susceptible to degradation from carbonic acid,” says Lutz Auerswald, a fisheries biologist at Stellenbosch University in South Africa. “That could make [sharks] especially vulnerable.” They did admit that they could adapt internally physiologically, and were exposed in upwelling to a pH of 6.6, but no mention of enamel. Fisheries biologists should know better. A number of molluscs live well in a pH of 7.3.

      As to Oceanus– “But other species seemed as if they would not be harmed, and crustaceans, such as lobsters, crabs, and prawns, appeared to increase their shell-building (see interactive).” Read the scientific literature before 2000. Amazing what ‘ancient’ biologists did. They knew that ‘might, may, could,’ were hypothetical. WHOI ain’t what it used to be.

      • Batterton, C. V. and J. N. Cameron. 1978. Characteristics of resting ventilation and response to hypoxia, hypercapnia, and emersion in the blue crab Callinectes sapidus (Rathbun). Journal of Experimental Zoology. 203:403-418.

        I have several other references important to blue crab physiology from to 1978 to 1989. Easy to find.

    • Salute!

      OMG!!!! Hell!

      Can Discovery Channel ever run another “Shark Week”? Maybe we can watch re-runs on History Channel.

      Gums asks…

  16. Sharks have been around like forever and now they want to claim that they depend on the CO2 concentration. How stupid do they think we and the sharks are? It’s embarrassing.

    Organisms have physiological power that handles these weak chemical changes that the alarmists would like to think are fatal to everything on Earth. One has to remember that the world has been through huge climate swings over 600 million years and life is still here.

  17. So a simple question… Did this shark species survive the last time CO2 was this high in the atmosphere?

    If yes, then the study is obviously bogus. (I could not find any references to fossils of this shark)

    If no, then this is a relatively new species and is adapted to a very specific environment, and therefore more prone to extinction. Generalists generally survive change, specialists often do not (it depends on the change).

    So having read the posting, I am wondering if they were dunking the sharks into vats of hydrochloric acid? It says “acidified water”, the last I checked sea water is alkaline.

    • The paper does not say “acidified water” it says “hypercapnic” and it is achieved in the experiments by adding CO2.

  18. Puffadder Shysharks – really! I don’t recall seeing any of these when I was growing up around Bremerton, WA [Puget Sound]. These are clearly one of the more common specie of shark! NOT! I must have just missed them. Perhaps they are not common precisely because they show some sensitivity to ocean acidity.

    • nw sage
      From the original article, “Puffadder shysharks are already adapted to a highly variable environment and are restricted in their distribution to the Southern tip of Africa without a possibility of a range shift to mitigate against negative effects of climate change.” So, don’t expect to be seeing them in Puget Sound.

  19. Charles
    You commented, “PH of 7.3 expected in the year 2300, probably under RCP 8.5.” Actually it is totally hypothetical, based on the following rationalization: “The hypercapnic level (pH 7.3, expected by year 2300 according to IPCC scenario) was chosen to be below the range of what occurs regularly during upwelling and taking into account that pH levels are usually well below the global average pH of 8.1 in the BCLME.” That is, they are extrapolating 200 years into the future to discern what might happen to a creature adapted to acute decreases in pH, if the conditions were to become chronic and worsen. So, if definitely is a worst-case scenario.

  20. Fresh water ph is normally in the acidic range ie 7.0
    Therefore bull sharks – that regularly inhabit rivers – cannot have denticles.
    Basic logic!

    • The fresh water from the source for our drinking water is usually in the 7.5 to 8.5 range (It has approached 8.9 in the summer as algae removes CO2 from the water). In 30+ years of treating it I’ve never seen it “acidic”.
      Of course other bodies of fresh water pH values can vary depending on what feeds them, but I doubt if 7.0 and below is the norm.

  21. Does this give these sharks a somewhat ability to fly ?

    If this is true, with all these extreme events linked to CO2, mankind may face Sharknadoes !

  22. Sharks evolved in the Ordovician and Silurian eras.
    Since then they have survived 400-500 million years during which atmospheric CO2 has ranged from 200 up to 5-10,000 ppm.
    But today, an increase of atmospheric CO2 from 280 to 500 ppm is somehow going to dissolve their scales?

    Shark scales were just fine at 5000 ppm CO2.
    Why would they dissolve at 500 ppm?
    Is it too alkaline form them?

  23. Here is a Silurian shark.
    Sharks evolved in the Ordovician and Silurian during which atmospheric CO2 ranged approximately from 1000-10,000 ppm.

    https://images.app.goo.gl/SQ8pV73eZraynFbh6

    On the shark’s skin, the scales did just fine and the oceans were just as alkaline then as now.
    In the shark’s brains, the first developments were taking place that would later evolve into human’s ability to fabricate false climate disaster stories as a strategy to gain power in hominid societies.

    • Machael 2
      It is telling that the sharks have evolved the ability to replace the denticles, much as they do their teeth. The question is whether the denticle replacement is a fixed period or a response to decrease in swimming efficiency. Also unknown, is if it is currently a fixed period, whether that might be changed by reduced swimming efficiency.

  24. My bs-o-meter has just gone off the scale.
    Consider the Bull Shark (a.k.a “Zambezi shark” and “Lake Nicaragua shark”)
    “Bull sharks can thrive in both salt and fresh water and can travel far up rivers. They have been known to travel up the Mississippi River as far as Alton, Illinois, about 700 miles from the ocean.” [wiki “Bull Shark”]
    “… it was discovered that they were able to jump along the rapids of the San Juan River (which connects Lake Nicaragua and the Caribbean Sea), almost like salmon. As evidence of these movements, bull sharks tagged inside the lake have later been caught in the open ocean (and vice versa), with some taking as little as 7–11 days to complete the journey.” [wiki ‘Lake Nicaragua’]
    I wonder what are the pHs of the Mississippi River and Lake Nicaragua?

    • Bull sharks would likely travel further up the Mississippi if there were no locks and dams. Alton is where the dams begin.

  25. Charles Rotter / ~cr comment: always good for an unexpected / undeserved laugh:

    ::::::::::::::::::::::::::::::::::::::::::::::::

    Marine biology: Acidified oceans may corrode shark scales

    Prolonged exposure to high carbon dioxide (acidified) seawater may corrode tooth-like scales (denticles) covering the skin of puffadder shysharks, a study in Scientific Reports suggests. As ocean CO2 concentrations increase due to human activity, oceans are becoming more acidic, with potential implications for marine wildlife. Although the effects of acidified water have been studied in several species, this is the first observed instance of denticle corrosion as a result of long-term exposure.

    Lutz Auerswald and colleagues investigated the effects of exposure to acidified seawater in puffadder shysharks. The authors found that in three sharks housed in acidified seawater for nine weeks, 25% of denticles on average were damaged, compared to 9.2% of denticles in a control group of three sharks that had been housed in non-acidic water.

    They suggest that such corrosion may impair the sharks’ skin protection and open-water sharks’ ability to swim, as denticle surface affects their swimming speed. They also speculate that similar corrosion may occur in sharks’ teeth (which have the same structure and composition as denticles), which may negatively impact their feeding.

    However, the authors also found that although exposure was linked with increased carbon dioxide concentrations in blood taken from a total of 36 sharks housed in acidified seawater for different periods of time, concentrations of carbonate also increased. This prevented the blood from becoming more acidic, suggesting that these sharks may be able to adjust to high CO2 conditions during periods of exposure.

    ###

    Article and author details

    Acid-base adjustments and first evidence of denticle corrosion caused by ocean acidification conditions in a demersal shark species

    Corresponding author:

    Lutz Auerswald
    Department of Environment, Forestry and Fisheries and Stellenbosch University, Stellenbosch, South Africa DOI 10.1038/s41598-019-54795-7

    Online paper:

    https://www.nature.com/articles/s41598-019-54795-7

    From EurekAlert!

    ~cr comment.  PH of 7.3 expected in the year 2300, probably under RCP 8.5

  26. Another miracle of self-propagation:

    – ocean warms, outgassing CO₂

    – CO₂ warming atmosphere: warms the oceans

    – external energy supply unneeded for that “tipping points game!”

    – poor sharks can’t help, shortened life expectancy AND maroded living quality due to teeth maladies.

    ____________________________________

    What will Mrs. Shark think of Mr. “bad teeth” Shark.

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