Fish adapt to ocean acidification by modifying gene expression


Research News


Human-driven global change is challenging the scientific community to understand how marine species might adapt to predicted environmental conditions in the near-future (e.g. hypoxia, ocean warming, and ocean acidification). The effects of the uptake of anthropogenic atmospheric CO2 by oceans affects (i.e. ocean acidification) propagate across the biological hierarchy, from changes in the building blocks of life at nano-scales to organism, physiology and behaviour through ecosystem processes and their properties.

To survive in a reduced pH environment, marine organisms have to adjust their physiology which, at the molecular level, is achieved by modifying the expression of genes. The study of such changes in gene expression can aid in revealing the adaptive mechanisms of life under predicted future ocean acidification conditions.

Making use of natural laboratories

There are a few places on this planet where volcanic activity has CO2 bubbling from the seafloor creating conditions that are similar to those predicted to occur across the oceans in the near-future. Such natural laboratories can then help us to understand what will happen to marine organisms in the future under an ocean acidification scenario. Therefore, researchers from Research Division for Ecology & Biodiversity of the University of Hong Kong (HKU) and Swire Institute of Marine Science, jointly with researchers from the University of Adelaide, travelled to a remote volcanic island of New Zealand called White Island. They collected samples from CO2 seeps and nearby locations, and analysed molecular data from a fish species (the Common triplefin) with ecological evidence of being successfully adapted to acidified environments at CO2 volcanic vents. The findings were published in a peer-reviewed open access journal Evolutionary Applications.

Studying evolutionary mechanism through species mutations

The study found a higher gene expression in gonads in fish living in the CO2 vents with reduced pH than those from control environments with ambient CO2 and pH conditions. Most of those genes were functionally involved in the maintenance of pH homeostasis, increased metabolism, and regulatory functions of downstream biological processes revealing important processes a fish needs to adjust to live in a lower pH environment. Interestingly, it was mainly the male fish with this expression signature hinting at reproductive consequences as males provide parental care of the nests.

When looking at the actual sequence of these genes and their genetic variation, the authors found evidence of a long-term process of natural selection. The genetic changes, which we call mutations, providing the fish with adaptive advantages for living in an acidified, are located in DNA sequences regulating the expression of the genes. These mutations in regulatory sequences would not impact the fitness of the individuals carrying them when living in an ambient pH environment, but these might allow fine-tuned physiological regulation in a reduced pH environment. Such standing genetic variation in DNA regulatory sequences could provide for the adaptive potential to near-future ocean acidification in fishes.

Moreover, the authors propose an evolutionary mechanism by means this adaptive potential to ocean acidification could be maintained in natural populations of fishes. Fish species tend to occur across wide geographical ranges with different pH. Thus, it is likely that similar to what happens in Common triplefins, the genetic variation allowing for life in slightly reduced or variable pH environments already exist within many fish populations. Highly dispersive larvae of fishes contribute to the flow of this genetic variation among the populations of a species. Hence, it might be expected that the genetic variation in regulatory sequences of gene expression efficiently adjusting the physiological responses to reduced pH will provide the raw material for adaptive natural selection in the near-future under increasing ocean acidification.

“The findings of this study imply that one of the more relevant things in terms of the capacity of the marine species to respond to future changes in their environmental conditions is their current genetic variation. Thus, the assessment of the levels of genetic diversity of different marine species is the most important, and we are currently working on it,” said Dr Natalia PETIT-MARTY, first author of the paper and Postdoctoral Fellow in the group led by Dr Celia SCHUNTER at Research Division for Ecology and Biodiversity & Swire Institute of Marine Science, HKU.

“We are very fortunate to get to visit these remote places providing us with a glimpse of how the oceans may look like in the future. To make sure our findings are applicable across different marine ecosystems, we also travelled to CO2 vents at tropical coral reefs in Papua New Guinea and rocky reefs in the Mediterranean Sea, and will continue our research on the adaptive potential of marine fishes to ocean acidification,” added Dr Celia SCHUNTER, Assistant Professor at Research Division for Ecology and & Swire Institute of Marine Science, HKU.


The complete study was first published in Evolutionary Applications on April 8th, 2021. N. Petit-Marty, I. Nagelkerken, S. D. Connell, and C. Schunter. (2021). Natural CO2 seeps reveal adaptive potential to ocean acidification in fish.

The research paper can be accessed from:

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Zig Zag Wanderer
May 29, 2021 10:05 pm

We are very fortunate to get to visit these remote places providing us with a glimpse of how the oceans may look like in the future. To make sure our findings are applicable across different marine ecosystems, we also travelled to CO2 vents at tropical coral reefs in Papua New Guinea and rocky reefs in the Mediterranean Sea

I really couldn’t understand why they were banging on about such obvious nonsense, and then I read this bit.

Nice work if you can get it!

Steve Case
Reply to  Zig Zag Wanderer
May 29, 2021 11:05 pm

Thanks for pointing out that bit of transparency. I don’t bother to read the original post when the title tells me the topic is total bullshit. I go straight to the comments for the laughs. Usually the personal notes are of the we put up with hardships to gather this important data. Openly admitting what a great time it is to be a tourist on the company’s dime isn’t the smartest move to make.

Ron Long
Reply to  Steve Case
May 30, 2021 3:55 am

Steve, you should read the report in this case because these educated idiots prove that fish adapt to a lowering of sea water Ph all on there own, no human intervention needed. Whenever I see the term “acidification” I know they are fishing for grant money.

Alan the Brit
Reply to  Ron Long
May 30, 2021 4:14 am

No scientist just a retired structural engineer, but if water becomes slightly less alkaline, it doesn’t mean it has become acidic!

Reply to  Ron Long
May 30, 2021 5:01 am

fish adapt to being put in plastic bags…shipped all over the world…and put in aquariums…where pH is always a compromise

film at 11

Reply to  Steve Case
May 30, 2021 5:35 am

White island also has some fantastic sports fishing huge Kingfish just love the deep reefs another reason to visit (just avoid the eruptions if you go ashore)

Rory Forbes
May 29, 2021 10:29 pm

Human-driven global change is challenging the scientific community to understand how marine species might adapt to predicted environmental conditions in the near-future (e.g. hypoxia, ocean warming, and ocean acidification).

I say that’s damned sneaky of those pesky “marine species” to have found a way to adapt to a non existent ocean condition. Ocean acidification is a ludicrous neologism invented by a clown (note) with a limited understanding of English and basic chemistry. As long as serious scientists continue to spout such nonsense, anything they say lacks credibility.

If anything is “challenged” it’s the authors of that silliness … and not in a good way.

The Total Myth of Ocean Acidification

by: David Middleton

(note) Ken Caldeira coined the term “ocean acidification.” in 2006. Caldeira is a climate modeller (I’m guessing with Play Dough)

Zig Zag Wanderer
Reply to  Rory Forbes
May 29, 2021 10:44 pm

I’m not so sure, Rory:

To make sure our findings are applicable across different marine ecosystems, we also travelled to CO2 vents at tropical coral reefs in Papua New Guinea and rocky reefs in the Mediterranean Sea

I think I would happily make up hogwash like this to travel to exotic locations on someone else’s dime!

Rory Forbes
Reply to  Zig Zag Wanderer
May 29, 2021 11:36 pm

It seems great minds think alike. Check out Steve Case’ comment, above. You guys have probably hit on the most compelling reason to specialize in climate fraud … huge budgets and exotic places.

Richard Page
Reply to  Rory Forbes
May 30, 2021 5:25 pm

So the paper uses an example of one type of fish adapting to specific circumstances to exploit a niche feeding area (probably over a huge time frame) to explain how all fish might/may/could adapt to something that they are afraid will happen in a very short period of time. Apart from the obvious idiocy of thinking acidification is happening in the first place, how is this paper in any way relevant?

Am I just being cynical in thinking that someone could only get their scientific study of these fish published if they strongly linked it to climate change?

Rory Forbes
Reply to  Richard Page
May 30, 2021 8:41 pm

might/may/could adapt

There is the “secret sauce” that ties all these climate crisis papers together … speculative qualifiers and blatant ambiguity. Cynicism might be the only thing that allows us to even read such pap.

Joel O'Bryan
May 29, 2021 10:36 pm

“Fish adapt to ocean acidification by modifying gene expression.”
If that is not the biggest “Duhhhh!” there ever was.
Human adaptation to high altitude (low O2 partial pressure) living has long been established (Queue the Quito Ecuadorans and Peruvians). Most of the climate scam gravy train riders in the biological world depend on the fact that most of the public are unaware of what science has already told us about adaptation of life to extreme conditions.
Our almost 21% O2 conditions today would be near normal to a late Cretacious dinosaur, but wonderful to an inhabitant of the Jurassic where slow moving metabolism and lots of water-swamps was king.

Please spare me junk science says the creatures in todays oceans (corals and shell formers included) cannot adpat to these changes that brings more life-giving carbon into their metabolic pathways.

Joel O'Bryan
Reply to  Joel O'Bryan
May 29, 2021 10:37 pm

More here:

Screen Shot 2021-05-29 at 10.37.12 PM.png
Zig Zag Wanderer
Reply to  Joel O'Bryan
May 30, 2021 12:53 am

It doesn’t even take generations to adapt to low air pressure. Athletes will train at high altitudes for weeks, and get significant advantage in subsequent competitions at lower altitudes. We adapt without evolving.

In fact, it has always impressed me that in order to do almost anything better, within obvious limits, animals merely have to keep doing it. We adapt extremely well.

Last edited 1 year ago by Zig Zag Wanderer
Krishna Gans
Reply to  Zig Zag Wanderer
May 30, 2021 9:55 am

In the case of athleths is another way of adaptation as it is a built-in one. not based on genetic changes.
May the fishes adapt maybe by epigenetic changes ?

May 29, 2021 10:54 pm

“Study” fiction and then write fiction about it. The only good thing I can say about this is that at least the US taxpayer isn’t paying for it.

May 29, 2021 10:57 pm

Yet another issue in ocean acidification is the role of nature. The ocean had acidified itself back in the PETM 50 million years ago.

May 29, 2021 11:28 pm

They actually came up with the wrong conclusion. They were supposed to find that fish wouldn’t be able to adapt and would thus become part of the next [drumroll] Great Extinction Event.

They might NOT get funding for their next excursion.

M Courtney
Reply to  Ralph Dave Westfall
May 30, 2021 7:11 am

Nope. If they found it was the end of the world then the job’s over.
his way, the next time they can find that “It’s worse than we thought”.

Rory Forbes
Reply to  M Courtney
May 30, 2021 10:43 am

Ah yes, the old WTW gambit … works every time. It’s air tight sciencing.

May 30, 2021 12:18 am

Human-driven global change…

Is all in the over anxious mind

Reply to  fretslider
May 30, 2021 5:42 am

Seems to me more like a sign of a less than active mind. One that does not question. One too lazy to check out claims to confirm their validity. One that goes along to get along.

May 30, 2021 1:08 am

The one big alleged problem with lower pH in the ocean is that shellfish will not be able to properly form their calcified shells. At one point I had the opportunity to find out for myself. I was on the island of Dominica in the Caribbean which has a great deal of volcanic activity. One active location is a beach known as “Champagne”. The name comes from the huge multitude of carbon dioxide bubble streams rising from the seafloor. Indeed, when there is a large gas release, the huge bubbling all around you makes it seem as if you are swimming in a glass of champagne. It is absolutely breathtaking.
There is no doubt that the seawater is heavily loaded with carbon dioxide.
The question is how are the shellfish doing in this hostile environment? Well, they are present in abundance. The little black circular lumps are a type of snail, I believe are periwinkles. I had never seen them in any large quantity anywhere in the Caribbean before, but here they were present in riotous abundance. They were growing all around the areas where the carbon dioxide vents were. So obviously the slightly lower pH did not bother them at all. Actually, this is not surprising. Most (if not all) life form have a biochemical pathway known as the “proton pump”. As the name implies, this is the cellular pH regulation mechanism. It is also notable that the proton pump is remarkably energy efficient. It seems these critters are well equipped to deal with even substantial variation in the pH of their environment:

The periwinkles of Dominica:
(The picture is fairly hi-res, so you can open it in another tab, then zoom in.)

Joao Martins
May 30, 2021 2:46 am

To all readers and contributors:

Fellows: when using the wording a la mode would you please refer to the reduction of alcalinity of the oceans consistently writing ocean “acidity” with the second word between quotation marks?

Reply to  Joao Martins
May 30, 2021 3:01 am


A) Going from any pH to any lower pH is properly termed “acidification”, simply because the [H+] is increased.

B) Is not, is alkaline, alkaline, alkaline. Can not have acidification above pH 7.

And the fight is on.

{As a side note, the Centigrade temperature scale was set aside in favor of Celsius. Times change, and nomenclature changes. Some people use “Celsius” but refuse to acknowledge the usage change in acid-base chemistry terms which happened at about the same time.}

Reply to  TonyL
May 30, 2021 3:50 am

Most water chemists know anything above pH 7 is alkaline.

Given that the current ocean pH is reportedly ~8.2 it’s anything but acidic.

What’s in a name…

Reply to  fretslider
May 30, 2021 5:16 am

Most water chemists know anything above pH 7 is alkaline.

This water chemist says “basic”, and not the computer language.
Where I come from, the biologists say “alkaline” to mean carbonates in water systems. This is distinguished from “total alkalinity” which means carbonates plus strong base (hydroxide). When the chemists and biologists work together, they have to be aware of each others usages or confusion reigns.

But wait, there’s more!
Then the EPA started using “alkalinity” and “total alkalinity” interchangably, without reference to what they meant. The reader had to infer the correct meaning from the context. (Leave it to the Govt. to make things worse.)

These days, chemists just say “basic”.

Reply to  TonyL
May 30, 2021 6:10 am

This water chemist says “basic”

But does not refute what I said. Just nitpicks.

These days, chemists just say “basic”.

There were days before these days

May 30, 2021 3:47 am

Same thing woods hole scientists found studying coral in low ph near volcanic activity . Coral was thriving . They were shocked real world was different than laboratory .

Alan the Brit
May 30, 2021 3:59 am

Has that not always been the case seeing that, as I understand it, the oceans contain 50 times as march CO2 as the atmosphere?

May 30, 2021 4:13 am

The authors apparently never heard of epigenetics.

May 30, 2021 7:04 am

I really am revolted by these constant references by warmists to a bogus process referred to as “ocean acidification”. There is no such thing.

If the oceans were ever going to be acidic, it would have been in the pre-Pleistocene eras when atmospheric CO2 was vastly higher than it is today.

Yet, instead of going acidic, oceans built up vast reefs of carbon-shelled sea life that got locked up in layers of limestone that is visible all over the planet.

Despite the warmists’ lies, carbon is never created or destroyed on earth – it is only constantly being redistributed in a stable balanced equilibrium process. Just like any other equilibrium in the world of chemistry. And the vast buffering capacity of salt water, along wiht the tiny proportion of our atmosphere that is CO2 ensures that the oceans will never go acidic no matter how much carbon might be absorbed from the atmosphere.

Rory Forbes
Reply to  Duane
May 30, 2021 10:54 am

The fact is; life on this planet is more in danger from oceans that sequester CO2 than from a CO2 buildup in the atmosphere. The preindustrial 280 ppm CO2 was far from optimum for diversity of life. Rising CO2 is a good thing for life.

H. D. Hoese
May 30, 2021 8:05 am

It could be my incompetence, or their rambling discussions, searching with only 4 decades of computer use, but I could not find any environmental data in paper or supplements. I spent even more time working with fish and some shellfish in low salinity estuaries with highly variable and even acid (in sediments) pH. Their results are not surprising, but all this important but faddish genetic work needs to be better correlated with ecological and physiological operations of phenotypes, including offspring. I haven’t searched it much, including in Evolutionary Applications but keep running into this concern, recent examples in taxonomy/systematics where similar criticism is being expressed. Old problem in biology mixing physiology with ecology. At least they got in the ocean.

May 30, 2021 9:33 am

The non-static world strikes again.

jim Turner
May 30, 2021 10:40 am

As a grumpy old chemist, having seen ‘Ocean Acidification’ in the title I was going to come on here and rant about the continued use of this term even though the incorrectness of it has been stated time and time again, however I see that plenty of others have already made the point. The question becomes why do we keep seeing it? The answer of course is that those that use it are impervious to reason. The comparison to temperature is bogus as that has an absolute value of zero at one extreme, the zero points in the Celsius and Farenheit scales are an arbitary convenience. pH on the other hand is logarithmic and zero is the mid-point. Approaching zero from either direction is neutralisation (or neutralization if you prefer). I suggest that it would be appropriate if the enlightened ones here use the term neutralisation in going from one basic pH to another slightly less basic pH in future.

Bruce of Newcastle
May 30, 2021 5:09 pm

Gosh who knew that creatures like fish and corals, which have hundreds or thousands of progeny per annum, might adapt quickly to environmental changes? It’s weird and unheard-of!

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