Carbon dioxide affecting fish brains: study

CO2 emissions reportedly cause changes in the chemical environment of the water in which fish and other species live
In this photo, released by The Nature Conservancy, fish are seen swimming over coral in Indonesia's Wakatobi archipelago. Rising human carbon dioxide emissions may be affecting the brains and central nervous systems of sea fish, with serious consequences for their survival, according to new research.

Rising human carbon dioxide emissions may be affecting the brains and central nervous systems of sea fish, with serious consequences for their survival, according to new research.

Carbon dioxide concentrations predicted to occur in the ocean by the end of this century will interfere with fishes' ability to hear, smell, turn and evade predators, the research found.

The Australian Research Council's Centre of Excellence for Coral said it had been testing the performance of baby coral fish in sea water containing higher levels of dissolved CO2 for several years.

"And it is now pretty clear that they sustain significant disruption to their central nervous system, which is likely to impair their chances of survival," said Phillip Munday, a professor who reported the findings.

In a paper published in the , Munday and his colleagues also detail what they say is world-first evidence that high in sea water disrupts a key brain receptor in fish.

This causes marked changes in their behaviour and sensory abilities.

"We've found that elevated CO2 in the oceans can directly interfere with fish neurotransmitter functions, which poses a direct and previously unknown threat to sea life," said Munday.

The team began by studying how baby clown and damsel fishes performed alongside their predators in CO2-enriched water.

They found that while the predators were somewhat affected, the baby fish suffered much higher rates of attrition.

"Our early work showed that the sense of smell of was harmed by higher CO2 in the water, meaning they found it harder to locate a reef to settle on or detect the warning smell of a predator fish," said Munday.

The team then examined whether fishes' sense of hearing -- used to locate and home in on reefs at night, and avoid them during the day -- was affected.

"The answer is, yes it was. They were confused and no longer avoided reef sounds during the day. Being attracted to reefs during daylight would make them easy meat for predators."

The research also showed that the fish also tended to lose their natural instinct to turn left or right -- an important factor in schooling behaviour.

"All this led us to suspect it wasn't simply damage to their individual senses that was going on, but rather that higher levels of carbon dioxide were affecting their whole ."

Munday said around 2.3 billion tonnes of human CO2 emissions dissolve into the world's oceans every year, causing changes in the chemical environment of the water in which fish and other species live.

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(c) 2012 AFP

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Jan 16, 2012
How much CO2 did they put in there? Sounds like the fish were swimming in selzer and not just a few ppm more CO2 than normal.

Jan 16, 2012
I agree with you Eikka, these kinds of speculative articles with vague data are not the best sources of information. Give us numbers, give us data, and don't simply assume you can force feed us BS in a scientific article. It almost seems like they do not want you to be able to refute these findings on scientific grounds.

Jan 16, 2012
Some researchers say the global warming is not harmful and is even good for us and other creatures in particular cases on this planet.

But this article says high CO2 level seems to destroy the most important abilities of residents in the oceans all over the world.

Is that true?

Jan 16, 2012
True or false, it's 90% propaganda 10% truth.

Jan 16, 2012
Well one thing is for sure, rising CO2 levels appear to significantly raise research funding.

Jan 16, 2012
The article itself is behind a paywall: http://www.nature...1352.pdf

Doesn't say anything about the actual level of CO2 used in the abstract, except that it's "Predicted future CO2 levels" whatever that means.

Jan 16, 2012
Found it:
The pair reared clownfish (Amphiprion percula) larvae in seawater with normal (450 microatmospheres) and elevated (900 microatmospheres) CO2 levels.

So, double the partial pressure.

The further question is, did they test the fish in high or low CO2 concentration water? Because the adult fish may have adapted to a higher level of the gas.

Jan 16, 2012
Though over the course of a 100 years, the time predicted to reach that level of CO2 in water, the fish that are affected by this phenomenon have all been eaten, and those who adapted, well, they weren't.

If the change happened overnight, it would be a disaster, but it won't.

Jan 17, 2012
It seems that the submit button doesn't work anymore if I try to paste a link to a wordpress site about cod living just fine at higher CO2 concentrations. Is there some sort of pre-emptive censoring going on here?


Physorg is just posting a propaganda article, with wording like "baby fish" designed to get an emotional response.

Jan 17, 2012
Right. The software didn't like something in the quote.

No effect on hatching, survival, development, and otolith size was found at any stage in the development of Baltic cod. Field data show that in the Bornholm Basin, the main spawning site of eastern Baltic cod, in situ levels of pCO2 are already at levels of 1,100 uatm with a pH of 7.2, mainly due to high eutrophication supporting microbial activity and permanent stratification with little water exchange. (...) Baltic cod seem to be robust to even high levels of OA (3,200 uatm), indicating an adaptational response to CO2.

So, not all fish are affected, and adaptations are possible.

Jan 17, 2012
What a joke! let me get some research people in a room with 5% Oxygen and see how they fare.....
CO2 levels rise slowly along with those species that can best adapt

Jan 17, 2012
CO2 levels rise slowly along with those species that can best adapt

Care to clarify your meaning?

Jan 17, 2012
Sorry Deepsand!
most changes to atmospheric CO2 occour slowly over time, organism's with short breeding cycles will be able to adapt.
As evidence points too. Even humans living in low O2 high altitude areas are adapted better to these conditions.
The point I tried to highlight is the above experiment basically grabs a couple of fish and sticks them in a foreign enviroment and expects them to have no issues....

Jan 17, 2012
How does that invalidate the study's findings?

And, while "most changes to atmospheric CO2" may "occour slowly over time," does that necessarily speak to aquatic conditions of the present or near future?

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