Rising human carbon dioxide emissions may be affecting the brains and central nervous system of sea fishes with serious consequences for their survival, an international scientific team has found.
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, says Professor Philip Munday of the ARC Centre of Excellence for Coral Reef Studies and James Cook University.
“For several years our team have been testing the performance of baby coral fishes in sea water containing higher levels of dissolved CO2 – 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,” Prof. Munday says.
That’s from an ARC news release on a new Nature Climate Change study, “Near-future carbon dioxide levels alter fish behaviour by interfering with neurotransmitter function” (subs. req’d).
The authors “report world-first evidence that high CO2 levels in sea water disrupts a key brain receptor in fish, causing marked changes in their behaviour and sensory ability.”
We’ve known for quite some time about the threat global warming and human activity poses to marine life (see Nature Geoscience study concludes ocean dead zones “devoid of fish and seafood” are poised to expand and “remain for thousands of years“). And we’ve known the threat ocean acidification poses to shell-forming mollusks and crustaceans (see The Great Oyster Crash and Why Ocean Acidification Is “A Ticking Time Bomb” for Both Marine Life and Humanity and links below).
Here’s more on this ground-breaking new paper:
“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,” Prof. Munday says.
Prof. Munday and his colleagues 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 baby fish 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. But we suspected there was much more to it than the loss of ability to smell.”
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.”
Other work showed the fish also tended to lose their natural instinct to turn left or right – an important factor in schooling behaviour which also makes them more vulnerable, as lone fish are easily eaten by predators.
“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 central nervous system.”
The team’s latest research shows that high CO2 directly stimulates a receptor in the fish brain called GABA-A, leading to a reversal in its normal function and over-excitement of certain nerve signals.
While most animals with brains have GABA-A receptors, the team considers the effects of elevated CO2 are likely to be most felt by those living in water, as they have lower blood CO2 levels normally. The main impact is likely to be felt by some crustaceans and by most fishes, especially those which use a lot of oxygen.
Prof. Munday said that 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.
“We’ve now established it isn’t simply the acidification of the oceans that is causing disruption – as is the case with shellfish and plankton with chalky skeletons – but the actual dissolved CO2 itself is damaging the fishes’ nervous systems.”
The work shows that fish with high oxygen consumption are likely to be most affected, suggesting the effects of high CO2 may impair some species worse than others – possibly including important species targeted by the world’s fishing industries.
Catastrophic global warming from unrestricted emissions of greenhouse gases remains the gravest preventable threat to humanity, biodiversity and food security (see “Nature Publishes My Piece on Dust-Bowlification and the Grave Threat It Poses to Food Security“).
The time to act was along time ago, but now is better than waiting until we have irreversibly destroyed our ability to feed the 9 billion people we are projected to have by midcentury.
Credit: Image courtesy of ARC Centre of Excellence in Coral Reef Studies)
Related Posts:
- Nature Geoscience study: Oceans are acidifying 10 times faster today than 55 million years ago when a mass extinction of marine species occurred
- Geological Society: Acidifying oceans spell marine biological meltdown “by end of century” — Co-author: “Unless we curb carbon emissions we risk mass extinctions, degrading coastal waters and encouraging outbreaks of toxic jellyfish and algae.”
Previous in TP Climate Progress
Language Intelligence: Lessons on persuasion from Jesus, Shakespeare, Lincoln, and Lady Gaga
“2.3 billion tonnes of human CO2 emissions dissolve into the world’s oceans every year”
I think that should read 2.3 billion tonnes of human CARBON. The CO2 would be more like 8 billion tonnes a year.
Repost + Trackback
http://climateforce.net/2012/01/23/carbon-dioxide-is-driving-fish-crazy-and-threatening-their-survival-study-finds/
Seems completely immoral to be imposing this kind of damage to the fish of the world just because we don’t want to clean up our energy supply.
Ocean acidification lasts effectively forever as far as humans are concerned. How many generations will hate us for trashing their future just so we could drive two tonnes of steel to the mall for donuts? How would we feel if the last generation left us a turbo-charged weather system and damaged ocean because they were too lazy to act responsibly?
Do we have no limits for how much damage we will do?
The human brain evolved especially once humans started to consume fish.
All vertebrate brains share a common underlying form, which appears most clearly during early stages of embryonic development. In its earliest form, the brain appears as three swellings at the front end of the neural tube; these swellings eventually become the forebrain, midbrain, and hindbrain (the prosencephalon, mesencephalon, and rhombencephalon, respectively). At the earliest stages of brain development, the three areas are roughly equal in size. In many classes of vertebrates, such as fish and amphibians, the three parts remain similar in size in the adult, but in mammals the forebrain becomes much larger than the other parts, and the midbrain becomes very small. http://en.wikipedia.org/wiki/Brain
Because humans are “Mammals”, they belong to the vertebrates (classification). Therefore it is likely that effects which alter the perception of fish to elevated Co2(dissolved Carbon), is also affecting human neuron transimission.
Related
Living in a Contaminated Estuary: Behavioral Changes and Ecological Consequences for Five Species http://www.bioone.org/doi/abs/10.1525/bio.2011.61.5.6
About eating fish: the fact that we’ve been doing something a long time hardly makes it right or appropriate. The same defense of human slavery was used in the 19th century. Our culture fosters this “man the predator” mythology to justifying our eating animals… It’s amazing how hard it is to challenge climate “hawks’” carnism. Nevermind it’s not necessary and is contributing massively to the problem you claim to care about. It’s an ethical tragedy. It’s lacking in intellectual and moral integrity not to live your values of energy awareness and compassion.
There’s something fishy about human brain evolution
Brain development and function requires ample supplies of a particular polyunsaturated fatty acid: docosahexaenoic acid (DHA). DHA is critical to proper neuron function. Human baby fat provides both an energy source for the rapidly growing infant grey matter, and also, says Dr. Cunnane, a greater concentration of DHA per pound than at any other time in life.
Aquatic foods are also rich in iodine, a key brain nutrient. Iodine is present in much lower amounts from terrestrial food sources such as mammals and plants.
It was this combination of abundant shoreline food and the “brain selective nutrients” that sparked the growth of the human brain, he says.
“Initially there wasn’t selection for a larger brain,” argues Dr. Cunnane. “The genetic possibility was there, but it remained silent until it was catalyzed by this shore-based diet.” http://www.eurekalert.org/pub_releases/2006-02/nsae-tsf021706.php
Would this qualify as one of the big “unknown unknowns” that you asked readers about? (Except of course now it is known, though probably not completely understood)
As far as I can tell from reading this blog, nobody thought of such an effect before, and this sounds like a true ecological disaster in the making.
The ARC news release differs from Science News (Janet Raloff) review on the key point of when this might occur in the ocean.
ARC attributes an “end of the century” estimate to Dr. Murray, while Raloff wrote, “The idea emerged after Philip Munday of James Cook University in Townsville, Australia, told Nilsson of behavioral quirks his laboratory fish were exhibiting in a high–carbon dioxide environment — conditions exemplifying ocean waters a half-century or more from now..”
Half century? Or 88 years?
http://www.sciencenews.org/view/generic/id/337677/title/Rising_carbon_dioxide_confuses_brain_signaling_in_fish
ARC review refers to Munday.
Consider areas with abruptly higher dissolved carbon, i.e. from methane hydrate destabilizing in the sea-bed. Or from higher erosion rates connected to permafrost thaw and river runoff.
Future expeditions of sea-bed methane, also should look at animal brains.
Looking at what aquatic animals exist at all in a methane-enriched environment might be a start in that line of research. How long does dissolved methane persist in the ocean is a related question.
The CO2 issue is somewhat different. As the researchers found out, CO2 concentration interferes with the ratio between concentrations of intracellular and extracellular ions, and that imbalance can reverse synaptic firing patterns. An increased CO2 concentration in the ocean is likely to persist, and for how long? By now I hope some researchers have done those estimates, I just haven’t come across them.
Joan, i was referring to the ESAS and similar regions. Very high carbon might be only related to relative low-lying coastel areas with less currents, all this is possibly leading to so called ocean dead zones (aonxic/hypoxia). The river runoff with carbon material and dissolved carbon in the sea is likely to be transported with the currents there (weathering). Which doesn’t mean that levels are not evalted. But in the instance of large carbon spikes in the water, it is likely that this is a precurosr for ocean dead zones and pronounced affects on most fauna and sea flora.
Maybe similar occurences (abrupt elavated carbon levels) are responsible for mass die off’s we can read from time to time.
i.e.
http://www.dailymail.co.uk/news/article-1344345/Animal-death-mystery-Jackdaws-Sweden-fish-Brazil-New-Zealand-crabs-England.html
Related
Broadcast study of ocean acidification to date helps scientists evaluate effects on marine life
Might a penguin’s next meal be affected by the exhaust from your tailpipe? The answer may be yes, when you add your exhaust fumes to the total amount of carbon dioxide lofted into the atmosphere by humans since the industrial revolution. One-third of that carbon dioxide is absorbed by the world’s oceans, making them more acidic and affecting marine life.
A UC Santa Barbara marine scientist and a team of 18 other researchers have reported results of the broadest worldwide study of ocean acidification to date. Acidification is known to be a direct result of the increasing amount of greenhouse gas emissions. The scientists used sensors developed at Scripps Institution of Oceanography at UC San Diego to measure the acidity of 15 ocean locations, including seawater in the Antarctic, and in temperate and tropical waters. http://www.eurekalert.org/pub_releases/2012-01/uoc–bso012312.php
Volcanic vents come to mind. Those are probably high-CO2 environments. Of course they are also unique ecosystems, with life evolved for those conditions. But still, they might hold some clues.
“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, says Professor Philip Munday of the ARC Centre of Excellence for Coral Reef Studies and James Cook University.”
Is the paper available on-line? I’d like to see some numbers for those concentrations.
Near-future carbon dioxide levels alter fish behaviour by interfering with neurotransmitter function
Göran E. Nilsson, et al. (2012)
Nature Climate Change
http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1352.html
The abstract and figures don’t give away the CO2 or H+ concentrations. Subscription required.
Now we know why the US government is acting dumber than dirt (with apologies to soil). Not only are these “representatives” poisoned by Federal Reserve Notes but they are literally poisoned like fishes from carbonic acid contamination.
So let’s oxidize more “frackin’” fossil methane and get crazy. Or use some “clean, safe” uranium for atomic fission.
I don’t believe this country knows the difference between sustainable energy policy planning versus mining pit holes in the ground and associated ecological suicide. Of course, the latter has been federally financed for a century (see federal subsidies).
The world community needs a sign change on those half trillion dollar, annual, global fossil subsidies (IEA, 2011). The USA might be an excellent place to start.