There is no mention in this
article about the levels of CO2 tested and one suspects effective CO2 poisoning
which will never happen in the real world.
Recall that maximum CO2 content in the atmosphere occurred a long time
ago and that we are presently in a CO2 low in terms of the geological
record. That means that life on Earth
has experienced far higher CO2 levels quite well thank you.
This makes the conclusions of
this study regarding global effects pretty weak.
We do learn that younger and
smaller are more likely to be negatively affected by high CO2 levels at least.
Carbon dioxide is driving fish crazy
by Staff Writers
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.
Rising human carbon dioxide emissions may be affecting the brains and
central nervoussystem 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 CoralReef 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.
In their latest paper, published in the journal Nature Climate Change,
Prof. Munday and colleagues 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 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.
The team's latest paper "Near-future
CO2 levels alter fish behaviour by interfering with neurotransmitter
function" by Goran E. Nilsson, Danielle L. Dixson, Paolo
Domenici, Mark I. McCormick, Christina Sorensen, Sue-Ann Watson, and Philip L.
Munday appears in the journal Nature Climate Change.
1 comment:
In a word, NONSENSE!
More climate alarmism by so called experts. These folks aren't practicing science, what they're really practicing is "Grantsmanship"
The only craziness going around is people who think human activity actually has any statistically significant effect on our climate. It doesn't!
fs
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