A new study has found that
rising human carbon dioxide emissions may in fact be affecting the
brains and central nervous systems of sea fishes, decreasing their
inherent ability to survive.
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 in Townsville, Australia.
“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.
“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.
The researchers studied how
baby clown and damsel fishes performed alongside their predators in
water saturated with carbon dioxide. The predators were somewhat
affected, but 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 the looked at whether
a fishes’ sense of hearing was affected by the increased carbon dioxide
levels. They fond that the fish were confused and no longer avoided
reef sounds during the day, making them easy prey for predators.
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