New study has revealed that increasing human carbon dioxide emissions affect the brains and central nervous system of sea fishes with aggressive consequences.
Researchers found that high CO2 levels in sea water disrupt a key brain receptor in fish, causing marked changes in their behavior and sensory abilities.
High intensity of carbon dioxide estimated to occur in the ocean by the end of this century will interfere with fishes' ability to hear, smell, turn and evade predators, said 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 clear that they sustain significant disruption to their central nervous system, which is likely to impair their chances of survival," Munday noted.
Munday clarified that elevated CO2 levels in the oceans can directly affect fish neurotransmitter functions, posing a direct and previously unknown threat to sea life.
The researchers studied how baby fishes performed alongside their predators in CO2-enriched water.
The study revealed that the sense of smell of baby fish was harmed by the CO2 in the water and they found it harder to locate a reef, to settle on or detect the warning smell of a predator fish.
Observing wider ability loss, the team then examined fishes' sense of hearing and identified that they were confused and no longer avoided reef sounds during the day. Therefore being attracted to reefs during daylight would make them be hunted by predators.
The team's latest research shows that high CO2 levels directly stimulate a receptor in the fish brain called GABA-A, leading to a reversal in its normal function and over-excitement of certain nerve signals.
Researchers concluded that effects of elevated CO2 levels are likely to be most felt by those living in water, as they have lower blood CO2 levels.
