Increased CO2 confuses adult fish too

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Increased ocean acidification can confuse adult reef fish as much as baby fish, according to a study published in a recent issue of the journal Global Change Biology.

Brynn Devine and coauthors tested the effects that near-future levels of carbon dioxide have on the ability of adult Five-lined cardinalfish (Cheilodipterus quinquelineatus) to home to their daytime resting sites after nightly feedings.

The authors allowed a cardinalfish to choose between the odours of conspecifics collected from the same home site as the test individual or one collected from a site about 400 m away.

Although the cardinalfish would choose the conspecific collected from its home site under normal conditions, this ability to distinguish between the two odours was impaired at elevated CO2 levels.

By displacing the test fish to test for their homing ability, the authors found that elevated CO2 levels reduced this by 22–31%. Even when the fish successfully reached their home shelter, they were more active and ventured further from their shelter.

For more information, see the paper: Devine, BM, PL Munday and GP Jones (2012) Homing ability of adult cardinalfish is affected by elevated carbon dioxide. Global Change Biology 168, pp. 269–276.

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