How some fish cope with rising CO2 in oceans

Sydney: Some coral reef fish may be better prepared to cope with rising carbon dioxide in the world’s oceans - thanks to their parents.

Researchers at the ARC Centre of Excellence for Coral Reef Studies (CoECRS) reported encouraging new findings that some fish may be less vulnerable to high CO2 and an acidifying ocean than previously feared.

“There has been a lot of concern around the world about recent findings that baby fish are highly vulnerable to small increases in acidity, as more CO2 released by human activities dissolves into the oceans,” says Gabi Miller of CoECRS and James Cook University, the journal Nature Climate Change reports.

[caption id=“attachment_365053” align=“alignleft” width=“380” caption=“Some coral reef fish may be better prepared to cope with rising carbon dioxide in the world’s oceans - thanks to their parents. Reuters”]  [/caption]

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“Our work with anemone fish shows that their babies, at least, can adjust to the changes we expect to occur in the oceans by 2100, provided their parents are also raised in more acidic water,” added Miller, according to a CoECRS statement.

“Human activity is expected to increase the acidity of the world’s oceans by the end of this century, on our present trends in CO2 emissions,” co-researcher Philip Munday says.

“Previous studies and our own research have shown that growth and survival of juvenile fish can be seriously affected when the baby fish are exposed to these sorts of CO2 and pH (aciditiy) levels,” Munday adds.

“However, when we exposed both parents and their offspring in more acidic water we found that the anemone fish, at least, were able to compensate for the change,” says Miller. Whether this effect lasts all their lives, remains to be seen, she adds.

How parent fish actually pass on this ability to deal with acidity to their offspring is still a mystery, says Munday. “The time interval is too short for it to be genetic adaptation in the normal sense.”

Based on evidence from past major extinction events, scientists have long feared that the acidity caused by the release of high levels of CO2 could cause havoc among sea-life, especially those which depend on calcium to form their bones and shells.

These findings will be presented at the 12th International Coral Reef Symposium, Cairns, Australia, on July 13, 2012.