The alarming threat to our oceans that most people have never heard of

WHEN most people think about damage to our oceans, rising sea levels, increased water temperature, overfishing and vast tangles of plastic pollutants readily come to mind.

Less well known is the threat of ocean acidification.

A chemical reaction that has occurred at an alarming rate since the late 19th century, acidification has only recently been identified by scientists and the marine conservation community is still coming to grips with what the long-term consequences might be.

“We didn’t even have a word for [ocean acidification] 15 years go,” says leading marine scientist Professor Ove Hoegh-Guldberg from the University of Queensland. “But basically as we’ve pumped Co2 into the atmosphere, about 30 per cent goes into the ocean where it chemically reacts with water to produce carbonic acid.

Perhaps the most alarming statistic about carbonic acid is the world’s scientists know with a high level of confidence that the ocean acidification that has accrued since about the 1870s “is the highest level in the last 65 million years, if not the last 300 million years,” says professor Hoegh-Guldberg.

If that’s not alarming enough, “It takes about 10,000 years for the ocean to recover from the ocean acidification we’ve already inflicted on it,” Professor Hoegh-Guldberg adds.

While scientists have only been looking closely at acidification over the past 10 years, there are already clear signs that the increase in the oceans’ pH level is having a significant effect on marine life.

A study by professor Philip Munday at James Cook University showed that ocean acidification adversely affects the sense of smell among the larvae of clownfish, which is vital to it the species being able to find a safe home. So there’s no doubt that “animal behaviour is affected by the acidification of the oceans,” professor Munday said.

Acidification has also caused a change in “carbonate ion” concentrations in the oceans which means corals and many other organisms that make shells and skeletons struggle to do so. “That’s a real problem,” says Professor Hoegh-Guldberg.

He points to multi-million dollar oyster fisheries on the US east coast where ocean acidification has prevented oyster larvae from developing.

“They can’t use ocean water in these places anymore for the fishery; they’re having to move the oysters to tanks where they’re manipulating the pH to decrease the acidity,” he says.

“Lots of organisms that have babies have similar issues; we know that some invertebrates and some other animals also have trouble building their adult skeletons and so on.

“So there’s a huge different range of things going on. It’s a bit like an iceberg because we know a little but probably what’s under the surface is huge.

“But this is just another consequence of carbon emissions causing climate change. The good news is we can beat this stuff. We can turn away from fossil fuels, we can embrace green technologies, we can drastically cut carbon emissions and the good guys can win.”

Craig Henderson, The Advertiser, 29 February 2016. Article.

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