[R-G] Acidic seas fuel extinction fears

[Richard Menec]

http://news.bbc.co.uk/2/hi/science/nature/7936137.stm

BBC News                Wednesday, 11 March 2009

Acidic seas fuel extinction fears

By Roger Harrabin
Environment analyst

Carbon dioxide emissions from human activities are acidifying the oceans and 
threaten a mass extinction of sea life, a top ocean scientist warns.

Dr Carol Turley from Plymouth Marine Laboratory says it is impossible to 
know how marine life will cope, but she fears many species will not survive.

Since the Industrial Revolution, CO2 emissions have already turned the sea 
about 30% more acidic, say researchers.

It is more acidic now than it has been for at least 500,000 years, they add.

The problem is set to worsen as emissions of the greenhouse gas increase 
through the 21st Century.

"I am very worried for ocean ecosystems which are currently productive and 
diverse," Carol Turely told BBC News.

"I believe we may be heading for a mass extinction, as the rate of change in 
the oceans hasn't been seen since the dinosaurs.

"It may have a major impact on food security. It really is imperative that 
we cut emissions of CO2."

Dr Turley is chairing a session on ocean acidification at the Copenhagen 
Climate Change Congress.


Testing times

The problem is most acute for creatures which make calcified shells

Laboratory tests suggest starfish may be wiped out before the end of the 
century if current emissions trends continue.

Scientists fear mussels may not be able to cope, either. Oysters may be less 
vulnerable, and farmed oysters may fare better than wild oysters.

"One thing is certain," says Dr Turley. "Things will change. We just don't 
know yet exactly how they will change.

"It is not a very wise experiment to be making."

Professor Andy Watson, an ocean biologist from the University of East 
Anglia, believes climate change and overfishing may ruin the seas before 
acidification does.

He condemns increases in CO2 from human activities, but points out that 
ocean acidity also fluctuates naturally.

He also wonders if some creatures might adapt to the changes over time.

"(In) many of the experiments that are being done at the moment, sudden 
changes are made; the CO2 is quickly raised, for example, or the acidity is 
quickly raised.

"Of course, that's not really what will happen in the real world," he told 
BBC News.

"There will be instead a gradual ramping up of CO2 and acidity. And we don't 
know whether organisms will be able to adapt or how quickly they'll be able 
to adapt."

Professor Tony Knapp runs the BIOS institute in Bermuda, where some of the 
key measurements of acidity are taken.

He defends his conclusion that the recent increase in acidity has been 
caused by CO2 emissions from burning fossil fuels.

"It took me a long time to determine that I was convinced... I'm a cynic at 
heart.

"But if you look at the data, and you're intimate with the data, there's 
really no other conclusion you could make".


Stormy waters

On the island of Ischia, in the Bay of Naples, Italy, scientists believe 
they have evidence that many creatures will fail to adapt to increased 
acidification.

The seawater around a part of the island has been more acidic for thousands 
of years thanks to volcanic CO2 vents that turn the seabed into a sort of 
jacuzzi.

If research here presents an accurate picture of future oceans, the 
prospects for shell-forming organisms are bleak.

Some of the creatures that appear to survive increased levels of acidity in 
short-term laboratory studies are not present here in the real world at the 
same levels of pH.

"We are very worried," says Dr Jason Hall-Spencer from Plymouth University, 
who researches the site with help from the Naples-based Benthic Ecology 
Laboratory at Stazione Zoologica.

"The changes here have clearly made life impossible for shell-forming 
creatures.

"When you start messing around with a complex ecosystem it is impossible to 
tell what will happen."

The Ischia site does not present a perfect experiment for future oceans 
because levels of acidity shift regularly as the currents change, whereas 
future oceanic pH levels will be more stable.

But the site does show clear winners and losers: the lush seagrass, 
hyper-fertilised by CO2, may be the tallest in the world.

The extra acidity will suit some creatures, but Dr Hall-Spencer argues that 
the diversity of the site is reduced and therefore it is likely that 
productivity of valuable species will diminish in future acidified oceans.

Ocean acidification is increasingly known as "the other CO2 problem".

It is a new branch of science and researchers were initially uncertain how 
seriously to take the threat.

"In 2004, I did a Google search for ocean acidification and got 17 hits," 
says Dr Turley.

"Now you get hundreds of thousands. There is much more evidence to show this 
will be a problem for the future - indeed it may even be a problem for now."

For many people it will strike a sobering note that humans appear to be 
changing the chemistry of the mighty oceans.

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