Put another prawn on the barbie?
Not by 2070 if Dr Selina Ward of the University of Queensland is correct about ocean acidification.
What is this strange term and why might it endanger your gastronomic enjoyment, the Great Barrier Reef and the entire oceanic ecosystem?
Broadly speaking, ocean acidification is when the acidity balance (pH) of the ocean tips towards the more acidic end of the scale.
So what?
What this means to our future boils down to one word: carbonate.
This ion is currently found at such high levels in the world’s oceans that corals, krill and other shellfish can incorporate it into their skeletons as calcium carbonate via a process called calcification. These animals provide food and shelter to most of the fauna on the reef.
But upset this balance by increasing acidity, say via dissolving more carbon dioxide into the ocean and those organisms can’t incorporate it into their skeleton.
Really skew this balance and the ionic mix of seawater starts to take leach out the carbonate in the corals or the shellfish.
At a public lecture last week, Dr Ward told disbelieving students of how molluscs raised in a high acidity tank had their shells dissolved entirely.
“They were left with these little jelly-like creatures wandering around the tank,” Dr Ward explained.
Under such conditions, Dr Ward warns, the shellfish are defenceless and are easy prey in the wild.
But surely that experiment is a scare-tactic, an extreme example to garner grants to support the flashy rock and roll lifestyles of marine biologists?
This is where the solid, peer-reviewed evidence comes in.
Antarctic ice core analysis allow us to delve into the past, with water and micro-organisms like krill and algae millions of years old trapped in the ice.
Dr Ward says these cores show us that since pre-industrial times, the world’s oceans have dropped by 0.1 of a pH unit.
This means the oceas are 10 times more acidic than they were before the invention of the stream engine.
In other studies, scientists have shown a decrease in calcification of some marine organisms, over this same time scale, suggesting a link between ocean acidification and this decrease in calcification.
When Dr Ward was asked about what ramifications this could have on the Great Barrier Reef, the coral expert was lost for words.
“So many things in the ocean depend on these things – whales, for example,” she said haltingly, as if trying to comprehend what that would mean for the reef and humanity itself.
“Maybe not in 2050, but in 2070, we could see whole food webs collapse.”
That means no krill, no crabs, molluscs and no coral reefs.
Or fish, sharks, dolphins, whales, or anything else that feeds on these creatures.
Finishing her lecture on a sombre note, many of Dr Ward’s students looked surprisingly unconcerned after being told that ocean life as we know it would disappear.
Afterwards, the Brisbanetimes.com.au overheard a most optimistic thought from one of the students rushing from the hall. “On the plus side, we’re got 60 years to enjoy the prawns,” he said.
Andrew Wight, Brisbane Times 2 June 2008. Article.
