A delicate balance: rising acidity in our oceans is putting marine ecosystems at risk.
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Increasing ocean acidity is rapidly damaging marine ecosystems, and urgent action is needed to limit its effects, according to the world's top ocean scientists.
More than 150 leading scientific experts expressed their concern by signing the Monaco Declaration, a document calling for global action and outlining the efforts needed, released last Friday.
The Declaration is based on results from the Second International Symposium on the Ocean in a High-CO2 World, held in Monaco last October, which emphasised the clear-cut ties between rising ocean acidity and rising carbon dioxide emissions.
"The ocean now absorbs about 30 per cent of the yearly emissions of carbon dioxide, which dissolves in water to form a weak acid that is increasing the acidity of the oceans...[and this] carbon dioxide uptake is occurring at a rate exceeding the natural buffering capacity of the ocean," explained Tasmanian oceanographer Will Howard, from the Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart.
As such, unlike global warming, which is an indirect effect of greenhouse emissions, "ocean acidification is a direct impact from rising atmospheric CO2 levels," said Ben McNeil, an Australian signatory of the Declaration from the Climate Change Research Centre, at the University of New South Wales in Sydney.
"[It] is yet another reason why it is in our best interests to stabilise atmospheric CO2 levels by rapidly cutting our...emissions over the coming decades," he said.
Comments
In shallow waters where most corals presently grow, carbonate is not in short supply. But at greater depths carbonate concentration decreases until it reaches a point beyond which shell- and reef-production is no longer possible.
That critical threshold is rising closer to the surface as oceans grow increasingly acidic, limiting the depths at which corals and other organisms can live.
In the new study, the Munday team raised clownfish (Amphiprion percula) larvae in sea water with acidity at levels either current levels or equivalent to 1000 ppm of carbon dioxide -the upper level predicted by 2100 unless we can cut CO2 emissions.
In the lab, larvae that are at the age when they would usually be searching for a reef habitat are attracted to the scent of tropical tree leaves, and repelled by those of a type of tea tree plant that grows in swamps. The ability to discriminate between smells is thought to help the youngsters find a suitable reef habitat, as clownfish prefer to live on reefs surrounding vegetated islands. The larvae also avoid the scent of their parents, presumably to prevent inbreeding.
However, when larvae raised in acid water were given the choice of swimming in water carrying different scents, although they were still attracted by the leaves of a tropical tree called the golden penda, they were no longer repelled by tea tree leaves. Nor were they repelled by their parents' scent.
Great article on ocean acidification. CO2 continues to be one of biggest threats to the survival of animals and life across the globe. So far not enough research has been done into this important subject. More money needs to put into ocean acidification and global warming research.