From: http://www.independent.co.uk
Published November 25, 2008 10:06 AM
Acidic seas threaten coral and mussels
Rising carbon dioxide levels are increasing acidity in the oceans 10
times faster than scientists thought, posing a greater threat to
shell-forming creatures such as coral and mussels.
An eight-year project in the Pacific has found that rising marine acid
levels will challenge many organisms, because their shell-making chemistry
is critically dependent on a less acidic, more alkaline environment. The
study monitored seawater pH levels at the north-east Pacific island of
Tatoosh off Washington state in the United States.
Timothy Wootton, from Chicago University, said scientists found that acidity
levels increased at more than 10 times the rate predicted by computer models
designed to study the link between atmospheric concentrations of carbon
dioxide and ocean acidity.
Atmospheric carbon dioxide
levels have increased by about 100 parts per million since the start of the
industrial revolution and are now at their highest point in at least 650,000
years.
About a third of man-made
carbon dioxide emissions has dissolved into the oceans. As carbon dioxide
dissolves in seawater, it forms carbonic acid, which lowers the ocean's
alkalinity and pH level, making it more acidic.
The Intergovernmental Panel
on Climate Change (IPCC) predicted last year that most coral reefs would
disappear by the century's end because of rising temperatures and ocean
acidity.
However, this latest study,
published in the journal Proceedings of the National Academy of Sciences,
suggests that the rate of ocean acidification may be far higher than the
rate used by the IPCC scientists in their assessment of future prospects for
shell-forming marine creatures such as corals.
Professor Wootton said: "An alarming surprise is how rapidly pH has declined
over the study period ... These data point to the urgency of obtaining a
globally extensive set of ocean pH data through time, and suggest that our
understanding of ocean pH may be incomplete.
"The results showed that variation on ocean pH through time was most
strongly associated with increasing atmospheric carbon dioxide, which
supports the prediction that increasing release of CO2 to the atmosphere
leads to ocean acidification."
The study was unusual in that it looked at acidity in the ocean's intertidal
region, inhabited by shell-forming creatures such as barnacles and mussels.
Professor Wootton said there was a shortage of data on ocean acidification,
especially in non-tropical regions, which this study addressed.
"Our study reveals the strongest negative impacts of declining pH are on
several species of particular importance – large calcifying mussels and
goose barnacles. This finding illustrates several reasons why the effects of
declining ocean pH are of general concern, as these species create critical
habitats for other coastal species, are important players in coastal
nutrient processing, and reflect the more general risks to shellfish
harvesting."
Originally published at: http://www.independent.co.uk/environment/nature/acidic-seas-threaten-coral-and-mussels-1033805.html
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