Traditional marine communities containing creatures such as sea urchins and snails are being destroyed as CO2 emissions make their environment more acidic.
Algae which is vital for the well-being of coral reefs is also retreating as acidity increases and is being replaced by invasive species which don’t offer coral the same protection.
The changes have been witnessed for the first time by a British-led team monitoring volcanic carbon dioxide vents off the Italian coast in the Mediterranean.
Until now marine scientists have only been able to use laboratory experiments and modelling techniques to predict what the possible consequences of increased CO2 levels for marine life will be.
But observations by the international team led by Royal Society University Research Fellow Jason Hall-Spencer at the University of Plymouth have confirmed fears that entire ecosystems face possibly catastrophic change.
advertisement
Dr Hall-Spencer said; “Nobody has looked at the biological effects of ocean acidification on this scale before.
Previous studies have been small scale, short-term and laboratory-based, so it has been very difficult to predict the wider effects of increasing CO2 emissions on marine life. We show how whole marine communities and ecosystems change due to the long-term effects of acidification.”
CO2 levels are expected to be double that of pre-industrial levels by 2100 and will be considerably higher than at any time for millions of years.
The world’s oceans are the principal sink for man-made CO2 which is estimated to have caused a 30% increase in the concentration of hydrogen in surface waters since the early 1900s and making sea water more acidic.
Working in the Mediterranean the team found different gradients of acidity caused by gases emerging from the volcanic vents which allowed them to use it as a ‘time tunnel’ and to look at the type of conditions expected in our oceans in 2020, 2050, 2100 and beyond.
Concentrating on the levels of acidity expected by the end of the century they found that key marine group such as coral, coralline algae and sea urchins die out. They are replaced by groups more tolerant of acidic waters such as brown seaweed and seagrasses.
Because these species are common in oceans and seas across the globe the changes are a clear indicator that biodiversity will decrease dramatically worldwide.
Dr Hall-Spencer said: “What we saw was very dramatic and shocking.
“All the predictions made in lab experiments about acidity causing the disappearance of species is coming true.
“When we looked in the field it was already happening.
I must admit I though a lot of the claims being made about species disappearing amounted to scaremongering but now I have seen it with my own eyes.
“Our field studies provide a window on the future of the oceans in a high CO2 world. We show the dramatic ecological consequences of ocean acidification including the removal of corals, snails and sea urchins and the proliferation of invasive alien algae.”
“Our observations verify concerns, based on laboratory experiments and model predictions, that marine food webs will be severely disrupted and major ecological tipping points are likely if human CO2 emissions continue unabated.”
Paul Eccleston, Telegraph.co.uk, 8 June 2008. Article.
