EMECO

The Ocean in a High CO2 World

The Second International Symposium on "The Ocean in a High CO2 World" was held in Monaco, 6-9 October 2008. The main sponsors were SCOR, IOC, IAEA and IGBP. ICES and PICES sponsored a joint theme session on "Fisheries, food webs, ecosystem impacts". The symposium was well attended by about 250 scientists from 31 countries. Ocean acidification as seen by an increase of the pH value is not a new phenomenon. It was first described in 1957 since when there is a clear trend of increasing CO2 in the world ocean. If it continues, there will be only 20 years left until tropical coral reefs, for instance, will not have sufficient calcium carbonate available in seawater for aragonite precipitation and growth. Other effects may emerge well before. There is obvious lack of knowledge of the impacts of ocean acidification on all ecosystem levels from cell to ecosystem.

The joint ICES/PICES theme session had two invited presentations from ICES. Jan Helge Fossa of IMR, Bergen spoke on "Consequences of ocean acidification on fisheries". He took a conservative approach, taking into account the uncertainties which still exist with respect to physiological, species and ecosystem impacts of an increasing pH. His talk focussed instead on the key parameters determining stock dynamics such as recruitment and growth and used collapses of big fisheries such as anchovy and herring as examples of what may happen if management does not respond to worsening or unfavourable environmental conditions. He concluded that healthy and robust fish stocks need to be maintained in order to meet the challenge of future ocean acidification.

Jason Hall-Spencer of the Marine Institute, Plymouth University spoke on "Natural CO2 vents reveal ecological tipping points due to ocean acidification". Along Europe's coasts there are several sites near areas of volcanic activities where CO2 is naturally leaking out of the marine sediments. These sites can be used as "open air" underwater laboratories to study high pH marine environments and the consequences for marine life. Hall-Spencer reported on his studies from a Mediterranean site near Sicily and he showed impressively the direct impacts of high pH such as thinned and even dissolved shells of limpets and corals. Sea grass was positively affected due to reduction of calcareous epiphytes; fish are virtually unaffected due to their motility. There is huge potential for such studies on sites worldwide.

Please click here for the Symposia website.