Volcanic carbon dioxide vents show ecosystem effects of ocean acidification

Jason M. Hall-Spencer, Riccardo Rodolfo-Metalpa, Sophie Martin, Emma Ransome, Maoz Fine, Suzanne M. Turner, Sonia J. Rowley, Dario Tedesco, Maria Cristina Buia

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1074 Scopus citations


The atmospheric partial pressure of carbon dioxide (pCO2) will almost certainly be double that of pre-industrial levels by 2100 and will be considerably higher than at any time during the past few million years. The oceans are a principal sink for anthropogenic CO2 where it is estimated to have caused a 30% increase in the concentration of H+ in ocean surface waters since the early 1900s and may lead to a drop in seawater pH of up to 0.5 units by 2100 (refs 2, 3). Our understanding of how increased ocean acidity may affect marine ecosystems is at present very limited as almost all studies have been in vitro, short-term, rapid perturbation experiments on isolated elements of the ecosystem. Here we show the effects of acidification on benthic ecosystems at shallow coastal sites where volcanic CO2 vents lower the pH of the water column. Along gradients of normal pH (8.1-8.2) to lowered pH (mean 7.8-7.9, minimum 7.4-7.5), typical rocky shore communities with abundant calcareous organisms shifted to communities lacking scleractinian corals with significant reductions in sea urchin and coralline algal abundance. To our knowledge, this is the first ecosystem-scale validation of predictions that these important groups of organisms are susceptible to elevated amounts of pCO2. Sea-grass production was highest in an area at mean pH 7.6 (1,827 μatm pCO2) where coralline algal biomass was significantly reduced and gastropod shells were dissolving due to periods of carbonate sub-saturation. The species populating the vent sites comprise a suite of organisms that are resilient to naturally high concentrations of pCO2 and indicate that ocean acidification may benefit highly invasive non-native algal species. Our results provide the first in situ insights into how shallow water marine communities might change when susceptible organisms are removed owing to ocean acidification.

Original languageAmerican English
Pages (from-to)96-99
Number of pages4
Issue number7200
StatePublished - 3 Jul 2008

Bibliographical note

Funding Information:
Acknowledgements We thank the staff of Anton Dohrn Benthic laboratory, Ischia for technical help. J.M.H.-S. was funded by a Royal Society University Research Fellowship and was first shown the gas vent sites by M. Taviani in 2002; R.R.-M. and S.M.T. were funded by the Leverhulme Trust. A. de Simone, A. Ferrara and M. Laurenti helped with field measurements, V. King took photo 4d, and O. Hoegh Guldberg and P. Liss helped improve the manuscript.

Funding Information:
15. Kleypas, J. A. et al. Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers: A Guide for Future Research. Report of a workshop held 18–20 April 2005, St. Petersburg, FL, sponsored by NSF, NOAA, and the US Geological Survey (2006).


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