Ziveri P. auteur aut IRD Passaro M. auteur aut IRD Incarbona A. auteur aut IRD Milazzo M. auteur aut IRD Rodolfo-Metalpa Riccardo auteur aut IRD Hall-Spencer J. M. auteur aut IRD text journalArticle eng text/pdf born digital access A natural pH gradient caused by marine CO2 seeps off Vulcano Island (Italy) was used to assess the effects of ocean acidification on coccolithophores, which are abundant planktonic unicellular calcifiers. Such seeps are used as natural laboratories to study the effects of ocean acidification on marine ecosystems, since they cause long-term changes in seawater carbonate chemistry and pH, exposing the organisms to elevated CO2 concentrations and therefore mimicking future scenarios. Previous work at CO2 seeps has focused exclusively on benthic organisms. Here we show progressive depletion of 27 coccolithophore species, in terms of cell concentrations and diversity, along a calcite saturation gradient from Omega(calcite) 6.4 to <1. Water collected close to the main CO2 seeps had the highest concentrations of malformed Emiliania huxleyi. These observations add to a growing body of evidence that ocean acidification may benefit some algae but will likely cause marine biodiversity loss, especially by impacting calcifying species, which are affected as carbonate saturation falls. specialized MEDITERRANEE ITALIE 034 036 226 3 282-290 2014 0006-3185 https://www.documentation.ird.fr/hor/fdi:010062569 0006-3185 [F B010062569] https://www.documentation.ird.fr/hor/fdi:010062569 https://www.documentation.ird.fr/intranet/publi/2014/10/010062569.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2014-11-04 2017-08-23 fdi:010062569 fre