(Figure 1) Mean canopy forming macroalgal cover from sites at North Vulvano Island

R1-R3 = reference sites away from the CO2 vents, and hence representative of 'present day' pCO2 conditions. S1-S3 = sites with increasing proximity to the vents thus provided a gradient of decreasing pH/increasing pCO2. Given are % of total benthic cover. Corallinaceae includes Amphiroa criptarthrodia Zanardini, Amphiroa rigida J.V. Lamouroux, Corallina elongata J. Ellis & Solander , Corallina officinalis Linnaeus, Corallinaceae Lamouroux, Hydrolithon boreale (Foslie) Y.M. Chamberlain, Hydrolithon cruciatum (Bressan) Y.M. Chamberlain, Hydrolithon farinosum (J.V. Lamouroux) D. Penrose & Y.M. Chamberlain , Jania rubens (Linnaeus) J.V. Lamouroux , Lithophyllum incrustans Philippi, Lithophyllum sp.Philippi, Mesophyllum sp. Lemoine, Neogoniolithon brassica-florida (Harvey) Setchell & L.R. Mason, Phymatolithon cfr lenormandii (J.E. Areschoug) W.H. Adey, Phymatolithon lenormandii (J.E. Areschoug) W.H. Adey, Pneophyllum fragile Kützing, Titanoderma pustulatum (J.V. Lamouroux) Nägeli , Titanoderma sp. Nägeli in Nägeli & Cramer.