Effects of ocean acidification and diet on thickness and carbonate elemental composition of the test of juvenile sea urchins.
Continuous anthropogenic CO2 emissions to the atmosphere and uptake by the oceans will cause a reduction of seawater pH and saturation state (Ω) of CaCO3 minerals from which marine calcifiers build their shells and skeletons. Sea urchins use the most soluble form of calcium carbonate, high-magnesium calcite, to build their skeleton, spines and grazing apparatus. In order to highlight the effects of increased pCO2 on the test thickness and carbonate elemental composition of juvenile sea urchins and potential differences in their responses linked to the diet, we performed a laboratory experiment on juvenile Paracentrotus lividus, grazing on calcifying (Corallina elongata) and non-calcifying (Cystoseira amentacea, Dictyota dichotoma) macroalgae, under different pH (corresponding to pCO2 values of 390, 550, 750 and 1000 μatm). Results highlighted the importance of the diet in determining sea urchin size irrespectively of the pCO2 level, and the relevance of macroalgal diet in modulating urchin Mg/Ca ratio. The present study provides relevant clues both in terms of the mechanism of mineral incorporation and in terms of bottom-up processes (algal diet) affecting top-down ones (fish predation) in rocky subtidal communities.
DiSTAV - University of Genoa, C.so Europa 26, 16132 Genoa, Italy. Electronic address: valentina.asnaghi@unige.it.
Valentina
V
Asnaghi
Université de Nice-Sophia Antipolis, EA 4228 ECOMERS, 28 Avenue de Valrose, BP 71, 06108 Nice Cedex 2, France.
Luisa
L
Mangialajo
CNRS-INSU, Laboratoire d'Océanographie de Villefranche, BP 28, 06234 Villefranche-sur-Mer Cedex, France; Université Pierre et Marie Curie-Paris 6, Observatoire Océanologique de Villefranche, 06230 Villefranche-sur-Mer Cedex, France.
Jean-Pierre
JP
Gattuso
Université de Nice-Sophia Antipolis, EA 4228 ECOMERS, 28 Avenue de Valrose, BP 71, 06108 Nice Cedex 2, France.
Patrice
P
Francour
DiSTAV - University of Genoa, C.so Europa 26, 16132 Genoa, Italy.
Davide
D
Privitera
DiSTAV - University of Genoa, C.so Europa 26, 16132 Genoa, Italy.
Mariachiara
M
Chiantore
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002254:Carbonates / Q000378:metabolism*; D004032:Diet; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D047328:Paracentrotus / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D000459:Phaeophyceae; D000461:Rhodophyta; D012623:Seawater / Q000737:chemistry*
D002254:Carbonates; D008274:Magnesium; D002118:Calcium
Acidification; Carbon cycling; Coastal zone; Feeding; Mineralogical composition; Paracentrotus lividus; pH