Inter- and intra-specimen variability masks reliable temperature control on shell Mg/Ca ratios in laboratory and field cultured <i>Mytilus edulis</i> and <i>Pecten maximus</i> (bivalvia) - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Biogeosciences Discussions Année : 2008

Inter- and intra-specimen variability masks reliable temperature control on shell Mg/Ca ratios in laboratory and field cultured Mytilus edulis and Pecten maximus (bivalvia)

Résumé

The Mg/Ca ratios of biogenic calcites are commonly seen as a valuable palaeo-proxy for reconstructing past ocean temperatures. The temperature dependence of Mg/Ca ratios in bivalve calcite has been the subject of contradictory observations. The palaeoceanographic use of a geochemical proxy, like Mg/Ca ratios, is dependent on initial, rigorous calibration and validation of relationships between the proxy and the ambient environmental variable to be reconstructed. Shell Mg/Ca ratio data are reported for the calcite of two bivalve species, Mytilus edulis (common mussel) and Pecten maximus (king scallop), for the first time grown in laboratory culturing experiments at controlled and constant aquarium seawater temperatures over a range from ~10 to ~20°C. Furthermore, Mg/Ca ratio data of laboratory-grown and field-grown M. edulis specimens were compared. Only a weak, albeit significant, shell Mg/Ca ratio?temperature relationship was observed in the two bivalve species: M. edulis (r2=0.37, p<0.001 laboratory cultured specimens and (r2=0.50, p<0.001 for field cultured specimens) and P. maximus (r2=0.21, p<0.001, laboratory cultured specimens only). In the two species, shell Mg/Ca ratios also were not found to be controlled by shell growth rate and salinity. Furthermore, measurement of Mg/Ca ratios in the shells of multiple specimens illustrated that a large degree of variability in the measured shell Mg/Ca ratios was significant at the species, inter- and intra-individual shell levels. The study data suggest the use of bivalve calcite Mg/Ca ratios as a reliable, precise and accurate temperature proxy still remains limited, at least in the species studied to date. Such limitations are most likely due to the presence of significant physiological effects on Mg incorporation in bivalve calcite, with such variability differing both within single shells and between shells of the same species that were precipitated under the same ambient conditions.
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Dates et versions

hal-00297969 , version 1 (18-06-2008)

Identifiants

  • HAL Id : hal-00297969 , version 1

Citer

P. S. Freitas, L. J. Clarke, H. A. Kennedy, C. A. Richardson. Inter- and intra-specimen variability masks reliable temperature control on shell Mg/Ca ratios in laboratory and field cultured Mytilus edulis and Pecten maximus (bivalvia). Biogeosciences Discussions, 2008, 5 (1), pp.531-572. ⟨hal-00297969⟩

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