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www.biogeosciences-discuss.net/5/3665/2008/
doi:10.5194/bgd-5-3665-2008
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High frequency Barium profiles in shells of the Great Scallop Pecten maximus: a methodical long-term and multi-site survey in Western Europe
1Laboratoire de Chimie Analytique Bio-Inorganique et Environnement (LCABIE) – Institute Pluridisciplinaire de Recherche sur l'Environnement et les Matériaux (IPREM), UMR 5254 CNRS – Univ. de Pau et des Pays de l'Adour (UPPA), Hélioparc Pau-Pyrénées
2Laboratoire des sciences de l'Environnement MARin (LEMAR) – Institute Univ. Européen de la Mer (IUEM), UMR 6539 CNRS – Univ. de Bretagne Occidentale (UBO), Plouzané, France
3Institute de Recherche pour le Développement (IRD) – Laboratoire des sciences de l'Environnement MARin (LEMAR), Centre IRD de Brest, Plouzané, France
4College of Marine and Earth Studies, University of Delaware, Newark, DE, USA
*now at: Laboratoire de Radiochimie et des Sciences Analytiques et Environnement (LRSAE/EA 1175) – Université de Nice Sophia Antipolis (UNSA), Nice, France
**now at: Johannes Gutenberg University, Institute of Geosciences, Department of Applied and Analytical Paleontology, Mainz, Germany
Abstract. Skeletal barium/calcium ([Ba]/[Ca])shell ratios were measured every third daily striae in 39 flat valves of the Great Scallop Pecten maximus (2-year old; 3 shells/year) collected in temperate coastal environments of Western Europe. Variations of ([Ba]/[Ca])shell ratio were first demonstrated reproducible for several scallop individuals from the same population, over a 7-year period (1998–2004), and from different coastal environments in France (42–49° N). As in previous studies, ([Ba]/[Ca])shell profiles exhibited a background ratio punctuated by transient maxima occurring in summer. Background partition coefficient (DBa=0.11±0.03, in 2000) was similar to that previously reported in P. maximus shells (DBa=0.18), suggesting a direct shell uptake of dissolved seawater Ba (Gillikin et al., 2008). Special attention was then dedicated to the complete monitoring of high resolution ([Ba]/[Ca])shell profiles in bivalve shells (7 years, Bay of Brest) to better constrain environmental processes influencing both the occurrence and the amplitude of summer peaks. In 2000, seawater Ba analyses underlined significant particulate Ba inputs at the seawater interface (SWI) during ([Ba]/[Ca])shell peak events. These Ba inputs are suggested to be subsequent to and rather induced by a pelagic biogenic process. The long term survey revealed first that archived Ba within the shell cannot be used as a direct paleo productivity tracer, and second that complex pelagic/benthic processes in the Ba cycle are responsible of particulate Ba inputs to the SWI, subsequently taken up by the bivalve and recorded as higher ([Ba]/[Ca])shell ratios. When these processes will be better constrained, high frequency observations of Ba in scallop shells would provide new insights into filter feeding dynamics and into Ba biogeochemistry in coastal environments.
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Citation: Barats, A., Amouroux, D., Chauvaud, L., Pécheyran, C., Lorrain, A., Thébault, J., Church, T. M., and Donard, O. F. X.: High frequency Barium profiles in shells of the Great Scallop Pecten maximus: a methodical long-term and multi-site survey in Western Europe, Biogeosciences Discuss., 5, 3665-3698, doi:10.5194/bgd-5-3665-2008, 2008. Bibtex EndNote Reference Manager XML
