delta super(13)C of fluvial mollusk shells (Rhone River): A proxy for dissolved inorganic carbon?

The relationship between the delta super(13)C of dissolved inorganic carbon (DIC) and modern mollusk aragonite from rivers was calibrated for the purpose of reconstructing DIC paleochemistry from the shell record. The delta super(13)C values of aragonitic bivalves (Dreissena polymorpha, Corbicula fl...

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Bibliographic Details
Published in:Limnology and oceanography 2003-11, Vol.48 (6), p.2186-2193
Main Authors: Aucour, A-M, Sheppard, SMF, Savoye, R
Format: Article
Language:English
Subjects:
Auricularia
Bithynia tentaculata
Corbicula fluminea
Dreissena polymorpha
Freshwater
Theodoxus fluviatilis
Viviparus viviparus
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Summary:The relationship between the delta super(13)C of dissolved inorganic carbon (DIC) and modern mollusk aragonite from rivers was calibrated for the purpose of reconstructing DIC paleochemistry from the shell record. The delta super(13)C values of aragonitic bivalves (Dreissena polymorpha, Corbicula fluminea), prosobranch gastropods (Bithynia tentaculata, Theodoxus fluviatilis, Viviparus viviparus), and an air-breathing pulmonate gastropod (Limnea auricularia) were analyzed from several locations on the Rhone River (-13.7ppt to -6.0ppt) and its major tributary, the Saone River (-11.4ppt to -10.2ppt). The delta super(13)C sub(DIC) varied from -11.5ppt to -7.5ppt, and the delta super(13)C of particulate inorganic matter (POM) varied from -31.7ppt to -25.4ppt. At a given site, the delta super(13)C of all species except the pulmonate were within 1ppt of each other. Whole-shell delta super(13)C correlated positively with delta super(13)C sub(DIC), with a slope close to unity. Bioaragonite-DIC fractionations were 0-1.5ppt for bivalves and 0-2.7ppt for gastropods (excluding the pulmonates). Applying these fractionations, bivalves that live in open water are a reliable proxy, monitoring the average delta super(13)C sub(DIC) value to within its natural similar to 2ppt temporal variation within the growth period. For the suspension feeders (bivalves) using POM as a food source, the delta super(13)C of whole shells and bulk POM indicated that the incorporation of carbon derived from respiratory sources lay in the range 10-30%. Fine-scale analyses of growth increments of C. fluminea could not be related simply to delta super(13)C DIC because metabolic and seasonal variations in delta super(13)C sub(DIC) produced similar isotopic fluctuations ( less than or equal to 2.5ppt).
ISSN:0024-3590