pdf: http://www.perc.plymouth.ac.uk/paleopa....CMS.pdf

Experimental measurements of the 18O/16O isotope fractionation between the biogenic aragonite of Viviparus contectus (Gastropoda) and its host freshwater were undertaken to generate a speciesspecific thermometry equation. The temperature dependence of the fractionation factor and the relationship between Dd18O (d18Ocarb. – d18Owater) and temperature were calculated from specimens maintained under laboratory and field (collection and cage) conditions. The field specimens were grown (Somerset, UK) between August 2007 and August 2008, with water samples and temperature measurements taken monthly. Specimens grown in the laboratory experiment were maintained under constant temperatures (15-C, 20-C and 25-C) with water samples collected weekly. Application of a linear regression to the datasets indicated that the gradients of all three experiments were within experimental error of each other (W2 times the standard error); therefore, a combined (laboratory and field data) correlation could be applied. Comparisons made with existing aragonitic thermometry equations reveal that the linear regression for the combined Viviparus contectus equation is within 2 times the standard error of previously reported aragonitic thermometry equations. This suggests there are no species-specific vital effects for Viviparus contectus. Seasonal d18Ocarb. profiles from specimens retrieved from the field cage experiment indicate that during shell secretion the d18Ocarb. of the shell carbonate is not influenced by size, sex or whether females contained eggs or juveniles.