Seasonal records and temperature relationships from bivalve shell carbonates using Ca isotope and stable isotope ratio profiles

Ca isotopes of bivalve carbonate, used in combination with light stable isotopes and metal/Ca ratios may provide a useful archive of annual and seasonal parameters such as temperature, salinity or nutrient level, and therefore for high-resolution palaeoclimate reconstructions. Thus, the reliability of these proxies remains questionable given potential vital and microenvironmental effects. Conducting field experiments in the Dutch Wadden Sea near the Netherlands Institute for Sea Research (NIOZ), we investigated these potential effects in the blue mussel Mytilus edulis and in juveniles of the ocean quahog Arctica islandica by directly comparing time series of instrumental environmental data, changing growth rate and shell chemistry. Our study is completed using samples from growth experiments on young Arcitca’s which were performed at the NIOZ laboratory. These individuals were cultured in five temperature controlled basins, ranging from 1 to 12 deg Celcius. Here, temperature should be resolvable as the dominating effect on the growth and on the Ca isotopic composition of similar sized specimens.