The geochemistry of Arctica islandica shells provides an opportunity to reconstruct intra-annual resolution climate records in temperate latitudes, and the annual banding allows close temporal constraint. Stable isotope analyses of carbon and oxygen from an Arctica islandica live-collected at 6 m depth from Irvine Bay, UK are presented. Seawater temperature ranges reconstructed from shell δ18O agree, within error, with instrumental sea surface temperature measurements. The saw-tooth profile of the seasonal δ 18O signal (compared with the sinusoidal seawater temperature) indicates that shell accretion rate is not constant throughout the year. Modelling the expected δ18O profile from water temperature, salinity and shell growth rate suggest that A. islandica at this site has significant variation in the shell extension rate during the year. Material deposited during shell damage shows a positive shift in δ18O. A strong ontogenetic effect is seen in δ13C and damage to the shell is associated with a significant (>0.5‰) and sustained shift of δ 13C.