Validation of the seasonality in growth lines in the shell of Macoma balthica using stable isotopes and trace elements

► We validate the seasonality in growth lines in the shell of Macoma balthica. ► δ18O profiles showed that annual growth lines are due to autumn growth stop. ► Internal lines visible in the cross-section give accurate estimate of age. ► Counting external lines causes overestimation of age and underestimation of growth. ► Sr/Ca ratios and δ18O can be used to estimate age of M. balthica.