The analysis of stable isotopes of the shell applied to the determination of the age of four bivalves of the “Normano-Breton” gulf, Western Channel

The analysis of stable isotopes of the shell is applied to four bivalves of the "Normand-Breton" gulf (Western Channel), with the aim of validating the reading of growth increments.

The individual age of bivalves is usually determined by counting shell's striae. Oxygen stable isotope analyses of the aragonite of the shells of Venus verrucosa Linne, Tapes rhomboides (Pennant), Spisula ovalis Sowerby, and Glycymeris glycymeris Linne, allowed to check the annual periodicity of the formation of the striae. It is further shown that the annual striae appear, on the average, during the colder months of the year.