A study of the stable carbon and oxygen isotope composition of recent shells of Mytilidae, especially of oxygen values in relation to temperature

Analyses of the stable isotopes 18 O and 13 C were made of modern marine shells of the widely distributed Mytilidae, primarily intertidal species, collected from beaches in Europe and southern Africa, as well as from Australia and Argentina. At sites facing the open sea and where the field data of annual mean sea-surface temperatures have been recorded a comparison could be made between the stable isotope values of the shells and the seawater temperatures. The comparison shows that there is a good negative correlation between the seawater temperatures and the δ 18 O values of the Mytilidae shells. The analyses of a series of samples from the outer layer of the valves from five different sites, at right angles to the annual increments, reflected the seasonal variations of the seawater temperatures. The recorded amplitudes of the isotope temperatures in the shells based on the δ 18 O values were similar to the amplitudes of the recorded sea