Explosive volcanism as a cause for mass mortality of pteropods

► The first documented effects of volcanic ash upon pteropods. ► Horizons of pteropods were found to coincide with deposits of volcanic ash in cores from Montserrat. ► Pteropod dissolution was analysed using the Limacina Dissolution Index. ► Ash mixing experiments determined the likely extent of seawater acidification. ► Ash-related seawater acidification was most likely the cause of pteropod decimation.