The demographic structure of stable populations is usually modelled by a simple exponential decay mode. For 3 mollusc species, this model has been improved by taking inlo account monthly sea-temperature anomalies calculated on a 20 yr daily temperature chronicle. For the 3 species examined, Tapes rhomboïdes, Glycymeris glycymeris and Spisula ovalis, from the southern part of the Western English Channel, only temperature anomalies during the 2 mo following the major spawning period were positively eorrelated with density anomalies, probably in eonneetion with larval stage sensitivity. Comparison of temperature anomalies and mean annual growth va riability suggests an apparent positive effeet of temperature during autumn or winter months, significant for T. rhomboïdes only. ln spring and summer, temperature anomalies were negatively correlated with annual growth; although this phenomenon did not reach statistieal significanee, it may be linked with the well-known competition between gonadie development and somatie growth .