Sea-temperature anomalies and population dynamics variations: effects on growth and density of three bivalves

Abstract

The demographic structure of stable population s is usually modelled by a simple exponential decay mode!. For 3 mollusc species, this model has been improved by taking inlo aecount monthly sea-temperature anomalies ealculated on a 20 yr daily tempe rature ehronicle. For the 3 species examined, Tapes rhomboides, Glycymeris glycymeris and SpisuJa 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 variability suggests an apparent positive effeet of te mperature during autumn or winter months, signifieant for T. rhomboides only. ln spring and summer, te mperature 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.