Behavioral and mortality responses of the bivalves Scrobicularia plana and Cerastoderma edule to temperature, as indicator of climate change's potential impacts

Abstract

tTemperature is one of the most important abiotic factors affected by climate change. It determines phys-iological processes, ecological patterns and establishes the limits of geographic distribution of species.The induced thermal stress frequently results in physiological and behavioral responses and, in extremecases, may lead to mortality episodes. Scrobicularia plana and Cerastoderma edule behavioral and mortalityresponses to temperature were evaluated. Specimens were sampled in the Mondego estuary (Portugal),acclimated and exposed to different temperature treatments (5–35◦C). Individual activity and mortal-ity were registered during 120 h laboratory assays. Both species showed a thermal optimum for theiractivity (S. plana: 15–23◦C; C. edule: 20–23◦C), and survival was mainly affected by high temperature(S. plana: LC50120 h= 28.86◦C; C. edule: LC50120 h= 28.01◦C), with 100% mortality above critical values(≥32◦C). Results further indicated that both species are more affected the higher the temperature and thelonger the exposure time. This study indicates that the occurrence of extreme climatic events, especiallyheat waves, may be particularly impairing for these species.