Meeting Abstract

48.4  Jan. 6  Who’s hot and who’s not? Species-specific thermal histories may determine the biogeographies of Mytilid mussels in the US. JONES, S.J.*; MIESZKOWSKA, N.; WETHEY, D.S.; Univ. of S. Carolina, Columbia; Univ. of S. Carolina, Columbia; Univ. of S. Carolina, Columbia sierra@biol.sc.edu

Most organisms have latitudinally discreet biogeographical distributions. While various factors may affect species� distributions, the range limits are believed to be set primarily by environmental temperature. Thus, with changing climatic conditions, the biogeographic ranges of organisms are predicted to shift polewards in response to shifting seasonal isotherms. Intertidal ecosystems are likely to be strongly affected due to the large variations in temperature these habitats experience in response to the diurnal cycle of emersion and immersion. In the Northern Hemisphere, the southern limit of a species should be a sensitive indicator in response to climate warming, where species are often living very close to their thermal tolerance limits. Laboratory experiments were performed to determine the lethal limits of four Mytilid species from locations in the USA. Differences in response to elevated air and water temperatures were examined, as well as the potential for seasonal acclamatory effects. Short-term thermal history has been found to be important in determining lethality, and thus poses serious consequences for these species in relation to a warming climate, where heatwave events are predicted to increase in frequency and duration in the coming decades.