Meeting Abstract
Global climate change is causing an increase in the number of extreme weather events such as heat waves, which can have far greater effects on organisms and ecosystems than simple changes in mean conditions. Physiological vulnerability to extreme events also varies significantly among species, populations and even conspecific individuals. We studied the effects of heat waves of varying intensity and duration on the intertidal gastropod Littorina littorea, an abundant and ecologically important species in the North Atlantic. We measured the thermal LT50 of L. littorea from six populations in the Gulf of Maine spanning 2 degrees of latitude. In our experiment, we 1) looked at changes in mortality through repeated 6h exposures (1, 2 or 3 days) to aerial temperatures ranging from 35°C to 43°C and 2) examined how responses varied among the six populations. We hypothesized that L. littorea from different locations will vary in their thermal tolerances due to local adaptation, but that these differences may only be detectable after repeated exposures. We also hypothesized that multiple exposures to high temperatures would reduce thermal tolerance. Our results demonstrated a significant decrease in LT50 from 1st day to 3rd day exposures across all sites. However, although there was slight variation of LT50 across sites, we found no significant difference among the three sites. Exploring inter-population variability in vulnerability to repeated exposures is critical if we are to understand how climate change will affect distribution patterns in nature, yet experiments such as these have not been conducted for most intertidal species.
