"Individual, population and community-level effects of stress in a soft-sediment intertidal system: implications for the invertebrate community and foraging shorebirds."

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Effects of thermal stress in soft-sediment intertidal systems have been under-studied. This is a problem because animals living in these systems often experience large daily thermal shifts related to tidal flow. Many of these animals may be living near their maximum thermal tolerance now, so increasing temperatures in the future could be problematic for both the species in question and the community as a whole. For this reason, mudflat communities in the upper Bay of Fundy, Canada, are vulnerable to effects of climate change. The invertebrate community in this area is dominated by the amphipod Corophium volutator. Also common are mudsnails (Ilyanassa obsoleta), which have negative effects on Corophium through a variety of interactions. Migratory shorebirds, particularly Semipalmated Sandpipers (Calidris pusilla) stop in the region each year in late summer en route from their Arctic breeding grounds to South American wintering grounds. The area is a crucial stopover point for them, and during their time here they feed extensively on mudflat invertebrates, particularly Corophium. Based on this, I propose to investigate, using lab and field studies, the effects of temperature and exposure to other stresses on Corophium survival and reproduction, both on an individual physiological level and in term of effects on the population. I will also examine the effects of stress on the interaction between Corophium and mudsnails. Further, I will implement a 5-year study of sandpiper movement and feeding throughout the Bay of Fundy. This work will involve radiotracking shorebirds and taking blood samples for stable isotope analysis, which will allow us to estimate diet. We will determine residence time, weight gain on different diets (important knowledge because adequate weight gain is essential for successful migration), and annual survival of birds visiting this region. Overall, this work will improve our understanding of effects of thermal and other stressors in this and similar systems, and will help us to predict the implications of climate change for mudflats, and for sandpipers that depend on them.