DISSERTATION RESEARCH: The effect of temperature on species interactions and food web structure in lake plankton communities

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Environmental temperature is an important determinant of species distributions. Temperature influences the performance of an organism both directly, by altering physiological processes, but also indirectly by influencing food availability or the intensity of species interactions such as predation and competition. One predicted consequence of anthropogenic climate change is that certain regions of the world are expected to increase in temperature by as much as 8 degrees C during the next century. As such, it is important to understand how both direct and indirect effects of changes in temperature may alter the future distribution of both native and non-native species. This research project has two main objectives. First, it will examine how temperature influences interactions between native and non-native species in freshwater ecosystems, focusing on the case study of a non-native freshwater invertebrate (Daphnia lumholtzi) and its interaction with native Daphnia species. Second, it will examine how temperature might impact lake food webs indirectly via the surrounding watershed. Terrestrial ecosystems provide important energy and material contributions to aquatic ecosystems, and autumn leaf drop in deciduous forests represents a direct and potentially important contribution from terrestrial to aquatic ecosystems. The leaves of deciduous trees provide nutrients and organic carbon that can increase productivity in both decomposer-based "brown" and plant-based "green" food webs. As leaf chemistry is sensitive to changes in temperature, the objective of this research is to determine how changes in temperature, through altering terrestrial vegetation, will impact lake food webs. This research will contribute to an improved understanding of how changes in temperature can alter species composition and the ability of lakes to provide important ecosystem services, such as food production. It will also train future scientists by including both undergraduate and high school students as research assistants, including female research interns recruited through Dartmouth's Women in Science Project (WISP), and through hands-on research projects with K-12 students. In addition, both PIs currently work with the outreach and educational organization, the Lake Sunapee Protective Association, providing a route to disseminate findings to the broader public.