Parasites comprise a large fraction of biodiversity within most ecosystems and can exert strong effects on individuals, populations and communities of their hosts. Despite their ubiquity, the roles of parasites in ecosystem processes, such as fluxes of energy and matter, remain largely unknown due to the rarity of integration between ecosystem ecology and disease research. The central aim of this proposal is to examine the influences of parasites on two fundamental ecosystem processes in freshwaters ? nutrient cycling and primary production. The proposed research will first quantify the effects of infection by trematode parasites on two functional traits of snail hosts (grazing and nutrient excretion) and then use a realistic outdoor mesocosm experiment to quantify the direct and indirect mechanisms through which trematodes influence nutrient cycling and primary production. Collectively, this research will help to advance a conceptual understanding of the roles of parasites in ecosystem processes, which is a pressing topic in light of changes in parasite communities driven by ongoing disease emergence, losses of free living biodiversity, and introductions of novel hosts. The Co-PI will build upon a proven track record of community education and outreach by implementing an effective K-12 science curriculum that focuses on freshwater ecology and global change. The curriculum is novel in its use of a classroom mesocosm experiment utilizing 1 L glass jars containing field-collected pond organisms to create miniature freshwater ecosystems that are subsequently impacted by two widespread forms of global change: nutrient pollution from fertilizer and invasive species in the form of non-native snails. The students will closely track the development of their mesocosms while gaining knowledge on both global change issues and science standards at the elementary and middle school levels (e.g., hypothesis testing and critical thinking). In conjunction with outreach, the Co-PI will enhance ongoing efforts to serve underrepresented students by providing research opportunities to four undergraduates during the summer field seasons at the Hopland Research and Extension Center in Mendocino County, California.
