Grazer Diversity, Foodweb Architecture, and Ecosystem Function in Eelgrass Beds

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This project will employ an integrated program of mesocosm and field experiments to determine the influence of grazer diversity on trophic processes (plant productivity and functional group composition, secondary production, and trophic transfer) in beds of eelgrass (Zostera niarina), an important ecological engineer in coastal regions throughout the northern hemisphere. Vegetated estuarine systems are particularly suited to addressing links between grazer diversity and ecosystem processes because of the well documented impacts of grazers on both plant assemblages and predator production in these systems, and their relatively rapid responses to manipulation. The investigator's previous research demonstrated that small invertebrate grazers can be pivotal in maintaining normal structure and function in this and other vegetated benthic ecosystems. Yet the importance of grazers in the context of the multi-level seagrass food webs remains poorly understood. Accordingly, the study three goals: 1) to test the relative importance of grazing and resource limitation to structure and function of eelgrass communities, and the role of grazer diversity in mediating them; 2) to test the impact of grazer diversity on penetrance of the trophic cascade, using the eelgrass community as a model system; and 3) to test the hypothesized link between biodiversity and ecosystem stability by comparing variance in production and trophic processes across years and seasons as a function of grazer diversity.