Collaborative research: Biodiversity and ecosystem functioning in plant-grazer systems: experimental tests in a marine benthic community

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The maintenance of biological diversity and the ecosystem processes dependent on it are key goals of conservation biology and are issues of great societal concern. Influential research in terrestrial habitats has shown that several ecosystem processes are related to plant diversity. Yet links between plant diversity and function remain poorly studied in marine ecosystems. Moreover, consumers play central roles in regulating primary production and community structure, particularly in the oceans. But the importance of consumer diversity in mediating plant diversity and production relationships as well as other important ecosystem processes is poorly known for any system. With increasing human perturbation of marine habitats and the growing likelihood of unprecedented extinctions, there is a pressing need to understand the functional roles of the identity and diversity of marine plants and animals. This research project will address the foregoing issues using a diverse assemblage of marine macroalgae and their herbivores, including amphipods, isopods, gastropods, urchins, crabs, and fish, in mesocosm and field experiments in North Carolina. Factorial manipulations of algal and consumer identity and diversity, as well as resource availability (i.e., nutrients and light), will test the relative independent and interactive effects of these factors on primary and secondary productivity, and individual and community?wide consumption rates. Several characteristics of this system make it exceptionally tractable for this study, including a detailed understanding of its natural history and ecology. Specifically, this project will address the following five questions: 1) How do algal identity and diversity affect net primary production? 2) How do algal identity and diversity affect individual and whole?community consumption rates and secondary production? 3) How do consumer identity and diversity affect net primary production? 4) What are the relative independent and interactive effects of plant and herbivore identity and diversity in controlling net primary production? 5) How do plant diversity and herbivory interact with resource availability to control net primary production? What is the relative importance of these interacting factors?This will be one of the first studies to test the effects of species diversity on ecosystem properties using field manipulations in a marine community, and one of the few studies in any system to consider simultaneously the roles of prey and consumer diversity in a factorial design. In doing so this research will directly test how the widely publicized effects of plant diversity on ecosystem processes are altered through realistic levels of consumer pressure. This research program also brings together three principle investigators with complementary strengths in experimental benthic marine ecology, restoration and landscape ecology, and specializations in macrophyte, fish, and invertebrate biology. The research fits within the Biological Diversity in Marine Systems special theme of emphasis of the NSF Biological Oceanography Program. The results will help ecologists and policy makers understand the potential consequences of the ongoing loss of species diversity, potentially benefiting society by helping to wisely conserve similar systems. In addition, this project will have broader impacts in education and training by providing research opportunities to young scientists at a range of educational levels (from undergraduate to postdoctoral scientists) and backgrounds, including groups that are underrepresented in science. Results will be disseminated through publications in top journals, and to the general public through articles in non?technical magazines, our web sites, and public seminars.