April 22, 2010 – "Food Webs in River Networks: Algal Mediated Linkages of Rivers to Watershed and Nearshore Marine Ecosystems"
Mary Power, Professor of Integrative Biology, University of California Berkeley
We know too little about the spatial and temporal contexts of food webs to forecast how they will respond to environmental change. Interacting web members often derive their energy and constituent molecules from different environmental source areas ("resource sheds"). Better knowledge of consumers' resource sheds would help us predict the population and food web consequences of spatially explicit environmental change. Organisms can also block resource fluxes to other consumers. Mapping out these "resource shadows" would help us understand consequences of population changes, invasions or losses of species. Resource fluxes and species performances and interactions are strongly influenced by topography and large vegetative structure. We have been using a "predictive mapping" approach to investigate how resource fluxes and food web regimes change with partially predictable changes in environmental controls down a river drainage network. In this talk, Mary Power will focus on regimes that control the production and fate of dominant primary producers (macroalgae, diatoms and cyanobacteria), and explore how predictive mapping might help us forecast ecosystem response, including algal-mediated linkages of river, aerial, and nearshore marine ecosystems, to changes in climate, land use, or biota.
Mary Power's lab at the University of California Berkeley investigates food webs in rivers and their watersheds. She is interested in how attributes of species influence their effects in food webs, and how species interactions change under different environmental regimes. Topics of current interest include: interplay of trophic dynamics with hydrologic and productivity regimes in rivers potential effects of climate change on food webs in rivers and meadows; impacts of invading exotic species food web links between rivers and their watersheds, specifically, the influence of river-derived insect production on terrestrial consumers in watersheds (spiders, lizards, bats); effects of fine bed sediments on juvenile steelhead and the food webs that support their growth changes in energy sources to food webs down drainage networks; landscape controls on stream metabolism, fluxes, and consumer-resource interactions; and the interplay between spatial fluxes of energy and nutrients to food webs and outcomes of local species interactions.