The Effects of Pulsed Subsidies on Island Food Webs

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Spatial and temporal variation in the availability of resources can have profound effects on the structure and the dynamics of natural communities. Resource pulses are short-term increases in resource availability; on islands in the Bahamas, seaweed deposited during large storms represents an important resource pulse, or subsidy, for predatory lizards. This project will combine experimental and observational studies to determine how seaweed subsidies shape island communities, which are comprised mainly of plants, herbivores, web spiders, and lizards. Major goals are to understand how community responses differ with the frequency and magnitude of seaweed pulses, the ability of consumers such as lizards to aggregate in areas with pulsed resources, the indirect effects of resources on predators' alternative prey, and the various pathways - for example, predation versus nutrient enrichment - by which these complex interactions are manifested. Experiments will be initiated that manipulate both seaweed pulses and lizard densities to address these goals. These field studies will be integrated with mathematical modeling in order to develop a general theory of community responses to resource pulses. Through partnerships with the University of California at Davis Bohart Museum of Entomology and Friends of the Environment in the Bahamas, the project will integrate outreach and education for K-12 students. Researchers will give classroom presentations, train teachers to integrate science in their curriculum, and develop and distribute teaching materials via the web. The research will strengthen an international partnership via collaboration with a Japanese scientist. It also will contribute to the development of a diverse national scientific community and workforce by involving undergraduate and graduate students from under-represented groups in the research process. Results will contribute to a firmer understanding of the ecological consequences of rapid environmental change. As anthropogenic disturbances such as overfishing and eutrophication facilitate shifts towards algae-dominated marine ecosystems, and as climate change causes more frequent and intense Atlantic storms, the effects of marine resource pulses or subsidies on island and coastal communities are predicted to intensify.