Tuesday, November 27 2018
10:55am
Room 1005, Roger A. and Helen B. Krone Engineered Biosystems Building (EBB), 950 Atlantic Dr NW, Atlanta, GA 30332
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Climate Change, Food Webs, and New Theory in Ecology
Brian Silliman, Ph.D.
Nicholas School of the Environment
Duke University
 
Abstract
Consumer–prey interactions form the foundation of food webs and are affected by the physical environment. Over the past 15 years, our work on food-web-physical stress interactions has overturned the bottom-up only paradigm of coastal wetland ecology and served as a catalyst to advance theory on biophysical coupling. In ecology, highly-cited foundational theories [e.g., the environmental stress model (ESM), the stress–gradient hypothesis (SGH), and ecosystem resilience theory] assume increased physical stress dampens top-down control of prey. In the large majority of our field studies and in an extensive review of empirical studies, however, physical stress either does not affect or amplifies consumer control. Additive and synergistic impacts of physical stress on consumer control appear more common, for example, for herbivory versus predation, and for warm- versus cold-blooded consumers.  We also found that climate-generated physical stress can interact with spatial processes to generate powerful consumer fronts (e.g., of microbes, urchins, insects, ungulates, sea stars) that can destroy whole ecosystems. I conceptualize a synergistic stress hypothesis and model that highlight how coupled intensification of physical stress and enhanced consumer pressure can trigger increased occurrence of consumer fronts and expand classical theories in ecology so that their assumption about physical stress–consumer control relationships can be inclusive of what primarily occurs in nature.

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