Omnivorous Fish and the Stability of Aquatic Food Webs

Miami University, Oxford OH

Investigators

Abstract

AWARD ABSTRACT Michael J. Vanni Miami University Proposal Number: DEB-9982124 The PI proposes to investigate the role of an omnivorous fish, the gizzard shad, in the resistance and resilience of aquatic food webs to perturbations in the form of large pulses of nutrients. They hypothesize that food webs with omnivorous fish, like these shad, are more stable (i.e., resistant and resilient) in repines to perturbations of allochthonous nutrients than are those without omnivorous fish. The enhanced stability might be due to the large steady supply of nutrients transported by omnivorous fish from sediments or to the additional trophic links formed by incorporating the omnivorous fish in the food webs. The objectives of this work are to test predictions generated by the omnivory-stability hypothesis and to determine the underlying mechanisms responsible for observed changed in stability. Replicated pond experiments will be performed to assess how fish influence resistance and resilience of food webs to pulses of nutrients, and if so, whether the mechanism is via nutrient-transport or via a food web-structure role, or both. Modeling will also be used to explore the role of omnivorous fish in the stability of aquatic food webs over a range of ecosystem structures and perturbation types.