Effects of an Introduced Predator on Ecosystem Subsidy and Amphibian Decline

University Of California-Davis, Davis CA

Investigators

Abstract

Summary/Abstract: Effects of an introduced predator on ecosystem subsidy and amphibian decline. S. P. Lawler, P.I. The purposes of this project are to test whether stocked trout decrease the amount of emerging aquatic species that serve as prey for terrestrial wildlife, and to assess whether a declining amphibian responds to trout removal. This is important because the indirect effects of introduced trout on terrestrial species are poorly understood, and because trout have been implicated in amphibian declines. This study also addresses the broader topic of 'ecosystem subsidy', wherein local ecosystems are influenced by flows of nutrients and organisms from other areas. Currently, it is unknown how species interactions within ecosystems affects subsidies to adjacent biological communities. We will quantify differences in aquatic and terrestrial communities in basins under four fisheries management schemes: active stocking, discontinued stocking, fish removals, and historically unstocked. We will test impacts of trout on aquatic species, relate abundances of amphibians and aquatic insects to population sizes of bats, birds and snakes, and measure the distribution of insects in uplands. We will also quantify population sizes and habitat use of the declining Cascades frog. Our main intellectual contribution will be to measure the importance of ecosystem subsidy on a large scale, and to assess the role of introduced species in altering subsidies. Broader impacts include providing research training for students from under-represented groups, promoting inter-agency partnerships, and providing information vital to managing mountain wildernesses.