A rewired food web impedes rebuilding of collapsed fishery populations in an invaded lake

Session: Poster session

Daisuke Goto, University of Toronto, [email protected]
Erin Dunlop, ON Ministry of Natural Resources, Trent University, [email protected]
Don Jackson, University of Toronto, [email protected]

Abstract

Species invasion facilitated by human activities has physically, chemically, and biologically modified lake ecosystems around the world, disrupting species interaction and ecosystem functions. Understanding food web regulation in an ecosystem context is thus critical in guiding fisheries management in invaded systems. Lake Simcoe, a large, impacted lake in southern Ontario, Canada, has experienced multiple human-induced stresses since early 1900s including the recent invasions by nonnative species such as dreissenid mussels and spiny water flea. Here, we aim to understand complexity of historical food web dynamics and recovery processes of collapsed fisheries under varying habitat quality and management actions as well as species invasion. We reconstruct historical food web dynamics using an Ecopath with Ecosim model parameterized with long-term field survey data to explore potential impacts of the stressors on recovery of three collapsed fishery species, Lake Trout, Lake Whitefish, and Lake Herring.  Our scenario simulations show that species invasion may have played a large role in slow recovery of the collapsed species by replacing their historically dominant prey and creating alternative energy pathways. We further explore hypothesized mechanisms underlying long-term impacts of species invasion on the food web dynamics to evaluate their implications for multispecies fisheries management.

1. Keyword
ecosystem modeling

2. Keyword
Dreissena

3. Keyword
fisheries