Evaluating the potential role of predation by native fish regulating the abundance of invasive spiny water flea

Abstract

Predation by native predators can hinder the success of an invasive species. Bythotrephes, an invasive zooplankton species, established in Trout Lake, Vilas County, Wisconsin, USA, in 2014. However, by 2020, Bythotrephes densities dropped to densities where they were barely detectable. Cisco (Coregonus artedi), a native zooplanktivore, is an abundant fish species in Trout Lake and has been shown to significantly prey on Bythotrephes. Given the decline in Bythotrephes, we asked whether Cisco predation could have played a role in the observed decline in Bythotrephes densities. We modeled Cisco consumption of Bythotrephes using bioenergetic modeling and Bythotrephes production from a production to biomass model. The model results suggested that Cisco consumption was lower than Bythotrephes production during the early years of the invasion, but since 2017 Cisco consumption exceeded Bythotrephes production and has likely played a role in the observed Bythotrephes density declines. Our study provides quantitative context for predation on Bythotrephes, and alongside other studies, suggests native predators can control Bythotrephes densities. Leveraging predation by native species could be an invasive species management tool, so it is important to synthesize and document cases in which predation may control or reduce impacts of invasive species.