Which Traits Predict Invasive Success in Lake and Stream Environments in the Laurentian Great Lakes Basin?

Abstract

Freshwater ecosystems are experiencing environmental and socio-economic impacts from nonindigenous species that are causing losses in ecosystem services. Lake and stream ecosystems have fundamental differences in abiotic and biotic factors such as flow, water temperature, and depth. These environmental differences can filter which species are most successful in each of these ecosystems by favoring certain traits. However, it is not well-understood which species traits (e.g., body size, fecundity, habitat breadth, or temperature) allow species to more successfully invade lake versus stream ecosystems. Focusing on the Great Lakes Basin, I address the following questions about nonindigenous freshwater species: (1) Are different traits associated with nonindigenous species occurring more often in lakes versus streams?, (2) Which traits predict which species will spread farther across freshwater taxa?, (3) Which traits predict which species will spread farther among fish species?, and (4) Do lake or stream species spread farther? I performed stepwise multiple regression between traits and two spread measures: the number of Great Lakes sub-basins colonized and the distance spread by each species. Traits including body size, life history traits, and environmental tolerances are associated with nonindigenous species occurring more often in lakes versus streams. I found that nonindigenous freshwater taxa, generally, and fishes, specifically, with smaller maximum size occurred more often in lakes than streams. When looking at life-history traits across broad nonindigenous taxa, I found that species in lakes had lower fecundity while nonindigenous fish species in lakes had a higher age at maturity. Large body size predicted high spread distance across nonindigenous freshwater taxa while I found the opposite result when only looking at fish species. In terms of life history traits, I found that nonindigenous freshwater taxa with high fecundity spread farther. While, nonindigenous fish species with high fecundity, high maximum lifespan, and high age at maturity also spread farther. Nonindigenous freshwater taxa that spread farther displayed generalist traits such as wide depth range, wide habitat breadth, and wide temperature range. Nonindigenous freshwater taxa and fish species that occurred more often in streams had spread farther compared to taxa and species in lakes. Understanding the traits that are favorable for nonindigenous species in lakes versus streams can be used to manage the spread of invaders and predict future invaders.