The dynamics of the invasion of the rusty crayfish, Faxonius rusticus (Girard, 1852) (Decapoda: Astacidea), in two New York state, USA stream systems

Abstract I used 20 years of sampling data to describe the dynamics of the invasion of the rusty crayfish, Faxonius rusticus (Girard, 1852), of two stream systems in New York state (USA) and compare this invasion to invasions of this species of lakes elsewhere in North America. Rusty crayfish typically increased rapidly in abundance while displacing native crayfishes, becoming > 90% of crayfish captured in an average of 9 years. As in lakes, overall crayfish abundance increased as the invasion progressed. The F. rusticus population spread at a median rate of 3 km yr–1 upstream and 8.1 km yr–1 downstream. The hypothesis that an Allee effect would occur at the invasion front was not supported, since the rate of change of F. rusticus abundance did not increase as the invasion progressed. Qualitatively, the dynamics of F. rusticus’s invasion of streams are similar to previous findings for lakes, suggesting that the main processes affecting the invasions are similar.