AUTHORS: Dalton Clayton, Department of Natural Resource Ecology and Management, Iowa State University;
Dr. Michael Moore, USGS Iowa Cooperative Fish and Wildlife Research Unit;
Dr. Michael Weber, Department of Natural Resource Ecology and Management, Iowa State University;
ABSTRACT: The introduction of aquatic invasive species can have negative ecological impacts on invaded ecosystems. Rusty Crayfish (Faxoninus rusticus), a species native to the Ohio River Basin, has extended its range into 28 US states, 3 Canadian provinces, and Western Europe. Rusty Crayfish can displace native crayfishes through competition, destabilize aquatic food webs, alter habitat through bioturbation and consumption of aquatic vegetation, and predate on fish eggs, presenting management challenges. Managers currently lack information on Rusty Crayfish distribution and habitat selection in shallow lakes and wetlands in the glaciated, agriculturally dominated landscapes found near the southern and western margins of their introduced range. Thus, our objective is to determine the habitat associations of Rusty Crayfish in Storm Lake, IA, to help understand Rusty Crayfish habitat selection in a novel habitat on their invasion front and its relationship to native crayfish habitat selection. To explore our objective, we deployed 708 baited minnow traps to sample crayfishes from June through August of 2023 and 2024, across three depths bins (~0-1.5m, 2-3m, 3+m). We also collected habitat data, including dissolved oxygen, pH, water temperature, dominant substrate, and presence of cobble and macrophytes at each trap location. We captured 85 invasive Rusty Crayfish and 47 native Virile Crayfish (Faxonius virlis). Rusty crayfish capture probability increased with cobble substrate, macrophytes, and earlier in the summer. Virile Crayfish capture probability was positively associated with macrophytes, they were more likely to be captured later in the summer and were more likely to captured in the medium and deep depth bins. Our results suggest that Rusty Crayfish and Virile Crayfish are not overlapping in habitat usage, which may suggest competition or niche partitioning.
