AUTHORS: Eric R. Larson, University of Illinois; Caitlin C. Bloomer, University of Illinois; Don Eaton, Minnesota Department of Natural Resources; Denver Link, University of Minnesota; Reagan Oller, University of Illinois; Gretchen J.A. Hansen, University of Minnesota
ABSTRACT: The signal crayfish (Pacifastacus leniusculus), native to the Pacific Northwest of North America, is among the most invasive crayfish species globally, with populations widely established throughout Europe and Japan. Signal crayfish have never been detected from eastern North America, although previous research has identified the Upper Mississippi and Great Lakes watersheds as environmentally suitable for this invasive species. In October of 2023, ten signal crayfish individuals were trapped from a lake in west central Minnesota by a commercial bait harvester. We report here molecular surveillance of this possible, incipient signal crayfish invasion. Mitochondrial DNA (mtDNA) barcoding identified the collected crayfish as P. leniusculus, resembling non-native populations of the species known from the Lake Tahoe area of California and Nevada. We collected environmental DNA samples in summer and autumn of 2024, including through sampling kits distributed to lake association volunteers, and used quantitative PCR with a signal crayfish-species primer and probe assay to survey for evidence of this species in the original lake and neighboring freshwater ecosystems. Our preliminary results are relevant to management responses for this novel, potentially impactful invasive species in the Midwest.
AUTHORS: Caden J. Jungbluth, Wisconsin Cooperative Fishery Research Unit, Molecular Conservation Genetics Lab; Amy L. Springer, Wisconsin Cooperative Fishery Research Unit, Molecular Conservation Genetics Lab; Stephen F. Spear, U.S. Geological Survey, Upper Midwest Environmental Sciences Center; Jared J. Homola, U.S. Geological Survey, Wisconsin Cooperative Fishery Research Unit
ABSTRACT: Prevention of new invasive species often hinges on early detection and quick removal. Aquatic invasive species can be especially difficult to detect without extensive sampling due to habitat complexity and low initial abundances. Point-of-use biomolecule detection methods provide a possible solution via near real-time identification of DNA or other biological materials. Loop-mediated isothermal amplification (LAMP) provides a user-friendly approach for environmental (e)DNA detection that can be easily deployed in the field and yield diagnostic results within 40 minutes. Water can be filtered and the eDNA can be rapidly extracted with a Chelex resin and a portable heat block. We are developing a LAMP assay for red swamp crayfish (Procambarus clarkii) to enable identification of introductory pathways (e.g. the pet trade) and monitoring of the spread of established invasion sites. We generated 36 candidate primer sets that we evaluated in silico for red swamp crayfish specificity using the program BLAST to identify DNA sequence alignments to other species in the NCBI database. Sixteen species-specific candidate primer sets were then optimized for temperature of the LAMP reaction and brand of master mix. The optimal set of conditions were then used to further evaluate species-specificity through test amplifications of extracted DNA of related species (i.e. other Procambarus crayfish). Finally, we performed limit of detection testing down to a concentration of 1 copy/μL of target DNA, with consistent detections present at 100 copies/μL. Field collection of eDNA water samples from known infested waterbodies is underway to identify potential environmental inhibitors to our ability to detect red swamp crayfish presence. This tool could be implemented to detect—and possibly prevent—invasions through rapid field-based monitoring in areas where red swamp crayfish are a concern for introduction and spread.
AUTHORS: William Ota, Michigan State University; Aaron Sullivan, Michigan State University; Sarah Walker, Michigan State University; Brian Roth, Michigan State University
ABSTRACT: Red swamp crayfish (Procambarus clarkii) are the planet's most widely distributed invasive crayfish. They are a keystone species that can alter shoreline stability, macroinvertebrate communities, trophic interactions, water quality, and macrophytes in invaded ecosystems. This species became established in Michigan in 2017 within ponds and lakes, initiating an adaptive management plan to monitor, mitigate, and/or eradicate invasive populations. From 2021-2023, we tracked red swamp crayfish using radio telemetry in seven ponds in Southeast Michigan. Crayfish from 32 - 42 mm were tagged and tracked weekly for 5-6 months per individual over 2 years. A total of 235 crayfish were tagged and successfully tracked. Red swamp crayfish home range size was significantly affected by pond size (p
AUTHORS: Sarah Walker, Michigan State University; Brian Roth, Michigan State University; William Ota, Michigan State University; Colin Assenmacher, Michigan State University; Aaron Sullivan, Michigan State University
ABSTRACT: Red swamp crayfish (Procambarus clarkii) are global invaders that negatively affect ecosystems worldwide through bank erosion, trophic interactions, and competition. There is limited research about their habitat preferences in invaded areas inside North America or in lentic ecosystems. Our study evaluates habitat selectivity by red swamp crayfish in southeastern Michigan ponds where red swamp crayfish were first found in 2017. We used radio telemetry to track the movement and habitat characteristics of confirmed locations for 46 crayfish at 4 sites in June through September of 2022. We used remotely sensed habitat characteristics from 2022 NAIP aerial imagery and determined macrophyte cover, terrestrial vegetation cover, and shore use of each detection. We then analyzed these classifications for selectivity using Ivlev’s Electivity Index. We gave further context to these classifications and selectivity by analyzing them with our field habitat observations in a logistic regression. Our index indicated a strong avoidance of shore areas, an avoidance of no cover areas, and a non-selective use of macrophyte areas. We also demonstrated slightly more selectivity for areas with terrestrial cover in male I crayfish and less avoidance of terrestrial vegetation cover areas in ponds with less macrophytes. Field observed deep water habitat characteristics significantly (p-value
AUTHORS: Colin Assenmacher, Michigan State University; William Ota, Michigan State University; Kathleen Quebedeaux, Michigan Department of Natural Resources, Fisheries Division; Brian Roth, Michigan State University
ABSTRACT: Procambarus clarkii are the world’s most widespread invasive crayfish species established in Michigan since 2017. P.clarkii is of high concern due to their extensive burrowing behavior, which can damage human infrastructure through bank erosion and decreased bank stability. Our research aimed to investigate how soil and environmental characteristics of pond banks relate to P.clarkii burrow density. We measured key soil characteristics and potentially influential environmental variables from July to August of 2024 at 74 sites invaded by P.clarkii in Southeast Michigan to quantify which physical properties influence variations in burrow density within a waterbody and across multiple waterbodies. These sites were spread across 13 invaded waterbodies at three golf courses with varying burrow densities. Calculated burrow density was based on surveys conducted during the 2023 and 2024 field seasons and ranged from 0 to 8.42 burrows per square meter across sample sites and targeted waterbodies. We collected soil cores at each site to determine particle size, percent organic matter, penetration resistance, bulk density, and profile soil horizons. Bank slope, percent vegetation cover, and canopy cover were measured at each coring location. Preliminary analysis indicates regions of low burrow density are associated with steeper pond banks, particularly in the first 50 cm from the waterline. Mean vegetation cover ranged from 80 to 84% across burrow density classes and 35 to 99% over all sites. Penetration resistance was highest in areas of no burrow activity. We found less variation in soil bulk density and percent canopy cover in areas with high burrow density. This indicates that P.clarkii has preferred soil and environmental characteristics when burrowing. These findings help to identify the physical characteristics of high burrowing areas, which will be used to assist in the development of preventative management strategies against P.clarkii establishment and burrowing.
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.
AUTHORS: John F. Bieber, Loyola University Chicago; Ivàn Beck, Colorado College; Reuben Keller, Loyola University Chicago
ABSTRACT: The Chicago River represents a system that is at the edge of several invasion fronts; two of which are the invasive crayfish P.clarkii and F. rusticus. For years, these populations have remained in distinct areas of the Chicago River with little overlap, however; the factor(s) that limits their spread is not known. This project used complimentary field and lab experiments to investigate how stress levels (measured via hemolymph glucose) differed among the populations along a gradient in the Chicago River to inform where populations are in the river.
For the field study, we trapped crayfish in the Chicago River and immediately drew hemolymph from captured individuals. We hypothesized that stress would be the greatest for P.clarkii near Lake Michigan, where populations have not yet been found, and simultaneously would be the lowest for F.rusticus as they are established in Lake Michigan.
In the lab study, we collected P.clarkii along with water from the area where they were captured for holding in lab. Crayfish acclimated in lab before the tanks were filled with Lake Michigan water, and hemolymph was collected after a 90 min period. We hypothesized that P.clarkii populations near Lake Michigan would show lower relative stress to immersion in lake water compared to individuals further downstream and compared to individuals that were not flushed with lake water.
Interestingly, we found that individuals further downstream exhibited elevated glucose compared to individuals closer to Lake Michigan, and our lab studies showed that immersion in Lake Michigan water reduces stress compared to individuals without immersion. Collectively, our results suggest environmental contaminants may be driving the distribution of crayfish. Additionally, this work highlights the importance of considering physiology when managing an invading species.
AUTHORS: Cheyenne E. Stratton, Missouri Department of Conservation; Donald C. Behringer, University of Florida; Jamie Bojko, Teesside University; Margaret L. Taylor, University of Florida; Lindsey S. Reisinger, University of Florida
ABSTRACT: Parasites can affect their hosts’ ecological impacts by reducing host density and altering host traits such as behavioral traits. Most research focuses on density-mediated impacts, but trait-mediated impacts may be equally or more important as they control the interactions among organisms. Parasites can act as top-down forces in ecosystems and can trigger trophic cascades through density- or trait-mediated effects. We investigated how a parasite alters the well-documented ecological impacts of the invasive rusty crayfish (Faxonius rusticus). In 2019, we discovered a significant decline in the F. rusticus population in a Wisconsin lake corresponding to an outbreak of a microsporidian parasite, Nosema rusticus, which reduced infected crayfish activity levels. We hypothesized that infected crayfish, due to reduced activity and lethargy, would have lesser impacts on lower trophic levels including macrophytes and leaf litter (i.e., a trait-mediated trophic cascade). We also predicted that N. rusticus would increase crayfish mortality. To test this, we conducted a 4-week mesocosm experiment in which we varied parasite prevalence to test the trait-mediated indirect effects of the microsporidium on resource biomass and abundance. We also varied crayfish density to compare the strength of trait-mediated effects to a reduction in crayfish density. In support of our hypothesis, we found that less macrophytes and leaf litter were consumed in mesocosms with infected crayfish. Our results also suggest that this parasite is likely to cause density-mediated effects because crayfish infected with N. rusticus had higher mortality rates. These results suggest that parasites can mitigate the impacts of invasive species through both trait- and density-mediated trophic cascades.
