Photo by Julian D. Olden
MAISRC researchers are investigating the initial discovery of invasive signal crayfish (Pacifastacus lenisculus) in Minnesota, aiming to potentially identify the first known population establishment east of the continental divide and trace the source population from the invasion. Understanding the population status is imperative for the protection of Minnesota lakes due to the potential for rapid expansion and detrimental ecological effects.
Background:
In October 2023, the DNR confirmed the presence of signal crayfish in Lake Winona, near-adjacent to Alexandria in Douglas County. This was the first confirmation of signal crayfish in Minnesota waters. The project's main objectives include using mitochondrial DNA to determine the geographic source of signal crayfish and assessing the population status of signal crayfish in Lake Winona and surrounding lakes. Traditional sampling methods and environmental DNA will be employed for this purpose. Based on the determined source population, MAISRC researchers intend to propose likely vectors of invasion and communicate this information to prevent future establishments. The feasibility of future control efforts will be assessed based on the signal crayfish population status determined in the project.
To achieve these objectives, MAISRC researchers plan to extract DNA from signal crayfish tissue. They will then sequence COI and 16S markers using Sanger sequencing to compare them to known populations in native and non-native ranges. Genetic information will be crucial in identifying appropriate environmental DNA sampling assays. In support of the second objective, the researchers will conduct multiple visits to Lake Winona and surrounding lakes to deploy crayfish traps and filter lake water for environmental DNA. They aim to make up to 100 environmental DNA self-preserving filter packs and water sampling kits available to interested volunteers. Collaboration between UMN staff, students, and the Minnesota Department of Natural Resources staff will be essential in field sampling activities.
The importance of this research lies in the impact of signal crayfish on native crayfish, fish communities, and entire ecosystems in their invaded range. The confirmation of multiple signal crayfish in Lake Winona in Douglas County, MN, by the Minnesota Department of Natural Resources in October 2023 raises concerns about population size, reproductive potential, extent of invasion, and source population. Evaluating the current population is critical due to the threat of population expansion and profound ecological impacts. The results of this study will inform lake managers of likely invasion vectors and potential control measures.
Learn more about signal crayfish.
Progress update: August 2024
Over the past six months, significant progress has been made by MAISRC researchers in genetic and field sampling to assess the distribution of signal crayfish in Alexandria, Minnesota. They successfully sequenced signal crayfish specimens captured from Lake Winona in October 2023 using mitochondrial DNA (mtDNA). The sequencing results identified a common, invasive lineage of signal crayfish known from other non-native populations in Europe, California, and Nevada, suggesting that the Winona population likely originated from the coastal Pacific Northwest. These data provide valuable information on the origins of the invasion and are critical for selecting and refining primers to test for signal crayfish through eDNA assays.
Researchers conducted two sampling events using physical trapping methods for both adult and juvenile crayfish as well as eDNA sampling to assess the prevalence of signal crayfish. The trapping methods included baited funnel traps for adult crayfish and artificial refuge traps for juvenile crayfish. No signal crayfish were captured during the field sampling. One juvenile crayfish, appearing to be a native virile crayfish (Faxonius virilis), was captured. Due to the challenges of visually identifying juvenile crayfish, this specimen will undergo mtDNA sequencing to confirm its identification. Approximately 40 eDNA samples were collected from Lakes Winona, Agnes, and Henry during the two field sampling events. These samples are currently undergoing DNA extraction at the University of Illinois and will provide additional information on the presence of signal crayfish in Lake Winona and nearby systems.
Throughout the project, researchers collaborated with Douglas County Land and Resource Management and the Minnesota Department of Natural Resources. They distributed 13 community eDNA kits to interested community members, enabling them to target surrounding lakes in the Alexandria area that were not sampled by the research team. These community samples are also currently undergoing DNA extraction. An additional sampling event is planned for the end of July, which will include physical trapping and eDNA collection. Juvenile refuge traps left in the lake for one month will be checked to increase the chances of capturing juvenile crayfish. About 100 more eDNA kits will be made available to the public due to widespread interest in sampling.
As a positive note, initial trapping efforts have not resulted in finding signal crayfish in the same system where they were captured last fall, suggesting they are living in low density or may not be present. Additional trapping efforts are scheduled to continue the search for signal crayfish if they are present. Community engagement through eDNA kits ensures local resource users are aware of the ongoing research. The collaborative approach with various agencies and community members enhances the robustness of the sampling efforts and ensures comprehensive coverage of lakes in the Alexandria area.