Edgar M., Kimmel, N. and M. S. Poesch. (2025) Community trophic structure within reservoirs change in the presence of invasive Chinese Mystery Snail (Cipangopaludina chinensis) and Northern Crayfish (Faxonius virilis). Aquatic Sciences.

Abstract

The expansion of invasive species significantly threatens ecosystem biodiversity and stability, often leading to alterations in food web dynamics and trophic interactions. This study examines the impacts of two invasive species, the Chinese Mystery Snail (Cipangopaludina chinensis) and Northern Crayfish (Faxonius virilis), in Alberta’s reservoir ecosystems. These species, originally from Asia and Canada’s eastern regions respectively, have established populations in Alberta, raising concerns about their effects on local aquatic food webs. Using stable isotope analysis across five reservoirs with varying invasive species presence, we assessed shifts in trophic structure, resource use, and isotopic niche overlap among native and invasive species. Findings reveal that reservoirs with invasive species showed significant changes in food web length, trophic diversity, and isotopic niche overlap, especially in systems where both species coexisted. Notably, both invasive species reduced macrophyte availability, or availability of isotopically similar resources, leading to shifts in fish diets toward higher trophic levels and affecting their trophic positions. Additionally, niche overlap between the two invasives suggests potential competition for resources, with Northern Crayfish possibly predating on Chinese Mystery Snail in resource-scarce environments. These results indicate that invasive species presence can significantly impact trophic structures, leading to competitive exclusion, changes in fish feeding strategies, and broader ecosystem productivity alterations. Future management should prioritize containment and monitor these invasives’ long-term impacts, particularly given their potential to disrupt biodiversity and ecosystem function.

Citation: Edgar M.*, Kimmel, N. and M. S. Poesch. (2025) Community trophic structure within reservoirs change in the presence of invasive Chinese Mystery Snail (Cipangopaludina chinensis) and Northern Crayfish (Faxonius virilis). Aquatic Sciences.

Also Read:

Edgar M.*, Hanington P., Lu R., Proctor H., Zurawell R., Kimmel N. and M.S. Poesch (2022) The First Documented Occurrence and Life History Characteristics of the Chinese Mystery Snail (Cipangopaludina chinensis, Mollusca: Viviparidae) in Alberta, Canada. BioInvasions Records 11(2): 449-460.

*Lab members: Megan Edgar and Mark Poesch. Check out opportunities in the lab!

Van Mierlo V. A.*, Green S. J., Emmerton C. A., Nasr M., Buendia C., Wyatt F. and M. S. Poesch. (2022). Occupancy of invasive Northern Crayfish (Faxonius virilis) in northern systems is driven primarily by tributary water temperature. Freshwater Science 41(4): 650-664.

Abstract:

Invasive species are the 2nd-greatest threat to global freshwater biodiversity. Crayfish are especially robust invaders due to their omnivorous nature and ability to compete both directly (resource procurement) and indirectly (habitat occupation and modification) with native species. The Northern Crayfish (Faxonius virilis Hagen, 1870) was introduced to the North Saskatchewan River basin (Alberta, western Canada) and has persisted there since the early 1990s. Faxonius virilis’ impacts on native fish assemblages in the North Saskatchewan River have yet to be assessed, even though the watershed is ecologically, economically, and culturally valuable and home to multiple sensitive and at-risk fish species. We aimed to identify the instream environmental characteristics associated with F. virilis occupancy in the North Saskatchewan River basin and to determine which currently unoccupied tributaries are most vulnerable to F. virilis invasion. We used occupancy modeling to meet these objectives. We deployed 24-h baited crayfish traps and measured water temperature, turbidity, flow velocity, and physical complexity at 37 sites along the Alberta portion of the North Saskatchewan River basin. We detected F. virilis at 13/37 sites with no occurrences detected in the upper basin. Occupancy model selection and averaging revealed that water temperature alone was associated with occupancy of F. virilis in the North Saskatchewan River basin. Streams with mean summer water temperatures >∼19.7 C were ≥50% more likely to be occupied by F. virilis than cooler streams and are at highest risk of invasion. Further, we found that streams with mean summer water temperatures <∼15.7 C had a <25% chance of becoming occupied by F. virilis than warmer streams. Coldwater streams may thus have some natural protection against F. virilis invasion. The results from this study provide practical guidelines for watershed management of invasive F. virilis populations in western Canadian river basins. Managing F. virilis is particularly important and time sensitive because F. virilis’ range will likely expand when water temperatures in the basin rise because of climate change.

Citation: Van Mierlo V.A., Green S.J., Emmerton C.A., Nasr M., Buendia C., Wyatt F. and M.S. Poesch. (2022). Occupancy of invasive Northern Crayfish (Faxonius virilis) in northern systems is driven primarily by tributary water temperature. Freshwater Science 41(4): 650-664.

Also Read:

Edgar M.*, Hanington P., Lu R., Proctor H., Zurawell R., Kimmel N. and M.S. Poesch (2022) The First Documented Occurrence and Life History Characteristics of the Chinese Mystery Snail (Cipangopaludina chinensis, Mollusca: Viviparidae) in Alberta, Canada. BioInvasions Records 11(2): 449-460.

*Lab members: Victoria Van Mierlo. Check out opportunities in the lab!

Nature Alberta – The Invasive Northern Crayfish: An Unwelcome Visitor to Alberta’s watersheds.

Citation: Van Mierlo, V. 2022. The Invasive Northern Crayfish: An Unwelcome Visitor to Alberta’s watersheds. Alberta Nature: Fall 2022.

Link to article

Also Read:

Van Mierlo V. A.*, Green S. J., Emmerton C. A., Nasr M., Buendia C., Wyatt F. and M. S. Poesch. (2022). Occupancy of invasive Northern Crayfish (Faxonius virilis) in northern systems is driven primarily by tributary water temperature. Freshwater Science 41(4).

*Lab members: Victoria Van Mierlo. Check out opportunities in the lab!