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Abstract Predator–prey coupling can result in oscillations of predator–prey densities. These oscillations in predator–prey densities correspond to oscillations in intraspecific competition where a high population density causes high intraspecific competition. Strong coupling of native species can however be disrupted by the introduction of invasive species into food webs. Here, we investigated how the body condition (body mass relative to body length) of a predator, lake trout, and its primary prey, cisco, changed as their respective population densities shifted. We found that the body condition of lake trout and cisco was strongly influenced by their respective population densities, that is, density dependence. The body conditions of lake trout and cisco were also inversely related, which highlights strong predator–prey coupling. Further, we were able to detect the impacts of a recent invasive species,Bythotrephes, as we saw size‐specific shifts in the body condition of prey following the invasion. Overall, this study highlights how the long‐term study of a simple measure, body condition, can reveal predator–prey coupling and yield new insights into the impacts of an invasive species.
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This content will become publicly available on January 22, 2026
Invasive control and native restoration: Directing ecosystem transformation through purposeful food web manipulations
ABSTRACT Ecosystems are abruptly changing due to invasive species and global climate change. In lakes, invasive Rainbow Smelt Osmerus mordax can cause negative ecosystem effects through competitive and predatory interactions with native species leading to food web shifts away from native species dominance, altered zooplankton communities, and the decline or extirpation of native cool and coldwater fishes. We conducted two whole-lake removals of invasive Rainbow Smelt and simultaneous introductions of native Cisco Coregonus artedi through stocking. About 327 and 1.6 adult Rainbow Smelt/ha were removed and about 45 adult Cisco/ha were stocked over 4 years into the two experimental lakes. In one system, native Yellow Perch Perca flavscens relative abundance and density significantly increased by 556% and 143% post-manipulation, respectively. In the other system, native Walleye Sander vitreus relative abundance increased by 26% and became consistently present in the pelagic zone post-manipulation (allowing for density estimation). Rainbow Smelt relative abundance and density decreased by >85% in both experimental lakes. The two ecosystems shifted to native species dominance while invasive Rainbow Smelt became insignificant components of the food webs. In these two intensive whole-lake manipulations, we applied the Resist–Accept–Direct (RAD) climate adaptation framework to test an applicable ecological adaptation strategy and used panarchy theory as an ecologically grounded pathway to purposefully direct ecosystem transformation. We used this holistic management framework to better understand and manage undesired ecological change—“food web thinking.” In the context of our study, two ecosystems were purposefully directed towards native food web structures, species interactions, and processes, which mitigated Rainbow Smelt driven negative effects.
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- Award ID(s):
- 2025982
- PAR ID:
- 10571749
- Publisher / Repository:
- American Fisheries Society
- Date Published:
- Journal Name:
- Fisheries
- ISSN:
- 0363-2415
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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