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A Habitat and a Parasite : Adult and Larval Parasitic Freshwater Mussels Impact Habitat Choice and Predator–Prey Interactions of a Host Fish and Its Prey

Rock, Sebastian L. LU ; Elmlund, Anna M. ; Nilsson, P. Anders LU orcid ; Watz, Johan ; Calles, Olle and Österling, Martin (2025) In Ecology and Evolution 15(12).
Abstract

Parasitic freshwater mussels are endangered ecosystem engineers with an array of impacts on multiple trophic levels and life stages. While the impacts of adult mussels on separate trophic levels have been studied, few have directly tested how adult mussels can impact trophic interactions, or investigated the impacts of the parasitic mussel larvae (glochidia) on such interactions. We present a laboratory study which mimics two-stream substrates for the endangered thick-shelled river mussel (Unio crassus): one dominated by gravel and one by cobbles. First, the preference of a gammarid (Gammarus pulex) for mussel-dominated habitats was tested in the presence/absence of chemical cues from the predator bullhead (Cottus gobio). Second, the... (More)

Parasitic freshwater mussels are endangered ecosystem engineers with an array of impacts on multiple trophic levels and life stages. While the impacts of adult mussels on separate trophic levels have been studied, few have directly tested how adult mussels can impact trophic interactions, or investigated the impacts of the parasitic mussel larvae (glochidia) on such interactions. We present a laboratory study which mimics two-stream substrates for the endangered thick-shelled river mussel (Unio crassus): one dominated by gravel and one by cobbles. First, the preference of a gammarid (Gammarus pulex) for mussel-dominated habitats was tested in the presence/absence of chemical cues from the predator bullhead (Cottus gobio). Second, the preference of bullhead for mussel-dominated habitats was tested under or without glochidia infestation. Third, the effect of infestation on bullhead predation on gammarids was assessed in the presence of adult mussels. Gammarids only significantly preferred mussel habitats in the absence of predator cues, whereas infested bullhead tended to prefer mussel habitats in cobble substrates. The presence of adult mussels only significantly reduced bullhead predation on gammarids in the gravel habitat, whereas infestation did not affect bullhead predation. Despite gammarids not preferring mussel habitat in the presence of predator cues, mussel beds represent valuable habitat to gammarids as mussel presence can facilitate a reduction of predation by bullhead. Infestation did not affect the rate of bullhead predation on gammarids but did attract bullhead to mussel habitat in cobble substrates. Our results suggest that mussel beds may be valuable habitat for both their host fish and the prey of their hosts, attracting both and increasing predator–prey interactions. This study highlights the cross-trophic mechanisms by which multiple life stages of parasitic mussels can impact the interactions of their surrounding benthic community, underscoring their importance as ecosystem engineers.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
community ecology, conservation, ecosystem function, endangered species, freshwater, microhabitat, parasitism, Unionida
in
Ecology and Evolution
volume
15
issue
12
article number
e72601
publisher
Wiley-Blackwell
external identifiers
  • scopus:105024013434
  • pmid:41356507
ISSN
2045-7758
DOI
10.1002/ece3.72601
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 The Author(s). Ecology and Evolution published by British Ecological Society and John Wiley & Sons Ltd.
id
6f9a7555-1927-4235-8c69-d81b4845a2f6
date added to LUP
2026-02-16 13:29:02
date last changed
2026-02-17 03:14:37
@article{6f9a7555-1927-4235-8c69-d81b4845a2f6,
  abstract     = {{<p>Parasitic freshwater mussels are endangered ecosystem engineers with an array of impacts on multiple trophic levels and life stages. While the impacts of adult mussels on separate trophic levels have been studied, few have directly tested how adult mussels can impact trophic interactions, or investigated the impacts of the parasitic mussel larvae (glochidia) on such interactions. We present a laboratory study which mimics two-stream substrates for the endangered thick-shelled river mussel (Unio crassus): one dominated by gravel and one by cobbles. First, the preference of a gammarid (Gammarus pulex) for mussel-dominated habitats was tested in the presence/absence of chemical cues from the predator bullhead (Cottus gobio). Second, the preference of bullhead for mussel-dominated habitats was tested under or without glochidia infestation. Third, the effect of infestation on bullhead predation on gammarids was assessed in the presence of adult mussels. Gammarids only significantly preferred mussel habitats in the absence of predator cues, whereas infested bullhead tended to prefer mussel habitats in cobble substrates. The presence of adult mussels only significantly reduced bullhead predation on gammarids in the gravel habitat, whereas infestation did not affect bullhead predation. Despite gammarids not preferring mussel habitat in the presence of predator cues, mussel beds represent valuable habitat to gammarids as mussel presence can facilitate a reduction of predation by bullhead. Infestation did not affect the rate of bullhead predation on gammarids but did attract bullhead to mussel habitat in cobble substrates. Our results suggest that mussel beds may be valuable habitat for both their host fish and the prey of their hosts, attracting both and increasing predator–prey interactions. This study highlights the cross-trophic mechanisms by which multiple life stages of parasitic mussels can impact the interactions of their surrounding benthic community, underscoring their importance as ecosystem engineers.</p>}},
  author       = {{Rock, Sebastian L. and Elmlund, Anna M. and Nilsson, P. Anders and Watz, Johan and Calles, Olle and Österling, Martin}},
  issn         = {{2045-7758}},
  keywords     = {{community ecology; conservation; ecosystem function; endangered species; freshwater; microhabitat; parasitism; Unionida}},
  language     = {{eng}},
  number       = {{12}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Ecology and Evolution}},
  title        = {{A Habitat and a Parasite : Adult and Larval Parasitic Freshwater Mussels Impact Habitat Choice and Predator–Prey Interactions of a Host Fish and Its Prey}},
  url          = {{http://dx.doi.org/10.1002/ece3.72601}},
  doi          = {{10.1002/ece3.72601}},
  volume       = {{15}},
  year         = {{2025}},
}