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Effects of mussel and host fish density on reproduction potential of a threatened unionoid mussel : prioritization of conservation locations in management trade-offs

  • Lea D. Schneider
  • P. Anders Nilsson
  • Johan Höjesjö
  • E. Martin Österling
Publishing year: 2019-02
Language: English
Pages: 259-273
Publication/Series: Biodiversity and Conservation
Volume: 28
Issue: 2
Document type: Journal article
Publisher: Springer

Abstract english

Management decisions in conservation of threatened species require trading off social needs against biodiversity values, including the prioritization of conservation locations, i.e. where conservation efforts should take place. To improve conservation decisions for the thick-shelled river mussel, Unio crassus, a highly threatened temporary parasite on fish, we performed a field study on how mussel and host fish density (European bullhead, Cottus gobio, and common minnow, Phoxinus phoxinus) affect reproduction potential of the mussel at different sites along a river. We assumed that the proportions of gravid mussels would be higher at high mussel density, and result in enhanced glochidia (mussel larvae) encapsulation rates on fish. We also expected the highest ‘glochidia density’—a proxy for the potential number of recruits per stream area, assessed by multiplying glochidia encapsulation rates on fish by fish density, to occur at high mussel density sites. Such river sites, producing many offspring and conveying important conservation values, may thus be prioritized. However, contrary to our assumptions, higher glochidia density and higher proportions of gravid mussels occurred at lower density mussel sites. We also found that P. phoxinus had higher glochidia encapsulation rates than C. gobio, possibly related to species-specific behavioural and life-history traits. Even so, glochidia density was similar for both fish species, reflecting comparable ecological functions in hosts. The results of this study suggest that mussel and host fish densities should be considered along with glochidia density in conservation prioritization and management trade-offs.


  • Ecology
  • Endangered species
  • Host-parasite system
  • Host fish availability
  • Unio crassus
  • Unionoida


  • ISSN: 0960-3115
Anders Nilsson
E-mail: anders [dot] nilsson [at] biol [dot] lu [dot] se


Aquatic ecology

+46 46 222 83 65

+46 70 346 25 66



Research group

Aquatic Ecology


Doctoral students and postdocs

Main supervisor

Varpu Pärssinen

Assistant supervisor

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