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Publications (10 of 74) Show all publications
Skov, C., Hansen, J. H., Baktoft, H., Brodersen, J., Brönmark, C., Hansson, L.-A., . . . Nilsson, P. A. (2019). Biomanipulating streams: A supplementary tool in lake restoration. Hydrobiologia, 829(1), 205-216
Open this publication in new window or tab >>Biomanipulating streams: A supplementary tool in lake restoration
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2019 (English)In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 829, no 1, p. 205-216Article in journal (Refereed) Published
Abstract [en]

Removal of cyprinid fish is a widely used biomanipulation tool to transform turbid shallow eutrophic lakes in north temperate regions into a clear water state. We here evaluate the removal of cyprinids from streams as a supplement to lake fishing. Since cyprinids often aggregate in high densities in lake inlet/outlet streams during winter migration, removal of fish in this space-confined habitat may be cost-efficient as compared to fish removal in the lake habitat. In two consecutive years, we annually removed up to 35% of the dominant cyprinids from an inlet stream to a lake and argue that this could easily be increased with a more targeted fishing effort. Concurrently, we monitored species- and length-specific variation in migration propensity, to explore how this relates to efficient fish removal. Smaller planktivores generally had a much higher migratory propensity than larger benthivores. Hence, stream fishing specifically targets species and size groups that are less efficiently controlled with traditional lake fishing methods. As a rule of thumb, stream fishing is most efficient when water temperature is 2–6°C. Prior to implementing fish removals from streams, the potential evolutionary consequences of the targeted removal of migratory phenotypes should be considered. 

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Cost-effective, Cyprinid fishes, Evolutionary consequences, Fish removal, Migration
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-70585 (URN)10.1007/s10750-018-3832-4 (DOI)000456178700015 ()2-s2.0-85057100636 (Scopus ID)
Available from: 2018-12-20 Created: 2018-12-20 Last updated: 2019-04-04Bibliographically approved
Watz, J. (2019). Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers. Animal Conservation, 1-11
Open this publication in new window or tab >>Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers
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2019 (English)In: Animal Conservation, ISSN 1367-9430, E-ISSN 1469-1795, p. 1-11Article in journal (Refereed) Epub ahead of print
Abstract [en]

Conservation programmes for endangered, long-lived and migratory species often have to target multiple life stages. The bottlenecks associated with the survival of juvenile anguillid eels migrating into inland waters, the survival and growth of the freshwater life stage, as well as the recruitment and survival of silver eels, migrating back to the ocean to spawn, must be resolved. In this study, we focus on the efficiency of passage solutions for upstream migrating juveniles. Such solutions can consist of inclined ramps lined with wetted climbing substrata. We evaluated different commonly used substrata in a controlled experiment, recorded eel behaviour at the entrance of the ramp with infrared videography and validated the experimental results at a hydropower dam, where we also investigated the effects of ramp placement on performance. In the experiment on eel substratum selection, 40 % of the eels passed in lanes with studded substratum, whereas only 21 and 5 % passed using open weave and bristle substrata, respectively. Video analysis revealed that the studded substratum attracted more approaches and initiated climbs than the other substrata, but once a climb had been initiated, passage success rates did not differ between substrata. Eels using the studded substratum climbed 26 % faster than those using the bristle substratum and almost four times as fast as those climbing in the open weave. The superior performance of the studded substratum was supported by data from the field validation. Moreover, ramps positioned by the bank with low water velocities caught the most eels, but proximity to the dam had no effect on performance. To strengthen the European eel population, more juveniles need to reach their freshwater feeding grounds. A critical step to achieve this increase is to equip upstream passage solutions with suitable substrata and to optimize ramp placement at migration obstacles.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
anguillid, fishway, hydropower, migration, recruitment, passage solutions, migration obstacles
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-71418 (URN)10.1111/acv.12485 (DOI)
Funder
Swedish Research Council Formas, 2015-824
Available from: 2019-03-04 Created: 2019-03-04 Last updated: 2019-03-21Bibliographically approved
Schneider, L. D., Nilsson, P. A., Höjesjö, J. & Österling, M. (2019). Effects of mussel and host fish density on reproduction potential of a threatened unionoid mussel: Prioritization of conservation locations in management trade-offs. Biodiversity and Conservation, 28(2), 259-273
Open this publication in new window or tab >>Effects of mussel and host fish density on reproduction potential of a threatened unionoid mussel: Prioritization of conservation locations in management trade-offs
2019 (English)In: Biodiversity and Conservation, ISSN 0960-3115, E-ISSN 1572-9710, Vol. 28, no 2, p. 259-273Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Endangered species, Host-parasite system, Host fish availability, Unio crassus, Unionoida
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-70354 (URN)10.1007/s10531-018-1652-5 (DOI)000454777600001 ()2-s2.0-85055991288 (Scopus ID)
Note

Artikeln ingick som manuskript i Schneiders (2017) doktorsavhandling Conservation ecology of the thick-shelled river mussel Unio crassus: The importance of parasite-host interactions

Available from: 2018-11-29 Created: 2018-11-29 Last updated: 2019-04-04Bibliographically approved
Skov, C. & Nilsson, P. A. (2018). Biology and ecology of pike. Boca Raton: CRC Press
Open this publication in new window or tab >>Biology and ecology of pike
2018 (English)Book (Refereed)
Place, publisher, year, edition, pages
Boca Raton: CRC Press, 2018
National Category
Ecology Zoology
Identifiers
urn:nbn:se:kau:diva-65812 (URN)9781482262902 (ISBN)978-1-4822-6292-6 (ISBN)
Available from: 2018-01-24 Created: 2018-01-24 Last updated: 2018-07-06Bibliographically approved
Blake, C. A., Andersson, M. L., Hulthén, K., Nilsson, P. A. & Brönmark, C. (2018). Conspecific boldness and predator species determine predation-risk consequences of prey personality. Behavioral Ecology and Sociobiology, 72(8), 1-7, Article ID 133.
Open this publication in new window or tab >>Conspecific boldness and predator species determine predation-risk consequences of prey personality
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2018 (English)In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 72, no 8, p. 1-7, article id 133Article in journal (Refereed) Published
Abstract [en]

Abstract: Individual variation in the behavior of prey can influence predation risk in complex ways. We ran individual roach (Rutilus rutilus), a common freshwater fish, through a standard refuge emergence protocol to characterize their boldness, a key animal personality trait. We then paired a bold and a shy roach and exposed the pair to one of two predator species that have contrasting hunting modes to ascertain how personality traits shaped their survival during predator encounters. When a paired bold and shy prey fish interacted with a perch predator (active foraging mode), bold and shy prey were consumed in almost equal numbers. However, pike predators (ambush foraging mode) selectively consumed more shy prey, and prey body size and boldness score both contributed significantly to which prey fish was eaten. Our findings support the idea that multiple predators with different foraging modes, and hence differential selection on prey personality, could contribute to maintaining variation in personality in prey populations. Furthermore, for social species, including shoaling fish, the ultimate consequences of an individual’s personality may depend upon the personality of its nearby conspecifics. Significance statement: Animals of the same species often look similar, but individuals show differences in their behavior that can have important consequences, for instance when these individuals interact with predators. The common roach is a freshwater fish that shows inter-individual variation in its propensity to take risks, a key personality trait often termed boldness. Variation in boldness may affect the outcome when roach interact with predators, i.e., if they get eaten or survive. However, we found the impact of roachs’ personality type depends on what species of predatory fish they face. When we put a shy and a bold roach together with predatory perch, the roachs’ personality did not significantly affect which individual was eaten. But when the predator was a pike, the predators selectively ate more shy roach, and the likelihood an individual would be eaten depended on their body size.

Place, publisher, year, edition, pages
Springer-Verlag New York, 2018
Keywords
Behavioral type, Boldness, Predator-prey interactions, Social context, Animalia, Rutilus rutilus
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-69051 (URN)10.1007/s00265-018-2544-0 (DOI)2-s2.0-85050141389 (Scopus ID)
Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2018-09-13Bibliographically approved
Watz, J., Nilsson, P. A., Degerman, E., Tamario, C. & Calles, O. (2018). Enhancing upstream passage solutions for juvenile eels: Effects of climbing substrate and ramp placement. In: : . Paper presented at International Conference on River Connectivity (Fish Passage 2018), 10-14 december 2018, Albury, Australia.
Open this publication in new window or tab >>Enhancing upstream passage solutions for juvenile eels: Effects of climbing substrate and ramp placement
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2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Juvenile anguillid eels migrating into inland waters often face migration barriers. Upstream passage solutions normally consist of inclined ramps lined with a wetted climbing substrate. In this study, we compared the performance of three commonly used substrate types in a controlled experiment, using European eel as the test species. We also analyzed climbing behavior with videography and validated the experimental results under natural conditions at a hydropower plant. In addition, we investigated the effects of ramp placement. Studded substrate attracted more approaches and climbs and passed more eels at a higher climbing velocity than open weave and bristle substrates, results that were confirmed by the field validation. Moreover, ramps placed in the tailrace caught more eels in low than in high water velocities. To conserve anguillid eels, both safe routes for downstream-migrating adult silver eels and improved recruitment at the freshwater feeding life stage must be achieved. Optimizing ramp position and equipping upstream passage solutions with functioning climbing substrate are key factors to enhance the performance of eel ramps.

National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-70694 (URN)
Conference
International Conference on River Connectivity (Fish Passage 2018), 10-14 december 2018, Albury, Australia
Available from: 2019-01-11 Created: 2019-01-11 Last updated: 2019-01-31Bibliographically approved
Nilsson, P. A. & Eklöv, P. (2018). Finding food and staying alive. In: Skov, Christian & Nilsson, Anders P. (Ed.), Biology and ecology of pike: . Boca Raton: CRC Press
Open this publication in new window or tab >>Finding food and staying alive
2018 (English)In: Biology and ecology of pike / [ed] Skov, Christian & Nilsson, Anders P., Boca Raton: CRC Press, 2018Chapter in book (Refereed)
Place, publisher, year, edition, pages
Boca Raton: CRC Press, 2018
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-69240 (URN)9781482262902 (ISBN)
Available from: 2018-09-16 Created: 2018-09-16 Last updated: 2019-03-06Bibliographically approved
Persson, A., Nilsson, P. A. & Brönmark, C. (2018). Trophic interactions. In: Skov, Christian & Nilsson, Anders P. (Ed.), Biology and ecology of pike: . Boca Raton: CRC Press
Open this publication in new window or tab >>Trophic interactions
2018 (English)In: Biology and ecology of pike / [ed] Skov, Christian & Nilsson, Anders P., Boca Raton: CRC Press, 2018Chapter in book (Refereed)
Place, publisher, year, edition, pages
Boca Raton: CRC Press, 2018
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-69241 (URN)9781482262902 (ISBN)
Available from: 2018-09-16 Created: 2018-09-16 Last updated: 2019-02-26Bibliographically approved
Watz, J., Calles, O., Carlsson, N., Teemu, C., Huusko, A., Jörgen, J., . . . Nyqvist, D. (2018). Wood addition in the hatchery and river environments affectspost-releaseperformance of overwintering brown trout. Freshwater Biology, 64(1), 71-80
Open this publication in new window or tab >>Wood addition in the hatchery and river environments affectspost-releaseperformance of overwintering brown trout
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2018 (English)In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 64, no 1, p. 71-80Article in journal (Refereed) Published
Abstract [en]

1. Habitat structural complexity affects the behaviour and physiology of individuals,and responses to the environment can be immediate or influence performancelater in life through delayed effects.

2. Here, we investigated how structural enrichment, both pre-release in the hatcheryrearing environment and post-release in the wild, influenced winter growthand site fidelity of brown trout stocked into side channels of a regulated river.

3. Experiencing structural enrichment in the rearing environment during 3 months inautumn had no pre-release effect on growth, but a delayed positive effect afterrelease during the subsequent winter. Moreover, trout recaptured in wood-treatedsections of the side channels had grown more than trout recaptured in controlsections. Wood enrichment in the side channels also increased overwinter sitefidelity.

4. These results show that adding structure during a relatively short period may altergrowth trajectories, and adding wood to side channels is a cost-effective methodto enhance winter habitat carrying capacity for juvenile salmonids in regulatedrivers.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
growth, habitat complexity, restoration, site fidelity, stream wood
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-69976 (URN)10.1111/fwb.13195 (DOI)000453853500006 ()
Funder
Knowledge Foundation, ProSpekt 15-20160021
Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2019-03-07Bibliographically approved
Schneider, L. D., Nilsson, P. A. & Österling, M. (2017). Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus. Hydrobiologia, 810(1), 283-293
Open this publication in new window or tab >>Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus
2017 (English)In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 810, no 1, p. 283-293Article in journal (Refereed) Published
Abstract [en]

Adaptation to temperature regimes and host presence may enhance fitness in parasites. In an experimental study, we evaluated the timing of glochidia release by Unio crassus subjected to three spring water temperature regimes in the presence and absence of the host fish Cottus gobio. The timing of glochidia release was delayed at (i) constantly low temperatures (<10°C), in contrast to earlier and pronounced releases at (ii) natural temperature increases that level off at intermediate temperatures (10–15°C), and (iii) higher-than-normal temperatures (10–20°C). Mussels from treatment (i) that had not released glochidia during the experiment did so soon after being moved to the temperature in (ii), indicating a temperature threshold for glochidia release. Neither host fish presence nor the combined effect of temperature and host fish presence significantly affected the timing of glochidia release. The treatment with natural spring water temperatures indicated possible fitness benefits for U. crassus through combined effects of high intensities of glochidia releases and high survival of released glochidia. The furthered understanding of climate change effects on mussel and host phenology in seasonal environments, potentially inducing temporal mismatches of glochidia release to host availability, is key to mussel conservation

Place, publisher, year, edition, pages
Springer, 2017
National Category
Ecology Zoology
Identifiers
urn:nbn:se:kau:diva-65810 (URN)10.1007/s10750-017-3217-0 (DOI)
Available from: 2018-01-24 Created: 2018-01-24 Last updated: 2018-07-06Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3541-9835

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