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  • 1.
    Arvidsson, Björn
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Hultman, Jens
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Öringtäthet och rekrytering hos flodpärlmussla2006Chapter in book (Other academic)
  • 2.
    Arvidsson, Björn L
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Karlsson, Jens
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin E
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Recruitment of the threatened mussel Margaritifera margaritifera in relation to mussel population size, mussel density and host density2012In: Aquatic conservation, ISSN 1052-7613, E-ISSN 1099-0755, Vol. 22, p. 526-532Article in journal (Refereed)
    Abstract [en]

    Anthropogenic, abiotic factors are considered main causes of recruitment failure of unionid mussels, including the freshwater pearl mussel (Margaritifera margaritifera). In this large-scale investigation, we instead examined the relationship between biotic factors and mussel recruitment.

    Juvenile mussel density was positively related to both mussel population size and density of which the last appeared to be a more accurate measure of recruitment.Host fish density of young-of-the-year and older brown trout (Salmo trutta) were positively related to recruitment. Moreover, the mean density of both age classes of fish, when grouped into density classes was positively related to juvenile mussel density, an effect that decreased at trout densities above 10 trout 100 m-2.There was a higher relative importance of mussel population size and density than trout density to recruitment.To increase recruitment of juvenile mussels, managers may apply measures that increase mussel density, and trout density up to about 10 trout 100 m-2 in connection to mussel beds. Mussel beds may also be managed and one possible measure within small and sparse mussel populations may be to concentrate the remaining mussels to areas where trout density is high. Likewise, young-of-the-year trout may also be moved to areas of high mussel density, as young trout individuals are relatively resident during their first year. This may increase mussel larval infection rates and mussel recruitment.

  • 3. Bergengren, Jakob
    et al.
    Olsson, Ivan
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    The thick shelled river mussel (Unio crassus) brings LIFE+ back to rivers.2012Conference paper (Refereed)
  • 4.
    Calles, Olle
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Griffioen, Ben
    IMARES Wageningen UR, Netherlands.
    Winter, Erwin
    IMARES Wageningen UR, Netherlands.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Nyqvist, Daniel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Hagelin, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Gustafsson, Stina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Greenberg, Larry
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Fish Migration River Monitoring Plan2014Report (Other academic)
    Abstract [en]

    Fish have problems passing the Afsluitdijk Dam that separates the Wadden Sea from Lake IJsselmeer. To re-establish the connectivity and thereby allow fish to pass there is an initiative to build a fishway, the Fish Migration River (FMR), at the Konwerderzand sluice complex. This report proposes a monitoring program to evaluate the functionality of the FMR, but also to monitor passage possibilities through the existing sluices. The goals of the monitoring plan are to estimate 1) The overall passage past the Afsluitdijk dam to and from Lake IJsselmeer, 2) The attraction efficiency, 3) The passage efficiency, and 4) The use of the FMR as habitat and for acclimatization for the transition into freshwater.

    We present an overview of previous and ongoing monitoring in the area to establish the current state of knowledge. The report also includes a presentation of available and suitable methods for a future monitoring program considering the broad spectra of target fish species, and their abundances. The proposed program includes a description of study design and available techniques and cost-estimates of the monitoring program.

    The proposed program will target ten species: European eel (aal), flounder (bot), three-spined stickleback (dreidoornige stekelbaars), twait shad (fint), North Sea houting (houting), river lamprey (rieverprik), smelt (spiering), Atlantic salmon (zalm), brown trout (forel) and sea lamprey (zeeprik). The monitoring program includes plans for how to capture, tag and track the study fish using the most suitable tagging techniques. Furthermore, the most optimal sites for installation of automatic data detection stations are identified.

    The total cost for the proposed project is 3.5 M€ and covers both investments in equipment and costs for personnel. However, if costs for investments in techniques such as RFId-stations and fish counters are excluded, the total cost is reduced to 1 M€ for a program running two years before and four years after the completion of the FMR. The program is considered sufficient to evaluate the FMR at Kornwerederzand from the most important perspectives: the overall passage efficiency and the use of the FMR as habitat.

    It should be noted that this report is the first step towards a full-scale monitoring program, giving insight into possible methods, study design and associated costs. The next important step will be to develop the program in more detail and to start the initial phase of the monitoring project. We predict that such activities will identify the need for, and the relevance of, a more extensive monitoring program to study the effects of the FMR on a population level and on a large geographical scale.

  • 5.
    Calles, Olle
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Gustafsson, Stina
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Naturlika fiskvägar i dag och i morgon2012Report (Other academic)
  • 6.
    Calles, Olle
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Andersson, Jonas
    Gustafsson, Stina
    Vezza, Paolo
    Comoglio, Claudio
    Levein, Ulf
    Löfqvist, Magnus
    Ålprojekt Alsterälven - Lägesrapport för 20102010Report (Other academic)
  • 7.
    Calles, Olle
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Gustafsson, Pär
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Nyberg, Lars
    Karlstad University, Faculty of Social and Life Sciences, Centre for Climate and Safety.
    Forsberg, Jan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Hebrand, M
    Olsson, M
    Renöfält, B
    Karlsson, H
    Johansson, M
    Biokanalers egenskaper och möjligheter2009Report (Other academic)
  • 8.
    Calles, Olle
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Gustafsson, S
    Ålprojekt 2007-2013, Naturresurs rinnande vatten2011Conference paper (Other (popular science, discussion, etc.))
  • 9.
    Calles, Olle
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Gustafsson, Stina
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Rees, Nina
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Ett riktigt ålamörker: Barnens universitet, Karlstads universitet, 17 oktober 2011.2011Other (Other (popular science, discussion, etc.))
  • 10.
    Calles, Olle
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Kläppe, S
    Alenäs, I
    Återställning av vandringsväg för fisk vid Hertings kraftstation i Ätran2009Report (Other academic)
  • 11.
    Filipsson, Karl
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Gothenburg University, Sweden.
    Brijs, Jeroen
    Gothenburg University, Sweden.
    Näslund, Joacim
    Gothenburg University, Sweden.
    Wengström, Niklas
    Gothenburg University, Sweden; Swedish Anglers Association, Gothenburg, Sweden.
    Adamsson, Marie
    Gothenburg University, Sweden.
    Závorka, Libor
    Gothenburg University, Sweden; Toulouse University, France.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Höjesjö, Johan
    Gothenburg University, Sweden.
    Encystment of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae coincides with increased metabolic rate and haematocrit in juvenile brown trout (Salmo trutta)2017In: Parasitology Research, ISSN 0932-0113, E-ISSN 1432-1955, Vol. 116, p. 1353-1360Article in journal (Refereed)
    Abstract [en]

    Gill parasites on fish are likely to negatively influence their host by inhibiting respiration, oxygen transport capacity and overall fitness. The glochidia larvae of the endangered freshwater pearl mussel (FPM, Margaritifera margaritifera (Linnaeus, 1758)) are obligate parasites on the gills of juvenile salmonid fish. We investigated the effects of FPM glochidia encystment on the metabolism and haematology of brown trout (Salmo trutta Linnaeus,1758). Specifically, we measured whole-animal oxygen uptake rates at rest and following an exhaustive exercise protocol using intermittent flow-through respirometry, as well as haematocrit, in infested and uninfested trout. Glochidia encystment significantly affected whole-animal metabolic rate, as infested trout exhibited higher standard and maximum metabolic rates. Furthermore, glochidia-infested trout also had elevated levels of haematocrit.The combination of an increased metabolism and haematocrit in infested fish indicates that glochidia encystment has a physiological effect on the trout, perhaps as a compensatory response to the potential respiratory stress caused by the glochidia. When relating glochidia load to metabolism and haematocrit, fish with low numbers of encysted glochidia were the ones with particularly elevated metabolism and haematocrit. Standard metabolic rate decreased with substantial glochidia loads towards levels similar to those of uninfested fish. This suggests that initial effects visible at low levels of encystment may be countered by additional physiological effects at high loads, e.g. potential changes in energy utilization, and also that high numbers of glochidia may restrict oxygen uptake by the gills.

  • 12.
    Filipsson, Karl
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Göteborgs universitet.
    Petersson, Tina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Hojesjo, Johan
    Göteborgs universitet.
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Naslund, Joacim
    Göteborgs universitet.
    Wengstrom, Niklas
    Göteborgs universitet; Swedish Anglers Assoc, Gothenburg,.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Heavy loads of parasitic freshwater pearl mussel (Margaritifera margaritifera L.) larvae impair foraging, activity and dominance performance in juvenile brown trout (Salmo trutta L.)2018In: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633, Vol. 27, no 1, p. 70-77Article in journal (Refereed)
    Abstract [en]

    The life cycle of the endangered freshwater pearl mussel (Margaritifera margaritifera) includes a parasitic larval phase (glochidia) on the gills of a salmonid host. Glochidia encystment has been shown to affect both swimming ability and prey capture success of brown trout (Salmo trutta), which suggests possible fitness consequences for host fish. To further investigate the relationship between glochidia encystment and behavioural parameters in brown trout, pairs (n = 14) of wild-caught trout (infested vs. uninfested) were allowed to drift feed in large stream aquaria and foraging success, activity, agonistic behaviour and fish coloration were observed. No differences were found between infested and uninfested fish except for in coloration, where infested fish were significantly darker than uninfested fish. Glochidia load per fish varied from one to several hundred glochidia, however, and high loads had significant effects on foraging, activity and behaviour. Trout with high glochidia loads captured less prey, were less active and showed more subordinate behaviour than did fish with lower loads. Heavy glochidia loads therefore may negatively influence host fitness due to reduced competitive ability. These findings have implications not only for management of mussel populations in the streams, but also for captive breeding programmes which perhaps should avoid high infestation rates. Thus, low levels of infestation on host fish which do not affect trout behaviour but maintains mussel populations may be optimal in these cases.

  • 13.
    Gustafsson, Stina
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Jostein, Skurdal
    Stiftelsen Lillehammer museum.
    Vezza, Paolo
    Department of Environment, Land and Infrastructure Engineering Politecnico di Torino.
    Comoglio, Claudio
    Department of Environment, Land and Infrastructure Engineering Politecnico di Torino.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Functional organization and colonization of macroinvertebrates in a nature-like fishway with added habitat heterogeneityManuscript (preprint) (Other academic)
  • 14.
    Gustafsson, Stina
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Skurdal, Jostein
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Invertebrate colonization of a nature-like fishway in Eldforsen, Sweden; the effect of habitat design2012Conference paper (Refereed)
  • 15.
    Gustafsson, Stina
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    A test for suitable fish hosts for the threatened freshwater pearl mussel (Margaritifera margaritifera) prior to reintroductionManuscript (preprint) (Other academic)
  • 16.
    Gustafsson, Stina
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Calles, Olle
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Technical fishways, nature-like fishways or biocanals?2011Conference paper (Refereed)
  • 17.
    Gustafsson, Stina
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Calles, Olle
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Technical fishways, nature-like fishwaysor biocanals? IRSAE conference. Evenstad, Norge. 10 Augusti, 20102010Conference paper (Other academic)
  • 18.
    Gustafsson, Stina
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Brown trout habitat choice: relative importance of woody debris and river morphology in nature-like fishwaysManuscript (preprint) (Other academic)
  • 19.
    Gustafsson, Stina
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Skurdal, Jostein
    Schneider, Lea Dominique
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Macroinvertebrate colonization of a nature-like fishway: The effects of adding habitat heterogeneity2013In: Ecological Engineering: The Journal of Ecosystem Restoration, ISSN 0925-8574, Vol. 61, p. 345-353Article in journal (Refereed)
    Abstract [en]

    Nature-like fishways are designed to imitate the characteristics of natural streams, thereby providing both fish passage and habitat for a variety of aquatic organisms. To date, however, the potential for habitat rehabilitation of nature-like fishways has not been fully realized. To develop the concept of how to design a nature-like fishway, a 500-m long nature-like fishway, termed the biocanal, was constructed at the Eldforsen hydroelectric facility, Sweden. It included four habitat types: riffle, pool, floodplain and braided (i.e. with islands), each replicated three times. The riffle sections were considered controls for typical Swedish nature-like fishways. Thus the biocanal had a more varied in-stream environment than those of conventional fishways. To test the prediction that the biocanal had a positive effect on biodiversity, we compared the physical habitat and benthic fauna composition of the more diverse habitat types in the biocanal to the riffle habitats. We also made comparisons between the biocanal and six natural reference streams in the area. After two years, 63% of the benthic fauna families found in the reference streams had colonized the biocanal. Families present in the reference streams, but not in the biocanal, were predominantly slow colonizers or taxa linked to riparian vegetation, which was scarce and in an early successional stage along the biocanal. In the biocanal, pool and floodplain habitats contained the highest number of families, the highest family diversity (Shannon-Weaver) and the highest densities of Ephemeroptera, Plecoptera and Trichoptera. Since these habitats contained more families and had higher diversities than the riffle habitats which are typical of conventional nature-like fishways, we suggest that the construction of biocanals indeed possesses the potential for high biodiversity. (C) 2013 Elsevier B.V. All rights reserved.

  • 20.
    Hart, Paul BJ
    et al.
    Department of Biology, University of Leicester, Leicester LE1 7RH, UK.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Eriksson, Stina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Gustafsson, Stina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Lans, Linnea
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Norrgård, Johnny R
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Piccolo, John J
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Rees, Nina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Greenberg, Larry
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Familiarity with a partner facilitates the movementof drift foraging juvenile grayling (Thymallus thymallus) into a new habitatarea2014In: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 97, no 5, p. 515-522Article in journal (Refereed)
    Abstract [en]

    Preferring one social partner over another can enhance fitness. This paper reports that juvenile grayling were significantly more likely to enter and forage in new, upstream habitats when paired with familiar versus unfamiliar social partners. Fish paired with unfamiliar partners or when alone were more reluctant to enter the new area. The entry times for both fish in a familiar pair were significantly correlated, but uncorrelated for unfamiliar fish. These differences between familiars and unfamiliars were consistent over a 2-week period. Fish with familiar partners spent more time within three body lengths of each other than did those with unfamiliars. The results are discussed in relation to optimality models of drift foraging, which do not included sociality. It is suggested that the social dimension creates a more dynamic foraging response to variable environmental conditions and could have consequences for growth.

  • 21. Henrikson, Lennart
    et al.
    Arvidsson, BjörnKarlstad University, Faculty of Social and Life Sciences, Department of Biology.Österling, MartinKarlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Aquatic Conservation with Focus on Margaritifera margaritifera: Proceedings of the International Conference in Sundsvall, Sweden, 12-14 August, 20092012Conference proceedings (editor) (Other academic)
    Abstract [en]

    The freshwater pearl mussel Margaritifera margaritifera (L.) has attracted a large human interest, since the mussel is fascinating from biological, cultural andenvironmental perspectives. The mussel has a complicated life cycle dependingon host fish, and has great demands on its habitat. Furthermore, the mussel is anenvironmental indicator, and is used as an umbrella and flagship species. Pearl fishing has been described in Sweden as early as in the 16th century and by Carl Linnaeus in the 18th century.

    Many freshwater pearl mussel populations have insufficient recruitment and therefore decrease in numbers, and many populations are even extinct. Therefore, conservation work on the freshwater pearl mussel is going on all over Europe. Actions to preserve the freshwater pearl mussel will also favour other aquatic species – freshwater pearl mussel conservation is aquatic biodiversity conservation! WWF (World Wide Fund for Nature) Sweden implemented the project “The Freshwater Pearl Mussel and its habitats in Sweden” during 2004-2009 (LIFE04NAT/SE/000231). The overall objective was to improve the habitats of juvenile freshwater pearl mussels and the host fish brown trout Salmo trutta in21 streams. The actions were improvements of the biotopes, re-introduction of mussels, information to the stakeholders, and development of planning methods. An international conference “Aquatic Conservation with Focus on the Freshwater Pearl Mussel Margaritifera margaritifera” was held in Sundsvall 12–14 August, 2009. In these proceedings, presentations from the conference are published.

  • 22.
    Nylin, Soren
    et al.
    Stockholms universitet.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Janz, Niklas
    Stockholms univesitet.
    Embracing Colonizations: A New Paradigm for Species Association Dynamics2018In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 33, no 1, p. 4-14Article in journal (Refereed)
    Abstract [en]

    Parasitehost and insectplant research have divergent traditions despite the fact that most phytophagous insects live parasitically on their host plants. In parasitology it is a traditional assumption that parasites are typically highly specialized; cospeciation between parasites and hosts is a frequently expressed default expectation. Insectplant theory has been more concerned with host shifts than with cospeciation, and more with hierarchies among hosts than with extreme specialization. We suggest that the divergent assumptions in the respective fields have hidden a fundamental similarity with an important role for potential as well as actual hosts, and hence for host colonizations via ecological fitting. A common research program is proposed which better prepares us for the challenges from introduced species and global change.

  • 23.
    Schneider, Lea Dominique
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Nilsson, P. Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Department of Biology – Aquatic Ecology, Lund University, Sweden.
    Höjesjö, Johan
    Department of Biology and Environmental Sciences, University of Gothenburg, Sweden.
    Österling, E. Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Manuscript: Local adaptation studies and conservation: parasite-host interactions between freshwater mussels and fishManuscript (preprint) (Other academic)
  • 24.
    Schneider, Lea Dominique
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Nilsson, P. Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Department of Biology – Aquatic Ecology, Lund University, Sweden.
    Österling, E. Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Manuscript: Spring temperature-dependent reproduction in the parasitic freshwater mussel Unio crassusManuscript (preprint) (Other academic)
  • 25.
    Schneider, Lea Dominique
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Lunds universitet.
    Höjesjö, J.
    Göteborgs universiet.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Effects of mussel and host fish density on reproduction potential of a threatened unionoid mussel: Prioritization of conservation locations in management trade-offs2018In: Biodiversity and Conservation, ISSN 0960-3115, E-ISSN 1572-9710Article in journal (Refereed)
    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.

  • 26.
    Schneider, Lea Dominique
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Höjesjö, Johan
    Göteborgs universitet.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Local adaptation studies and conservation: Parasite–host interactions between the endangered freshwater mussel Unio crassus and its host fish2017In: Aquatic conservation, ISSN 1052-7613, E-ISSN 1099-0755, Vol. 27, p. 1261-1269Article in journal (Refereed)
    Abstract [en]

    1.Parasite–host interactions can involve strong reciprocal selection pressure, and may lead to locally adapted specializations. The highly threatened unionoid mussels are temporary parasites on fish, but local adaptation has not yet been investigated for many species. 2.Patterns of local adaptation of one of Europe's most threatened unionoids, the thick‐shelled river mussel (Unio crassus) were investigated. Eurasian minnows (Phoxinus phoxinus) from two rivers (separate drainage areas) were cross‐infested in the laboratory with sympatric and allopatric mussel larvae, while bullheads (Cottus gobio), inhabiting only one of the rivers, were infested with sympatric or allopatric mussel larvae. Larval encystment, juvenile mussel excystment and survival were measured. 3.For one river, but not the other, juvenile excystment from P. phoxinus was highest when infested with sympatric mussels. The opposite pattern was found for C. gobio in this river, where juvenile excystment and post‐parasitic juvenile survival from allopatric C. gobio were highest. The results thus cannot confirm local adaptation of U. crassus to P. phoxinus in the study rivers, as excystment was not consistently higher in all sympatric mussel–host combinations, whereas there were potential maladaptive signs of U. crassus in relation to C. gobio. There was no loss of encysted larvae 3 days after infestation until juvenile excystment. Most juveniles were excysted between 17 and 29 days after infestation, and the numbers of excysted juveniles increased with fish size. 4.The results have implications for parasite–host ecology and conservation management with regard to unionoid propagation and re‐introduction. This includes the need to (1) test suitability and adaptation patterns between U. crassus and multiple host fish species, (2) evaluate the suitability of certain unionoids and host fish strains after more than 3 days, and (3) determine whether large fish produce more juvenile mussels than smaller fish

  • 27.
    Schneider, Lea Dominique
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus2017In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 810, no 1, p. 283-293Article in journal (Refereed)
    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

  • 28.
    Schneider, Lea Dominique
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Wengström, Niklas
    Department of Biology and Environmental Sciences, University of Gothenburg, Sweden;Swedish Anglers Association, Sweden .
    Nilsson, P. Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Department of Biology – Aquatic Ecology, Lund University, Sweden.
    Eldenäs, Pia
    Department of Bioinformatics and Genetics – Swedish Museum of Natural History, Sweden.
    Höjesjö, Johan
    Department of Biology and Environmental Sciences, University of Gothenburg, Sweden.
    Olsson, Ivan
    County Administrative Board of Skåne, Sweden.
    Österling, E. Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Host-Fish Composition And Glochidia Encapsulation For The Endangered Thick-Shelled River Mussel Unio CrassusManuscript (preprint) (Other academic)
  • 29. Schneider, Lea
    et al.
    Nilsson, P. Anders
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Bergengren, Jakob
    Olsson, Ivan
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Host-fish mapping and re-introduction of Unio crassus in Swedish streams.2012Conference paper (Refereed)
  • 30.
    Shafer, Aaron B. A.
    et al.
    Uppsala Univ, Ecol & Genet Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Wolf, Jochen B. W.
    Uppsala Univ, Ecol & Genet Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Alves, Paulo C.
    Univ Porto, Fac Ciencias, CIBIO InBIO, P-4485661 Oporto, Portugal..
    Bergstrom, Linnea
    Uppsala Univ, Ecol & Genet Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Bruford, Michael W.
    Cardiff Univ, Sch Biosci, Cardiff CF10 3AX, S Glam, Wales..
    Brannstrom, Ioana
    Uppsala Univ, Ecol & Genet Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Colling, Guy
    Musee Natl Hist Nat Luxembourg, L-2160 Luxembourg, Luxembourg..
    Dalen, Love
    Swedish Museum Nat Hist, S-10405 Stockholm, Sweden..
    De Meester, Luc
    Katholieke Univ Leuven, B-3000 Louvain, Belgium..
    Ekblom, Robert
    Uppsala Univ, Ecol & Genet Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Fawcett, Katie D.
    Univ Groningen, Behav Ecol & Selforg, NL-9712 Groningen, Netherlands..
    Fior, Simone
    ETH, CH-8092 Zurich, Switzerland..
    Hajibabaei, Mehrdad
    Univ Guelph, Guelph, ON N1G 2W1, Canada..
    Hill, Jason A.
    Univ Stockholm, S-10691 Stockholm, Sweden..
    Hoezel, A. Rus
    Univ Durham, Durham DH1 3LE, England..
    Hoglund, Jacob
    Uppsala Univ, Ecol & Genet Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Jensen, Evelyn L.
    Univ British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada..
    Krause, Johannes
    Univ Tubingen, D-72070 Tubingen, Germany..
    Kristensen, Torsten N.
    Aalborg Univ, DK-9220 Aalborg, Denmark..
    Kruetzen, Michael
    Univ Zurich, Anthropol Inst & Museum, CH-8057 Zurich, Switzerland..
    McKay, John K.
    Colorado State Univ, Ft Collins, CO 80523 USA..
    Norman, Anita J.
    Swedish Univ Agr Sci, S-90183 Umea, Sweden..
    Ogden, Rob
    Royal Zool Soc Scotland, WildGenes Lab, Edinburgh EH12 6TS, Midlothian, Scotland..
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Ouborg, N. Joop
    Radboud Univ Nijmegan, NL-6500 GL Nijmegen, Netherlands..
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Popovic, Danijela
    Univ Warsaw, Ctr New Technol, PL-00681 Warsaw, Poland..
    Primmer, Craig R.
    Univ Turku, Turku 20014, Finland..
    Reed, Floyd A.
    Univ Hawaii Manoa, Honolulu, HI 96822 USA..
    Roumet, Marie
    ETH, CH-8092 Zurich, Switzerland..
    Salmona, Jordi
    Inst Gulbenkian Ciencias, Populat & Conservat Genet Grp, P-2780156 Oeiras, Portugal..
    Schenekar, Tamara
    Karl Franzens Univ Graz, A-8010 Graz, Austria..
    Schwartz, Michael K.
    USDA, Forest Serv, Rocky Mt Res Stn, Ft Collins, CO USA..
    Segelbacher, Gernot
    Univ Freiburg, D-79106 Freiburg, Germany..
    Senn, Helen
    Royal Zool Soc Scotland, WildGenes Lab, Edinburgh EH12 6TS, Midlothian, Scotland..
    Thaulow, Jens
    Norwegian Inst Water Res, N-0349 Oslo, Norway..
    Valtonen, Mia
    Univ Eastern Finland, Joensuu 80101, Finland..
    Veale, Andrew
    Univ British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada..
    Vergeer, Philippine
    Wageningen Univ, NL-6708 PB Wageningen, Netherlands..
    Vijay, Nagarjun
    Uppsala Univ, Ecol & Genet Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Vila, Caries
    Conservat & Evolutionary Genet Grp, Estac Biol Donana, Almonte 41092, Spain..
    Weissensteiner, Matthias
    Uppsala Univ, Ecol & Genet Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Wennerstrom, Lovisa
    Univ Stockholm, S-10691 Stockholm, Sweden..
    Wheat, Christopher W.
    Univ Stockholm, S-10691 Stockholm, Sweden..
    Zielinski, Piotr
    Jagiellonian Univ, Inst Environm Sci, PL-30387 Krakow, Poland..
    Genomics and the challenging translation into conservation practice2015In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 30, no 2, p. 78-87Article in journal (Refereed)
    Abstract [en]

    The global loss of biodiversity continues at an alarming rate. Genomic approaches have been suggested as a promising tool for conservation practice as scaling up to genome-wide data can improve traditional conservation genetic inferences and provide qualitatively novel insights. However, the generation of genomic data and subsequent analyses and interpretations remain challenging and largely confined to academic research in ecology and evolution. This generates a gap between basic research and applicable solutions for conservation managers faced with multifaceted problems. Before the real-world conservation potential of genomic research can be realized, we suggest that current infrastructures need to be modified, methods must mature, analytical pipelines need to be developed, and successful case studies must be disseminated to practitioners.

  • 31.
    Shafer, Aaron B. A.
    et al.
    Uppsala Univ, Ecol & Genet, Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Wolf, Jochen B. W.
    Uppsala Univ, Ecol & Genet, Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Alves, Paulo C.
    Univ Porto, Ctr Invest Biodiversidade & Recursos Genet, P-4485661 Oporto, Portugal.;Fac Ciencias, P-4485661 Oporto, Portugal..
    Bergstrom, Linnea
    Uppsala Univ, Ecol & Genet, Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Colling, Guy
    Musee Natl Hist Nat Luxembourg, Populat Biol, L-2160 Luxembourg, Luxembourg..
    Dalen, Love
    Swedish Museum Nat Hist, Bioinformat & Genet, S-10405 Stockholm, Sweden..
    De Meester, Luc
    KU Leuven Univ Leuven, Aquat Ecol Evolut & Conservat, B-3000 Leuven, Belgium..
    Ekblom, Robert
    Uppsala Univ, Ecol & Genet, Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Fior, Simone
    Swiss Fed Inst Technol, Integrat Biol, CH-8092 Zurich, Switzerland..
    Hajibabaei, Mehrdad
    Univ Guelph, Integrat Biol, Guelph, ON N1G 2W1, Canada..
    Hoezel, A. Rus
    Univ Durham, Biol & Biomed Sci, Durham DH1 3LE, England..
    Hoglund, Jacob
    Uppsala Univ, Ecol & Genet, Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Jensen, Evelyn L.
    Univ British Columbia Okanagan, Biol, Kelowna, BC V1V 1V7, Canada..
    Kruetzen, Michael
    Univ Zurich, Anthropol Inst & Museum, CH-8057 Zurich, Switzerland..
    Norman, Anita J.
    Swedish Univ Agr Sci, Wildlife Fish & Environm Studies, S-90183 Umea, Sweden..
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Ouborg, N. Joop
    Radboud Univ Nijmegen, Expt Plant Ecol, NL-6500 GL Nijmegen, Netherlands..
    Piccolo, John J.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Primmer, Craig R.
    Univ Turku, Biol, Turku 20014, Finland..
    Reed, Floyd A.
    Univ Hawaii Manoa, Biol, Honolulu, HI 96822 USA..
    Roumet, Marie
    Swiss Fed Inst Technol, Integrat Biol, CH-8092 Zurich, Switzerland..
    Salmona, Jordi
    Inst Gulbenkian Ciencias, Populat & Conservat Genet Grp, P-2780156 Oeiras, Portugal..
    Schwartz, Michael K.
    USDA, Forest Serv, Rocky Mt Res Stn, Missoula, MT 59801 USA..
    Segelbacher, Gernot
    Univ Freiburg, Wildlife Ecol & Management, D-79106 Freiburg, Germany..
    Thaulow, Jens
    Norwegian Inst Water Res, Freshwater Biol, N-0349 Oslo, Norway..
    Valtonen, Mia
    Univ Eastern Finland, Biol, Joensuu 80101, Finland..
    Vergeer, Philippine
    Wageningen Univ, Nat Conservat & Plant Ecol, NL-6708 PB Wageningen, Netherlands..
    Weissensteiner, Matthias
    Uppsala Univ, Ecol & Genet, Evolutionary Biol Ctr, S-75236 Uppsala, Sweden..
    Wheat, Christopher W.
    Stockholm Univ, Zool, S-10691 Stockholm, Sweden..
    Vila, Carlese
    Estn Biol Donana, Conservat & Evolutionary Genet Grp, Seville 41092, Spain..
    Zielinski, Piotr
    Jagiellonian Univ, Inst Environm Sci, PL-30387 Krakow, Poland..
    Genomics in Conservation: Case Studies and Bridging the Gap between Data and Application Reply2016In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 31, no 2, p. 83-84Article in journal (Refereed)
  • 32.
    Watz, Johan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Enefalk, Åsa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Gustafsson, Stina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Hagelin, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Nilsson, P. Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Norrgård, Johnny
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Fortum generation.
    Nyqvist, Daniel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Piccolo, John J.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Schneider, Lea Dominique
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Greenberg, Larry
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Bror, Jonsson
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Norsk institutt for naturforskning, Oslo.
    Ice cover alters the behavior and stress level of brown trout Salmo trutta2015In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 26, no 3, p. 820-827Article in journal (Refereed)
    Abstract [en]

    Surface ice in rivers and lakes buffers the thermal environment and provides overhead cover, protecting aquatic animals from terrestrial predators. We tested if surface ice influenced the behavior (swimming activity, aggressive encounters, and number of food items eaten) and stress level (coloration of eyes and body) of stream-living brown trout Salmo trutta at temperatures of 3–4 °C in indoor experimental flumes. We hypothesized that an individual’s resting metabolic rate (RMR, as measured by resting ventilation rate) would affect winter behavior. Therefore, groups of 4 trout, consisting of individuals with high, low, or mixed (2 individuals each) RMR, were exposed to experimental conditions with or without ice cover. Ice cover reduced stress responses, as evaluated by body coloration. Also, trout in low RMR groups had a paler body color than those in both mixed and high RMR groups. Trout increased their swimming activity under ice cover, with the highest activity found in high RMR groups. Ice cover increased the number of aggressive encounters but did not influence the number of drifting food items taken by each group. In mixed RMR groups, however, single individuals were better able to monopolize food than in the other groups. As the presence of surface ice increases the activity level and reduces stress in stream-living trout, ice cover should influence their energy budgets and production. The results should be viewed in light of ongoing global warming that reduces the duration of ice cover, especially at high latitudes and altitudes.

  • 33.
    Wengström, Niklas
    et al.
    Göteborgs universitet. Swedish Anglers Assoc, Gothenburg, Sweden.
    Wahlqvist, Fredrik
    Göteborgs universitet.
    Näslund, Joacim
    Göteborgs universitet.
    Aldvén, David
    Göteborgs universitet.
    Závorka, Libor
    Göteborgs universitet. Univ Toulouse 3, CNRS, UMR EDB Toulouse 5174, Midi Pyrenees, France..
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Höjesjö, Johan
    Göteborgs universitet.
    Do individual activity patterns of brown trout (Salmo trutta) alter the exposure to parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae?2016In: Ethology, ISSN 0179-1613, E-ISSN 1439-0310, Vol. 122, no 9, p. 769-778Article in journal (Refereed)
    Abstract [en]

    The hypothesis that inter-individual differences in the activity of brown trout alter the exposure to parasitic freshwater pearl mussel glochidia was tested in a Swedish stream. Wild yearling brown trout (N=103) were caught, individually tagged for identification, and scored for open-field activity during standardized laboratory tests in June. Fifty gravid freshwater pearl mussels were relocated to the stream, where after the trout were released back into the stream. The fish were recaptured in October (N=35), checked for glochidia encystment (infested individuals: n=6), and re-scored for open-field activity traits. Swimming velocity during the test was higher in fish infected with glochidia, suggesting that high activity could increase their exposure to glochidia. Potentially, as metabolism and ventilation rate typically increase with activity, elevated activity may lead to an increased likelihood of glochidia passing over the gills. This novel finding suggests that glochidia infestation is non-random and that the behavior of the host fish can influence the likelihood of glochidia infestation.

  • 34.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Anthropogenic impact on recruitment, growth and host-fish of Margaritifera margaritifera.2010Conference paper (Other academic)
  • 35.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Anthropogenic impact on recruitment, growth and host-fish of Margaritifera margaritifera.2011Conference paper (Refereed)
  • 36.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Bevarandebiologi flodpärlmusslan – Status, habitatförsämring och åtgärder.2008Conference paper (Other academic)
  • 37.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Bevarandebiologi flodpärlmusslan – Status, habitatförsämring och åtgärder.2010Conference paper (Other (popular science, discussion, etc.))
  • 38.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Bevarandebiologi flodpärlmusslan Status, habitatförsämring och åtgärder2008Conference paper (Refereed)
  • 39.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Biotiska och abiotiska faktorers betydelse för flodpärlmusslans fortplantning och överlevnad i Ljungans biflöden2010Report (Other academic)
    Abstract [sv]

    Stormusslorna är en av de organismgrupper i sötvatten som är allra mest hotad. En av Sveriges stormusslor är flodpärlmusslan, vilken minskar i antal inom hela sitt utbredningsområde och som sedan maj 2010 är klassad som starkt hotad i den Internationella naturvårdsunionens rödlista. Målet med föreliggande projekt var att undersöka vad som begränsar flodpärlmusslans reproduktion och överlevnad. I anslutning till undersökningarna gjordes dessutom en film som berättar om projektet. Projektet är ett samarbete mellan Karlstads universitet och Fortums nordiska miljöfond och utfördes under åren 2007 och 2008 i 26 biflöden till Ljungan i Västernorrland.

    Flodpärlmusslan reproducerar sig på sommaren, då musslan släpper sina glochidielarver i vattnet. Larverna måste träffa på öring eller lax, där larverna kapslas in på fiskens gälar för att sedan leva där som parasit under 10-12 månader. När de små musslorna släppt från värdfiskens gälar lever de nedgrävda i sedimentet under några år. Från 10-20 års ålder räknas musslan som vuxen och kan delta i reproduktionen.

    I många musselvattendrag saknas juvenila musslor. Eftersom musslan har en så komplicerad livscykel är det flera livscykelstadier som bör undersökas för att ta reda på när rekryteringen av juvenila musslor begränsas. I detta projekt undersöktes följande livscykelstadier i 26 vattendrag i Ljungans avrinningsområde: gravida musslor, glochidieinfektion på öring och juvenila musslor. För att mäta  glochidielarvernas infektion på öringen utan att avliva öringen utvecklades en ny metod att uppskatta infektionsgraden m.h.a. fotografering av larverna på öringens gälar. Dessutom undersöktes öringtätheter och förändring i musseltäthet mellan 1990-1991 och 2005-2006. Slutligen undersöktes hur abiotiska faktorer såsom turbiditet, sedimentation, sedimentvattenkemi och vattentemperaturer påverkade musslans livscykelstadier.

    Resultaten visade att musseltätheten ökade generellt i vattendrag med rekrytering av juvenila musslor, men minskade i vattendrag utan rekrytering från 1990-1991 till 2005-2006. En minskning i musseltäthet sker alltså idag i vattendrag utan rekrytering och har troligtvis också skett under längre tid, vilket sannolikt resulterat i den lägre musseltäthet som finns idag i vattendrag utan rekrytering i Ljungans biflöden. Därmed är situationen allvarlig, där glesare populationer kan resultera i lägre reproduktion och förändra musslornas viktiga funktioner som filtrerare och paraplyart i vattendragen. På sikt är risken stor att arten försvinner helt från dessa vattendrag om man inte finner problemen och åtgärdar dem.

    Gravida musslor verkar inte vara det livscykelstadium som begränsar rekryteringen, eftersom ungefär hälften av musslorna var gravida, både i vattendrag med och utan rekrytering. Däremot var musslorna gravida tidigare i vattendrag utan rekrytering än i vattendrag med rekrytering. Gravida musslor var också kortare än musslor som inte var gravida i vattendrag utan rekrytering men inte i vattendrag med rekrytering. Proportionen gravida musslor ökade också som en funktion av musseltätheten. Sammantaget visar detta att larvproduktionen kanske inte fungerar helt optimalt i vattendrag utan rekrytering.

    Den nya metoden att mäta larver på öringens gälar genom att fotografera gälarna som utvecklades inom projektet fungerade bra. Ett akvarieexperiment visade att tillväxt eller överlevnad hos öring inte försämrades på grund av fotometoden. Detta visar alltså på att man kan undersöka infektionen av mussellarver på öring utan att öringen tar skada.

    Med hjälp av fotometoden kunde infektionsstadiet av mussellarver på öring av olika ålder mätas. Infektionen av mussellarver var högre i vattendrag med rekrytering än i vattendrag utan rekrytering på årsungar och på äldre öring. För infektionen på årsungarna berodde detta främst på en högre täthet av årsungar i vattendrag med rekrytering än i vattendrag utan rekrytering. Detta tyder på att årsungarnas täthet är negativt påverkad av någon faktor, vilket i sin tur leder till färre antal larver hos årsungarna i vattendrag utan rekrytering. Skillnaden i infektionen på äldre öring var orsakad av en högre musseltäthet i vattendrag med rekrytering än i vattendrag utan rekrytering. Den minskande musseltätheten i vattendrag utan rekrytering resulterar troligtvis i sin tur i en minskad produktion av glochidielarver. Sammantaget verkar det alltså som att en lägre täthet av öringens årsungar och en låg musseltäthet bidrar till lägre antal glochidielarver i vattendrag utan rekrytering, vilket sannolikt resulterar i en lägre rekrytering av juvenila musslor.

    Nästa tidiga livscykelstadium, juvenila musslor, var även det påverkat av musseltäthet och årsungarnas täthet. Detta tyder på att både infektionsstadium och juvenila musslor är negativt påverkade. Tätheten av juvenila musslor var negativt relaterad till turbiditet. Hög turbiditet hänger ofta ihop med hög sedimentation, vilket kan begränsa juvenila musslors överlevnad genom låga syrehalter och höga ammoniumhalter i sedimentet. Den sämre vattenomsättningen som uppmättes i vattendrag utan rekrytering kan vara ett resultat av en hög sedimentation och därmed resultera i dåliga förhållanden i sedimenten med en låg överlevnad av juvenila musslor som följd. Dessutom kan högre vattentemperaturer, vilket uppmättes på sommaren i vattendrag utan rekrytering, försämra tillväxt och överlevnad hos juvenila musslor.

    Turbiditet visade sig ha högst förklaringsgrad för frånvaron av juvenila musslor, följt av vattentemperaturen, medan täthet av årsungar av öring, musseltäthet och täthet av äldre öring, i nämnd ordning, var viktiga för rekryteringen av juvenila musslor. Detta pekar på att en minskning av sedimenttillförsel till vattendragen skulle kunna vända trenden med avsaknad av musselrekrytering. Minskad sedimentation skulle också kunna förbättra öringens reproduktion och därmed även förbättra rekryteringen av musslan, om en högre sedimenttransport också påverkar öringäggens utveckling negativt.

    Brukande av marken bredvid vattendrag kan vara en viktig orsak till hög turbiditet och sedimentation och kan också orsaka höga vattentemperaturer på grund av ökad solinstrålning. För överlevnaden av juvenila flodpärlmusslor är det också viktigt att naturliga flödestoppar inte förhindras, utan tillåts byta ut vattnet i sedimentet. En kombination av lågt vattenflöde och avsaknad av en beväxt kantzon på sommaren kan troligtvis bidra till dåliga förhållanden i bottenvattnet och för höga vattentemperaturer, vilket kan påverka både musslor och öring negativt.

    För att uppnå bättre förhållanden för flodpärlmusslan bör brukandet av marken utföras så att silt och sand inte släpps ut i vattendragen. Genom att inte störa marken närmast vattendragen genom dikning och skogsavverkning kan en ökad sedimentation förhindras. Om man lämnar intakta kantzoner närmast vattendragen kan dessa även stabilisera vattendragen mot erosion. Dessutom kan ökad beskuggning av vegetationen i en intakt kantzon förhindra alltför höga vattentemperaturer sommartid. Samtidigt bör regleringen av dammar uppströms musselpopulationer vara sådan att högflödestoppar, vilka bidrar till att vatten spolas genom sedimenten, inte begränsas. Om marken bredvid bäckarna och vattenregleringen sköts på rätt sätt  kan det bidra till att rekryteringen av flodpärlmusslor återupptas. Detta bör dock ske inom en snar framtid eftersom effekter av restaurering av vattendrag ofta tar lång tid och det också tar lång tid för flodpärlmusslan att återkolonisera när tätheterna har reducerats mycket.

  • 40.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Biotiska och abiotiska faktorers betydelse för flodpärlmusslans reproduktion och överlevnad i Ljungans biflöden2010Book (Other academic)
  • 41.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Ecology of freshwater mussels in disturbed environments2007Conference paper (Other (popular science, discussion, etc.))
  • 42.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Ecology of the freshwater pearl mussel2003Conference paper (Other (popular science, discussion, etc.))
  • 43.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Effects of filamentous green algal mats on benthic macrofaunal functional feeding groups2001In: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 263, p. 159-183Article in journal (Refereed)
  • 44.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Flodpärlmussla – En indikator för gränsöverskridande biologisk mångfald. Conservation.2008Conference paper (Other academic)
  • 45.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Flodpärlmusslan Status, hot och populationsreglering2006Conference paper (Other (popular science, discussion, etc.))
  • 46.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Flodpärlmusslan i Ljungans avrinningsområde.2008Conference paper (Other (popular science, discussion, etc.))
  • 47.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Habitat degradation and early life stages of M. margaritifera – Ljungans Catchment Area, Västernorrland.2008Conference paper (Other academic)
  • 48.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Habitat degradation and early life stages of M. margaritifera – threats and conservation.2008Conference paper (Other (popular science, discussion, etc.))
  • 49.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Hot mot flodpärlmusslans tidiga livscykelstadier i södra och mellersta Sverige.2009Conference paper (Other academic)
  • 50.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Hot mot flodpärlmusslans tidiga livscykelstadier i södra och mellersta Sverige2009Other (Other (popular science, discussion, etc.))
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