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  • 1. Brönmark, Christer
    et al.
    Brodersen, Jakob
    Chapman, Ben B.
    Nicolle, Alice
    Nilsson, P. Anders
    Lund University.
    Skov, Christian
    Hansson, Lars-Anders
    Regime shifts in shallow lakes: the importance of seasonal fish migration2010In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 646, p. 91-100Article in journal (Refereed)
    Abstract [en]

    Shallow eutrophic lakes commonly existin two alternative stable states: a clear-water state anda turbid water state. A number of mechanisms,including both abiotic and biotic processes, buffer therespective states against changes, whereas othermechanisms likely drive transitions between states.Our earlier research shows that a large proportion of zooplanktivorous fish populations in shallow lakesundertake seasonal migrations where they leave thelake during winter and migrate back to the lake inspring. Based on our past research, we propose anumber of scenarios of how feedback processesbetween the individual and ecosystem levels mayaffect stability of alternative stable states in shallowlakes when mediated by fish migration. Migrationeffects on shallow lakes result from processes atdifferent scales, from the individual to the ecosystem.Our earlier research has shown that ecosystemproperties, including piscivore abundance and zoo-plankton productivity, affect the individual state of zooplanktivorous fish, such as growth rate or condi-tion. Individual state, in turn, affects the relativeproportion and timing of migrating zooplanktivorousfish. This change, in turn, may stabilize states orcause runaway processes that eventually lead to stateshifts. Consequently, such knowledge of processescoupled to seasonal migration of planktivorous fishshould increase our understanding of shallow lakedynamics.

  • 2.
    Enefalk, Åsa
    et al.
    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.
    Effects of fine wood on macroinvertebrate drift in four boreal forest streams2016In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 765, no 1, p. 317-327Article in journal (Refereed)
    Abstract [en]

    Most studies of stream wood have focused on pieces a parts per thousand yen0.1 m diameter. However, this approach may overlook an important feature of small streams, where wood < 0.1 m can constitute the majority of wood pieces. We examined the effect of fine wood (FW) on local drift of stream macroinvertebrates. The study was carried out at seven sites in four boreal forest streams, from early June to mid-August 2011. This was done by anchoring bundles of FW at each site and measuring drift upstream and downstream of each bundle. We hypothesized that FW would increase drift density, biomass and diversity of aquatic invertebrates. Ten weeks after FW addition, aquatic drift density was higher downstream than upstream of FW bundles, while drift biomass and drift diversity did not differ significantly downstream and upstream of FW.

  • 3.
    Gosselin, Marie-Pierre
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Petts, G. E.
    Univ Westminster, London W1R 8AL, England..
    Maddock, I. P.
    Univ Worcester, Inst Sci & Environm, Henwick Grove WR2 6AJ, Worcs, England..
    Mesohabitat use by bullhead (Cottus gobio)2010In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 652, no 1, p. 299-310Article in journal (Refereed)
    Abstract [en]

    Habitat composition and connectivity within a stream vary with changing flows but the influence of changing flow on habitat use by fish is not well understood. Meso- and microhabitat surveys were used to investigate habitat use by bullhead (Cottus gobio Linnaeus) in response to discharge variation in a small tributary of the Upper Severn, England. Mesohabitat mapping surveys were carried out over a range of summer flows (0.016-0.216 m(3) s(-1)) and were coupled with direct underwater observations (snorkelling) of fish location. Five mesohabitat types-glides, runs, riffles, chutes and pools-were present in the reach at all flows surveyed and 'backwaters' were found at three flows. The macro-morphology of the reach comprised six riffle-pool sequences divided into 27 mesohabitats with the maximum diversity (23 mesohabitats) at intermediate flows (Q (43)) and only 15 mesohabitats at Q (95). Despite low numbers of fish (N = 78), bullhead displayed a strong association (51% of the fish) with glides-relatively deep habitats having high rates of velocity increase with flow. However, 54% of the fish were observed in two large, persistent mesohabitats, a glide (34%) and a pool (20%), both located below a faster flowing mesohabitat. Habitat use curves based upon micro-habitat data showed bullhead favoured low velocities (< 0.30 m s(-1)), depths less than 0.30 m and a cobble substratum. This study illustrates the value of cross-scale investigations in linking fish ecology, flow and physical habitat variability and suggests mesohabitat size, persistence and arrangement may influence fish distribution.

  • 4.
    Jönsson, Mikael
    et al.
    Lunds universitet.
    Ranåker, Lynn
    Lunds universitet.
    Nicolle, Alice
    Lunds universitet.
    Ljungberg, Peter
    Fagerberg, Tony
    Lunds universitet.
    Hylander, Samuel
    Lunds universitet.
    Jephson, Therese
    Lunds universitet.
    Lebret, Karen
    Lunds universitet.
    von Einem, Jessica
    Lunds universitet.
    Hansson, Lars-Anders
    Nilsson, P. Anders
    Lund University.
    Balseiro, Esteban
    Modenutti, Beatriz
    Glacial clay affects foraging performance in a Patagonian fish and cladoceran2011In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 663, no 1, p. 101-108Article in journal (Refereed)
  • 5.
    Linløkken, Arne
    et al.
    Hedmark County, Environmental Administration, Fylkeshuset, Hamar, Norway.
    Kleiven, Einar
    Aust-Agder County, Environmental administration, Arendal, Norway.
    Matzow, Dag
    Aust-Agder County, Environmental administration, Arendal, Norway.
    Population structure, growth and fecundity of perch (Perca fluviatilis) in an acidified river system in southern Norway1991In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 220, no 3, p. 179-188.Article in journal (Refereed)
  • 6.
    Nilsson, P. Anders
    et al.
    Lund University.
    Skov, Christian
    DTU-AQUA, Denmark.
    Farrell, ohn
    State University of New York.
    Current and future directions for pike ecology and management: a summary and synthesis2008In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 601, p. 137-141Article in journal (Refereed)
  • 7.
    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).
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus2018In: 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

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  • 8.
    Skov, Christian
    et al.
    Technical University of Denmark, Denmark.
    Hansen, Joan H.
    Technical University of Denmark, Denmark.
    Baktoft, Henrik
    Technical University of Denmark, Denmark.
    Brodersen, Jakob
    EAWAG Swiss Federal Institute of Aquatic Science and Technology, Switzerland; Institute of Ecology and EvolutionUniversity of Bern, Switzerland.
    Brönmark, Christer
    Lund University, Sweden.
    Hansson, Lars-Anders
    Lund University, Sweden.
    Hulthén, Kaj
    Lund University, Sweden.
    Chapman, Ben B.
    University of Manchester, UK.
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Lund University, Sweden.
    Biomanipulating streams: A supplementary tool in lake restoration2019In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 829, no 1, p. 205-216Article in journal (Refereed)
    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. 

  • 9.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Stress responses of juvenile brown trout under winter conditions in a laboratory stream2017In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 802, no 1, p. 131-140Article in journal (Refereed)
    Abstract [en]

    Winter can be a challenging period for fish in northern temperate rivers and streams, particularly in those that are channelized, structurally simple or regulated by, for instance, hydropower. In these systems, dynamic sub-surface ice formation commonly occurs and stable periods with ice cover may be short. Under these adverse conditions, access to shelters has been shown to be an important factor that influences overwinter survival, and exclusion from shelters by anchor ice may cause stress. Here, stress responses of juvenile brown trout under simulated winter conditions in an artificial stream were studied. Trout were subjected to three treatments in which the trout (1) were excluded from an instream wood shelter, simulating the effects of anchor ice, (2) had access to the shelter or (3) had surface ice cover in addition to the shelter. There was a positive correlation between ventilation frequency and plasma cortisol concentration. Trout without access to shelter had 30% higher ventilation frequency than trout with instream shelter and surface ice, but no differences in cortisol concentration or stress colour were found between the treatments. River regulation that reduces surface ice and increases anchor ice formation may lead to increased stress and consequently reduce overwinter survival rates.

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  • 10.
    Österling, Martin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Högberg, Jan-Olov
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    The impact of land use on the mussel Margaritifera margaritifera and its host fish Salmo trutta2014In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 735, p. 213-220Article in journal (Refereed)
    Abstract [en]

    Today, land use impacts a major proportion of all streams. Here, landscape features in corridors along streams and water chemical factors were analyzed in relation to recruitment of the threatened freshwater pearl mussel (Margaritifera margaritifera) and its host fish the brown trout (Salmo trutta). Mussel recruitment and trout density were negatively related to forest clear-cuts. Mussel recruitment was negatively related to water color and turbidity. Therefore, the threats to the mussel may be severe, as low mussel recruitment may be caused by direct effects on the juvenile mussels and indirect effects on the host fish. High proportions of lakes and ponds were found to be positive for recruitment and for trout, and deciduous forest was positively related to trout. The combination of investigations at different scales at the landscape level and at in-stream levels may be applicable to find threats to other threatened species. The results indicate that forestry activities may negatively affect recruitment of freshwater pearl mussels and its host fish. Reductions of forestry activities and the retaining of intact quantity and quality of the riparian zones next to streams, both for the mussel and its host fish may be important conservation measures to restore freshwater pearl mussel populations.

1 - 10 of 10
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