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  • 101.
    Lee, Marcus
    et al.
    Lund University, Sweden.
    Zhang, Huan
    Lund University, Sweden ; Chinese Academy of Sciences, China.
    Sha, Yongcui
    Lund University, Sweden.
    Hegg, Alexander
    Lund University, Sweden.
    Ugge, Gustaf Ekelund
    Lund University, Sweden.
    Vinterstare, Jerker
    Lund University, Sweden.
    Skerlep, Martin
    Lund University, Sweden.
    Parssinen, Varpu
    Lund University, Sweden.
    Herzog, Simon David
    Lund University, Sweden.
    Bjorneras, Caroline
    Lund University, Sweden.
    Gollnisch, Raphael
    Lund University, Sweden.
    Johansson, Emma
    Lund University, Sweden.
    Hu, Nan
    Lund University, Sweden.
    Nilsson, Per Anders
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013). Lund University, Sweden.
    Hulthen, Kaj
    Lund University, Sweden ; North Carolina State University, USA.
    Rengefors, Karin
    Lund University, Sweden.
    Langerhans, R. Brian
    North Carolina State University, USA ; North Carolina State University, USA.
    Bronmark, Christer
    Lund University, Sweden.
    Hansson, Lars-Anders
    Lund University, Sweden.
    Low-latitude zooplankton pigmentation plasticity in response to multiple threats2019Ingår i: Royal Society Open Science, E-ISSN 2054-5703, Vol. 6, nr 7, s. 1-10, artikel-id 190321Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Crustacean copepods in high-latitude lakes frequently alter their pigmentation facultatively to defend themselves against prevailing threats, such as solar ultraviolet radiation ( UVR) and visually oriented predators. Strong seasonality in those environments promotes phenotypic plasticity. To date, no one has investigated whether low-latitude copepods, experiencing continuous stress from UVR and predation threats, exhibit similar inducible defences. We here investigated the pigmentation levels of Bahamian 'blue hole' copepods, addressing this deficit. Examining several populations varying in predation risk, we found the lowest levels of pigmentation in the population experiencing the highest predation pressure. In a laboratory experiment, we found that, in contrast with our predictions, copepods from these relatively constant environments did show some changes in pigmentation subsequent to the removal of UVR; however, exposure to water from different predation regimes induced minor and idiosyncratic pigmentation change. Our findings suggest that low-latitude zooplankton in inland environments may exhibit reduced, but non-zero, levels of phenotypic plasticity compared with their high-latitude counterparts.

  • 102.
    Lilja, Joakim
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper.
    Kan nedbrytning av drunknade älgarpåverka ett vattendrags näringsbudget?2009Självständigt arbete på grundnivå (kandidatexamen)Studentuppsats (Examensarbete)
    Abstract [sv]
    • Energiflöden mellan terrestra och akvatiska ekosystem har uppmärksammats mycket den senaste tiden. I den här studien undersöker jag betydelsen av ett terrestert djur, älgen (Alces alces), som dör i vattendrag och avger näring till vattnet. Genom litteraturstudier och teoretiska beräkningar uppskattade jag hur vanligt det är att älgar dör i vattendrag och om dessa älgar har någon inverkan på vattendragets totala näringsbudget. Jag fann att drunkning hos älgar tas upp som en parameter för naturliga dödsorsaker i flera artiklar från USA, Canada och Polen. Orsakerna till att älgar drunknar, trots att de är duktiga simmare, kan vara t.ex. att stranden är för brant, att de tvingas ner i vattnet av rovdjur, att skadeskjutna älgar söker sig till vatten på grund av törstkänningar i samband med blodförlust eller att de går igenom svaga isar. Utifrån teoretiska beräkningar fann jag även att en älg som dött i ett vattendrag bidrar till mycket liten del av den totala näringsbudgeten. Min hypotes är att det endast blir en lokal påverkan nedströms djuret. Hur denna påverkan ser ut och om den kommer primärproducenter och fiskar tillgodo är mycket komplext och undersöks inte i denna studie.
  • 103.
    Lind, Lovisa
    et al.
    Umeå University, Umeå, Sweden.
    Alfredsen, Knut
    University of Science and Technology, 7491 Trondheim, Norway.
    Kuglerova, Lenka
    University of British Columbia, V6T 1Z4 Vancouver, Canada.
    Nilsson, Christer
    Umeå University, Umeå, Sweden.
    Hydrological and thermal controls of ice formation in 25 boreal stream reaches2016Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 540, s. 797-811Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Northern Hemisphere has a high density of fluvial freshwater ecosystems, many of which become ice-covered during winter. The development and extent of ice have both ecological and socio-economic implications. For example, ice can cause freezing of riparian vegetation and fish eggs as well as influence hydropower production; however, when, where and why ice develops in small streams is not well known. We used observations from 25 stream reaches to study the factors controlling ice development during two consecutive winters, addressing where in the catchment surface or anchor-ice is most likely to develop, how stream morphology influences ice formation, and how climate influences ice processes. Reaches far downstream from lake outlets, or without any upstream lakes, were most prone to develop anchor-ice, but other factors also influenced ice formation. Anchor-ice was most common where water temperature and groundwater inputs were low and stream power high. Given cold air temperature and water supercooling, the in-stream substrate as well as the current velocity were also important for the development of anchor-ice. Climate and substrate seemed to be important factors for the development of surface ice. This study shows that ice processes are substantial during the hydrological year and may therefore have large implications for the ecology and engineering around boreal streams.. The study also demonstrates that ice formation in the studied streams was complex, involving many variables and physical processes. We constructed a conceptual model describing the likelihood for various ice types to develop, based on the large dataset. As such, this model will be useful for practitioners and scientists working in small watercourses in the Northern Hemisphere.

  • 104.
    Lind, Lovisa
    et al.
    Umeå University, Sweden.
    Nilsson, Christer
    Umeå University, Sweden.
    Vegetation patterns in small boreal streams relate to ice and winter floods2015Ingår i: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 103, nr 2, s. 431-440Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In-stream and riparian vegetation are species rich, productive and dynamic. Their patterns insmall boreal streams are largely driven by seasonal flow regimes. Traditionally, flow-related processes during the growing season, particularly the spring flood, have been seen as the most important, whereas vegetation has been viewed as being dormant and ‘less affected’ during winter. Riparian and in-stream vegetation were inventoried during the summers 2011–2013 in eight reaches of northern Swedish streams. Along each reach, the ice formation was surveyed during winter by visual inspections and with permanently placed cameras. We then evaluated the potential effects of ice regimes and winter flooding on riparian and in-stream vegetation during 3 years by relating the abundance of winter floods caused by anchor ice to the cover, composition and biomass of vegetation. We found that the numbers of winter floods were higher along reaches with anchor-ice formation than in reaches without. We also found that species diversity of riparian vegetation was higher inthe reaches with anchor ice. This resulted from a lower cover of riparian dwarf shrubs and a higher cover of graminoids and forbs along reaches with anchor ice. We also found a lower cover of instream algae but a higher cover of bryophytes in anchor-ice reaches. These patterns were consistent throughout the study period although there were interannual differences in temperature, water levels and ice cover. During our study period, we encountered an average of 20 shifts per winter between freezing and thawing, while there was an average of 10 shifts per winter during 1960–1990. This indicates a warming climate in high latitudes. Higher temperatures and more shifts between freezing and thawing may initially increase ice dynamics. However, with further increases in mean temperature, ice production should eventually decrease. Synthesis. Ice and winter floods caused by anchor ice appear to be important disturbance agents that allow less competitive species to establish along small boreal streams. If ice dynamics is reduced, the composition and production of riparian and in-stream vegetation may be changed, with possible consequences for the entire stream ecosystem.

  • 105.
    Lind, Lovisa
    et al.
    Umeå University, Umeå, Sweden.
    Nilsson, Christer
    Umeå University, Umeå, Sweden.
    Polvi, Lina E.
    Umeå University, Umeå, Sweden.
    Weber, Christine
    Umeå University, Umeå, Sweden.
    The role of ice dynamics in shaping vegetation in flowing waters2014Ingår i: Biological Reviews, ISSN 1464-7931, E-ISSN 1469-185X, Vol. 89, nr 4, s. 791-804Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ice dynamics is an important factor affecting vegetation in high-altitude and high-latitude streams and rivers. During the last few decades, knowledge about ice in streams and rivers has increased significantly and a respectable body of literature is now available. Here we review the literature on how ice dynamics influence riparian and aquatic vegetation. Traditionally, plant ecologists have focused their studies on the summer period, largely ignoring the fact that processes during winter also impact vegetation dynamics. For example, the freeze-up period in early winter may result in extensive formation of underwater ice that can restructure the channel, obstruct flow, and cause flooding and thus formation of more ice. In midwinter, slow-flowing reaches develop a surface-ice cover that accumulates snow, protecting habitats under the ice from formation of underwater ice but also reducing underwater light, thus suppressing photosynthesis. Towards the end of winter, ice breaks up and moves downstream. During this transport, ice floes can jam up and cause floods and major erosion. The magnitudes of the floods and their erosive power mainly depend on the size of the watercourse, also resulting in different degrees of disturbance to the vegetation. Vegetation responds both physically and physiologically to ice dynamics. Physical action involves the erosive force of moving ice and damage caused by ground frost, whereas physiological effects - mostly cell damage - happen as a result of plants freezing into the ice. On a community level, large magnitudes of ice dynamics seem to favour species richness, but can be detrimental for individual plants. Human impacts, such as flow regulation, channelisation, agriculturalisation and water pollution have modified ice dynamics; further changes are expected as a result of current and predicted future climate change. Human impacts and climate change can both favour and disfavour riverine vegetation dynamics. Restoration of streams and rivers may mitigate some effects of anticipated climate change on ice and vegetation dynamics by, for example, slowing down flows and increasing water depth, thus reducing the potential for massive formation of underwater ice.

  • 106.
    Lind, Lovisa
    et al.
    Umeå University, Umeå, Sweden.
    Nilsson, Christer
    Umeå University, Umeå, Sweden.
    Weber, Christine
    Umeå University, Umeå, Sweden.
    Effects of ice and floods on vegetation in streams in cold regions: implications for climate change2014Ingår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 4, nr 21, s. 4173-4184Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Riparian zones support some of the most dynamic and species-rich plant communities in cold regions. A common conception among plant ecologists is that flooding during the season when plants are dormant generally has little effect on the survival and production of riparian vegetation. We show that winter floods may also be of fundamental importance for the composition of riverine vegetation. We investigated the effects of ice formation on riparian and in-stream vegetation in northern Sweden using a combination of experiments and observations in 25 reaches, spanning a gradient from ice-free to ice-rich reaches. The ice-rich reaches were characterized by high production of frazil and anchor ice. In a couple of experiments, we exposed riparian vegetation to experimentally induced winter flooding, which reduced the dominant dwarf-shrub cover and led to colonization of a species-rich forb-dominated vegetation. In another experiment, natural winter floods caused by anchor-ice formation removed plant mimics both in the in-stream and in the riparian zone, further supporting the result that anchor ice maintains dynamic plant communities. With a warmer winter climate, ice-induced winter floods may first increase in frequency because of more frequent shifts between freezing and thawing during winter, but further warming and shortening of the winter might make them less common than today. If ice-induced winter floods become reduced in number because of a warming climate, an important disturbance agent for riparian and in-stream vegetation will be removed, leading to reduced species richness in streams and rivers in cold regions. Given that such regions are expected to have more plant species in the future because of immigration from the south, the distribution of species richness among habitats can be expected to show novel patterns.

  • 107.
    Lind, Lovisa
    et al.
    Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, USA; Umeå universitet.
    Schuler, Matthew S.
    Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, USA.
    Hintz, William D.
    Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, USA.
    Stoler, Aaron B.
    Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, USA; Stockton University, NJ, USA.
    Jones, Devin K.
    Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, USA; University of South Florida, FL, USA .
    Mattes, Brian M.
    Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, USA.
    Relyea, Rick A.
    Department of Biological Sciences, Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, USA.
    Salty fertile lakes: how salinization and eutrophication alter the structure of freshwater communities2018Ingår i: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 9, nr 9, s. 1-19, artikel-id e02383Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The quality of freshwater ecosystems is decreasing worldwide because of anthropogenic activities. For example, nutrient over-enrichment associated with agricultural, urban, and industrial development has led to an acceleration of primary production, or eutrophication. Additionally, in northern areas, deicing salts that are an evolutionary novel stressor to freshwater ecosystems have caused chloride levels of many freshwaters to exceed thresholds established for environmental protection. Even if excess nutrients and road deicing salts often contaminate freshwaters at the same time, the combined effects of eutrophication and salinization on freshwater communities are unknown. Thus by using outdoor mesocosms, we investigated the potentially interactive effects of nutrient additions and road salt (NaCl) on experimental lake communities containing phytoplankton, periphyton, filamentous algae, zooplankton, two snail species (Physa acuta and Viviparus georgianus), and macrophytes (Nitella spp.). We exposed communities to a factorial combination of environmentally relevant concentrations of road salt (15, 250, and 1000 mg Cl-/L), nutrient additions (oligotrophic, eutrophic), and sunlight (low, medium, and high) for 80 d. We manipulated light intensity to parse out the direct effects of road salts or nutrients from the indirect effects via algal blooms that reduce light levels. We observed numerous direct and indirect effects of salt, nutrients, and light as well as interactive effects. Added nutrients caused increases in most producers and consumers. Increased salt (1000 mg Cl-/L) initially caused a decline in cladoceran and copepod abundance, leading to an increase in phytoplankton. Increased salt also reduced the biomass and chl a content of Nitella and reduced the abundance of filamentous algae. Added salt had no effect on the abundance of pond snails, but it caused a decline in banded mystery snails, which led to an increase in periphyton. Low light negatively affected all taxa (except Nitella) and light levels exhibited multiple interactions with road salt, but the combined effects of nutrients and salt were always additive. Collectively, our results indicate that eutrophication and salinization both have major effects on aquatic ecosystems and their combined effects (through different mechanisms) are expected to promote large blooms of phytoplankton and periphyton while causing declines in many species of invertebrates and macrophytes.

  • 108.
    Lindegren, Martin
    et al.
    Lund University.
    Vigliano, Pablo
    Univ Nacl Comahue, Argentina.
    Nilsson, P. Anders
    Lund University.
    Alien invasions and the game of hide and seek in patagonia2012Ingår i: PLoS ONE, E-ISSN 1932-6203, Vol. 7, nr 10, artikel-id e44350Artikel i tidskrift (Refereegranskat)
  • 109.
    Lindgren, Robin
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Habitatets inverkan på förekomst av Europeisk ål (Anguilla anguilla) i svenska vattendrag2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Data över förekomst av två storleksklasser (0-150 mm och >150 mm) av Europeisk ål (Anguilla anguilla) i vattendrag på svenska västkusten hämtades från SERS (Svenskt ElfiskeRegiSter vid SLU). Dessa analyserades genom logistisk regression för att avgöra vilka olika makrohabitat-, landskaps- och hindervariabler som bäst kunde användas för att förutspå förekomst av ål. Resultatet visade att det för makrohabitatvariablerna var vattendragets bredd, vattenhastighet och vegetationsmängd som bäst förutspådde förekomst av båda storleksklasserna. För landskapsvariablerna var det avstånd till mynningen, fosforkoncentration och vattentemperatur som bäst förutspådde förekomsten av båda storleksklasserna. Därtill var även sjöprocent en viktig variabel för att förklara förekomsten av den större klassen ål. För variabler som beskriver vandringshinder var det dammar, ålyngelledare och naturlika fiskvägar som bäst förutspådde ålförekomst av båda storleksklasserna. Därtill var även avstånd till uppströms hinder viktigt för att förklara förekomsten av större ål (>150 mm). Mängden lämpliga tillväxthabitat för ålen kan därför troligtvis ökas genom åtgärder riktade mot lokalens vattendragsbredd, vattenhastighet och vegetationsmängd.

  • 110.
    Lindh, Sara
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Fin död veds påverkan på evertebratsamhället i små vattendrag: En undersökning av taxonomisk sammansättning, abundans, biomassa och biodiversitet i det driftande evertebratsamhället, i relation till bottensubstrat2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Död ved är av stor betydelse för evertebratsamhället i rinnande vatten. Syftet med denna studie var att undersöka hur fin död ved påverkar biomassa, abundans och diversitet hos det driftande evertebratsamhället i rinnande vatten, samt att relatera detta till fint och grovt bottensubstrat. Hypoteserna var att (1) en ökning av fin död ved ökar abundans, biomassa och biodiversitet samt förändrar taxonomisk sammansättning hos det driftande evertebratsamhället (2) en ökning av fin död ved har en större effekt, på abundans och biomassa i evertebratsamhället i vattendrag med fint bottensubstrat än i vattendrag med grovt bottensubstrat. Studien utfördes på sex lokaler i Ölmans avrinningsområde i Karlstad kommun, tre med fint och tre med grovt bottensubstrat. Driftprover togs på samtliga lokaler, uppströms och nedströms en utplacerad bunt fin ved, under fem tillfällen juni-oktober 2017. Ingen signifikant skillnad i biomassa, abundans eller biodiversitet visades uppströms och nedströms veden, varken på lokaler med fint eller grovt bottensubstrat. Det fanns däremot en tydlig signifikant skillnad i taxonomisk sammansättning uppströms och nedströms veden på lokaler med fint bottensubstrat, då andelen Trichoptera var högre nedström veden än uppströms veden (tre av fem provtagningstillfällen). Det fanns även en signifikant skillnad i taxonomisk sammansättning mellan lokaler med grovt och fint bottensubstrat, med en högre andel Diptera i lokaler med fint bottensubstrat (samtliga provtagningstillfällen) och en högre andel Plecoptera i lokaler med grovt bottensubstrat (tre av fem provtagningstillfällen).

  • 111.
    Linløkken, Arne
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effect of temperature and group size on swimming speed and capture rate of perch (Perca fluviatilis) and roach (Rutilus rutilus).Manuskript (Övrigt vetenskapligt)
  • 112.
    Linløkken, Arne
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Holt Seeland, Per Arne
    Environmental correlates of population variables of perch (Perca fluviatilis) in boreal lakes2008Ingår i: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 82, nr 4, s. 401-408Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We examined relationships among perch population variable parameters in two types of lakes, lakes with perch (P-lakes, n = 15) and lakes with perch and roach (PR-lakes, n  = 10) using redundancy analysis (RDA) to relate population variables to environmental factors. Effects from environmental factors were tested for significance by means of permutation tests (Monte Carlo). Three factors, pH, altitude and fraction of roach (by number) in the gill net catches, explaining 47.9% of the variation, had significant effects on perch population variables. The significance of pH was improved by partialing out the effect of conductivity and roach. Similarly, the significance of altitude was improved by partialing out the effect of pH and roach, and the significance of roach was improved by partialing out the effect of pH and altitude. When the fraction of pike in the catch was included in the analysis, the effect of roach was not significant and vice-versa, as roach and pike fractions were correlated with each other. The effect of pike was significant when roach was not included, but the effect was not as strong as the effect of roach. A biplot was constructed by plotting population variables on the first and second RDA axis, with arrows showing five selected environmental factors. Growth of 3+ to 5+ perch was positively related to pH and altitude, perch catch per unit effort was negatively related to pH and altitude, and age specific perch weight was negatively related to fraction of roach. The relationship between growth of 2+ perch and pH was not as strong as the relationship between pH and the growth of older perch. Moreover, the growth of 2+ perch was negatively related to the fraction of roach, probably due to competition between young zooplankton feeding perch and roach.

  • 113.
    Linløkken, Arne
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Hesthagen, Trygve
    Norwegian Instiute of Nature Research, Trondheim, Norway.
    Environmental effects on size and growth of perch (Perca fluviatilis) and roach (Rutilus rutilus)Manuskript (Övrigt vetenskapligt)
  • 114.
    Lund Björnås, Kristine
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Spatially explicit models: planning salmonid habitat restoration in regulated rivers2019Rapport (Övrigt vetenskapligt)
  • 115.
    Lund Bjørnås, Kristine
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Modeling Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) responses to river habitat alteration2020Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Half the world’s river volume is affected by flow alterations and/or fragmentation, a figure that is likely to increase with the current global surge in hydropower development. At the same time, freshwater biodiversity is in rapid decline. In fluvial ecosystems, streamflow is a master variable, shaping riverine species’ habitat over space and time. Atlantic salmon (Salmo salar) and brown trout (S. trutta) are examples of species that need fluvial habitats for reproduction and juvenile rearing, and whose flow needs can come in conflict with hydropower production objectives. This necessitates tools for predicting the effect of fluvial habitat alteration on fish production.

    In this thesis, I applied the individual-based model inSTREAM to simulate salmon and trout in the Gullspång Rapids, a residual flow stretch of the Gullspång River, Sweden, over a ten-year period. InSTREAM uses sub-daily time steps to simulate individual fish interacting with their biotic and physical environment, and tracks the fitness consequences of their main actions: habitat and activity selection. For inSTREAM input, I had to describe key habitat features, create a 2D hydraulic model of the rapids, model river temperature, and gather data on salmon and trout eco-physiology and life history characteristics in the Gullspång River. I ran simulation experiments varying either flow input, the number of spawners, spawning gravel, shelter and boulder availability, or temperature. Flow alterations had limited benefit. Only the scenario where the current minimum flow was set three times higher yielded increased production, and only for trout. Trout dominated salmon in competition, and production was density dependent. The model predicted that the only way to increase production of both species at current spawner numbers was to add instream structures offering more energetically profitable feeding positions.

  • 116.
    Lundberg, Ida
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Flodpärlmusslans (Margaritifera margaritifera) påverkan på öringens (Salmo trutta) födosök och rörelsemönster2013Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Öringens gälar (Salmo trutta) fungerar inte bara som ett andningssystem för fisken utan också som ett fastsättningsställe för flodpärlmusslans (Margaritifera margaritifera) parasitiska larver. Larverna kallas glochidielarver och när de släpps ifrån modermusslan måste de hitta sin värd relativt snabbt för att inte dö. Om de lyckas hitta sig en öring så fäster de sig på fiskens gälar där de sedan kapslas in av fiskens epitelceller. Glochidielarverna lever sedan där i ca 3-10 månader främst beroende på temperaturen. Eftersom mussellarven är en parasit tar den sin näring och energi ifrån värdfisken.

    I denna studie undersöktes skillnader mellan låginfekterade och höginfekterade odlade öringar (+0, medelvikt 1,77g +/- 0,11) och hur deras beteende skilde sig åt när det gäller rörlighet och antal fångade byten. Fiskarna testades både individuellt och i par. Experimentet utfördes i ett strömakvarium och hypoteserna var att låginfekterade öringar tar fler byten än höginfekterade, och att de individuella fiskarna tar mer byten än fiskarna i par. Det undersöktes också i vilken omfattning fiskarna simmade uppströms eller nedströms när de fångade sina byten och om det var någon skillnad mellan låg- och höginfekterade öringar. Resultatet visade att det fanns en signifikant skillnad (p=0,0046) mellan låg- och höginfekterade öringar när det gäller antal tagna byten, där låginfekterade öringar tar mer byten än höginfekterade. Det fanns igen signifikant skillnad mellan antlal simrörelser nedströms/uppströms mellan låg- och höginfekterade, däremot fanns det en signifikant skillnad (p=0,0027) mellan antal simrörelser uppströms och nedströms oavsett låg- eller höginfekterad, där det visade sig att öringen simmar mer nedströms än uppströms från sin focal point när den fångar byten. När det gäller antal tagna byten hos de individuella fiskarna vs. fiskarna i par, så tog de individuella fiskarna fler byten än vad var och en av fiskarna i par gjorde (medeltal: fiskar i par 28, individuella 36), men det fanns ingen signifikant skillnad (p=0,06). Utifrån resultaten kan man antyda att infektering av flodpärlmusslans glochidielarver kan ha en negativ effekt på öringens fysiska prestanda. Öringen får mindre energi till födosök och därmed sämre förutsättningar till t.ex. tillväxt. 

  • 117.
    Marker, Jeffery
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effect of distance to urban areas on saproxylic beetles in urban forests2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Urban forests play key roles in animal and plant biodiversity and provide important ecosystem services.  Habitat fragmentation and expanding urbanization threaten biodiversity in and around urban areas.  Saproxylic beetles can act as bioindicators of forest health and their diversity may help to explain and define urban-forest edge effects.  I explored the relationship between saproxylic beetle diversity and distance to an urban area along nine transects in the Västra Götaland region of Sweden.  Specifically, the relationships between abundance and species richness and distance from the urban-forest boundary, forest age, forest volume, and tree species ratio was investigated Unbaited flight interception traps were set at intervals of 0, 250, and 500 meters from an urban-forest boundary to measure beetle abundance and richness.  A total of 4182 saproxylic beetles representing 179 species were captured over two months.  Distance from the urban forest boundary showed little overall effect on abundance suggesting urban proximity does not affect saproxylic beetle abundance.  There was an effect on species richness, with saproxylic species richness greater closer to the urban-forest boundary.  Forest volume had a very small positive effect on both abundance and species richness likely due to a limited change in volume along each transect.  An increase in the occurrence of deciduous tree species proved to be an important factor driving saproxylic beetle abundance moving closer to the urban-forest.  Overall, analysis showed inconsistent effects on both abundance and richness as functions of proximity to the urban-forest boundary.  Urban edge effects, forest volume, forest age, and forest tree species make up are all variables that may effect saproxylic abundance and species richness.  Forest managers should consider these variables when making management decisions.

  • 118.
    Möller, Rebecka
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Effekten av vägsalt på djurplankton: - ett sötvattensexperiment i oligotrofa och eutroa vatten2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Pollution or changes in abiotic factors can be stressful if they exceed a species tolerance level, it can for example prevent the species ability to reproduce and disperse. High nutrition- and salt levels may be limiting for species in higher concentrations and affects all species since indirect, interactive and additive effects of high nutrient or salt levels lead to changes in the community structures. Algae blooms are a major problem in many lakes around the world and a reduced population of zooplankton had contributed to faster growth in phytoplankton and therefore eutrophication. The purpose of the study is to investigate species composition of zooplankton in a eutrophic- and oligotroph nutrient levels with different salt concentration and how it changes over time. Three salt concentrations (15, 250 and 1000 mg Cl-/L) along with the two nutritional levels resulted in six possible combinations replicated four times each, a total of 24 units. Zooplankton samples were taken from all units on day 19 and 78. A total of 51 different species were found throughout the study, of which a total of 34 species was found in the first sample and a total of 36 species in the second sample. The result showed an increase in Nauplii and Philodina spp. and a decrease in Daphnia pulex and Daphnia rosea. In the first sample a significant difference in the number of species was found between the salt concentrations 1000 mg Cl-/L and 15 mg Cl-/L and also between 1000 mg Cl-/L and 250 mg Cl-/L, where the total number of species decreased. There was also a significant difference in the species community between the nutrient levels from the first to the second sample, where a more even community was found between the first and second sample. The reduction in the number of species from the first to the second sampling may have been the reason why the species turned into communities that looked more like each other at the second test occasion, while the higher nutritional level may be what contributed to a community with higher evenness and similarity due to a greater opportunity to utilize food resources for the zooplankton without competition. The conclusion is that the salt concentration reduced the number of species, although the results show that salt concentrations with oligotrophic nutrient levels were more similar and had a greater similarity in amount of different species. Preserving lakes together with protective efforts is needed to reduce the ecological consequences of road salt, to be able to preserve species diversity and biodiversity in freshwater ecosystem.

  • 119.
    Naslund, Joacim
    et al.
    University Gothenburg, Sweden.
    Rosengren, Malin
    University Gothenburg, Sweden.
    Del Villar, Diego
    Technical University Denmark, Denmark.
    Gansel, Lars
    SINTEF Fisheries & Aquaculture, Trondheim, Norway.
    Norrgard, Johnny R.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Persson, Lo
    Swedish University Agricultuaral Sciences, Sweden.
    Winkowski, John James
    Canada.
    Kvingedal, Eli
    Norway.
    Hatchery tank enrichment affects cortisol levels and shelter-seeking in Atlantic salmon (Salmo salar)2013Ingår i: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 70, nr 4, s. 585-590Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stocking programs using hatchery-reared salmon are often implemented for augmenting natural populations. However, survival of these fish is often low compared with wild conspecifics, possibly because of genetic, physiological, and behavioural deficiencies. Here, we compared presmolt Atlantic salmon (Salmo salar) from three different environmental treatments (barren environment, plastic tube enrichment, and plastic shredding enrichment) with regard to plasma cortisol levels, shelter-seeking behaviour, and fin deterioration. Basal plasma cortisol levels were higher in barren-reared fish, indicating higher stress levels, while no differences were found in acute cortisol response after a 30 min confinement test. Shelter-seeking was higher in salmon reared in enriched tanks when tested alone, but not when tested in small groups. Barren-reared fish had higher levels of fin deterioration over winter, potentially owing to higher aggression levels. These results suggest that enrichment can reduce the impact of stressors experienced in the hatchery and thus increase fish welfare. Tank enrichment may also be used to produce salmon better adapted for the more complex environment encountered after release.

  • 120.
    Nilsson, Anders
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Roach partial migration: predation, personality and propensity2015Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Migration may confer benefits, such as foraging opportunity and predator avoidance, but partial migration, i.e. that not the whole population migrates, can be expected if benefits differ between individual phenotypes. We here show that seasonal migration from lakes to connected streams in the freshwater fish roach is strongly affected by risk of cormorant predation. We show that the duration away from the lake, as well as roach individual body size, influence the probability of being predated by cormorants. We also present novel field data showing that cormorant predation acts as a selective pressure against individuals with bold personality, providing a mechanism behind the evolution and maintenance of behavioural phenotypic diversity along the bold-shy continuum. Accordingly, we argue that bold individuals have a higher migratory propensity to avoid cormorants, and that cormorant predation on bold individuals may shift animal-personality composition of roach populations, with consequences for selective processes and lake system composition and function.

  • 121.
    Nilsson, Christer
    et al.
    Umeå University, Umeå, Sweden.
    Jansson, Roland
    Umeå University, Umeå, Sweden.
    Kuglerova, Lenka
    Umeå University, Umeå, Sweden.
    Lind, Lovisa
    Umeå University, Umeå, Sweden.
    Ström, Lotta
    Umeå University, Umeå, Sweden.
    Boreal riparian vegetation under climate change2013Ingår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 16, nr 3, s. 401-410Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Riparian zones in boreal areas such as humid landscapes on minerogenic soils are characterized by diverse, productive, and dynamic vegetation which will rapidly react to climate change. Climate-change models predict that in most parts of the boreal region these zones will be affected by various combinations of increased temperature, less seasonal variation in runoff, increased average discharge, changes in groundwater supply, and a more dynamic ice regime. Increasing temperatures will favor invasion of exotic species whereas species losses are likely to be minor. The hydrologic changes will cause a narrowing of the riparian zone and, therefore, locally reduce species richness whereas effects on primary production are more difficult to predict. More shifts between freezing and thawing during winter will lead to increased dynamics of ice formation and ice disturbance, potentially fostering a more dynamic and species-rich riparian vegetation. Restoration measures that increase water retention and shade, and that reduce habitats for exotic plant species adjacent to rivers can be applied especially in streams and rivers that have been channelized or deprived of their riparian forest to reduce the effects of climate change on riparian ecosystems.

  • 122.
    Nilsson, Christer
    et al.
    Umeå University, Umeå, Sweden.
    Polvi, Lina E
    Umeå University, Umeå, Sweden.
    Gardeström, Johanna
    Umeå University, Umeå, Sweden.
    Maher Hasselquist, Eliza
    Umeå University, Umeå, Sweden.
    Lind, Lovisa
    Umeå University, Umeå, Sweden.
    Sarneel, Judith M
    Umeå University, Umeå, Sweden.
    Riparian and in-stream restoration of boreal streams and rivers: success or failure?2015Ingår i: Ecohydrology, ISSN 1936-0584, E-ISSN 1936-0592, Vol. 8, nr 5, s. 753-764Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We reviewed follow-up studies from Finnish and Swedish streams that have been restored after timber floating to assess the abiotic and biotic responses to restoration. More specifically, from a review of 18 case studies (16 published and 2 unpublished), we determined whether different taxonomic groups react differently or require different periods of time to respond to the same type of restoration. Restoration entailed returning coarse sediment (cobbles and boulders) and sometimes large wood to previously channelized turbulent reaches, primarily with the objective of meeting habitat requirements of naturally reproducing salmonid fish. The restored streams showed a consistent increase in channel complexity and retention capacity, but the biotic responses were weak or absent in most species groups. Aquatic mosses growing on boulders were drastically reduced shortly after restoration, but in most studies, they recovered after a few years. Riparian plants, macroinvertebrates and fish did not show any consistent trends in response. We discuss seven alternative explanations to these inconsistent results and conclude that two decades is probably too short a time for most organisms to recover. We recommend long-term monitoring using standardized methods, a landscape-scale perspective and a wider range of organisms to improve the basis for judging to what extent restoration in boreal streams has achieved its goal of reducing the impacts from timber floating.

  • 123.
    Nilsson, Christer
    et al.
    Umeå University, Umeå, Sweden.
    Polvi, Lina E
    Umeå University, Umeå, Sweden.
    Lind, Lovisa
    Umeå University, Umeå, Sweden.
    Extreme events in streams and rivers in arctic and subarctic regions in an uncertain future2015Ingår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 60, nr 12, s. 2535-2546Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We review the predicted changes in extreme events following climate change in flowing waters in arctic and subarctic regions. These regions are characterised by tundra or taiga ecosystems in either erosional or depositional glacial landforms or presently glacierised areas of the Northern Hemisphere. The ecological and geomorphic effects of extreme meteorological and hydrological events, such as episodes of strongly increased precipitation, temperatures and flows, can be exacerbated by altered base conditions. For example, winter temperature variations between frost and thaw will become more frequent at many places because mean temperature during the winter is closer to 0 °C, potentially leading to changes in the production of ice and intensified disturbance of riparian and aquatic habitats during extreme floods. Additionally, thawing of permafrost and glaciers can lead to increased bank erosion because of thaw slump and glacial outburst floods. We discuss the abiotic and biotic effects of these and other extreme events, including heavy precipitation, floods, drought and extreme air or water temperatures, and summarise our findings in a model that aims to stimulate further research in this field.

  • 124.
    Nilsson, Christer
    et al.
    Umeå University, Umeå, Sweden.
    Sarneel, Judith M.
    Umeå University, Umeå, Sweden; Utrecht UniversityUtrechtThe Netherlands.
    Palm, Daniel
    Umeå University, Umeå, Sweden.
    Gardeström, Johanna
    Umeå University, Umeå, Sweden.
    Pilotto, Francesca
    Umeå University, Umeå, Sweden.
    Polvi, Lina E.
    Umeå University, Umeå, Sweden.
    Lind, Lovisa
    Umeå University, Umeå, Sweden.
    Holmqvist, Daniel
    Utrecht University, Utrecht, The Netherlands.
    Lundqvist, Hans
    Ume/Vindel River Fishery Advisory BoardLyckseleSweden.
    How do biota respond to additional physical restoration of restored streams?2017Ingår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 20, nr 1, s. 144-162Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Restoration of channelized streams by returning coarse sediment from stream edges to the wetted channel has become a common practice in Sweden. Yet, restoration activities do not always result in the return of desired biota. This study evaluated a restoration project in the Vindel River in northern Sweden in which practitioners further increased channel complexity of previously restored stream reaches by placing very large boulders (> 1 m), trees (> 8 m), and salmonid spawning gravel from adjacent upland areas into the channels. One reach restored with basic methods and another with enhanced methods were selected in each of ten different tributaries to the main channel. Geomorphic and hydraulic complexity was enhanced but the chemical composition of riparian soils and the communities of riparian plants and fish did not exhibit any clear responses to the enhanced restoration measures during the first 5 years compared to reaches restored with basic restoration methods. The variation in the collected data was among streams instead of between types of restored reaches. We conclude that restoration is a disturbance in itself, that immigration potential varies across landscapes, and that biotic recovery processes in boreal river systems are slow. We suggest that enhanced restoration has to apply a catchment-scale approach accounting for connectivity and availability of source populations, and that low-intensity monitoring has to be performed over several decades to evaluate restoration outcomes.

  • 125.
    Nilsson, Per Anders
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013). Lunds universitet.
    Eklöv, Peter
    Uppsala universitet.
    Finding food and staying alive2018Ingår i: Biology and ecology of pike / [ed] Skov, Christian & Nilsson, Anders P., Boca Raton: CRC Press, 2018Kapitel i bok, del av antologi (Refereegranskat)
  • 126.
    Nilsson, Per Anders
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013). Lunds universitet.
    Hulthén, Kaj
    Lunds universitet.
    Chapman, Ben
    University of Nottingham & University of Manchester, UK.
    Hansson, Lars-Anders
    Lunds universitet.
    Brodersen, Jakob
    Department of Fish Ecology and Evolution, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Center for Ecology, Evolution and Biogeochemistry, Kastanienbaum, Switzerland.
    Baktoft, Henrik
    Technical University of Denmark, Denmark.
    Vinterstare, Jerker
    Lunds universitet.
    Brönmark, Christer
    Lunds universitet.
    Skov, Christian
    Technical University of Denmark, Denmark.
    Species integrity enhanced by a predation cost to hybrids in the wild2017Ingår i: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 13, nr 7, s. 1-4, artikel-id 20170208Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Species integrity can be challenged, and even eroded, if closely related species can hybridize and produce fertile offspring of comparable fitness to that of par- ental species. The maintenance of newly diverged or closely related species therefore hinges on the establishment and effectiveness of pre- and/or post- zygotic reproductive barriers. Ecological selection, including predation, is often presumed to contribute to reduced hybrid fitness, but field evidence for a predation cost to hybridization remains elusive. Here we provide proof-of- concept for predation on hybrids being a postzygotic barrier to gene flow in the wild. Cyprinid fishes commonly produce fertile, viable hybrid offspring and therefore make excellent study organisms to investigate ecological costs to hybrids. We electronically tagged two freshwater cyprinid fish species (roach Rutilus rutilus and bream Abramis brama) and their hybrids in 2005. Tagged fish were returned to their lake of origin, exposing them to natural predation risk from apex avian predators (great cormorant, Phalacrocorax carbo). Scanning for regurgitated tags under cormorant roosts 3–4 years later ident- ified cormorant-killed individual fish and allowed us to directly test for a predation cost to hybrids in the wild. Hybrid individuals were found significantly more susceptible to cormorant predation than individuals from either parental species. Such ecological selection against hybrids contributes to species integrity, and can enhance species diversification.

  • 127.
    Norrgård, Johnny
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Schmitz, Monika
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effects of feeding regimes and early maturation on migratory behaviour of landlocked hatchery-reared Atlantic salmon Salmo salar smolts2014Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 85, nr 4, s. 1060-1073Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The migratory behaviour of hatchery-reared landlocked Atlantic salmon Salmo salar raised under three different feeding regimes was monitored through the lower part of the River Klarälven, Sweden. The smolts were implanted with acoustic transmitters and released into the River Klarälven, 25 km upstream of the outlet in Lake Vänern. Early mature males, which had matured the previous autumn, were also tagged and released. To monitor migration of the fish, acoustic receivers were deployed along the migratory route. The proportion of S. salar that reached Lake Vänern was significantly greater for fish fed fat-reduced feed than for fish given rations with higher fat content, regardless of ration size. Fish from the early mature male group remained in the river to a greater extent than fish from the three feeding regimes. Smolt status (degree of silvering), as visually assessed, did not differ among the feeding regime groups, and moreover, fully-silvered fish, regardless of feeding regime, migrated faster and had a greater migration success than fish with less developed smolt characteristics. Also, successful migrants had a lower condition factor than unsuccessful ones. These results indicate that the migration success of hatchery-reared S. smolts released to the wild can be enhanced by relatively simple changes in feeding regimes and by matching stocking time with smolt development.

  • 128.
    Norrgård, Johnny R
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Landlocked Atlantic salmon Salmo salar L. and trout Salmo trutta L. in the regulated River Klarälven, Sweden: Implications for conservation and management2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Conservation and management of migratory salmonids requires an understanding of their ecology at multiple scales, and a holistic view, including assessment of historical and present anthropogenic impacts. In the regulated River Klarälven, with 11 hydropower dams, populations of landlocked Atlantic salmon Salmo salar and migratory brown trout Salmo trutta have declined due to human activities. Maintaining viable populations of salmon in the River Klarälven has high priority, given there are fewer than 10 native stocks of landlocked salmon in Europe. To date, natural smolt production has been maintained by collecting and transporting spawners past eight hydroelectric plants in the river, where they are released to spawn. No functioning fish passage facilities are available that allow the fish to return to the lake. To evaluate the situation for landlocked salmon and migratory trout in Lake Vänern and the River Klarälven, an analysis of catch and river return data, based on data sets covering time periods from 15 to 200 years, was performed. In addition, the loss rates and behavior of downstream-migrating wild salmon smolts as they swam past eight power stations in the regulated River Klarälven was quantified.

    For the migration study, wild salmon smolts were tagged with acoustic transmitters, and the smolts were monitored as they swam along a 180 km long river segment, including eight dams, with regulated and unregulated stretches. The loss due to HEP passages was estimated to be 76%, which contrasts with the 8% loss along unregulated control stretches. Kaplan-Meier estimations showed that only 16% of the smolts passed all eight dams. Migration speed was 83% lower along regulated stretches than along unregulated stretches, and migration speed at regulated stretches was dependent on fish size, with large fish moving slower than small fish.

    The analysis of historical data showed that annual returns of wild salmon are less than 3% of what they were at the beginning of the 19th century. Returns of wild trout are even lower, with just some 30 fish caught annually. Lack of basic ecological information, as river return and fisheries catch rates, estimates of wild smolt production and survival, and releases of hatchery-reared fish, complicate an effective management of these unique populations. There is need for coordination of present and future research, monitoring, and restoration strategies. In this thesis I identify some measures to improve the status of the River Klarälven salmon and trout that should be of broad interest to resource and fishery managers.

  • 129.
    Norrgård, Johnny R
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Migration and quality of landlocked Atlantic salmon smolt: Implications for conservation and management2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Atlantic salmon Salmo salar has a complex life cycle, including long migrations and habitat shifts for both juveniles and adults. As such, salmon populations are vulnerable to habitat degradation and fragmentation along their migratory routes. This makes management and conservation a complex task requiring knowledge of salmon ecology at different temporal and spatial scales. In this thesis I highlight the use of a holistic life-history based approach in the conservation and management of wild and hatchery-reared salmon in regulated rivers and lakes.

    Small populations of wild-reproducing landlocked salmon and trout Salmo trutta exist in the regulated River Klarälven, Sweden. Since the 1930s, transportation of adult spawners upstream of eight dams has given the fish access to spawning grounds. The number of returning wild spawners became critically low in the 1960s, but stocking of hatchery smolts resulted in an increase in spawners that continues today. My data show that wild smolt may suffer high mortality due to multiple dam passages. To ensure viable populations of wild populations, future management should include both up- and downstream solutions that ensure connectivity in the system.

    The recreational and commercial salmonid fishery are maintained by compensatory stockings, yielding annual catches of about 75 tons, and a river return rate of hatchery fish of about 1%. As a large portion of the stocked smolts does not survive downstream migration to the lake, there has been discussion about the quality of the stocked smolt and about stocking strategies. Based on my studies, producing hatchery smolts more closely resembling wild-born conspecifics should result in reduced loss rates. I suggest changes in the hatchery and stocking procedures to increase the survival of stocked smolts. The results of my research should be applicable to other regulated systems, particularly those with mixed stocks of wild and hatchery salmonid populations.

  • 130.
    Norrgård, Johnny R
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Multiplicative loss of Salmo Salar L. smolts during downstream migration through multiple dams2012Konferensbidrag (Refereegranskat)
  • 131.
    Norrgård, Johnny R
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Adam, Ludvigsson
    Länsstyrelsen i Västra Götalands län, Vänersborg, Sverige.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Predation by northern pike Esox lucius on migrating hatchery-reared salmonid smoltsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Supplementary stocking of hatchery-reared smolts is the main method used to mitigate and compensate for lost production of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) populations in rivers. The survival of hatchery reared smolts in nature is generally low, and predation is one explanation for this. In the River Klarälven, Sweden, approximately 175 000 hatchery reared salmon and trout smolts are annually released into the rivr approximately 25 km upstream of Lake Vänern, to where they migrate and remain until maturity. During 2006-2010 half of the released hatchery reared smolts tagged with telemetry transmitters did not reach Lake Vänern. The loss rate of smolts was higher in river reaches with shallow vegetated areas and in reaches with deep pool areas than in the dominant habitat type, consisting of intermediate depths and sandy, uniform bottom substrates. Similarly, average CPUE of northern pike (Esox Lucius) was high in the same habitats as where smolts were lost. Gut content analyses of pike showed that they fed chiefly on European smelt (Osmerus eperlanus) in April, hatchery-reared salmonid smolts in May and European river lamprey (Lampetra fluviatilis) in June. We argue that when these different energy and lipid rich alternative prey occur at high densities during their spawning periods they are probably an easily caught energetically favorable prey. Our results indicate that there may be ecological windows of opportunity for stocking hatchery-reared smolts that could increase survival in the River Klarälven.

  • 132.
    Norrgård, Johnny R
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Bergman, Eva
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Greenberg, Larry
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Schmitz, Monika
    Uppsala University.
    Effects of feed quality and quantity on growth, early maturation and smolt development in hatchery-reared landlocked Atlantic salmon Salmo salar2014Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 85, nr 4, s. 1192-1210Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of feed quality and quantity on growth, early male parr maturation and development of smolt characteristics were studied in hatchery reared landlocked Atlantic salmon Salmo salar. A 2x2 factorial design was used, with two levels of feed rations and lipid content of the feed. The fish were reared from first feeding until release in May the second year. At the end of the experiment salmon fed high rations, regardless of lipid content, grew the most, whereas salmon fed low lipid feed with low rations grew the least. In addition, fish fed low lipid feed had lower body lipid levels than fish fed high lipid feed. Fish from all treatments showed some reduction in condition factor (CF) and lipid levels during their second spring. Smolt status was evaluated using both physiological and morphological variables. These results, based on Na+, K+-ATPase (NKA) enzyme activity, saltwater tolerance challenges and visual assessments, were consistent with each other, showing that salmon from all treatments except the treatment in which fish were fed low rations with low lipid content, exhibited characteristics associated with smolting at two-years of age. Smolting was mainly affected by feed rations; fish fed higher rations experienced enhanced smolting. Sexually mature male parr from the high ration, high lipid content treatment were also subjected to saltwater challenge tests, and were found to be unable to regulate plasma sodium levels. Low feed rations noticeably reduced the proportion of sexually mature male parr, while there was no difference related to lipid content of feed. Fish fed low rations with low lipid content exhibited the highest degree of severe fin erosion.

  • 133.
    Norrgård, Johnny R
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry A
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Piccolo, John J
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Schmitz, Monika
    Uppsala university.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Multiplicative loss of landlocked Atlantic salmon Salmo salar L. smolts during downstream migration through multiple dams2013Ingår i: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 29, nr 10, s. 1306-1317Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Relatively little is known about the downstream migration of landlocked stocks of Atlantic salmon Salmo salar L. smolts, as earlier migration studies have generally focused on upstream migration. However, in watersheds with many hydroelectric plants (HEPs), multiplicative loss of downstream-migrating salmon smolts can be high, contributing to population declines or extirpations. Here we report the results from a study of wild landlocked Atlantic salmon smolts in the River Klaralven. Salmon smolts, tagged with acoustic transmitters, were released at different locations and followed as they passed 37 receivers along a 180-km-long river segment, including eight dams as well as free-flowing control stretches. We found that 16% of the smolts successfully migrated along the entire river segment. Most losses occurred during HEP passages, with 76% of the smolts being lost during these passages, which contrasts with the 8% smolt loss along unregulated control stretches. Migration speed was 83% slower along regulated stretches than along unregulated stretches. The observed lower migration speed at regulated stretches was dependent on fish size, with large fish moving slower than small fish. Discharge affected migration speed but not losses. As previously shown for anadromous populations, our study of landlocked salmon demonstrates similar negative effects of multiple passages of HEPs by downstream-migrating smolts. On the basis of this and previous migration studies, we advocate using a holistic approach in the management and conservation of migratory fish in regulated rivers, which includes safe passage for both upstream- and downstream-migrating fish. Copyright (c) 2012 John Wiley & Sons, Ltd.

  • 134. Norrman, Emmy
    Vildkaniner som naturvårdare?: En studie om hur kaniner påverkar pH, mängden öppen sand och vegetation på en sandstäpp i sydöstra Skåne.2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Sandstäpp, eller ”xeric sand calcareous grasslands”, är en starkt hotad naturtyp i Sverige. Sandstäpp hyser många unika och sällsynta växter som kräver bland annat högt pH-värde och uppbrutet vegetationstäcke. De största hoten mot sandstäppen är försurning och igenväxning. I denna studie undersöktes om vildkaniner (Oryctolagus cuniculus) kan motverka dessa hot genom att gräva upp kalkrik sand och därmed gynna sandstäppens unika vegetation. Studien utfördes i sydöstra Skåne och hypoteserna var att pH-värdet, mängden öppen sand samt den relativa täckningsgraden av sandstäppstypiska växter sjunker/minskar med ökat avstånd från kaninhålor. Jordprover togs och vegetationsinventering gjordes vid åtta olika avstånd längs transekter från totalt åtta kaninhålor. Resultaten visar att kaninerna har en positiv påverkan på markförhållandena, de bidrar till höjt pH-värde och ökad mängd öppen sand. Resultaten visar också att den relativa täckningsgraden av den sandstäppstypiska sandskruvmossan (Syntrichia ruraliformis) minskar med ökat avstånd till kaninhålor. Vissa andra sandstäppstypiska växter ökade däremot med avståndet från kaninhålorna. Om detta beror på negativ påverkan från kaninerna är dock osäkert och kräver vidare undersökningar.

  • 135.
    Nyberg, Lars
    et al.
    Karlstads universitet, Institutionen för natur och miljö.
    Calles, Olle
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Impact of short-term regulation on hyporheic water quality in a boreal river2008Ingår i: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 24, nr 4, s. 407-419Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Water regulation may alter hydraulic head gradients with consequences for the exchange of water between the river and the hyporheic zone. The objective of this study was to investigate the effect of discharge on hyporheic water quality in a regulated Swedish boreal river during a 10-day experimental period with a sequence of alternating high- and low-flow episodes. A 250 m reach was instrumented with 28 piezometers placed at 150 and 300 mm below the river bed or below the mean groundwater level in the floodplain, and these piezometers were used to measure temperature, oxygen, electric conductivity and pH. High daily variation in air temperature during the first 3 days was transmitted vertically through the stream water into the hyporheic zone within hours. An oxygen saturation of 100% in the river water corresponded to 60–70% saturation at 150 mm depth and 30% at 300 mm depth. The hyporheic oxygen concentration at 150 mm depth decreased during the experimental period, falling into a range that is potentially harmful to incubating salmonid eggs. This was interpreted as a long-term response to the overall regulation regime, rather than a response to short-term water regulation during the experiment. Even though the effect of short-term regulation on the quality of hyporheic water in the river bed was limited, there was a more pronounced effect on the quality of floodplain hyporheic water. Most of the driving forces for temporal variation of water quality in the river bed came vertically from the river water, rather than from the lateral exchange.

  • 136.
    Nyqvist, Daniel
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Bergman, Eva
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Calles, Olle
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Greenberg, Larry
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Intake Approach and Dam Passage by Downstream-migrating Atlantic Salmon Kelts2017Ingår i: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 33, nr 5, s. 697-706Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Studying fish behaviour at hydropower dams is needed to facilitate the design and improvement of fish passage solutions, but few studies have focused on Atlantic salmon kelts. Here, we used radio telemetry (n = 40, size range = 50–81 cm) and acoustic sonar to study kelt movements in the forebay as well as their dam passage survival and subsequent migration success past multiple dams. We also compare radio telemetry and acoustic sonar observations of fish behaviour and used acoustic sonar to measure the depth distribution of fish approaching the turbine intake zone. Passage success at the dam was 41%, and mortality was largely associated with turbine passage (62%). The two fish that passed via the spill gates survived and continued their downstream migration. At the dam, all but one radio-tagged kelt approached the intake zone shortly after arrival to the forebay, and sonar data showed that approaching fish were predominantly surface oriented (72%, 88% and 96% of the observations were less than 1, 2 and 3 m deep, respectively). Turbine passage rate from the intake zone was higher at night than at day, indicating that the lack of visual cues may reduce the barrier effect of the 70-mm conventional trash rack. Turbine passage rate also increased with increasing hydropower generation. The percentage of observed upstream movements away from the intake zone compared with the total number of observations was considerably greater in the radio telemetry data (41%) than in the sonar data (4%). Only one fish survived passage of all eight hydropower dams to reach the lake. This low-passage survival underscores the need for remedial measures to increase the survival of migrating kelts, and the fish's surface orientation as well as their rapid approach to the intake rack should be taken into account when designing such measures.

  • 137.
    Nyqvist, Daniel
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Calles, Olle
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Bergman, Eva
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Hagelin, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Post-Spawning Survival and Downstream Passage of Landlocked Atlantic Salmon (Salmo salar) in a Regulated River: Is There Potential for Repeat Spawning?2016Ingår i: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 32, nr 5, s. 1008-1017Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Repeat salmonid spawners may make large contributions to total recruitment and long term population stability. Despite their potential importance, relatively little is known about this phase of the life history for anadromous populations, and nothing has been reported for landlocked populations. Here, we studied post-spawning behaviour and survival of landlocked Atlantic salmon in relation to downstream dam passage in the River KlarÀlven, Sweden. Eight hydropower stations separate the feeding grounds in Lake VÀnern from the spawning grounds in the River KlarÀlven, and no measures to facilitate downstream migration are present in the river. Forty-nine percent of the salmon survived spawning and initiated downstream migration. Females and small fish had higher post-spawning survival than males and large fish. The post-spawners migrated downstream in autumn and spring and remained relatively inactive in the river during winter. Downstream migration speed in the free flowing part of the river was highly variable with a median of 9.30km/day. Most fish passed the first hydropower station via upward-opening spill gates after a median residence time in the forebay of 25min. However, no tagged fish survived passage of all eight hydropower stations to reach Lake VÀnern. This result underscores the need for remedial measures to increase the survival of downstream migrating kelts.

  • 138.
    Nyqvist, Daniel
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Greenberg, Larry
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Calles, Olle
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Goerig, Elsa
    nst Natl Rech Sci, Ctr Eau Terre & Environm, Quebec City, PQ, Canada.
    Bergman, Eva
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Ardren, William
    S Fish & Wildlife Serv, Western New England Complex, Essex Jct, VT USA.
    Castro-Santos, Theodore
    USGS Leetown Sci Ctr, SO Conte Anadromous Fish Res Ctr, Turners Falls, MA USA.
    Migratory delay leads to reduced passage success of Atlantic salmon smolts at a hydroelectric dam2017Ingår i: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633, Vol. 26, nr 4, s. 707-718Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Passage of fish through hydropower dams is associated with mortality, delay, increased energy expenditure and migratory failure for migrating fish and the need for remedial measures for both upstream and downstream migration is widely recognised. A functional fish passage must ensure safe and timely passage routes that a substantial portion of migrating fish will use. Passage solutions must address not only the number or percentage of fish that successfully pass a barrier, but also the time it takes to pass. Here, we used radiotelemetry to study the functionality of a fish bypass for downstream-migrating wild-caught and hatchery-released Atlantic salmon smolts. We used time-to-event analysis to model the influence of fish characteristics and environmental variables on the rates of a series of events associated with dam passage. Among the modelled events were approach rate to the bypass entry zone, retention rates in both the forebay and the entry zone and passage rates. Despite repeated attempts, only 65% of the tagged fish present in the forebay passed the dam. Fish passed via the bypass (33%), via spill (18%) and via turbines (15%). Discharge was positively related to approach, passage and retention rates. We did not detect any differences between wild and hatchery fish. Even though individual fish visited the forebay and the entry zone on multiple occasions, most fish passed during the first exposures to these zones. This study underscores the importance of timeliness to passage success and the usefulness of time-to-event analysis for understanding factors governing passage performance.

  • 139.
    Nyqvist, Daniel
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    McCormick, S. D.
    S.O. Conte Anadromous Fish Research Center USGS-Leetown Science Center.
    Greenberg, Larry
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Ardren, W. R.
    U.S. Fish and Wildlife Service.
    Bergman, Eva
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Calles, Olle
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Castro-Santos, Theodore
    2 S.O. Conte Anadromous Fish Research Center USGS-Leetown Science Center.
    Downstream migration and multiple dam passage by Atlantic salmon smolts2017Ingår i: North American Journal of Fisheries Management, ISSN 0275-5947, E-ISSN 1548-8675, Vol. 4, nr 37, s. 816-828Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of this study was to investigate behavior and survival of radio-tagged wild and hatchery-reared landlocked Atlantic Salmon Salmo salar smolts as they migrated past three hydropower dams equipped with fish bypass solutions in the Winooski River, Vermont. Among hatchery-reared smolts, those released early were more likely to initiate migration and did so after less delay than those released late. Once migration was initiated, however, the late-released hatchery smolts migrated at greater speeds. Throughout the river system, hatchery-reared fish performed similarly to wild fish. Dam passage rates varied between the three dams and was highest at the dam where unusually high spill levels occurred throughout the study period. Of the 50 fish that did migrate downstream, only 10% managed to reach the lake. Migration success was low despite the presence of bypass solutions, underscoring the need for evaluations of remedial measures; simply constructing a fishway is not synonymous with providing fish passage.

  • 140.
    Nyqvist, Daniel
    et al.
    Institute of Marine Research, Norway.
    Zagars, Matiss
    Institute for Environmental solutions.
    Calles, Olle
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Comoglio, Claudio
    Politecnico di Torino, Italy.
    Behavior of trap-and-transported Atlantic salmon spawners of hatchery origin in the Daugava River system (Latvia)2019Ingår i: Journal of limnology, ISSN 1129-5767, E-ISSN 1723-8633, Vol. 78, nr 2, s. 210-219Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Where migrating fish have to pass multiple dams, very high passage performance is required at the series of obstacles to avoid accumulated negative effects of multiple dam passage. In some rivers, migrating fish are trapped, transported past several obstacles, and released to continue their migration. Such trap-and-transport solutions, however, have seldom been evaluated. In the Daugava River, Latvia, several dams with no functional fishways block the river for migrating fish. A remnant Atlantic salmon population is being sustained by a sea ranching regime, where returning spawners are caught and artificially spawned, the juveniles raised in hatcheries, and smolts released in to the river in time for their seaward migration. Hatchery released fish, however, differ substantially from wild conspecifics, and in Latvia, as elsewhere throughout the range of salmon, reduced dependency on hatchery production and the re-establishment of wild salmon populations are being discussed. In the Daugava River system, suitable spawning and rearing habitat remains upstream two dams and an associated large reservoir in a mainstem tributary, the Ogre River, offering the potential to restore a wild salmon population.  To explore the potential of a trap-and-transport solution to bring Atlantic salmon spawners in contact with remaining spawning grounds in the Daugava River system, spawners were caught, radio tagged, transported upstream of the two dams and the reservoir, and released to pursue their spawning migration in the tributary. Despite being unfamiliar with the river, some of the tagged spawners moved upstream, reaching areas up to 12 km from the release sites. Males were observed higher upstream in the river compared to females, and some males were tracked relatively close to potential salmon spawning habitat. Females, although displaying some movements in the lower parts of the river, were not observed close to any suitable spawning areas, highlighting potentially important sex differences in post trap-and-transport behaviour. Perhaps due to different responses to handling stress, such low post-transportation spawning success among females has the potential to negatively impact restoration efforts in the Daugava River system and elsewhere. The present study represents a first step towards the restoration of wild Daugava salmon, one of several unique Baltic Atlantic salmon populations, and a potential model for future restoration efforts.

  • 141.
    Olsson, Mattias
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Widén, Per
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Effects of highway fencing and wildlife crossings on moose Alces alces movements and space use in southwestern Sweden2008Ingår i: Wildlife Biology, ISSN 0909-6396, E-ISSN 1903-220X, Vol. 14, nr 1, s. 111-117Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Use of exclusion fencing is an effective method to reduce moose-vehicle collisions, and exclusion fences are commonly erected along Swedish highways. However, exclusion fences may pose a threat to the viability of wildlife populations because they serve as barriers to individual movements and may limit accessibility to resources. Various types of wildlife crossings intended to reduce road-kills and increase habitat connectivity across fenced highways have been constructed throughout the world. However, few studies have evaluated the effectiveness of these crossing structures with respect to movements before, during and after construction of highways and exclusion fencing. We studied movements of 24 GPS-collared moose Alces alces before, during and after an existing two-lane road was reconstructed to a fenced four-lane highway with three wildlife crossings designed for moose. We recorded 135 movements across the highway during 8,830 moose-monitoring days. Of these, 47 occurred before the construction began, 76 occurred during the construction, and 12 occurred after the highway was fenced. All movements registered after the fencing occurred across two of the three wildlife crossings. The average number of highway crossings per moose-day decreased by 67-89% after fencing. The number of moose-vehicle collisions decreased after the exclusion fencing, but the fenced highway served as a barrier to moose movements even though three wildlife crossings were created. Thus, exclusion fencing may reduce moose mortality and provide safer conditions for automobile travellers, but the fencing may have a negative impact on moose accessibility to resources, gene flow and recolonisation rates.

  • 142.
    Olsson, Mattias
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Widén, Per
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för hälsa och miljö.
    Larkin, Jeff
    Department of Biology, Indiana University of Pennsylvania, USA.
    Effectiveness of a highway overpass to promote landscape connectivity and movement of moose and roe deer in Sweden2008Ingår i: Landscape and Urban Planning, Vol. 85, nr 2, s. 133-139Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ungulate-vehicle accidents accounted for approximately 60% of the total police reported traffic accidents in Sweden during the 1990s. While exclusion fences are effective at reducing such collisions, they create a new threat to wildlife by limiting individual movements and access to resources. To promote movements across fenced highways, wildlife crossing structures have been constructed in many countries. We used infrared remote cameras, track count surveys, and GPS telemetry to monitor the use of a highway overpass by moose (Alces alces) and roe deer (Capreolus capreolus) in southwestern Sweden. Moose and roe deer used the overpass mostly during nocturnal hours (84 and 76%, respectively). Overpass use declined with increased traffic volume on the highway, indicating that highway traffic affected the frequency in which ungulates used the overpass. We calculated that 5–7 individual moose used the overpass annually which is enough to maintain gene flow between otherwise disjunct subpopulations.

  • 143.
    Pekcan-Hekim, Zeynep
    et al.
    University Helsinki, Finland.
    Hellen, Noora
    University Helsinki, Finland.
    Harkonen, Laura
    University Helsinki, Finland.
    Nilsson, Per Anders
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013). Lund University.
    Nurminen, Leena
    University Helsinki, Finland.
    Horppila, J
    University Helsinki, Finland.
    Bridge under troubled water: Turbulence and niche partitioning in fish foraging2016Ingår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 6, nr 24, s. 8919-8930Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The coexistence of competing species relies on niche partitioning. Competitive exclusion is likely inevitable at high niche overlap, but such divide between competitors may be bridged if environmental circumstances displace competitor niches to enhance partitioning. Foraging-niche dimension can be influenced by environmental characteristics, and if competitors react differently to such conditions, coexistence can be facilitated. We here experimentally approach the partitioning effects of environmental conditions by evaluating the influence of water turbulence on foraging-niche responses in two competing fish species, Eurasian perch Perca fluviatilis and roach Rutilus rutilus, selecting from planktonic and benthic prey. In the absence of turbulence, both fish species showed high selectivity for benthic chironomid larvae. R. rutilus fed almost exclusively on zoobenthos, whereas P. fluviatilis complemented the benthic diet with zooplankton (mainly copepods). In turbulent water, on the other hand, the foraging-niche widths of both R. rutilus and P. fluviatilis increased, while their diet overlap simultaneously decreased, caused by 20% of the R. rutilus individuals turning to planktonic (mainly bosminids) prey, and by P. fluviatilis increasing foraging on littoral/benthic food sources. We show that moderate physical disturbance of environments, such as turbulence, can enhance niche partitioning and thereby coexistence of competing foragers. Turbulence affects prey but not fish swimming capacities, with consequences for prey-specific distributions and encounter rates with fish of different foraging strategies (pause-travel P. fluviatilis and cruise R. rutilus). Water turbulence and prey community structure should hereby affect competitive interaction strengths among fish species, with consequences for coexistence probability as well as community and system compositions.

  • 144. Persson, Anders
    et al.
    Nilsson, Per Anders
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013). Lunds universitet.
    Brönmark, Christer
    Trophic interactions2018Ingår i: Biology and ecology of pike / [ed] Skov, Christian & Nilsson, Anders P., Boca Raton: CRC Press, 2018Kapitel i bok, del av antologi (Refereegranskat)
  • 145.
    Persson, Andreas
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper.
    Hur påverkar naturvårdsåtgärder mängden av vedlevande insekter: Manuellt dödade träd vs självdöda2012Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Today’s forest managers implement a large number of methods to increase the amount of dead wood in Swedish forests. They use everything from high cutting of trees to girdling trees and burning forests. However, implementation of these measures without proper knowledge of their consequences is a common problem. This study has been performed to increase knowledge about two of these measures, girdling and high cutting, and how these actions affect the number of wood-living insects living on dead trees. A total of 72 trees were randomly selected in four different locations in the municipality of Säffle. The trees, which were birch and alder, were all dead or dying and selected by three criteria, snags (as the reference tree type), girdling and high cut. A total of 15 trees of each type and measure were chosen. The trees which were either ring debarked or high cut were compared with snags to see if there were any differences in the number of wood-living insects. The collections of insects were made with so-called appropriate window traps. The traps were tied to the trees and left out for one week before emptying. The traps

    2

    were deployed on two separate occasions during June and July 2011. A total of 876 beetle individuals were captured during the study, including 13 longhorn beetles. There was a significantly smaller amount of families in high cut birch compared to the birch snags for the first period, but none for the second period. There were also a significantly smaller amount of families in the girdled birch than in the snags for the second period. There were no differences between the different types of dead trees when comparing insect species. There were no significant differences between the girdled alder and the alder snags, which indicate that girdling does not have a strong effect, although catches were greater for the girdled alder. High cut alder does not exist and therefore only girdled alder could be compared with the alder snags and no differences in insect catches were found. There were differences in sizes of the trees, with birch snags being larger than high cut and girdled birch and alder snags being smaller than debarked alder. There was also a significant difference in degradation rate of birch, with natural birch snags being less decayed than the high cut and girdled birch. There was no difference in the degree of decay for alder. 69 % of the trapped longhorn beetles were found in birch, 31 % on the alder, but this difference was not significant. The conclusion of the study was that high cutting birch leads to a smaller number of tree-living insects than found on natural snags and that the same applies to girdling. Alder requires further study.

  • 146.
    Petillon, J.
    et al.
    Univ. Rennes, Frankrike.
    Francois, A.
    Emirates Ctr Wildlife Propagat, Missour, Morocco.
    Lafage, Denis
    Univ. Rennes, Frankrike.
    Short-term effects of horse grazing on spider assemblages of a dry meadow (Western France)2018Ingår i: Animal Biodiversity and Conservation, ISSN 1578-665X, Vol. 41, nr 1, s. 19-32Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Short-term effects of horse grazing on spider assemblages of a dry meadow (Western France). In this study, the biodiversity impacts of a little studied herbivore, the horse, were assessed in a high conservation value habitat of dry meadows in Brittany (Western France). Spiders, a diversified and abundant group of predators, were used as bioindicators. Three complementary sampling techniques were used to assess changes in spider assemblages in both soil and vegetation strata, over time (diachronic comparison of managed unit before vs. after management) and space (synchronic comparison of managed vs. control units). Few effects of grazing, i.e. only one significantly indicative species, were found on assemblage composition (ANOSIM), and none on abundances, alpha- and beta-diversities (GLM on pitfall trap data). On the contrary, important differences were found between units before management took place. The main effects of grazing management were revealed over time (after one year), and not between managed and control units (CCA on pitfall trap data and x y -tests on guilds from each sampling method), showing the relevance of a diachronic approach more than a synchronic approach in such management monitoring. Grazing by horses could be relevant to manage meadows because it creates a high spatial heterogeneity, but further (long-term) studies including other model groups are required.

  • 147.
    Piccolo, John J.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper.
    Stoking the "Green Fire" 1: Bringing the Land Ethic to the Water2012Ingår i: Fisheries (Bethesda, Md.), ISSN 0363-2415, E-ISSN 1548-8446, Vol. 37, nr 11, s. 516-518Artikel i tidskrift (Refereegranskat)
  • 148.
    Piccolo, John J
    et al.
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Norrgård, Johnny R
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Greenberg, Larry A
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Schmitz, Monika
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Bergman, Eva
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, Avdelningen för biologi.
    Conservation of endemic landlocked salmonids in regulated rivers: a case-study from Lake Vänern, Sweden2012Ingår i: Fish and Fisheries, ISSN 1467-2960, E-ISSN 1467-2979, Vol. 13, nr 4, s. 418-433Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Conservation of migratory salmonids requires understanding their ecology at multiple scales, combined with assessing anthropogenic impacts. We present a case-study from over 100 years of data for the endemic landlocked Atlantic salmon (Salmo salar, Salmonidae) and brown trout (Salmo trutta, Salmonidae) in Lake Vänern, Sweden. We use this case-study to develop life history-based research and monitoring priorities for migratory salmonids. In Vänern, small wild populations of salmon and trout remain only in the heavily regulated Rivers Klar (Klarälven) and Gullspång (Gullspångsälven), and commercial and sport fisheries are maintained by hatchery stocking. These populations represent some of the last remaining large-bodied (up to 20 kg) landlocked salmon stocks worldwide. We found that one of four stocks of wild fish has increased since 1996; the other three remain critically low. Hatchery return rates for three of four stocks appear stable at roughly 1% and annual fisheries catch is roughly 75 metric tons, with an estimated 7.5% of hatchery smolts being recruited to the fishery; this also appears relatively stable since 1990. Our analysis reveals much uncertainty in key data requirements, including both river return and fisheries catch rates, estimates of wild smolt production and survival, and hatchery breeding and genetics protocols. These uncertainties, coupled with a lack of information on their riverine and lacustrine ecology, preclude effective management of these unique populations. We conclude with a framework for a life history-based approach to research and monitoring for Vänern salmon and trout, which should be applicable for all endemic, migratory salmonid populations.

  • 149.
    Piccolo, John
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Orlikowska, Ewa H.
    A biological risk assessment for an Atlantic salmon (Salmo salar) invasion in Alaskan waters2012Ingår i: Aquatic Invasions, ISSN 1798-6540, E-ISSN 1818-5487, Vol. 7, nr 2, s. 259-270Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present an event-tree biological risk assessment for a non-native Atlantic salmon (Salmo salar) invasion into Alaskan waters. Atlanticsalmon farming is prohibited in Alaska, USA, but large numbers of them are reared in ocean net-pens in Washinton (WA) USA, and BritishColumbia (BC), Canada. Large numbers of Atlantic salmon escape each year, and they have been recovered in both saltwater and freshwaterin WA, BC, and Alaska. There is limited evidence of successful spawning and rearing in BC, but none from Alaska. No stream-reared smoltsare known to have returned successfully from ocean migrations, but survey efforts for escaped adults and reared juveniles in streams havebeen very limited in time and space. Given recurring, large-scale escape events, propagule pressure could be great enough in any given yearfor a successful invasion. To date, such large numbers of adults have not been recorded ascending Alaskan streams, but again, monitoring isvery limited. Atlantic salmon could most likely successfully spawn and rear in Alaskan streams, so successful ocean migration appears to bethe factor most likely to limit their success. Successful invasion of BC waters, where propagule pressure is greater, followed by a subsequentinvasion of a pre-adapted stock by straying to Alaskan waters, may pose the greatest risk. The lack of adequate surveys, under-reporting ofescapes and recoveries, and inherent ecosystem variation, make it impossible to assign meaningful probabilities to the risk of an invasion ofAlaskan waters. We conclude that the short-term risk of invasion generally appears low, but that it might increase over time. We also notethat invasion is only part of the ecological risk of Atlantic salmon farming in Pacific waters. Disease, parasites, and pollution may also poserisks to local ecosystems – we do not assess these risks here.

  • 150.
    Piccolo, John
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för miljö- och livsvetenskaper (from 2013).
    Unfer, Günther
    University of Natural Resources and Life Sciences, Vienna, Austria.
    Lobón-Cerviá, Javier
    National Museum of Natural Sciences (CSIC), Madrid, Spain.
    Why conserve native brown trout?2017Ingår i: Brown Trout: Biology, Ecology and Management / [ed] Javier Lobón‐Cerviá, Nuria Sanz, Wiley-Blackwell, 2017, s. 641-647Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Brown trout are among the fishes most valued by humans for food and recreation. This has not prevented their decline, however, and today native brown trout are found at only a fraction of their historic abundance. Countless native populations have been extirpated by overfishing, habitat destruction, and indiscriminate stocking of hatchery fish; many remaining native populations are in danger of extirpation. If people value brown trout so highly, why have we been unable to stop their precipitous decline? A growing number of scientists and members of the public believe that a reassessment of our valuation of nature is warranted. We believe that a conservation ethic that openly acknowledges nature's intrinsic value is a necessary basis for truly sustainable resource management. In this chapter we briefly outline how Aldo Leopold's well-known Land Ethic, based on an eco-evolutionary worldview, can help us understand our duty to protect native brown trout for their own intrinsic value, in addition to the values they provide for humans.

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