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  • 1.
    Andersson, Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Catch and effort from a recreational trolling fishery in a large lake2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Over recent decades recreational fisheries have grown substantially throughout the world. Despite this increase, catches from recreational fisheries have often been ignored in fisheries management, although this is now being remedied. Monitoring recreational fisheries can be expensive, and the primary means used for monitoring is angler (creel) surveys, typically funded from sales of fishing licences. The studies presented in this thesis examine different approaches to monitoring recreational trolling fisheries’ catch and effort, where fishing licenses are not required and there are no reporting requirements. I present results from a complemented roving/mail-in survey undertaken during 2013-2014 to estimate recreational effort and catch of Atlantic salmon (Salmo salar) and brown trout (S. trutta) in the largest lake in the European Union, Lake Vänern, Sweden. I also evaluate different angler catch reporting methods (mail-in, tournament reports and face-to-face interviews) and compare catch rates within and among spring and fall fishing periods. In addition, mail-in survey data are examined for recall bias.

     

    I estimate that 28.7 tonnes of salmon and trout combined were harvested by the recreational trolling fishery in 2014, more than the commercial and subsistence fisheries combined. Seasonal differences in both recreational effort and catch were observed. Effort, in boat hours, was significantly higher in spring than in fall. Catch rates of trout were higher in fall than in spring, but there were no seasonal differences in catches of salmon. Harvest per boat day did not differ significantly among catch reporting methods, indicating that all three methods could be useful for managers interested in harvest rates. In contrast, total and released catch per boat day differed among reporting methods, with tournament anglers catching more fish in total. Finally, there was little evidence for recall bias in mail-in surveys, indicating that mail-in surveys are useful for collecting unbiased catch data. My study is the most comprehensive angler survey to date for Lake Vänern, and my results should be of immediate use to local fisheries managers and should also be of interest to researchers and managers interested in estimating catch and effort for fisheries at large spatial scales.

  • 2. Andersson, Anders
    et al.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Greenberg, Larry
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Comparing mail-in, interview and tournament catch rates for a recreational salmonid fisheryManuscript (preprint) (Other academic)
    Abstract
  • 3. Andersson, Anders
    et al.
    Greenberg, Larry
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Su, Zhenming
    Andersson, Magnus
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Estimating effort and catch of a recreational trolling fishery in one of Europe’s largest lakesManuscript (preprint) (Other academic)
    Abstract
  • 4.
    Andersson, Jan-Olov
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    A GIS-based landscape analysis of dissolved organic carbon in boreal headwater streams2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In boreal catchments, stream water chemistry is influenced and controlled by several landscape factors. The influence of spatially distributed variables is in turn dependent on the hydrological scale. Headwater streams have larger variability of water chemistry, and thus together represent a large biodiversity, and therefore need to be monitored in official environmental assessments. One objective of this study was, using Geographical Information Systems (GIS), to analyse co-variation between landscape variables and water chemistry and to determine which of the landscape variables have a major influence on the concentration of dissolved organic carbon (DOC) in headwater streams. Another objective was to find a simple method for predicting sources of DOC, using official map data and publically available GIS applications.

    Totally 85 headwater catchments (0.1-4 km2) in the county of Värmland, western south Sweden, were used in the study. Water chemistry was analysed for water sampled at low, medium and high flows, and landscape variables were extracted from official map data sources: topographic maps, a digital elevation model (DEM, 50 m grid), and vegetation data. Statistical analyses showed that topography (mean slope and mean topographic wetness index (TWI)) and wetland cover often correlated well with DOC in headwater catchments. Official map data could satisfactorily extract landscape variables (mean slope, mean TWI) that were useful in predicting stream water chemistry (DOC).

    A high-resolution elevation model, which was generated by interpolation of photogrammetric data, was used to calculate and evaluate two different wetness indices and their ability to predict the occurrence of wetlands in six catchments of different sizes and topography. The SAGA (System for Automated Geoscientific Analyses) wetness index (SWI) gave substantially better results than the TWI. The effects of resolution of DEMs on calculations of the SWI were investigated using 5, 10, 25 and 50 m grids. The results showed that SWI values increased with increasing cell size. The near linear increment of mean values for resolutions 10-50 m suggests a independence of terrain type and catchment size, which supported previous findings that indicated that mean slope and mean wetness index calculated from coarse elevation models may be used for prediction of DOC in headwater streams.

     

  • 5.
    Andersson, Jan-Olov
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    DEM resolution effects on SAGA wetness index in boreal forested catchmentsManuscript (preprint) (Other academic)
  • 6.
    Andersson, Sandra
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    The effects of artificial illumination on invertebrate drift2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 7.
    Bengtson, Johanna
    Karlstad University, Faculty of Social and Life Sciences.
    The relationship between behaviour and metabolic rate of juvenile Brown trout Salmo trutta2009Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In salmonids, the decision to migrate or remain resident is influenced by the status, and hence condition, of individuals. Status has been suggested to arise from the temperament of fish. In this study the links between standard metabolic rate and the levels of aggressiveness and shy/boldness were examined for 0+, hatchery-raised brown trout (Salmo trutta). I hypothesized, from the results of earlier studies (Cutts et al., 1998; Yamamoto et al., 1998), that high metabolic rates (MR) would be positively correlated to levels of aggression and boldness. The study was conducted in 200 L aquaria in which aggressiveness was measured by allowing each fish to interact with a mirror image of itself, and shy/boldness was tested by measuring the amount of time a fish used before exploring a new area. Standard metabolic rate was measured in a flow-through respirometer. In contrast to my expectations, there was no correlation between the different behavioural measures and the metabolic rate of fish. Also, no correlation between boldness and aggressiveness of fish was found. In additional testing aggressiveness correlated positively with the condition of fish (in coherence with Harwood et al., 2003) but, contrary to earlier studies (Överli et al., 2004; Schjolden & Winberg, 2007), not with the speed of acclimatization. The difference in results between this test and earlier studies, concerning the degree of correlation between MR and aggressiveness, suggests that the strength of this link differs between species of salmonids. Also, it may suggest changeability in the MR – behaviour link in different environments. Last, the status and condition of individuals cannot be unambiguously explained by temperament alone, but arise from a wider array of physiological and environmental factors.

     

  • 8.
    Bengtsson, Mikael
    Karlstad University, Division for Environmental Sciences.
    Utvärdering av omlöp vid Finsjö i Emån: Evaluation of natural fishways at Finsjö in the river Emån2009Student thesis
    Abstract [en]

    The purpose of this paper is to determine the extent to which trout used fishways to swim past two power plants at Finsjö in River Emån. Two different methods of  collecting data were used, radiotelemetry to determine if fish find the fishways (attraction efficiency) and PIT-tags to measure the number of fish that passed through the fishways (passage efficiency). The study showed that passageefficiency, being 89 % at lower Finsjö and 100 % at upper Finsjö, was high compared to other similar studies. Attraction efficiency was 75 % at lower Finsjö and 59 % at upper Finsjö, which indicates that the fish have difficulty finding the fishway entrances, particularly at upper Finsjö.

  • 9. Bergengren, Jakob
    et al.
    Olsson, Ivan
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    The thick shelled river mussel (Unio crassus) brings LIFE+ back to rivers.2012Conference paper (Refereed)
  • 10.
    Bergman, Eva
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Ecology of Atlantic Salmon and Brown Trout - Habitat as a Template for Life Histories2012In: Fish and Fisheries, ISSN 1467-2960, E-ISSN 1467-2979, Vol. 13, no 3, 360-360 p.Article, book review (Other academic)
  • 11.
    Bergman, Eva
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Salmon and trout in Lake Vänern - What can we do for the wild fish?2012Conference paper (Refereed)
    Abstract [en]

    Populations of migratorysalmon and trout have worldwide shown a decline due to human activities. Overthe years numerous measures have been undertaken to maintain these populations,and conservation of migratory salmonids requiresunderstanding of their ecology at multiple scales, combined with assessinganthropogenic impacts. Theregulated River Klarälven and Lake Vänern host endemic populations oflandlocked Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). The historically high abundances of the salmonids in theRiver Klarälven in the early 1800s have decreased dramatically, reachingall-time lows after the completion of all nine Swedish hydroelectric powerstations in the 1960s. After an extensive stocking program and transportationof spawners past eight hydroelectric plants catches from commercial,maintenance and sport fishing have again increased. Recently, increases in theproportion of wild salmon returning to the River Klarälven have generated interestsin establishment of wild salmon inhabiting the entire River Klarälven, includingupstream of the Norwegian border. How well are we equipped to meet these newdreams, taking into account our limited knowledge of the species different lifestages, coordination between different actors involved in the conservationprocesses, and our skills to communicate and understand everybody’s role inthis conservation process?

  • 12.
    Bergman, Eva
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Greenberg, Larry
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Norrgård, Johnny
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Schmitz, Monika
    Evolutionsbiologiskt centrum, Uppsala universitet.
    Lax och öring i Klarälven - möjligheter för vild fisk och kvalité på odlad fisk: Slutrapport 2008-20122013Report (Other academic)
    Abstract [sv]

    Data från 1800-talet visar att fångsterna av lax och öring i både älv och sjö varit mycket högre än idag. Storskaliga dämmen, kraftigt fiske i Dejeforsen, nio kraftverk i den svenska delen av Klarälvens huvudfåra, och användandet av älven för timmerflottning har bidragit till detta. Efter att utsättning av kompensationsodlad fisk startade ökade fångsten igen, även om den fortfarande är låg.

    Fältundersökningar av vild laxsmolt visade att 16 % av smolten klarade sig hela vägen förbi de åtta kraftverken mellan Edebäck och Forshaga. Under studien var vattenföringen, och därmed spillet, lågt, vilket troligen bidragit till de höga förlusterna. Normalt spills det inte under hela smoltvandringsperioden, vilket är olyckligt.

    Lax och öring uppfödda under normala odlingsförhållanden är oftast större och fetare än vild fisk. Vi födde upp lax med olika fodertyper och fodermängder. Mängden föda påverkade laxens tillväxt och smoltmognad, och lax som fått fettfattigt foder var mest ”naturlik”. Den klarade också vandringen bäst, 80 % tog sig till Vänern medan 55 % av laxen som fått normalt eller lite foder. Bara 20 % av tidigt könsmogna hanar tog sig till Vänern.

    Rapporten avslutas med implikationer och förslag till åtgärder och fortsatta studier.

  • 13.
    Bergman, Eva
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Norrgård, Johnny
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Gustafsson, Pär
    Nilsson, Fredrik
    Länstyrelsen i Västra Göralands län.
    Hart, Paul
    University of Leicester.
    Atlantic salmon and brown trout in Lake Vänern: A proposal for a co-management system2014In: Aquatic Ecosystem Health & Management, ISSN 1463-4988, E-ISSN 1539-4077, Vol. 17, no 4, 365-373 p.Article in journal (Refereed)
    Abstract [en]

    Co-management is of increasing interest for fisheries management. We explore possibilities for, and barriers to, developing a co-management system, using threatened populations of landlocked Atlantic Salmon and Brown Trout as examples. Good management of natural resources requires not only knowledge about the resource but also suitable tools to collect information and make decisions. In large ecosystems this can be difficult because many actors are involved, and various societal borders and traditions become barriers. Vänern is the largest lake in the EU and it holds several distinct populations of large-bodied landlocked Atlantic Salmon and Brown Trout. The lake is used for commercial, subsistence, and sport fishing as well as for other recreational activities, and in Klarälven, the largest river entering Vänern, sport fishing is popular. These salmonid populations were at critically low levels during the 1960s, but a stocking program since then has maintained the fishery, and at least one wild stock appears to be recovering since being protected in 1993. Ecosystem users all have different needs: in the lake, sport fishermen say that catches of hatchery fish have declined, and commercial fishermen have focused on other species. In the river, wild salmon may be recovering: sport fishing is popular and an ongoing project investigates the possibilities for salmon to be able to circumvent hydro-electrical plants and reach historical Norwegian spawning areas. Not only do we lack information about the salmonids’ different life stages, we also lack a suitable socio-political organization to find sustainable solutions to the different needs of diverse user groups. We argue that a co-management system that enfranchises user groups in the Vänern-Klarälven ecosystem will improve sustainable management of wild and hatchery fish.

  • 14.
    Bienau, Miriam J.
    et al.
    Germany.
    Kröncke, Michael
    Germany.
    Eiserhardt, Wolfgang
    Norway.
    Otte, Annette
    Germany.
    Graae, Bente
    Norway.
    Hagen, Dagmar
    Norway.
    Milbau, Ann
    Umeå University.
    Durka, Walter
    Germany.
    Eckstein, Rolf Lutz
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Synchronous flowering despite differences in snowmelt timing among habitats of Empetrum hermaphroditum2015In: Acta Oecologica, ISSN 1146-609X, E-ISSN 1873-6238, Vol. 69, 129-136 p.Article in journal (Refereed)
    Abstract [en]

    The topography within arctic-alpine landscapes is very heterogeneous, resulting in diverse snow distribution patterns, with different snowmelt timing in spring. This may influence the phenological development of arctic and alpine plant species and asynchronous flowering may promote adaptation of plants to their local environments.We studied how flowering phenology of the dominant dwarf shrub Empetrum hermaphroditum varied among three habitats (exposed ridges, sheltered depressions and birch forest) differing in winter snow depth and thus snowmelt timing in spring, and whether the observed patterns were consistent across three different study areas.Despite significant differences in snowmelt timing between habitats, full flowering of E. hermaphroditum was nearly synchronous between the habitats, and implies a high flowering overlap. Our data show that exposed ridges, which had a long lag phase between snowmelt and flowering, experienced different temperature and light conditions than the two late melting habitats between snowmelt and flowering.Our study demonstrates that small scale variation seems matter less to flowering of Empetrum than interannual differences in snowmelt timing.

  • 15.
    Brodersen, Jakob
    et al.
    Lund university, Sweden.
    Chapman, Ben B.
    Lund university, Sweden.
    Nilsson, P. Anders
    Lund university, Sweden.
    Skov, Christian
    Silkeborg university, Denmark.
    Hansson, Lars-Anders
    Lund university, Sweden.
    Bronmark, Christer
    Lund university, Sweden.
    Fixed and Flexible: Coexistence of Obligate and Facultative Migratory Strategies in a Freshwater Fish2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 3, e90294- p.Article in journal (Refereed)
  • 16.
    Brönmark, C
    et al.
    Lund University.
    Hulthén, K
    Lund University.
    Nilsson, Anders
    Lund University.
    Skov, C
    DTU-AQUA.
    Hansson, LA
    Lund University.
    Brodersen, J
    Lund University .
    Chapman, BB
    Lund University .
    There and back again: migration in freshwater fishes2014In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 92, no 6, 467-479 p.Article in journal (Refereed)
    Abstract [en]

    Animal migration is an amazing phenomenon that has fascinated humans for long. Many freshwater fishes also show remarkable migrations, whereof the spectacular mass migrations of salmonids from the spawning streams are the most well known and well studied. However, recent studies have shown that migration occurs in a range of freshwater fish taxa from many different habitats. In this review we focus on the causes and consequences of migration in freshwater fishes. We start with an introduction of concepts and categories of migration, and then address the evolutionary causes that drive individuals to make these migratory journeys. The basis for the decision of an individual fish to migrate or stay resident is an evaluation of the costs and benefits of different strategies to maximize its lifetime reproductive effort. We provide examples by discussing our own work on the causes behind seasonal migration in a cyprinid fish, roach (Rutilus rutilus (L., 1758)), within this framework. We then highlight different adaptations that allow fish to migrate over sometimes vast journeys across space, including capacity for orientation, osmoregulation, and efficient energy expenditure. Following this we consider the consequences of migration in freshwater fish from ecological, evolutionary, and conservation perspectives, and finally, we detail some of the recent developments in the methodologies used to collect data on fish migration and how these could be used in future research.

  • 17.
    Calles, Olle
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Bergdahl, Daniel
    Ålens nedströms passage av vattenkraftverk: Före och efter åtgärd2009Report (Other academic)
    Abstract [en]

    Fiskarter som är beroende av att kunna röra sig mellan sötvatten och hav för att fullfölja sina livscykler stöter ofta på problem i reglerade vattendrag, eftersom vattenkraftverk skapar vandringshinder. Vanligen försöker man lösa dessa problem genom att anlägga fiskvägar vid hindren, för att åter göra det möjligt för fisken att passera. Fokus för sådana åtgärder har legat på just uppströms passage, medan nedströms passage av kraftverk sällan uppmärksammats och ytterst sällan åtgärdats. Denna rapport beskriver nedströmspassagen för ål vid ett vattenkraftverk i Ätran, före och efter åtgärd.

    Före åtgärd satt en fingaller med 20 mm spaltvidd och 63,4° lutning i intagskanalen till Ätrafors kraftverk i Ätran. Förlusten för ål på väg nedströms mot havet var omfattande och dödligheten var 72 %. De flesta ålar som dog klämdes fast på intagsgallret eller skadades vid turbinpassage. Åtgärden bestod i att sätta in ett nytt fingaller i intagskanalen med 18 mm spaltvidd och 35° lutning. Dessutom anlades flyktöppningar i gallrets övre del för att erbjuda ålen en alternativ väg förbi kraftverket. Efter åtgärd minskade dödligheten för ål till 10%. Ca. 80% av ålarna hittade ut genom flyktöppningarna och ingen av dem fastnade på det nya gallret. Det nya gallrets utökade yta ledde även till att fallförlusten minskade med som mest 170 mm, vilket innebär en ökad framtida produktion vid kraftverket om man lyckas med att hålla gallret rent från löv och drivgods.

  • 18.
    Calles, Olle
    et al.
    Karlstad University, Division for Environmental Sciences.
    Greenberg, L.A.
    Karlstad University, Division for Environmental Sciences.
    The pre- and postspawning movements of anadromous brown trout in relation to two low-head power plantsManuscript (Other academic)
  • 19.
    Calles, Olle
    et al.
    Karlstad University, Division for Environmental Sciences.
    Greenberg, Larry
    Karlstad University, Division for Environmental Sciences.
    Survival and movement of wild brown trout smolts past two power plantsManuscript (Other academic)
  • 20.
    Calles, Olle
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Griffioen, Ben
    IMARES Wageningen UR, Netherlands.
    Winter, Erwin
    IMARES Wageningen UR, Netherlands.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Nyqvist, Daniel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Hagelin, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Gustafsson, Stina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Greenberg, Larry
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Fish Migration River Monitoring Plan2014Report (Other academic)
    Abstract [en]

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

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

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

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

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

  • 21.
    Calles, Olle
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Nyberg, Lars
    Karlstad University, Faculty of Social and Life Sciences, Centre for Climate and Safety.
    Greenberg, Larry
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Temporal and spatial variation in quality of hyporheic water in one unregulated and two regulated boreal rivers2007In: River research and applications, ISSN 1535-1459, Vol. 23, no 8, 829-842 p.Article in journal (Refereed)
    Abstract [en]

    This study describes the temporal and spatial variations in hyporheic water quality in three boreal rivers, the River Tobyälven, an unregulated river, the river Mangälven, a regulated river with a minimum discharge requirement and the river Järperudsälven, aregulated river without any minimum discharge requirements. A total of 43 permanent piezometers were used to measure dissolved oxygen (DO), temperature, electrical conductivity, pH, NO3 and NHþ4in the hyporheic water at 150mm and 300mmdepth, at monthly intervals from October 2001 to October 2002. Another seven piezometers were installed in brown trout redds and monitored during the incubation period, from December 2001 to April 2002. In the river Tobyälven, temporal patterns in hyporheic water chemistry correlated to variations in surface water chemistry and discharge. In the river Järperudsälven, the hyporheic water chemistry did not correlate to discharge or surface water chemistry. In the river Mangälven, the water chemistry was dominated by releases from a large upstream lake, and there were weak correlations between surface water chemistry and hyporheic water chemistry at some sites. The incubation conditions for brown trout eggs were most favourable in the unregulated river, characterized by high DO levels that remained high throughout the incubation period. In the river Järperudsälven the DO levels were variable during spawning, and then gradually declined to critically low levels during incubation, whereas in the river Mangälven the DO conditions were intermediate and stable. Thus we observed a stronger coupling between surface water conditions and hyporheic conditions, i.e. vertical connectivity, in the unregulated river than in the regulated river with minimum flow requirements, which in turn was stronger than in the river without minimum flow requirements.

  • 22.
    Carlsson, Niclas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Effekten av en kraftverksdamm på vandringsframgång hos migrerande öringsmolt2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Dammar fungerar som barriärer för migrerande fisk i rinnande vatten med minskad konnektivitet som följd. Predation och navigationssvårigheter är två stora orsaker till att nedströmsvandrande smolt uppvisar en låg vandringsframgång genom dammar. I Svedån undersöktes vandringsframgången för öringsmolt i en dammsträcka mot en fritt strömmande kontrollsträcka under perioden 15 april och 23 maj 2016. PIT-tagteknik (Passive Integrated Transponder) användes där totalt 117 öringar märktes med 12 mm PIT tag eller 23 mm PIT tag och följdes när de simmade förbi fyra installerade antennstationer som avgränsade de båda sträckorna. Resultatet visade en signifikant lägre vandringsframgång för de 29 öringarna i dammsträckan än för de 4 i kontrollsträckan, där endast 13,8% passerade dammsträckan och 75% passerade kontrollsträckan. Antal analyserad öring på kontrollsträckan var få, vilket skapar osäkerhet kring skattning på vandringsframgång på kontrollsträckan. Resultatet visar dock samma mönster från liknande studier som utförts rörande nedströmsvandrande öringsmolt. Orsakerna till den låga vandringsframgången kunde ej utredas men troliga orsakerna var predation, navigeringssvårigheter samt tvekan till passage vid dammens ytspill.

  • 23. Chapman, B.B.
    et al.
    Hulthén, K.
    Brönmark, C.
    Nilsson, Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Skov, C.
    Hansson, L-A.
    Brodersen, J.
    Shape up or ship out: migratory behaviour predicts morphology across spatial scale in a freshwater fish2015In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 84, 1187-1193 p.Article in journal (Refereed)
  • 24.
    de Paiva Affonso, Igor
    et al.
    Universidade Estadual de Maringá, Brazil; Universidade Tecnológica Federal do Paraná, Brazil.
    Cucolo Carling, Leticia
    Universidade Estadual de Maringá, Maringá, Brazil.
    Massato Takemoto, R
    Núcleo de Pesquisas em Limnologia Ictiologia e Aqüicultura – Nupélia, Maringá, Brazil.
    Carlos Gomez, Luiz
    Universidade Estadual de Maringá, Maringá, Brazil; Núcleo de Pesquisas em Limnologia Ictiologia e Aqüicultura – Nupélia, Maringá, Brazil.
    Nilsson, Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Light-triggered eye-fluke behavior may enhance parasite life-cycle progression2017In: Frontiers in Ecology and the Environment, ISSN 1540-9295, E-ISSN 1540-9309, Vol. 15, no 6, 340-341 p.Article in journal (Refereed)
  • 25.
    Eckstein, Rolf Lutz
    Uppsala University.
    Nitrogen retention by Hylocomium splendens in a subarctic birch woodland2000In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 88, no 3, 506-515 p.Article in journal (Refereed)
  • 26.
    Eckstein, Rolf Lutz
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Uppsala University.
    Karlsson, P S
    Uppsala University.
    Above-ground growth and nutrient use by plants in a subarctic environment: Effects of habitat, life-form and species1997In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 79, no 2, 311-324 p.Article in journal (Refereed)
  • 27.
    Eckstein, Rolf Lutz
    et al.
    Uppsala University.
    Karlsson, P S
    Uppsala University.
    Recycling of nitrogen among segments of Hylocomium splendens as compared with Polytrichum commune: Implications for clonal integration in an ectohydric bryophyte1999In: OIKOS, Vol. 86, no 1, 87-96 p.Article in journal (Refereed)
    Abstract [en]

    Physiological integration in clonal plants, which can be assumed to be dependent on vascular connections among ramets, is associated with several potential benefits, especially in nutrient-poor environments. However, some experimental evidence indicates that ectohydric bryophytes, i.e. species lacking specialised tissues for internal water conduction, also have physiologically integrated ramets. We tested this hypothesis by analysing nitrogen dynamics and tracing movements of a 15 N label among interconnected ramets of the ectohydric Hylocomium splendens over one season. The observed patterns were compared with translocation patterns in Polytrichum commune, an endohydric species that is known to show a high degree of clonal integration. Our aims were (1) to evaluate the degree of physiological integration among segments in H. splendens and (2) to study whether the pattern of 15 N movement obtained matched those depicted by changes in total nitrogen pool size. Current-year segments (G0) of both species were identified as strong sinks for nitrogen owing to their considerable increase in the 15 N pool during the season. In P. commune all other segments types showed a net loss of 15 N from June to September, which was probably due to autumn resorption of nitrogen to subterranean structures. In H. splendens one-year-old segments (G1) increased their 15 N pool, while older green segments (G2+) lost 50% of their initially absorbed 15 N. All the label lost from these source segments could be recovered in G0 and G1 segments. We suppose that most of the recycled nitrogen is provided by degeneration of three-year-old segments, which turn brown in parallel with the reallocation of nitrogen during the season. The high degree of physiological integration in H. splendens is discussed with respect to its life history and ecosystem nitrogen cycling.

  • 28.
    Eckstein, Rolf Lutz
    et al.
    Uppsala University.
    Karlsson, P S
    Uppsala University.
    Variation in nitrogen-use efficiency among and within subarctic graminoids and herbs2001In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 150, no 3, 641-651 p.Article in journal (Refereed)
  • 29.
    Eckstein, Rolf Lutz
    et al.
    Uppsala University.
    Karlsson, P S
    Uppsala University.
    Weih, M
    Uppsala University.
    Leaf life span and nutrient resorption as determinants of plant nutrient conservation in temperate-arctic regions1999In: New phytologist, Vol. 143, no 1, 177-189 p.Article in journal (Refereed)
  • 30.
    Eckstein, Rolf Lutz
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Uppsala University.
    Karlsson, P S
    Uppsala University.
    Weih, M
    Uppsala University.
    The significance of resorption of leaf resources for shoot growth in evergreen and deciduous woody plants from a subarctic environment1998In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 81, no 3, 567-575 p.Article in journal (Refereed)
  • 31.
    Ekström, Sara M.
    et al.
    Lund University.
    Sandahl, Margareta
    Lund University.
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Lund University.
    Kleja, Dan B.
    Swedish University of Agricultural Sciences.
    Kritzberg, Emma S.
    Lund University.
    Reactivity of dissolved organic matter in response to acid deposition2016In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 78, no 3, 463-475 p.Article in journal (Refereed)
    Abstract [en]

    Fluvial export of organic matter from the terrestrial catchment to the aquatic system is a large and increasing carbon flux. The successful reduction in sulfuric acid deposition since the 1980s has been shown to enhance the mobility of organic matter in the soil, with more terrestrially derived dissolved organic matter (DOM) reaching aquatic systems. Changes in soil acidity also affect the quality of the DOM. In this study we explore the consequences this may have on the reactivity and turnover of the terrestrially derived DOM as it reaches the aquatic system. DOM of different quality (estimated by absorbance, fluorescence and size exclusion chromatography) was produced through extraction of boreal forest O-horizon soils from podzol at two sulfuric acid concentrations corresponding to natural throughfall in spruce forest in Southern Sweden around 1980 and today. Extraction was done using two different methods, i.e. field leaching and laboratory extraction. The DOM extracts were used to assess if differences in acidity generate DOM of different reactivity. Three reactivity experiments were performed: photodegradation by UV exposure, biodegradation by bacteria, and biodegradation after UV exposure. Reactivity was assessed by measuring loss of dissolved organic carbon and absorbance, change in fluorescence and molecular weight, and bacterial production. DOM extracted at lower sulfuric acid concentration was more susceptible to photooxidation, and less susceptible to bacterial degradation, than DOM extracted at a higher sulfuric acid concentration. Thus the relative importance of these two turnover processes may be altered with changes in acid deposition.

  • 32.
    Enefalk, Åsa
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Effect of fine wood on juvenile brown trout behaviour in experimental stream channels2016In: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633, Vol. 25, no 4, 664-673 p.Article in journal (Refereed)
    Abstract [en]

    In-stream wood can increase shelter availability and prey abundance for stream-living fish such as brown trout, Salmo trutta, but the input of wood to streams has decreased in recent years due to harvesting of riparian vegetation. During the last decades, fine wood (FW) has been increasingly used for biofuel, and the input of FW to streams may therefore decrease. Although effects of in-stream FW have not been studied as extensively as those of large wood (LW), it is probably important as shelter for small-sized trout. In a laboratory stream experiment, we tested the behavioural response of young-of-the-year wild brown trout to three densities of FW, with trout tested alone and in groups of four. Video recordings were used to measure the proportion of time allocated to sheltering, cruising and foraging, as well as the number of aggressive interactions and prey attacks. Cruising activity increased with decreasing FW density and was higher in the four-fish groups than when fish were alone. Foraging decreased and time spent sheltering in FW increased with increasing FW density. Our study shows that juvenile trout activity is higher in higher fish densities and that trout response to FW is related to FW density and differs from the response to LW as reported by others. © 2015 John Wiley & Sons A/S.

  • 33.
    Enefalk, Åsa
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Greenberg, Larry
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Winter sheltering by juvenile brown trout (Salmo trutta): Effects of stream wood and an instream ecothermic predator2017In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 62, no 1, 111-118 p.Article in journal (Refereed)
    Abstract [en]

    In boreal streams, juvenile salmonids spend substantial amounts of time sheltering in the streambed and in stream wood, presumably as a means of protection against the physical environment and from terrestrial endothermic predators. Relatively little is known about sheltering by salmonids in response to instream ectothermic predators.We tested the effects of burbot (Lota lota) on the winter sheltering behaviour of PIT-tagged 0+ brown trout (Salmo trutta) in daylight and darkness. Sheltering in the streambed by trout was studied in the presence and absence of fine wood bundles.We found that the use of streambed and fine wood was lower in darkness than in daylight. Availability of fine wood significantly decreased sheltering in the streambed, and this effect was more pronounced in daylight than in darkness. The presence of a burbot significantly decreased sheltering in the streambed, had no effect on use of fine wood and resulted in a higher number of exposed trout.Our results indicate that juvenile brown trout decrease streambed sheltering in response to a burrowing, ectothermic predator.

  • 34.
    Greenberg, Larry
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Bergman, Eva
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Eklöv, Anders
    Effects of Predation and Intraspecific Interactions on Habitat Use and Foraging by Brown Trout in Artificial Streams1997In: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633, Vol. 6, no 1, 16-26 p.Article in journal (Refereed)
    Abstract [en]

    We studied habitat use, foraging rates and behavior of 10 cm and 12 cm long brown trout, Salmo trutta, at two densities, 1.5 and 3.0 fish. m−2, in artificial streams that contained either the amphipod, Gammarus pulex, alone or G. pulex together with the piscivore, northern pike, Esox lucius. Gammarus were stocked in and largely restricted to the pools at a density of 128 Gammurus. m−2. pool−1 Large trout (12 cm) used pools more and riffles less when small trout (10 cm) were present than when small trout were absent. Small trout consumed fewer Gammarus when together with large trout than when alone, but showed no difference in habitat use in the presence and abscnce of large trout. Habitat use and number of Gammarus consumed per trout were not affected by trout density for either size-class when alone. For both size-classes of trout, use of pools and foraging rates were higher in the absence than in the presence of pike, and pike primarily resided in the pools. The number of aggressive interactions by both size-classes of trout decreased when pike was present. Our results indicate that for habitats that differ in food resources and predation risk, size structure may affect habitat use and foraging by brown trout.

  • 35.
    Gustafsson, Pär
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Forest – stream linkages: Brown trout (Salmo trutta) responses to woody debris, terrestrial invertebrates and light2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Forests surrounding streams affect aquatic communities in numerous ways, contributing to energy fluxes between terrestrial and lotic ecosystems. The five papers in this thesis focus on woody debris, terrestrial invertebrates and light, three factors influenced by riparian zone structure, potentially affecting streams and brown trout (Salmo trutta). The individual strength of these stressors and their interactions with each other are not well studied, and their qualitative effects may differ both spatially and temporally as well as with the size-structure of specific fish populations.

    Using a combination of laboratory and field experiments, I examined the effects of woody debris, terrestrial invertebrates and light on prey availability and on the growth rates, diets and behavior of different size-classes of trout. My field experiments showed that addition of high densities of large wood affected trout growth in a positive way. This positive effect of large wood on trout growth may be related to prey abundance, as indicated by the high standing crop of aquatic macroinvertebrates on the wood. The positive effects on trout may also be related to decreased energy expenditures in wood habitats, as trout increased the ratio between numbers of prey captured and time spent active and that swimming activity and level of aggression decreased as wood densities were increased in a laboratory experiment. Terrestrial invertebrates are generally assumed to be a high quality prey resource for fish and my field experiments showed that reduction of terrestrial invertebrate inputs had a negative effect on trout growth. The availability of terrestrial prey in the stream was also coupled to trout diet and linked to growth, as fish with high growth rates had high proportions of terrestrial prey in their diets. Light, measured as PAR, did not have an effect on chlorophyll biomass, nor was there an effect on aquatic macroinvertebrates or trout. Hence, even if light levels were sufficient for increased photosynthesis, other factors such as low nutrient content may have limited the effects. Many of my results were dependent on fish-size. I observed, for example, that large trout had higher capture rates on surface-drifting terrestrial prey than small trout when prey densities were intermediate or high, but at low prey densities, the consumption of terrestrial prey by large and small trout were similar. Moreover, although large wood and terrestrial invertebrates affected growth of both small and large trout, the effects were generally more consistent for large trout.

    Although changes in riparian forests typically induce an array of interacting effects that certainly call for further research, the overall conclusion from this thesis is that many of the factors I have studied have profound effects on stream biota and trout. The positive effects from large wood also propose that adding trees to streams may partly compensate for negative effects associated with riparian deforestation.

  • 36.
    Gustafsson, Stina
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Macroinvertebrate colonization of a nature-like fishway: The effects of habitat designManuscript (preprint) (Other academic)
    Abstract [en]

    Nature-like fishways are designed to imitate the characteristics of natural streams, thereby providing passage and habitat for a variety of aquatic organisms. To develop the concept of nature-like design, a 500-meter long nature-like bypass channel, termed the biocanal, was constructed at the Eldforsen hydroelectric facility, Sweden. It included four habitat types; riffle, pool, floodplain and braided (i.e. with islands) habitats, each replicated three times.  The biocanal resembled a natural stream in terms of hydraulics, gradient, flow regime, substrate etc. and provided a range of habitats to potentially harbor a large biodiversity. Thus the biocanal had a much more varied instream environment than those of conventional fishways. To test the prediction that the biocanal had a positive effect on biodiversity, we compared the physical habitat and benthic fauna composition both among the four biocanal habitat types and with six natural reference streams. After two years 66.7% of the benthic fauna families found in the reference streams had colonized the biocanal. Families present in the reference streams, but not in the biocanal, were predominantly slow colonizers or taxa linked to riparian vegetation, which was scarce and in an early successional stage in the biocanal.

    In the biocanal, pool and floodplain habitats contained the highest number of families, the highest family diversity (Shannon-Weaver) and the highest densities of Ephemeroptera, Plecoptera and Trichoptera. Since these habitats contained more families and had higher diversities than the riffle habitats which are typical of conventional nature-like fishways, we suggest that the construction of biocanals indeed possesses the potential for high biodiversity. 

  • 37. Gustafsson, Stina
    The functional organization of the macroinvertebrate community in a nature-like fishway with habitat compensation propertiesManuscript (preprint) (Other academic)
    Abstract [en]

    Habitat compensation in streams can be integrated in the construction of nature-like fishways, creating structures that both facilitate passage and provide habitat. Few existing nature-like fishways, however, have been designed to maximize the habitat function. In 2009 a nature-like fishway with habitat compensation properties, termed the biocanal, was constructed in Eldforsen, Sweden. The functional feeding group approach was used to investigate the functional organization of the benthic community in the biocanal two years after its construction. Samples were also collected from six natural creeks in the area to be used as references. Comparisons of functional feeding group ratios, acting as substitutes of ecosystem attributes, implied that both the biocanal and the reference creeks were heterotrophic systems enriched in suspended FPOM. The ratios also showed that the systems contained an abundance of stable substrates for filter feeders and scrapers. The study also showed that even though the benthic fauna community composition in the biocanal and in reference creeks in the area differ, all functional feeding groups found in the six reference creeks where present in the biocanal. We therefore believe that the ecological function of the biocanal is similar to that of the natural reference creeks in the area. 

  • 38.
    Gustafsson, Stina
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Skurdal, Jostein
    Schneider, Lea Dominique
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Macroinvertebrate colonization of a nature-like fishway: The effects of adding habitat heterogeneity2013In: Ecological Engineering: The Journal of Ecosystem Restoration, ISSN 0925-8574, Vol. 61, 345-353 p.Article in journal (Refereed)
    Abstract [en]

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

  • 39.
    Hedgespeth, Melanie L.
    et al.
    Lund University.
    Nilsson, Per Anders
    Lund University.
    Berglund, Olof
    Lund university.
    Ecological implications of altered fish foraging after exposure to an antidepressant pharmaceutical2014In: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 151, 84-87 p.Article in journal (Refereed)
  • 40. Hedgespeth, Melanie
    et al.
    Nilsson, Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Berglund, Olof
    Assessing potential vulnerability and response of fish to simulated avian predation after exposure to psychotropic pharmaceuticals2016In: Toxics, Vol. 4, no 9Article in journal (Refereed)
    Abstract [en]

    Psychotropic pharmaceuticals present in the environment may impact organisms both directly and via interaction strengths with other organisms, including predators; therefore, this study examined the potential effects of pharmaceuticals on behavioral responses of fish to avian predators. Wild-caught juvenile perch (Perca fluviatilis) were assayed using a striking bird model after a seven-day exposure to psychotropic pharmaceuticals (the antidepressants fluoxetine or sertraline, or the -blocker propranolol) under the hypotheses that exposure would increase vulnerability to avian predation via increasing the probability of predator encounter as well as degrading evasive behaviors upon encounter. None of the substances significantly affected swimming activity of the fish, nor did they increase vulnerability by affecting encounter probability or evasive endpoints compared to control treatments. Counter to our expectations, fish exposed to 100 g/L fluoxetine (but no other concentrations or pharmaceuticals) were less likely to enter the open area of the arena, i.e., less likely to engage in risky behavior that could lead to predator encounters. Additionally, all fish exposed to environmentally relevant, low concentrations of sertraline (0.12 g/L) and propranolol (0.1 g/L) sought refuge after the simulated attack. Our unexpected results warrant further research as they have interesting implications on how these psychotropic pharmaceuticals may affect predator-prey interactions spanning the terrestrial-aquatic interface.

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

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

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

  • 42.
    Hulthen, K.
    et al.
    Lund University.
    Chapman, B. B.
    Lund University.
    Nilsson, Per Anders
    Lund University.
    Hansson, L. -A
    Lund University.
    Skov, C.
    Danmark.
    Baktoft, H.
    Danmark.
    Brodersen, J.
    Switzerland.
    Bronmark, C.
    Lund University.
    Sex identification and PIT-tagging: tools and prospects for studying intersexual differences in freshwater fishes2014In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 84, no 2, 503-512 p.Article in journal (Refereed)
  • 43.
    Hulthen, Kaj
    et al.
    Lund University, Sweden.
    Chapman, Ben B.
    Lund University, Sweden.
    Nilsson, P. Anders
    Lund University, Sweden.
    Hollander, Johan
    Lund University, Sweden.
    Bronmark, Christer
    Lund University, Sweden.
    Express yourself: bold individuals induce enhanced morphological defences2014In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 281, no 1776, 20132703- p.Article in journal (Refereed)
    Abstract [en]

    Organisms display an impressive array of defence strategies in nature. Inducible defences (changes in morphology and/or behaviour within a prey's lifetime) allow prey to decrease vulnerability to predators and avoid unnecessary costs of expression. Many studies report considerable interindividual variation in the degree to which inducible defences are expressed, yet what underlies this variation is poorly understood. Here, we show that individuals differing in a key personality trait also differ in the magnitude of morphological defence expression. Crucian carp showing risky behaviours (bold individuals) expressed a significantly greater morphological defence response when exposed to a natural enemy when compared with shy individuals. Furthermore, we show that fish of different personality types differ in their behavioural plasticity, with shy fish exhibiting greater absolute plasticity than bold fish. Our data suggest that individuals with bold personalities may be able to compensate for their risk-prone behavioural type by expressing enhanced morphological defences.

  • 44. Hulthén, K.
    et al.
    Chapman, B.B.
    Nilsson, Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Vinterstare, J.
    Hansson, L-A.
    Skov, C.
    Brodersen, J.
    Baktoft, H.
    Brönmark, C.
    Escaping peril: perceived predation risk affects migratory propensity2015In: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 11, 20150466Article in journal (Refereed)
  • 45.
    Jakubowski, Patrik
    Karlstad University.
    Halogen och LED påverkar tillväxt och fotosyntetisk aktivitet olika hos manetarten Cassiopeia sp.2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The jellyfish, Cassiopeia sp, maintain zooxanthellae symbionts in their tissue, which provide the jellyfish with photosynthetic products that are used for growth. In this study I investigated how halogen and LED lamps at two intensities influence the photosynthetic activity of these symbionts differently, and if growth differences between the jellyfishes were affected by lamp type. The experiment was running for 4 weeks and the results showed greater growth in the halogen groups at both intensity classes. Phosphate reduction in the surrounding water and oxygen production was used as a measure of photosynthetic activity, where oxygen production was higher in both groups of halogen compared to the LED groups. The phosphate test of the jellyfishes ambient water showed no significant differens depending on halogen and LED, but was depended on light intensity, where the individuals in the higher intensity classes assimilated greater amounts of phosphate. Overall, the study shows a difference between the lamp types where halogen results in greater photosynthetic activity by the symbionts than in the LED groups, which leads to greater growth measured as bell diameter. 

  • 46.
    Johansson, Patricia
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Evertebraters kolonisation på fin ved i semi-naturliga bäckar2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Wood can be added to streams to create microhabitats that provide macroinvertebrates with an opportunity for re-colonization by making the stream more heterogeneous. I examined colonization on wood substrate by macroinvertebrates in semi-natural streams in northern Finland during a three month period. Each of the streams was divided in three sections A, B and C, half of which were provided with wood. The focus has been on whether the density of macroinvertebrates changes with time, along an upstream-downstream direction in the streams, or in streams with two wood sections if macroinvertebrates will colonize the first section with wood that they come in contact with (upstream section) or if they continue downstream to the second section with wood. Wood from Salix sp. was placed in nine of the 18 enclosures during mid-June. Samples of wood were removed from the streams on three different occasions from August to October 2014. A total of 32 taxa were identified from the wood and assigned to functional feeding groups: shredders, scrapers, active filter feeders, passive filter feeders, collectors, miners, piercers and predators. The results showed that collectors, miners and piercers increased in density during the month of October and the abundance of scrapers was higher in the upstream location than in the downstream location. Total number of macroinvertebrates, collectors, passive filter feeders and predators had a higher colonization on the first substrate they came into contact with.

  • 47.
    Jonsson, Simon
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Identifiering av lek- och övervintringsområden för lax (Salmo salar) och öring (Salmo trutta) i Klarälven2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 48.
    Karlsson, P S
    et al.
    Uppsala University.
    Eckstein, Rolf Lutz
    Uppsala University.
    Weih, M
    Uppsala University.
    Seasonal variation in N-15 natural abundance in subarctic plants of different life-forms2000In: Ecoscience, ISSN 1195-6860, Vol. 7, no 3, 365-369 p.Article in journal (Refereed)
  • 49.
    Klenz, Martin
    Karlstad University, Faculty of Social and Life Sciences.
    Tidsanvändandet hos den svartvita stenskvättan (Oenanthe alboniger)2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Between Feb. 1st and Feb. 9th 2011, 23 different individuals of Hume´s Wheatear (Oenanthealboniger) with unspecified gender were observed in the area of the Hajjar– Mountains in the United Arab Emirates (UAE). The observed behavior was registered referring to seven pre-defined behavioral categories (Flying,chasing, singing, handling prey, nest-building, perching and preening) together with measurements of air-temperature (°C) and luminance (lux). The observed individuals spend on average 68,5 % of their time on perching, 12,6 % on handling prey, 10,3 % on flying, 6,1 % on singing and 2,5 % on preening, while categories “nest-building” and “chasing” did not occur once. Statistical analyses of the observation frequencies indicate that there is no significant difference between individuals; a very strong significant difference between category frequencies could be shown by the use of a one-factor analysis of variances (ANOVA). A correlation analysis of changes in temperature or luminance and frequency of shown behavior presented no existing relationship between measured environmental factors and behavior within the measured ranges and time-frame.

  • 50.
    Krange, Maria
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Change in the occurrence of the West European Hedgehog (Erinaceus europaeus) in western Sweden during 1950-2010.2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Hedgehog populations have declined all over Europe.  Here I describe population trends in three west Swedish counties, based on questionnaire surveys and interviews conducted in 1993 and 2010. I found that people questioned in 1993 had more recently seen hedgehogs than people asked in 2010, which indicates the hedgehog population has declined.  One of reasons for this decline may be the presence of badgers, as the occurrence of hedgehogs was inversely related to the presence of badgers. There was no difference in where hedgehog sightings occurred; sightings were equally likely to occur in suburban/urban areas as in rural areas, despite previous studies in Sweden and western Europe reporting a higher occurrence in suburban/urban areas.

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