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  • 601.
    Vikingsson, Amanda
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Vem kallar du för ´klimatflykting´?: En studie över hur svenska dagstidningar gestaltar klimatflyktingar2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The mean global temperatures have been rising with one degree since pre-industrial time. Effects is shown in the world today in terms of sea level rising, loss of sea ice in Artic and extreme weather conditions. International politics now states that migration is the single biggest effect caused by climate change. 

    The term ‘climate refugees’ is used as a definition of humans forced to flee their homes due to climate change. The purpose of the thesis is to show how the Swedish daily newspapers frame climate refugees after the climate conference in Paris in 2015. The purpose is more over to highlight existing power relations in this context. A qualitative content analysis is used on articles chosen from a number of Swedish daily papers. Political ecology and framing theory construct a theoretical framework, which helps to understand the themes which occurred in the analysis.

    The result shows a dehumanization of climate refugees. Climate refugees is highlighted as a negative effect of climate change. However, the term is rejected by people associated with it. In Sweden, there is a sense of denial to the problems caused around the world due to climate change. Faith is placed into ecological modernization. Voices in international politics states the urge to acknowledge the definition of ‘climate refugees’ in to international law. Not much help is offered to people who have lost their home to coastal erosion, flooding or destroyed lands. 

  • 602.
    Vinterstare, Jerker
    et al.
    Lund University.
    Hegemann, Arne
    Lund University.
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Lund University.
    Hulthen, Kaj
    Lund University.
    Bronmark, Christer
    Lund University.
    Defence versus defence: Are crucian carp trading off immune function against predator-induced morphology?2019In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 88, no 10, p. 1510-1521Article in journal (Refereed)
    Abstract [en]

    Numerous species adopt inducible defence strategies; that is, they have phenotypically plastic traits that decrease the risk of capture and consumption by potential predators. The benefits of expressing alternative phenotypes in high- vs. low-risk environments are well documented. However, inducible anti-predator traits are also expected to incur costs, as they are not expressed when predators are absent, yet empirical evidence of such costs remains scarce. Virtually, all animals in nature are simultaneously under strong selection to evade both capture by predators and infection by parasites or pathogens and, hence, display a diverse arsenal of defences to combat these threats, raising the possibility of trade-offs between defences. A classic example of a predator-induced morphological defence is the deep-bodied shape of crucian carp that reduces risk of predation from gape-size-limited predators. The goal of this study was to examine whether predator exposure affects also immune function in crucian carp, and whether the degree of expressed morphological defence is traded off against immune function in individuals. Following exposure to manipulations of perceived risk (predator presence/absence) in a long-term experiment (8 months), key aspects of innate immune function and individual differences in the expression of inducible morphological defence were quantified. Predator-exposed individuals showed lower haptoglobin levels and complement activity, but higher natural antibody titres than fish from predator-free conditions. When experimentally challenged with a mimicked bacterial infection (LPS injection), fish reared in the presence of a natural predator showed a weaker immune response. Moreover, among predator-exposed individuals, the magnitude of morphological defence expression correlated with both baseline immune function and the ability to mount an immune response. However, these relationships were not consistently supportive of a general trade-off among defences. Our results suggest that fish exposed to predators on average reduce investment in immune function, and, further, the observed relationships among defences in predator-exposed individuals can best be explained from individual fitness and pace-of-life perspectives.

  • 603.
    Virmaja, Tommy
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Skillnader i födoval mellan brunbjörnshonor (Ursus arctos) med och utan årsungar2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    According to foraging theory, animals seek and consume food in ways that maximize their ability to reproduce and have their genes represented in future generations. In order to achieve this, individuals must sometimes adapt their behaviors. Females of the brown bear (Ursus arctos) with cubs of the year must share the food they find with their cubs. To protect the cubs from being killed by males in the mating period, females with young have smaller home ranges than other adult females and move less on a daily basis than other females. In view of these differences my hypothesis is that females with yearlings consume different food items than other females. A fecal collection from GPS-marked brown bears was made in 2015 in the northern Dalarna county and northwestern county of Gävleborg in Sweden from 25 May to 11 October. Prior to the data analysis, the season was divided into two periods, 25 May to 15 July and 16 July to 11 October, based on differences in food availability and season (mating vs non-mating season). A frequency analysis detected no significant differences in food items consumed for either period. However, an exploratory data analysis of percent volume of different food items suggests that there may be differences in the amount of certain foods during the mating period. These differences were found for the food categories, bone, moose hair and other plant material. Although the study suffers from a small sample size with only four females with cubs of the year in each of the two periods, this study is relatively novel with a resolution at the individual level. Previous food item analyzes of the brown bear in Scandinavia have been done with fecal samples as the smallest unit.

  • 604.
    Voicu, Razvan
    et al.
    National Institute of Hydrology and Water management, Romania.
    Banaduc, Doru
    University of Sibiu, Romania.
    Greenberg, Larry
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Curtean-Banaduc, Angela
    University of Sibiu, Romania.
    Caras River Gorge aspects of salmonids' communities management- technical solutions2018In: Management of sustainable development, ISSN 2066-9380, Vol. 10, no 2, p. 5-12Article in journal (Refereed)
    Abstract [en]

    There are many obstacles in rivers that prevent or hinder passage of fish past barriers. Here, we present a specially designed solution for juvenile and adult brown trout so that they may to swim past discharge-regulating weirs in the upper Caraş River in both the upstream and downstream directions. The proposed solution relies on gravity flow and will have current velocities that will not inhibit weak swimmers swimming upstream to pass the weirs. Corrosion-resistant materials and the absence of components that could potentially injure the fish will be used in the construction of these technical solutions. Although testing of the functionality of this solutions for upstream - downstream and downstream - upstream passage of weirs is needed, we believe that if implemented, it should improve connectivity especially for brown trout and consequently conserve within-stream genetic diversity in the Caraş River and where appropriate in alike other Carpathian lotic systems with similar types of weirs.

  • 605.
    Voss, Nicole
    et al.
    Justus-Liebig-University, Giessen, Germany.
    Welk, Erik
    Martin Luther Univerity, Halle, Germany.
    Durka, Walter
    UFZ, Halle, Germany.
    Eckstein, Rolf Lutz
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Justus-Liebig-University Giessen, Germany.
    Biological flora of Central Europe: Ceratocapnos claviculata (L.) Liden2012In: Perspectives in plant ecology, evolution and systematics, ISSN 1433-8319, E-ISSN 1618-0437, Vol. 14, no 1, p. 61-77Article in journal (Refereed)
    Abstract [en]

    The eu-oceanic therophytic woodland herb Ceratocapnos claviculata has been expanding north- and eastwards into north temperate and subcontinental regions during the past decades. The rapid range expansion of the species may be an example of a species which is strongly profiting from global change. Against this background, in the present paper we review the taxonomy, morphology, distribution, habitat requirements, life cycle and biology of the species. (C) 2011 Elsevier GmbH. All rights reserved.

  • 606.
    Wahlberg, Sara
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Gericke, Niklas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Conceptual Demography in Upper Secondary Chemistry and Biology Textbooks' Descriptions of Protein Synthesis: A Matter of Context?2018In: CBE - Life Sciences Education, ISSN 1931-7913, E-ISSN 1931-7913, Vol. 17, no 3Article in journal (Refereed)
    Abstract [en]

    This study investigates how the domain-specific language of molecular life science is mediated by the comparative contexts of chemistry and biology education. We study upper secondary chemistry and biology textbook sections on protein synthesis to reveal the conceptual demography of concepts central to the communication of this subject. The term "conceptual demography" refers to the frequency, distribution, and internal relationships between technical terms mediating a potential conceptual meaning of a phenomenon. Data were collected through a content analysis approach inspired by text summarization and text mining techniques. Chemistry textbooks were found to present protein synthesis using a mechanistic approach, whereas biology textbooks use a conceptual approach. The chemistry texts make no clear distinction between core terms and peripheral terms but use them equally frequently and give equal attention to all relationships, whereas biology textbooks focus on core terms and mention and relate them to each other more frequently than peripheral terms. Moreover, chemistry textbooks typically segment the text, focusing on a couple of technical terms at a time, whereas biology textbooks focus on overarching structures of the protein synthesis. We argue that it might be fruitful for students to learn protein synthesis from both contexts to build a meaningful understanding.

  • 607.
    Walan, Susanne
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    From doing to learning: Inquiry- and context-based science education in primary school2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim of this thesis is to develop an understanding of primary school teachers’ knowledge of Inquiry- and Context-Based Science Education (IC-BaSE) from different perspectives: what it is, how to use it and why these strategies are used. There are at least two reasons for performing research in this field. First, there is a need for professional development in teaching science among primary school teachers. Second, IC-BaSE has been suggested to provide useful instructional strategies for stimulating students’ interests in learning science. The thesis contains four papers with the overall research question: How do primary school teachers reflect on Inquiry- and Context-based Science Education as a framework for teaching and learning in the primary school classroom? Both quantitative and qualitative research methods have been used. The main participants in the studies were twelve primary school teachers working with 10-12 year old students. The results are discussed with reference to theories mainly based on pragmatism, but also from a sociocultural perspective. Primary school teachers found IC-BaSE to provide useful instructional strategies in the primary school classroom, as it engaged their students and developed their skills in planning inquiries. The teachers developed their knowledge about IC-BaSE, what it is and how to use it.  Furthermore, the primary purpose of using IC-BaSE seemed to be that students should have fun. Students also responded positive to the use of IC-BaSE. However when teachers were informed about their students’ responses to IC-BaSE, they became more aware of the importance of informing the students about the purposes of the activities. The findings presented show that teachers need to move forward, not only be “doing”, but also knowing why they are doing the activities and how to do them. Students’ experiences can contribute to this awareness among teachers and develop the teaching practice.

  • 608.
    Walan, Susanne
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Star Wars Irl2017Conference paper (Other (popular science, discussion, etc.))
    Abstract [sv]

    Rymdmusik, finns det? Finns det ljud i rymden överhuvudtaget? Rymdfilmer, vad är sant och vad är falskt? Vilken roll spelar musiken i rymdfilmerna? Vi kombinerar fantastiska IRL rymdbilder med spännande musik.

  • 609.
    Walan, Susanne
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Students' responses to visits at some researchers' night events2017In: NFSUN 2017 Synopsis Book, 2017, p. 26-29Conference paper (Refereed)
    Abstract [en]

    Several activities around the world aim to stimulate students’ interest in science, technology, engineering and mathematics. The European Researchers' Nights are one example. In this study it was investigated how seven students in the age 15-19 years responded to a visit at Researchers' Nights events. The students were interviewed and answers were analysed based on content. The results showed that the students were all positive to the visit and in most cases it was better than they had expected. The results were organised into the main themes: expectations versus experiences, interest in research context and relevance of research. Most of the students were positive about being a scientist and could even imagine a future science career. The contexts presented at the events were catching the interest of the students and were relating to the daily life of the students, or found to be of relevance for society. The study is a pilot and will be followed by a future study with more students included.

  • 610.
    Walan, Susanne
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Teaching children science through storytelling combined with hands-on activities – a successful instructional strategy?2017In: Education 3-13, ISSN 0300-4279, E-ISSN 1475-7575, Vol. 47, no 1, p. 34-46Article in journal (Refereed)
    Abstract [en]

    Earlier studies have discussed the usefulness of storytelling and hands-on activities when teaching young children science. However, few studies have investigated the use of the two methods in combination. This study reports on five pre-school teachers’ experience of combining storytelling and hands-on activities in teaching science and their perceived effects of the combination. Interviews with the teachers and a supplementary observation served as the data material, which was transformed into narratives and member-checked by the participating teachers. Some found the combination of methods important while others argued that hands-on activities were effective without the use of stories. The teachers’ enjoyment in adopting the combinatory method and their appreciation of the stories also made a difference.

  • 611.
    Walan, Susanne
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    The dream performance - a case study of young girls' development of interest in STEM and 21st century skills, when activities in a makerspace were combined with drama2019In: Research in Science & Technological Education, ISSN 0263-5143, E-ISSN 1470-1138, p. 1-21Article in journal (Refereed)
    Abstract [en]

    Background: There is a shortage of people in the STEM sector, and it has been argued that more needs to be done, especially to attract girls. Furthermore, there is a need to develop twenty-first-century skills. No studies seem to have explored the combination of activities in makerspaces and the use of drama to stimulate interest in STEM and development of 21st century skills.Purpose: This study focused on a project with a unique combination of makerspace activities and the use of drama. The research questions investigated the outcomes that could be identified from combining drama and activities in a makerspace, with regard to the development of interest in STEM and twenty-first-century skills.Sample: Ten girls aged 7-11 years participated. A project leader, a drama teacher and three female engineering students supported the activities.Design and methods: The project lasted 3 months. Data were collected in the form of interviews and observations with video-recordings and field-notes, as well as documentation of props made by the girls. Analyses were conducted using thematic coding and discussed through the lens of Activity Theory.Results: The results showed that some of the girls developed an interest in science and technology. The girls also developed twenty-first-century skills, in terms of creativity, problem-solving and cooperation.Conclusions: Positive outcomes were found in this project, blending drama and making in a makerspace learning environment. Future studies could investigate how other skills and knowledge in different STEM subjects can be developed in similar projects.

  • 612.
    Walan, Susanne
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Chang Rundgren, Shu-Nu
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Investigating preschool and primary school teachers´ self-efficacy and needs in teaching science: A pilot study2014In: CEPS Journal, ISSN 1855-9719, Vol. 4, no 1, p. 51-67Article in journal (Refereed)
  • 613.
    Walan, Susanne
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Enochsson, Ann-Britt
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Department of Educational Studies (from 2013).
    The potential of using a combination of storytelling and drama, when teaching young children science2019In: European Early Childhood Education Research Journal, ISSN 1350-293X, E-ISSN 1752-1807, Vol. 27, no 6, p. 821-836Article in journal (Refereed)
    Abstract [en]

    Based on a sociocultural perspective, this study explores the outcome of using a model that combines storytelling and drama to teach young children science. The research question is: How is children’s learning affected when using a combination of storytelling and drama to explain a complex scientific concept?. Two preschools and one primary school were visited. Altogether 25 children aged 4–8 years participated. Each group listened to a story about The Rhinovirus Rita. No pictures were shown during storytelling. After the story was told, a play was performed with the children, telling the same story they just had listened to, and the children also made drawings. At a second visit to the schools, each child was interviewed individually and their drawings were used to stimulate recall. The results show that many of the children had learnt the names of immune system cells and how they work when someone has a cold. Moreover, they had also learnt that viruses cause colds. There were also a small number of children who did not show any learning development related to this specific content. Still, we argue that the combination of storytelling and drama is an instructional strategy that has positive potential when it comes to teaching children science.

  • 614.
    Walan, Susanne
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Gericke, Niklas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Barnens universitet - Intresseskapande STEM-aktivitet?2016Conference paper (Refereed)
  • 615.
    Walan, Susanne
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Gericke, Niklas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Factors from informal learning contributing to the children’s interest in STEM – experiences from the out-of-schoolactivity called Children’s University2019In: Research in Science & Technological Education, ISSN 0263-5143, E-ISSN 1470-1138, p. 1-21, article id doi.org/10.1080/02635143.2019.1667321Article in journal (Refereed)
    Abstract [en]

    Background: Previous studies have investigated effects of out-ofschoolSTEM activities aimed at stimulating children’s interest inscience with positive results. However, research has not discussedthe reasons why such activities are successful.

    Purpose: In this study, we address this gap by investigating whichfactors children themselves identified as interesting when they visitedevents at an out-of-school activity named The Children’s University.

    Sample: Children aged 8–12 participated in the study. Altogether,there were 353 children involved in the data collection.

    Design and methods: A mixed method design was used, includinga questionnaire and semi-structured interviews inwhich children’s selfreportedexperiences were collected. Likert scale questions in thequestionnairewere analysed based on descriptive statistics. The openendedquestions and data from the interviews were categorized bycontent analysis and analytically interpreted through ‘the Ecologicalframework for understanding learning across places and pursuits’.

    Results: The children were positive about their visit, and these utterancescould mainly be related to the development of the individuals’interest and knowledge according to the Ecological framework. Weidentified two new factors influencing student’s interest in STEM inout-of-school activities: appreciating the spectacular and learning;verifying two factors of importance previously suggested in the literature:appreciating the content and the learning environment.

    Conclusions: The study highlights the specific factors the childrenactually appreciated from their visits to out-of-school activities,which could be of interest for stakeholders arranging differentkinds of STEM events promoting informal learning. The contentin the activities is important as well as spectacular features. Tohave the opportunity to learn something new in an environmentthat is conducive to learning is also of importance for children.

  • 616.
    Walan, Susanne
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Gericke, Niklas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Factors from informal learning contributing to the children's interest in STEM: experiences from the out-of-school activity called Children's University2019In: Research in Science & Technological Education, ISSN 0263-5143, E-ISSN 1470-1138, p. 1-21Article in journal (Refereed)
    Abstract [en]

    Background: Previous studies have investigated effects of out-of-school STEM activities aimed at stimulating children's interest in science with positive results. However, research has not discussed the reasons why such activities are successful. Purpose: In this study, we address this gap by investigating which factors children themselves identified as interesting when they visited events at an out-of-school activity named The Children's University. Sample: Children aged 8-12 participated in the study. Altogether, there were 353 children involved in the data collection. Design and methods: A mixed method design was used, including a questionnaire and semi-structured interviews in which children's self-reported experiences were collected. Likert scale questions in the questionnaire were analysed based on descriptive statistics. The open-ended questions and data from the interviews were categorized by content analysis and analytically interpreted through 'the Ecological framework for understanding learning across places and pursuits'. Results: The children were positive about their visit, and these utterances could mainly be related to the development of the individuals' interest and knowledge according to the Ecological framework. We identified two new factors influencing student's interest in STEM in out-of-school activities: appreciating the spectacular and learning; verifying two factors of importance previously suggested in the literature: appreciating the content and the learning environment. Conclusions: The study highlights the specific factors the children actually appreciated from their visits to out-of-school activities, which could be of interest for stakeholders arranging different kinds of STEM events promoting informal learning. The content in the activities is important as well as spectacular features. To have the opportunity to learn something new in an environment that is conducive to learning is also of importance for children.

  • 617.
    Walan, Susanne
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Jeannie, Flognman
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Kilbrink, Nina
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Department of Educational Studies (from 2013).
    Building with focus on stability and construction: Using a story as inspiration when teaching technology and design in preschool2019In: Education 3-13, ISSN 0300-4279, E-ISSN 1475-7575Article in journal (Refereed)
    Abstract [en]

    In this study children's learning of the concept, stability, during some building activities were investigated. It was also examined how a story can create meaning, having the children build for some animals in the story. Two preschool teachers and 10 children participated. Data consisted of video-recordings from activities with the children and was analysed through thematic coding. The findings showed that the children enjoyed to build and showed an understanding of how to build stable constructions, however without using the word stable. There were connections to the story and new stories were also made by the children during building activities.

  • 618.
    Walan, Susanne
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Mc Ewen, Birgitta
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Health Sciences (from 2013).
    Students' reflections on participation in a science and technology school competition2018In: Electronic Proceedings of the ESERA 2017 Conference: Research, Practice and Collaboration in Science Education / [ed] Odilla Finlayson, Eilish McLoughlin, Sibel Erduran, Peter Childs, Dublin, Ireland, 2018, Vol. Part 2, p. 273-282Conference paper (Refereed)
    Abstract [en]

    Different kinds of efforts have been made in many countries to stimulate students' interest in science and technology, for example through school competitions. Few studies, however,have investigated the effect of school competitions in science and technology. This study centres onhow students participatingin the science and technology school competition The Technology Eightexperienced the outcomesof taking part inthe competition. Semi-structured interviews were conducted with seventeen 15-year-old students. Transcripts of the interviews were analysed based on contentand resulted in four categories: Social effects, Attitude to competitions, Stimulated interest in science and technology and Gained knowledge. The students enjoyed participating in the competition and found that it had a positive effect on the social situationin the classroom. Competitions were also appreciated and seen to encourage students to work harder. However, the competition didnot have much effect in changing interest in science and technology. Finally, the students found it difficult to express how the competition had contributed to gainingmore content knowledge in the subjects, but they emphasised the practical aspects of learning.

  • 619.
    Walan, Susanne
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Mc Ewen, Birgitta
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Health Sciences (from 2013).
    Teachers’ and principals’ reflections on student participation in a school science and technology competition2018In: Research in Science & Technological Education, ISSN 0263-5143, E-ISSN 1470-1138, Vol. 36, no 4, p. 391-412Article in journal (Refereed)
    Abstract [en]

    Background: The European Union asks for renewed pedagogies in schools according to teaching strategies and necessary competences for the twenty-first century, instead of the often-used transmissive pedagogies. The national Swedish competition in science and technology for grade eight, The Technology Eight, provides an opportunity for teachers to work with instructional strategies in line with suggested pedagogies.

    Purpose: To investigate teachers’ and principals’ reflections on the competition in schools.

  • 620.
    Walan, Susanne
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Nilsson, Pernilla
    Halmstad University.
    Mc Ewen, Birgitta
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Health Sciences (from 2013).
    Why Inquiry?: Primary Teachers' Objectives in Choosing Inquiry- and Context-Based Instructional Strategies to Stimulate Students' Science Learning2017In: Research in science education, ISSN 0157-244X, E-ISSN 1573-1898, Vol. 47, no 5, p. 1055-1074Article in journal (Refereed)
    Abstract [en]

    Studies have shown that there is a need for pedagogical content knowledge among science teachers. This study investigates two primary teachers and their objectives in choosing inquiry- and context-based instructional strategies as well as the relation between the choice of instructional strategies and the teachers' knowledge about of students' understanding and intended learning outcomes. Content representations created by the teachers and students' experiences of the enacted teaching served as foundations for the teachers' reflections during interviews. Data from the interviews were analyzed in terms of the intended, enacted, and experienced purposes of the teaching and, finally, as the relation between intended, enacted, and experienced purposes. Students' experiences of the teaching were captured through a questionnaire, which was analyzed inductively, using content analysis. The results show that the teachers' intended teaching objectives were that students would learn about water. During the enacted teaching, it seemed as if the inquiry process was in focus and this was also how many of the students experienced the objectives of the activities. There was a gap between the intended and experienced objectives. Hardly any relation was found between the teachers' choice of instructional strategies and their knowledge about students' understanding, with the exception that the teacher who also added drama wanted to support her students' understanding of the states of water.

  • 621.
    Washington, Haydn
    et al.
    Kensington Campus, Australia.
    Chapron, Guillaume
    Swedish University of Agricultural Sciences, Sweden.
    Kopnina, Helen
    International Business Management Studies, the Netherlands.
    Curry, Patrick
    The Ecological Citizen, United Kingdom.
    Gray, Joe
    University of London, United Kingdom.
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Foregrounding ecojustice in conservation2018In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 228, p. 367-374Article in journal (Refereed)
    Abstract [en]

    Justice for nature remains a confused term. In recent decades justice has predominantly been limited to humanity, with a strong focus on social justice, and its spin-off – environmental justice for people. We first examine the formal rationale for ecocentrism and ecological ethics, as this underpins attitudes towards justice for nature, and show how justice for nature has been affected by concerns about dualisms and by strong anthropocentric bias. We next consider the traditional meaning of social justice, alongside the recent move by some scholars to push justice for nature into social justice, effectively weakening any move to place ecojustice centre-stage. This, we argue, is both unethical and doomed to failure as a strategy to protect life on Earth. The dominant meaning of ‘environmental justice’ – in essence, justice for humans in regard to environmental issues – is also explored. We next discuss what ecological justice (ecojustice) is, and how academia has ignored it for many decades. The charge of ecojustice being ‘antihuman’ is refuted. We argue that distributive justice can also apply to nature, including an ethic of bio-proportionality, and also consider how to reconcile social justice and ecojustice, arguing that ecojustice must now be foregrounded to ensure effective conservation. After suggesting a ‘Framework for implementing ecojustice’ for conservation practitioners, we conclude by urging academia to foreground ecojustice. © 2018

  • 622.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. Hokkaido University, Japan.
    Brown trout in ice-covered streams: effects of surface ice on anti-predator behavior and habitat use2018Conference paper (Refereed)
  • 623.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Brown trout responses to ice cover2013Conference paper (Other academic)
  • 624.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Degerman, Erik
    Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Orebro, Sweden.
    Tamario, Carl
    Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, € Orebro, Sweden.
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers2019In: Animal Conservation, ISSN 1367-9430, E-ISSN 1469-1795, Vol. 22, no 5, p. 452-462Article in journal (Refereed)
    Abstract [en]

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

  • 625.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Overwintering behaviour of stocked brown trout: effects of the rearing environment and river habitat complexity2017In: 50th Anniversary Symposium of the Fisheries Society of the British Isles, Exeter, UK, 3-7 July, 2017, 2017Conference paper (Refereed)
    Abstract [en]

    In channelized and structurally simple temperature streams and rivers, adverse winter conditions may challenge the ability of riverine fishes to adapt in terms of their behaviour and physiology. Access to shelter is a key habitat factor that may influence overwinter survival chances and, consequently, population dynamics. In many river restoration projects, structural elements are added to the river to increase the complexity of the physical environment. When this habitat enhancement is combined with a stocking programme, the stocked fish mayadopt different behavioural strategies to cope with the winter season depending both onthe rearing environment in the hatchery and the level of habitat complexity in the river. In this study, young-of-the-year brown trout were reared in either barren or structurally enhanced tanks, and the effects of the rearing environment on resting ventilation rate (proxy for resting metabolic rate) and score in an open field test (proxy for activity) were assessed. In side channels of a Swedish regulatedriver, trout were then released at untreated control sites or at sites that were structurally enhanced by adding whole trees to the water. Throughout winter, trout were tracked on a weekly basis, and their movements as influenced by the river habitat complexity and the previous hatchery environment were analysed. The rearing environment affected resting metabolicrates and activity, which resulted in different behavioural overwintering strategies, and adding trees to the side channels increased apparent survival. These results have implications for managing river restoration projects and further studies of stream fish winter ecology.

  • 626.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Salmonid behaviour under winter conditions2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Winter conditions are believed to play an important role in the population dynamics of northern temperate stream fish, challenging the ability of fish to physiologically and behaviourally adapt. Climate change is predicted to increase both mean temperature and temperature fluctuations, especially during winter, leading to dynamic environmental conditions in terms of river ice production and flow. Therefore, knowledge about the winter ecology of stream fish is important for predicting and mitigating anthropogenic impacts on fish production in boreal streams. Stream salmonids are relatively active throughout winter, and behavioural responses to different winter conditions may be critical for survival. Yet, relatively little is known about overwintering behaviour of salmonids, particularly in streams with ice. In this doctoral thesis, I report the results from experimental field and laboratory studies on the behavioural ecology of juvenile salmonids under winter conditions. My results from the field show that salmonids grow more and use a broader range of habitats in the presence of surface ice than in its absence. Results from the laboratory experiments show that the presence of surface ice increases food intake rates, reduces stress and affects social interactions. These laboratory results may explain the positive effects of ice cover on growth that was found in the field experiment. Moreover, I show that drift-feeding ability is reduced at low temperatures, and that nocturnal drift foraging under winter conditions has a low efficiency.

  • 627.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Stress responses of juvenile brown trout under winter conditions in a laboratory stream2017In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 802, no 1, p. 131-140Article in journal (Refereed)
    Abstract [en]

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

  • 628.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Structural complexity in the hatchery rearing environment affects activity, resting metabolic rate and post‐release behaviour in brown trout Salmo trutta2019In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 95, no 2, p. 638-641Article in journal (Refereed)
    Abstract [en]

    The effects of structural enrichment in the hatchery rearing environment of brown trout Salmo trutta was linked to post‐release performance. Enrichment resulted in reduced swimming activity scored in an open field test and reduced movement in a natural river after release. Also, enrichment increased resting metabolic rates, which correlated positively with overwinter growth.

  • 629.
    Watz, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Winter behaviour of stream salmonids: effects of temperature, light, and ice cover2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In boreal streams, stream salmonids typically face low water temperatures and variable ice conditions during winter, and thus stream salmonids are expected to use different behavioural strategies to cope with these environmental conditions. The studies presented in this thesis explore how temperature, light intensity, and surface ice affect salmonid behaviour, with focus on drift-feeding and ventilation rates. The first paper reports results from a laboratory study designed to measure prey capture probabilities and reaction distances of drift-feeding Atlantic salmon, brown trout, and European grayling at light intensities simulating daylight and moonlight at seven temperatures ranging from 2 to 11°C. There was a positive relationship between water temperature and prey capture probability for all three species at both light levels, but the temperature-dependence did not scale according to the Metabolic Theory of Ecology. Reaction distance was also positively related to temperature for the three species, which may explain the temperature effects on prey capture probability. The results from this study should be of interest for those working with energetic-based drift-foraging models. In the second paper, the effects of ice cover on the diel behaviour and ventilation rate of brown trout were studied in a laboratory stream. Ice cover is believed to afford protection against endothermic predators, and thus the need for vigilance should be reduced under ice cover. This hypothesis was tested by observing ventilation rates at night, dawn, and during the day in the presence and absence of real, light-permeable surface ice. Further, trout were offered drifting prey during the day to test if ice cover increased daytime foraging activity. Ice cover reduced ventilation rates at dawn and during the day, but not at night. Moreover, trout made more daytime foraging attempts in the presence of ice cover than in its absence. These results suggest that ice cover affects the behaviour of brown trout and presumably has a positive effect on winter survival. Global warming, by reducing the extent or duration of surface ice, may therefore have negative consequences for many lotic fish populations in boreal streams.

  • 630.
    Watz, Johan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Enefalk, Åsa
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Gustafsson, Stina
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Hagelin, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Nilsson, P. Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Norrgård, Johnny
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Fortum generation.
    Nyqvist, Daniel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Piccolo, John J.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Schneider, Lea Dominique
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Greenberg, Larry
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Jonsson, Bror
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Norsk institutt for naturforskning, Oslo.
    Ice cover alters the behavior and stress level of brown trout Salmo trutta2015In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 26, no 3, p. 820-827Article in journal (Refereed)
    Abstract [en]

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

  • 631.
    Watz, Johan
    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.
    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.
    Effects of ice cover on the diel behaviour and ventilation rate of juvenile brown trout2013In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 58, no 11, p. 2325-2332Article in journal (Refereed)
    Abstract [en]
    1. Winter ice conditions in boreal streams are highly variable, and behavioural responses by fish to river ice may affect overwinter survival rates. One type of ice, surface ice, stabilises water temperatures, reduces instream light levels and may provide overhead cover.
    2. Because surface ice is believed to afford protection against endothermic predators, we predicted that metabolic costs associated with vigilance would be lower under surface ice than in areas lacking surface ice. This potentially favourable effect of ice cover was tested by observing ventilation rates of juvenile brown trout (Salmo trutta) in a laboratory stream at dawn, during the day and at night in the presence and absence of real, light-permeable surface ice. Further, we offered trout drifting prey during daylight to test whether ice cover increased daytime foraging activity.
    3. Ice cover reduced ventilation rates during the day, but not at night or dawn. Moreover, fish made more daytime foraging attempts in the presence of ice cover than in its absence.
    4. We suggest that the most plausible explanation for these results is that fish experience a reduced perceived predation risk under surface ice.
  • 632.
    Watz, Johan
    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.
    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.
    Ice cover affects the growth of a stream-dwelling fish2016In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 181, no 1, p. 299-311Article in journal (Refereed)
    Abstract [en]

    Protection provided by shelter is important for survival and affects the time and energy budgets of animals. It has been suggested that in fresh waters at high latitudes and altitudes, surface ice during winter functions as overhead cover for fish, reducing the predation risk from terrestrial piscivores. We simulated ice cover by suspending plastic sheeting over five 30-m-long stream sections in a boreal forest stream and examined its effects on the growth and habitat use of brown trout (Salmo trutta) during winter. Trout that spent the winter under the artificial ice cover grew more than those in the control (uncovered) sections. Moreover, tracking of trout tagged with passive integrated transponders showed that in the absence of the artificial ice cover, habitat use during the day was restricted to the stream edges, often under undercut banks, whereas under the simulated ice cover condition, trout used the entire width of the stream. These results indicate that the presence of surface ice cover may improve the energetic status and broaden habitat use of stream fish during winter. It is therefore likely that reductions in the duration and extent of ice cover due to climate change will alter time and energy budgets, with potentially negative effects on fish production.

  • 633.
    Watz, Johan
    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.
    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.
    Prey capture rates of two species of salmonids (Salmo trutta and Thymallus thymallus) in an artificial stream: effects of temperature on their functional response2014In: Marine and Freshwater Behaviour & Physiology, ISSN 1023-6244, E-ISSN 1029-0362, Vol. 47, no 2, p. 93-99Article in journal (Refereed)
    Abstract [en]

    The foraging success of predators depends on how their consumption of prey is affected by prey density under different environmental settings. Here, we measured prey capture rates of drift-feeding juvenile brown trout and European grayling at different prey densities in an artificial stream channel at 5 and 11 °C. Capture rates were lower at 5 than at 11 °C, and the difference was most pronounced at high prey densities. At high prey densities, we also observed that European grayling had higher capture rates than brown trout. Type III functional response curves, i.e. sigmoidal relationships between capture rates and prey densities, fitted the data better than type I (linear) and II (hyperbolic) curves for all four combinations of temperatures and species. These results may explain the dominance of grayling in stream habitats with low water velocities and results such as these may be of use when developing foraging-based food web models of lotic ecosystems that include drift-feeding salmonids.

  • 634.
    Watz, Johan
    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.
    Piccolo, John J.
    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.
    Winter Behavior of Brown Trout: The Presence of Ice Cover Influences Activity, Stress and Growth2015Conference paper (Refereed)
    Abstract [en]

    Predation on fish by mammals and birds may be high during winter in boreal streams, and juvenile salmonids respond by reducing their daytime activity to minimize exposure. Surface ice may offer protection from terrestrial predators, and salmonids under ice cover should spend less time on anti-predator behaviors and increase their activity. Using brown trout as a test species, these predictions were tested in laboratory and field experiments.

    In an artificial laboratory stream, the presence of ice cover reduced stress and increased swimming activity, foraging and aggression. The effect of ice cover on activity was greatest for trout with high resting metabolic rates, suggesting that individual intraspecific differences in metabolism may influence the strategies used to cope with different winter conditions. In a boreal forest stream, we simulated ice by suspending plastic sheeting over five 30-m-long stretches, and trout that spent winter under this simulated ice cover grew better than trout in control stretches. These results may explain why salmonid production is high in rivers with long periods of stable ice cover and should be viewed in light of ongoing global warming.

  • 635.
    Watz, Johan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan.
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Carlsson, Niclas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Teemu, Collin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Huusko, Ari
    Natural Resources Institute Finland (Luke), Kainuu Fisheries Research Station, Paltamo, Finland.
    Jörgen, Johnsson
    Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Lund University.
    Norrgård, Johnny
    Gammelkroppa Lax, Filipstad.
    Nyqvist, Daniel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Institute of Marine Research in Norway, Bergen, Norway.
    Wood addition in the hatchery and river environments affectspost-releaseperformance of overwintering brown trout2018In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 64, no 1, p. 71-80Article in journal (Refereed)
    Abstract [en]

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

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

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

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

  • 636.
    Watz, Johan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Elghagen, Jonas
    Elghagen Fiskevård.
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Department of Biology - Aquatic Ecology, Lund University.
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Evaluation of a novel mobile floating trap for collecting migrating juvenile eels, Anguilla anguilla, in rivers2017In: Fisheries Management and Ecology, ISSN 0969-997X, E-ISSN 1365-2400, Vol. 24, no 6, p. 512-514Article in journal (Refereed)
    Abstract [en]

    To improve the situation for the threatened European eel in regulated rivers, better methods need to be developed that more efficiently collect and transport juvenile eels past dams. In this study, a novel mobile, floating eel trap is described, and the results from an evaluation of the trap in two Swedish regulated rivers are presented. The mobile trap was designed to reduce the length of the climbing distance while maximizing the width of the entrance. The mobile trap caught more juvenile eels than a stationary eel ladder, serving as control. Furthermore, the mobility of the floating trap enables adaptive placement and thus offers managers the possibility to search for the spatial optimum for trapping efficiency.

  • 637.
    Watz, Johan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Lund University.
    Degerman, Erik
    Swedish University of Agricultural Sciences.
    Tamario, Carl
    Swedish University of Agricultural Sciences.
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Enhancing upstream passage solutions for juvenile eels: Effects of climbing substrate and ramp placement2018Conference paper (Refereed)
    Abstract [en]

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

  • 638.
    Watz, Johan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan.
    Otsuki, Y.
    Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan.
    Nagatsuka, K.
    Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan.
    Hasegawa, K.
    Hokkaido National Fisheries Research Institute, Japan Fisheries Research and Education Agency, Sapporo, Japan.
    Koizumi, I.
    Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan.
    Temperature-dependent competition between juvenile salmonids in small streams2019In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, p. 1534-1541Article in journal (Refereed)
    Abstract [en]

    Biotic interactions affect species distributions, and environmental factors that influence these interactions can play a key role when range shifts in response to environmental change are modelled. In a field experiment using enclosures, we studied the effects of the thermal habitat on intra- versus inter-specific competition of juvenile Dolly Varden Salvelinus malma and white-spotted charr Salvelinus leucomaenis, as measured by differences in specific growth rates during summer in allopatric and sympatric treatments. Previous laboratory experiments have shown mixed results regarding the importance of temperature-dependent competitive abilities as a main driver for spatial segregation in stream fishes, and no study so far has confirmed its existence in natural streams. Under natural conditions in areas where the two species occur in sympatry, Dolly Varden dominate spring-fed tributaries (cold, stable thermal regime), whereas both species often coexist in non-spring-fed tributaries (warm, unstable thermal regime). Enclosures (charr density = 6 per m2) were placed in non-spring-fed (10–14°C) and spring-fed (7–8°C) tributaries. In enclosures placed in non-spring-fed tributaries, Dolly Varden grew 0.81% per day in allopatry and had negative growth (−0.33% per day) in sympatry, whereas growth rates were similar in allopatry and sympatry in spring-fed tributaries (0.68 and 0.58% per day). White-spotted charr grew better in sympatry than in allopatry in both thermal habitats. In non-spring-fed tributaries, they grew 0.17 and 0.79% per day and in spring-fed tributaries 0.46 and 0.75% per day in allopatry and sympatry, respectively. The negative effect of inter-specific competition from white-spotted charr on Dolly Varden thus depended on the thermal habitat. However, there was no strong evidence of a temperature-dependent effect of intra- and inter-specific competition on white-spotted charr growth. Multiple factors may shape species distribution patterns, and we show that temperature may mediate competitive outcomes and thus coexistence in stream fish. These effects of temperature will be important to incorporate into mechanistic and dynamic species distribution models.

  • 639.
    Watz, Johan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Piccolo, John J.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Greenberg, Larry
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Bergman, Eva
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Temperature-dependent prey capture efficiency and foraging modes of brown trout Salmo trutta2012In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 81, no 1, p. 345-350Article in journal (Refereed)
    Abstract [en]

    Prey capture success and foraging mode were studied in brown trout Salmo trutta at temperatures ranging from 5·7 to 14·0° C. At low temperatures, there was a positive correlation between prey capture success and the proportion of time that the fish spent holding feeding stations. This correlation was not found at temperatures >10° C.

  • 640.
    Wengström, Niklas
    et al.
    Göteborgs universitet. Swedish Anglers Assoc, Gothenburg, Sweden.
    Wahlqvist, Fredrik
    Göteborgs universitet.
    Näslund, Joacim
    Göteborgs universitet.
    Aldvén, David
    Göteborgs universitet.
    Závorka, Libor
    Göteborgs universitet. Univ Toulouse 3, CNRS, UMR EDB Toulouse 5174, Midi Pyrenees, France..
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Höjesjö, Johan
    Göteborgs universitet.
    Do individual activity patterns of brown trout (Salmo trutta) alter the exposure to parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae?2016In: Ethology, ISSN 0179-1613, E-ISSN 1439-0310, Vol. 122, no 9, p. 769-778Article in journal (Refereed)
    Abstract [en]

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

  • 641.
    Wik, Malin
    et al.
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Karlstad Business School (from 2013).
    Nyberg, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Centre for Climate and Safety (from 2013). Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Karlstad Univ, Ctr Climate & Safety, SE-65188 Karlstad, Sweden.;Karlstad Univ, CNDS, SE-65188 Karlstad, Sweden..
    Magnusson, Monika
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Karlstad Business School (from 2013). Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Behov av datorbaserade metoder och verktyg för krisövning: Intervjustudie i Inre Skandinavien2017Report (Refereed)
    Abstract [sv]

    Inom ramen för projektet CriseIT (www.criseit.org) har en intervjustudie genomförts med norska och svenska krisberedskapsaktörer. 19 respondenter från totalt 16 aktörer intervjuades om deras syn på behovet av krisövning, vad som fungerar bra och dåligt med de övningsmetoder som vanligtvis används, och vilken nytta de kunde se med datorbaserade övningsverktyg. Svaren visar på ett stort behov av att öva mer, gärna i form av mindre och kortare övningar. Det finns en rörelse bort från scenariobaserade övningar till övningar där olika förmågor står i centrum. Flertalet aktörer anser att de planerar och genomför övningar med gott resultat men att det saknas en systematik i hur utvärderingar leds vidare i ett förbättringsarbete. Det finns intresse men också tveksamhet inför att involvera allmänheten i krisövning, men ett sätt att hantera bland annat säkerhetsaspekter vore att gå via frivilligorganisationer som kan bistå med organisering och viss utbildning.

    Respondenterna visar stort intresse för datorbaserade övningsverktyg som ett medel för att öka krismedvetenheten och kunskapen som stödjer den egna rollen. De kan också se potentiella problem, t ex att vissa personer har svårt att ta till sig ny teknik och att det kan finnas risk att resurser till andra övningsformer minskas. Bland de fördelar som nämndes var möjlighet att öva oftare, med fler aktörer, och att öva på olika platser vid olika tidpunkter. Man ser också förbättrade möjligheter att öva utdragna kriser. Den målgrupp som lyfts fram som särskild intressant fördatorbaserade övningsverktyg är krisledningsorganisationen, dvs. den strategiskan ivån. Flera nämner också behovet av bättre planeringsstöd för säkerhets-/beredskapssamordnarna.

    En slutsats vi dragit är att det är viktigt att digitala krisövningsverktyg är webbaserade och bygger på standarder. Detta för att möjliggöra att verktygen kan användas distribuerat, i samarbete mellan olika organisationer och inte kräver lokala installationer i de olika hårt styrda IT-miljöerna. Det bör också vara verktyg som fungerar på såväl smartphone som surfplatta och PC. I stort bör de system som används under verkliga kriser användas även under övning.

  • 642.
    Winser, Helena
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Host - parasite interactions:: the relationship between encystment load of the freshwater pearl mussel (Margaritifera margaritifera) and genetic diversity of its host (Salmo trutta)2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The freshwater pearl mussel (FPM, Margaritifera margaritifera) is an endangered bivalve mollusc with an obligatory larval parasitic phase on brown trout (Salmo trutta). The FPM has declined throughout its entire range due to causes such as habitat degradation, eutrophication, acidification, changed hydrology and lack of host fish. This study aimed to investigate if heterozygosity, allelic richness, number of alleles, inbreeding and differentiation of brown trout (Salmo trutta) are related to the encystment load of glochidia larvae of the FPM. The results showed that the observed heterozygosity was negatively related to encystment load. This may be a result of the fact that high heterozygosity is generally associated with a strong immune system that wards off parasities. High heterozygosity may also be an advantage for the host, because it results in a larger potential for selection against the parasite in the host-parasite arms race. There was also a positive relationship between the inbreeding coefficient and glochidia encystment. This makes sense since high inbreeding is negatively related to heterozygosity. High inbreeding of trout should thus reduce the ability of inbred trout populations to ward off parasites. The results may have implications for conservation management. Introductions of foreign trout strains that alter the genetic interactions between the host fish and the parasitic mussel should be managed. Small and fragmented trout mussel populations, with typically high inbreeding coefficients, may have a relatively high probability to reproduce and survive and it may therefore be worthwhile to protect these trout populations. However, inbred trout populations should be managed with care, since inbreeding increases the risk of extinction of the trout. If a trout population is extinct, their sympatric mussel population may thus face extinction as well. 

  • 643.
    Zetterlund, Sofie
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Potential för återintroduktion av lax (Salmo salar L.) i Bollnäsströmmarna: en sårbarhetsanalys2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Conservation of salmon is a complicated task that requires understanding both the biology of salmon and the anthropogenic impacts affecting it. Atlantic salmon is dependent on its migration to optimize growth, survival and reproduction. Hydropower plants affect salmon by causing highly irregular flows, reduced discharge and barriers along migration routes. The salmon stocks of the Baltic Sea declined considerably between the 1950s and 1980s as a result of dam development and overfishing. For the same reasons the local salmon stock in the River Ljusnan, Sweden began to decline already in the early 1900s, and today there are no salmon left in the River Ljusnan. To restore the population, actions to mediate migration and access to reproduction habitats and rearing habitats are needed. The 6.6 km long river section, “Bollnäsströmmarna”, is estimated to have accounted for 25 % of the total salmon production in the River Ljusnan. The aim of this study was to simulate a reintroduction of Atlantic salmon in Bollnäsströmmarna, and using a population viability analysis (PVA), investigate if stocking of eggs can result in a viable salmon population. Simulations were made on the basis of today’s conditions, with the condition that best practice passage solutions are implemented. In addition, the effects of increased passage mortality, habitat restoration and increased supplementary stocking of eggs were simulated. A total of nine PVA simulation (n= 100) scenarios were performed in the Vortex simulation program. The results of the study show that stocking of eggs can produce a salmon population that has a minimum extinction risk over a one-hundred year period. However, after an initial population increase over ten years, population growth steadily declines for the remaining ninety years, which most likely would result in extinction if a period longer than 100 years was considered. The salmon population was very sensitive to an increase in passage mortality, with a high extinction risk after only a small increase in mortality. Both habitat restoration and increased supplementary stocking impacted the population size positively, but no scenario produced a stable and viable population, which indicates that more measures are required for a successful long-term reintroduction.

  • 644.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Sedimentation affects emergence rate of host fish fry in unionoid mussel streams2019In: Animal Conservation, ISSN 1367-9430, E-ISSN 1469-1795, Vol. 22, no 5, p. 444-451Article in journal (Refereed)
    Abstract [en]

    Free-living, sympatric sedentary life stages of hosts and parasites are often adapted to similar environmental conditions. When the environment where these life stages occur is disturbed, both species can decline, causing strong negative effects on the parasitic species. For the highly threatened unionoid mussels with their larval parasitic life stage on fish, habitat degradation may simultaneously affect the conditions for the sedentary host fish eggs and the juvenile mussels in the sediment. This study provides novel information on the effect of sedimentation on the emergence rate of yolk sac fry, and its relation to mussel recruitment in two drainage basins, and is exemplified by the brown trout Salmo trutta, host fish for the threatened freshwater pearl mussel Margaritifera margaritifera. The results imply that turbidity and sedimentation can reduce the survival of trout eggs and yolk sac fry emergence rate regardless of trout strain and drainage basin. The results further suggest that low yolk sac fry emergence rates reduce the potential for mussel infestation and recruitment. The results indicate a year round negative effect of sedimentation, having strong and combined direct and indirect effects on juvenile mussel recruitment. Conservation measures that reduce anthropogenic sediment transportation into streams are a key factor for the conservation of mussels and their host fish. 

  • 645.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    The impact of some major anthropogenic treats to the freshwater pearl mussel: life cycle studies and different scales.2013Conference paper (Refereed)
  • 646.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Timing, growth and proportion of spawners of the threatened unionoid mussel Margaritifera margaritifera: Influence of water temperature, turbidity and mussel density2015In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 77, no 1, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Anthropogenic disturbances often cause decline and extinction of threatened species. The present study investigated how gravid freshwater mussels, Margaritifera margaritifera, were affected by turbidity and water temperature, and by mussel density. At an early date of mussel spawning, there were lower proportions of gravid mussels in streams with evidence of mussel recruitment than in streams without mussel recruitment. At a late spawning date, this pattern was reversed. Higher water temperature in streams without recruitment was probably responsible for this difference. The combination of high water temperature and turbidity may be one reason for reduced growth of gravid mussels in streams without recruitment. There was a positive relationship between adult mussel density and the proportions of gravid mussels. Early gravidity may lead to early release of larvae, early infestation on the host fish and an earlier start of the benthic phase, which may reduce survival rates. Clear-cutting of forests and global warming are factors that are likely to cause increased turbidity/sedimentation and water temperatures in streams. One restoration measure that reduces sediment input and water temperatures is maintaining or restoring riparian zones, but these are long-term measures that require many years before they have an effect in streams.

  • 647.
    Österling, Martin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Ferm, Julia
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Piccolo, John J.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Parasitic freshwater pearl mussel larvae (Margaritifera margaritifera L.) reduce the drift-feeding rate of juvenile brown trout (Salmo trutta L.)2014In: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 97, p. 543-549Article in journal (Refereed)
    Abstract [en]

    In this paper we describe, for the first time, the effects of freshwater pearl mussel (Margaritifera margaritifera L.) encystment on the drift-feeding behavior of juvenile brown trout (Salmo trutta L.). Because both mussel and salmonid populations are often threatened, this study not only adds knowledge to the understanding of host-parasite systems, but it is also of conservation value. Individual trout, mussel-encysted (25.1 ± 5.7 larvae · g-1 body weight, n = 5) or non-encysted (n = 5), were fed with chironomid larvae in a flow-through stream aquarium. Feeding trials were filmed and analyzed by counting the numbers of chironomid larvae each individual ate, and by estimating the prey-capture distance. Non-encysted trout had a significantly higher drift-foraging rate than did encysted trout, and they captured significantly more prey further away from their focal point. Thereduced foraging success of encysted trout was mainly due to their failure to catch prey relatively further from their focal point. This suggests that reduced foraging success of encysted trout may be due to poorer energetic status, butthe physical effects of mussel larvae on prey handling time cannot be ruled out. Encysted trout caught approximately 20% fewer prey, which would result in a reduction in growth potential during the period of mussel encystment. Reduced energetic status might also result in reduced competitive ability or in increased exposure to predation risk.

  • 648.
    Österling, Martin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Högberg, Jan-Olov
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    The impact of land use on the mussel Margaritifera margaritifera and its host fish Salmo trutta2014In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 735, p. 213-220Article in journal (Refereed)
    Abstract [en]

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

  • 649.
    Österling, Martin
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Soderberg, Hakan
    Cty Adm Board Vasternorrland, S-87186 Harnosand, Sweden..
    Sea-trout habitat fragmentation affects threatened freshwater pearl mussel2015In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 186, p. 197-203Article in journal (Refereed)
    Abstract [en]

    Habitat fragmentation is a major reason for the decline and extinction of migratory species. Many host populations for parasites are partly migratory, consisting of both migratory and resident individuals, and we asked the question whether these two subpopulations differ in parasite susceptibility. If so, barriers intercepting migration may change the parasite encystment rate and recruitment. We used the River Ljungan, Sweden, as study system, where eight hydroelectric power plants hinder access of sea-migrating trout to most tributaries. We compared the encystment of the threatened freshwater pearl mussel (Margaritifera margaritifera) larvae on sympatric tributary-resident brown trout and sea-migrating trout (Salmo trutta) as hosts for their parasitic larvae. We also compared eighteen tributary-resident brown trout populations with the sea-migrating trout as hosts for mussel larvae. Encystment decreased faster over time on the tributary-resident trout than on the sea-migrating trout. Encystment was therefore higher on the sea-migrating trout compared to the tributary-resident trout at the time of excystment of the larvae. Growth of encysted mussel larvae was higher on the sea-migrating trout than on the tributary-resident trout. The natural density of the tributary-resident trout populations was lower than that of the sea-migrating trout in the autumn, when the mussels infest the fish, and in early summer, just before the excystment of juvenile mussels from the fish. Estimations of total numbers of encysted mussel larvae per unit stream area were higher on the sea-migrating trout than the tributary-resident trout in the autumn and in the spring at the time of juvenile mussel excystment. The higher mussel larval growth and the higher encystment on the sea-migrating trout imply that even seemingly healthy tributary mussel populations are reduced because of the habitat fragmentation. As sea-migrating trout are threatened or extinct in many rivers, fragmentation may be a large-scale problem, not only for sea-migrating populations, but also indirectly for highly threatened mussel populations. Restoration activities should primarily focus on creating free pathways for original host fish populations instead of sustaining them by supplementary stocking. (C) 2015 Elsevier Ltd. All rights reserved.

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