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  • 1. Affonso, Igor de Paiva
    et al.
    Karling, Leticia Cucolo
    Takemoto, Ricardo Massato
    Gomes, Luiz Carlos
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Light-induced eye-fluke behavior enhances parasite life cycle2017In: Frontiers in Ecology and the Environment, ISSN 1540-9295, E-ISSN 1540-9309, Vol. 15, no 6, p. 340-341Article in journal (Refereed)
  • 2.
    Bengtson, Johanna
    Karlstad University, Faculty of Social and Life Sciences.
    The relationship between behaviour and metabolic rate of juvenile Brown trout Salmo trutta2009Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

     

  • 3.
    Bergman, Eva
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Ecology of Atlantic Salmon and Brown Trout - Habitat as a Template for Life Histories2012In: Fish and Fisheries, ISSN 1467-2960, E-ISSN 1467-2979, Vol. 13, no 3, p. 360-360Article, book review (Other academic)
  • 4. Cafaro, Philip
    et al.
    Butler, Tom
    Crist, Eileen
    Cryer, Paul
    Dinerstein, Eric
    Kopnina, Helen
    Noss, Reed
    Piccolo, John
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Taylor, Bron
    Vynne, Carly
    Washington, Haydn
    If we want a whole Earth, Nature Needs Half: a response to Buscher et al.2017In: Oryx, ISSN 0030-6053, E-ISSN 1365-3008, Vol. 51, no 3, p. 400-400Article in journal (Refereed)
  • 5.
    Drechsler, Michal
    Karlstad University, Faculty of Technology and Science.
    Syror och baser i gymnasieskolan2012In: Skola och naturvetenskap: - politik, praktik, problematik i belysning av ämnesdidaktisk forskning / [ed] Helge Strömdahl & Lena Tibell, Lund, 2012Chapter in book (Other academic)
  • 6.
    Filipsson, Karl
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). Gothenburg University, Sweden.
    Brijs, Jeroen
    Gothenburg University, Sweden.
    Näslund, Joacim
    Gothenburg University, Sweden.
    Wengström, Niklas
    Gothenburg University, Sweden; Swedish Anglers Association, Gothenburg, Sweden.
    Adamsson, Marie
    Gothenburg University, Sweden.
    Závorka, Libor
    Gothenburg University, Sweden; Toulouse University, France.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Höjesjö, Johan
    Gothenburg University, Sweden.
    Encystment of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae coincides with increased metabolic rate and haematocrit in juvenile brown trout (Salmo trutta)2017In: Parasitology Research, ISSN 0932-0113, E-ISSN 1432-1955, Vol. 116, p. 1353-1360Article in journal (Refereed)
    Abstract [en]

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

  • 7.
    Greenberg, Larry
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Calles, Olle
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Andersson, Jonas
    Länsstyrelsen i Värmland.
    Engqvist, Therese
    Länsstyrelsen i Kalmar.
    Effect of trash diverters ad overhead cover on downstream migrating brown trout smolts2012In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 48, no November, p. 25-29Article in journal (Refereed)
    Abstract [en]

    Power plant dams constitute barriers for downstream migration by smolts. The purpose of this study was to measure guidance efficiency of existing trash diverters and the use of overhead cover in combination with trash diverters to guide brown trout (

    Salmo trutta L.) smolts away from turbine intakes into trash spillway gates at two power plants in the Emån River, southern Sweden. A total of 44 trout smolts were caught, radio-tagged, released at the two power plants and tracked daily for six weeks. The trash diverter at the lower power plant had a significant guiding effect, as the proportion of smolt that entered the spillway gate was significantly greater than the relative proportion of water that flowed through the gate (52% vs 17%). In contrast, there was no evidence of a guidance effect at upper Finsjö, where the proportion of smolts that entered the spillway gate did not differ significantly from the relative proportion of water that flowed through the gate (0% vs 10%). The lack of a guidance effect at upper Finsjö could not be explained. The effect of overhead cover was tested at the upper power plant as illumination from outdoor, overhead lamps at the power station was believed to attract smolts to the turbine intake. This was accomplishing by setting up and removing a tarpaulin placed between the trash deflector and the turbine intake approximately every 2–5 days for about one month, so that 52.6% of the time the tarpaulin was in place and 47.4% of the time it was not. The presence of the tarpaulin reduced turbine passage, as 31% of the smolts swam through the trash spillway gate instead of the turbines when the tarpaulin was in place, whereas all smolts entered the turbines when no tarpaulin was used. For fish that passed through the turbines, mortality was higher at the upper power plant, equipped with two twin-Francis turbines, than at the lower one, equipped with a single Kaplan turbine.

  • 8. Guenard, G.
    et al.
    Boisclair, Daniel
    Ugedal, Ola
    Forseth, Torbjörn
    Fleming, Ian A.
    Jonsson, Bror
    The bioenergetics ofdensity-dependent growth in Arctic char (Salvelinus alpinus L.)2012In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 69, p. 1651-1662Article in journal (Refereed)
  • 9.
    Gustafsson, Stina
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Calles, Olle
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Skurdal, Jostein
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Invertebrate colonization of a nature-like fishway in Eldforsen, Sweden; the effect of habitat design2012Conference paper (Refereed)
  • 10. Jonsson, Bror
    et al.
    Finstad, Anders G.
    Jonsson, Nina
    Winter temperature and food quality affect age and size at maturity in ectotherms: an experimentaltest with Atlantic salmon2012In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 69, no 11, p. 1817-1826Article in journal (Refereed)
    Abstract [en]

    Field studies have revealed that many ectotherms mature younger and smaller in warmer environments although they grow faster. This has puzzled ecologists because the direct effect of factors that accelerate growth is expected to be larger, not smaller size. We tested this experimentally for Atlantic salmon (Salmo salar) at two winter temperatures and diets. Logistic regression revealed that the probability of maturation during the second year in sea water, relative to the probability of older maturation, increased with temperature and growth rate during the first winter. Also, large size and high condition factor 1 year prior to maturation stimulated maturation. In females, a high lipid diet increased the probability of maturation as one-sea-winter fish, and there were significant interactions between winter temperature and food quality and between body size and condition factor the first autumn in sea water. Thus, if the direct effect of temperature on growth rate is the main effect of warming, salmon are likely to attain maturity younger and smaller. Also, richer food decreased age at maturation in females. This finding has consequences for interpretations of climate change impacts on age at maturity in Atlantic salmon and may also hold for many other ectotherm species.

    Salmo salar) at two winter temperatures and

    diets. Logistic regression revealed that the probability of maturation during the second year in sea water, relative to the

    probability of older maturation, increased with temperature and growth rate during the first winter. Also, large size and

    high condition factor 1 year prior to maturation stimulated maturation. In females, a high lipid diet increased the probability of

    maturation as one-sea-winter fish, and there were significant interactions between winter temperature and food quality and

    between body size and condition factor the first autumn in sea water. Thus, if the direct effect of temperature on growth rate is

    the main effect of warming, salmon are likely to attain maturity younger and smaller. Also, richer food decreased age at

    maturation in females. This finding has consequences for interpretations of climate change impacts on age at maturity in Atlantic salmon and may also hold for many other ectotherm species.

  • 11.
    Lans, Linnea
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Behaviour and metabolic rates of brown trout and Atlantic salmon: Influence of food, environment and social interactions2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    For Atlantic salmon (Salmo salar) and brown trout (Salmo trutta), the decision to migrate or when to migrate is believed to be influenced by the individual’s metabolic rate (MR) relative its food intake. As MR was expected to be related to behaviour, the potential links between behaviour and metabolic costs was studied. For both salmon and trout the dominant individual had a higher standard metabolic rate (SMR) than its subordinate counterpart. Also, successful migrants of brown trout had a higher SMR than unsuccessful migrants, whereas no such difference was found for obligate migratory Atlantic salmon. Measures of variation in MR and boldness indicated that Atlantic salmon was more sensitive to stress than brown trout and became passive when stressed. When two trout were interacting, an increase in ventilation rate (VR) was positively correlated to fighting intensity. The first day after an interaction, VR did not differ between small dominant and subordinate trout (mean size 3.7g), whereas for large trout (26.0g) subordinates had higher VR than dominants. However, a combination of low temperature (10°C) and high water velocity (22cm/s) eliminated this difference. This probably reflects the high swimming activity of small dominants and the low motivation for dominants to defend a large territory when temperatures were low and the cost of moving was high. These results show that the relationship between MR and behaviour may differ depending on species, fish size and environmental factors.

  • 12.
    Olsson, Mattias
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Cox, John
    University of Kentucky, Department of Forestry, USA.
    Larkin, Jeff
    Indiana University of Pennsylvania, Department of Biology, USA.
    Widén, Per
    Karlstad University, Faculty of Social and Life Sciences, Department of Health and Environmental Sciences.
    Olovsson, Anders
    Karlstad University, Faculty of Social and Life Sciences.
    Space and habitat use of moose in southwestern Sweden2011In: European Journal of Wildlife Research, ISSN 1612-4642, E-ISSN 1439-0574, Vol. 57, no 2, p. 241-249Article in journal (Refereed)
  • 13.
    Piccolo, John
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    The role of ecology in the salmonid conservation: ecology in practice and didactics2012Conference paper (Refereed)
  • 14.
    Piccolo, John
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Time for an update of the Lake Vänern food web model2012Conference paper (Refereed)
  • 15.
    Schneider, Lea Dominique
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Höjesjö, Johan
    Göteborgs universitet.
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Local adaptation studies and conservation: Parasite–host interactions between the endangered freshwater mussel Unio crassus and its host fish2017In: Aquatic conservation, ISSN 1052-7613, E-ISSN 1099-0755, Vol. 27, p. 1261-1269Article in journal (Refereed)
    Abstract [en]

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

  • 16.
    Schneider, Lea Dominique
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Österling, Martin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus2017In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 810, no 1, p. 283-293Article in journal (Refereed)
    Abstract [en]

    Adaptation to temperature regimes and host presence may enhance fitness in parasites. In an experimental study, we evaluated the timing of glochidia release by Unio crassus subjected to three spring water temperature regimes in the presence and absence of the host fish Cottus gobio. The timing of glochidia release was delayed at (i) constantly low temperatures (<10°C), in contrast to earlier and pronounced releases at (ii) natural temperature increases that level off at intermediate temperatures (10–15°C), and (iii) higher-than-normal temperatures (10–20°C). Mussels from treatment (i) that had not released glochidia during the experiment did so soon after being moved to the temperature in (ii), indicating a temperature threshold for glochidia release. Neither host fish presence nor the combined effect of temperature and host fish presence significantly affected the timing of glochidia release. The treatment with natural spring water temperatures indicated possible fitness benefits for U. crassus through combined effects of high intensities of glochidia releases and high survival of released glochidia. The furthered understanding of climate change effects on mussel and host phenology in seasonal environments, potentially inducing temporal mismatches of glochidia release to host availability, is key to mussel conservation

  • 17.
    Skov, Christian
    et al.
    DTU AQUA, Danmark.
    Nilsson, Per Anders
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Biology and ecology of pike2018Book (Refereed)
  • 18.
    Vernerback, Claes
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Effect of incubation temperature on Atlantic salmon metabolism as indicated by ventilation rate2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The global mean temperature is predicted to increase by up to 5 °C during this century. For fish, being ectotherms, temperature is one of the most important environmental factors, influencing them in a number of different ways, including effects on physiological traits, timing of life history events and behavior. Atlantic salmon has been shown to grow faster after being incubated at warmer temperatures. One possible explanation for this could be that the increased incubation temperature causes decreased metabolic rates. The aim of this project was to examine whether this is true. Atlantic salmon eggs were incubated in three different temperature regimes: natural temperature conditions, heated water and a mixed temperature treatment, where eggs were incubated in increased temperature until the beginning of January and after that subjected to natural temperature conditions. Ventilation rate, a proxy for metabolism, was measured for fish from each treatment group, as well as fish length and weight. The results revealed significantly lower ventilation rates of the fish from the heated temperature treatment, but not of the fish from the mixed temperature treatment. This suggests that an increased incubation temperature causes lowered rates of metabolism in Atlantic salmon, and that the change occurs later than early January. Because of differences in size and life stage between fish from the different groups however, the results are uncertain and call for further investigations. A lowered metabolic rate will affect the fish’s behavior. A further development might therefore be to study fish survival in the wild in relation to a fish’s metabolic rate.

  • 19.
    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 1365-2656Article 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.

  • 20.
    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.

  • 21.
    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.

  • 22.
    Österling, Martin
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Test and application of a non-destructive photo-method investigating the parasitic stage of the threatened mussel Margaritifera margaritifera on its host fish (Salmo trutta)2012Conference paper (Refereed)
  • 23.
    Österling, Martin E
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Arvidsson, Björn L
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Greenberg, Larry A
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Habitat degradation and the decline of the threatened mussel Margaritifera maragaritifera: influence of turbidity and sedimentation on mussel an its host2010In: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 47, no 4, p. 759-768Article in journal (Refereed)
    Abstract [en]

    1. Habitat degradation is a major reason for species extinctions. For parasite–host interactions, the decline of a parasite may not only be related to the parasite’s tolerance to habitat degradation but also indirectly through the host’s tolerance to the same disturbance.

    2. Our objective was to explore the cause of population declines of the freshwater pearl mussel Margaritifera margaritifera by relating the age distribution, density and growth of the mussels with turbidity, sedimentation rates and density of the mussel’s host, trout Salmo trutta, in 26 Swedish streams.

    3. An analysis of the age structure of nine mussel populations showed that maximum age differed by 60 years, with five populations having low proportions of juvenile mussels. Adult mussel density was higher at sites where juvenile mussels occurred than at sites lacking juvenile mussels.

    4. Growth of adult mussels during the past 10 years was lower in the five streams lacking recent recruitment than in the four streams with recent recruitment, indicating that some environmental factor may be negatively impacting these populations.

    5. A comparison among 24 populations indicated that turbidity and sedimentation may be responsible for recruitment failure in 58% of the populations. The age of the youngest mussel was positively related to turbidity and sedimentation, and juvenile mussel density was negatively related to turbidity and sedimentation. In contrast, trout density was not related to recruitment of mussels or sedimentation, but was positively related to turbidity in all streams, both with and without recent mussel recruitment.

    6.Synthesis and applications. Recruitment failure of M. margaritifera appears to be related to its own vulnerability to turbidity and sedimentation rather than to its host’s response to this type of habitat degradation. The results from our study suggest that managers might be able to evaluate the potential viability of mussel populations by measuring stream turbidity. Restoration activities to improve the mussels’ environment should focus on reducing fine material transport into streams.

  • 24.
    Österling, Martin
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Biology.
    Söderberg, Håkan
    Anthropogenic changes of brown trout Salmo trutta and the impact on its parasitic mussel Margaritifera margaritifera.2012Conference paper (Refereed)
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