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  • 1. Agrell, C
    et al.
    Larsson, Per
    Lund university.
    Okla, L
    Agrell, J
    PCB congeners in precipitation, wash out ratios and depositional fluxes within the Baltic Sea region, Europe2002In: Atmospheric environment, Vol. 36, p. 371-383Article in journal (Refereed)
  • 2. Agrell, C
    et al.
    Okla, L
    Larsson, Per
    Lund university.
    Backe, C
    Wania, F
    Evidence of latitudinal fractionation of polychlorinated biphenyls along the Baltic Sea regions1999In: Environmental science and technology, Vol. 33, p. 1149-1156Article in journal (Refereed)
  • 3. Agrell, C
    et al.
    ter Schure, A F H
    Larsson, Per
    Lund university.
    Sveder, J
    Bokenstrand, A
    Zegers, B
    Polybrominated biphenyl ethers (PBDEs) at a solid waste incineration plant: Atmospheric concentrations2004In: Atmospheric environment, Vol. 38, p. 5139-5148Article in journal (Refereed)
  • 4. Backe, C
    et al.
    Cousins, I T
    Larsson, Per
    Lund university.
    PCB in soils and estimated soil-air exchange fluxes of selected PCB congeners in the South of Sweden2004In: Environmental pollution, Vol. 128, p. 59-72Article in journal (Refereed)
  • 5. Backe, C
    et al.
    Larsson, Per
    Lund university.
    Agrell, C
    Spatial and temporal variation of polychlorinated biphenyls (PCB) in precipitation in southern Sweden2002In: Science of the total environment, Vol. 285, p. 117-132Article in journal (Refereed)
  • 6. Backe, C
    et al.
    Larsson, Per
    Lund university.
    Okla, L
    Polychlorinated biphenyls in the air of southern Sweden – spatial and temporal variations2000In: Atmospheric environment, Vol. 34, p. 1481-1486Article in journal (Refereed)
  • 7.
    Berggren, Hanna
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nordahl, Oscar
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Testing for local adaptation to spawning habitat in sympatric subpopulations of northern pike by reciprocal translocation of embryos2016In: PLOS ONE, E-ISSN 1932-6203, Vol. 11, no 5, article id e0154488Article in journal (Refereed)
    Abstract [en]

    We tested for local adaption in early life-history traits by performing a reciprocal translocation experiment with approximately 2500 embryos of pike (Esox lucius) divided in paired split-family batches. The experiment indicated local adaptation in one of the two subpopulations manifested as enhanced hatching success of eggs in the native habitat, both when compared to siblings transferred to a non-native habitat, and when compared to immigrant genotypes from the other subpopulation. Gene-by-environment effects on viability of eggs and larvae were evident in both subpopulations, showing that there existed genetic variation allowing for evolutionary responses to divergent selection, and indicating a capacity for plastic responses to environmental change. Next, we tested for differences in female life-history traits. Results uncovered that females from one population invested more resources into reproduction and also produced more (but smaller) eggs in relation to their body size compared to females from the other population. We suggest that these females have adjusted their reproductive strategies as a counter-adaptation because a high amount of sedimentation on the eggs in that subpopulations spawning habitat might benefit smaller eggs. Collectively, our findings point to adaptive divergence among sympatric subpopulations that are physically separated only for a short period during reproduction and early development – which is rare. These results illustrate how combinations of translocation experiments and field studies of life-history traits might infer about local adaptation and evolutionary divergence among populations. Local adaptations in subdivided populations are important to consider in management and conservation of biodiversity, because they may otherwise be negatively affected by harvesting, supplementation, and reintroduction efforts targeted at endangered populations.

  • 8.
    Berggren, Hanna
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nordahl, Oscar
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Yildirim, Yeserin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Effects of environmental translocation and host characteristics on skin microbiomes of sun-basking fish2023In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 290, no 2013, article id 20231608Article in journal (Refereed)
    Abstract [en]

    Variation in the composition of skin-associated microbiomes has been attributed to host species, geographical location and habitat, but the role of intraspecific phenotypic variation among host individuals remains elusive. We explored if and how host environment and different phenotypic traits were associated with microbiome composition. We conducted repeated sampling of dorsal and ventral skin microbiomes of carp individuals (Cyprinus carpio) before and after translocation from laboratory conditions to a semi-natural environment. Both alpha and beta diversity of skin-associated microbiomes increased substantially within and among individuals following translocation, particularly on dorsal body sites. The variation in microbiome composition among hosts was significantly associated with body site, sun-basking, habitat switch and growth, but not temperature gain while basking, sex, personality nor colour morph. We suggest that the overall increase in the alpha and beta diversity estimates among hosts were induced by individuals expressing greater variation in behaviours and thus exposure to potential colonizers in the pond environment compared with the laboratory. Our results exemplify how biological diversity at one level of organization (phenotypic variation among and within fish host individuals) together with the external environment impacts biological diversity at a higher hierarchical level of organization (richness and composition of fish-associated microbial communities).

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  • 9.
    Berggren, Hanna
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Linnaeus University, Linnaeus Knowledge Environments, Water.
    Yildirim, Yeserin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Broman, Elias
    Stockholm University, Sweden.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lundin, Daniel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Linnaeus University, Linnaeus Knowledge Environments, Water.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Linnaeus University, Linnaeus Knowledge Environments, Water.
    Fish Skin Microbiomes Are Highly Variable Among Individuals and Populations but Not Within Individuals2022In: Frontiers in Microbiology, E-ISSN 1664-302X, Vol. 12, article id 767770Article in journal (Refereed)
    Abstract [en]

    Fish skin-associated microbial communities are highly variable among populations and species and can impact host fitness. Still, the sources of variation in microbiome composition, and particularly how they vary among and within host individuals, have rarely been investigated. To tackle this issue, we explored patterns of variation in fish skin microbiomes across different spatial scales. We conducted replicate sampling of dorsal and ventral body sites of perch (Perca fluviatilis) from two populations and characterized the variation of fish skin-associated microbial communities with 16S rRNA gene metabarcoding. Results showed a high similarity of microbiome samples taken from the left and right side of the same fish individuals, suggesting that fish skin microbiomes can be reliably assessed and characterized even using a single sample from a specific body site. The microbiome composition of fish skin differed markedly from the bacterioplankton communities in the surrounding water and was highly variable among individuals. No ASV was present in all samples, and the most prevalent phyla, Actinobacteria, Bacteroidetes, and Proteobacteria, varied in relative abundance among fish hosts. Microbiome composition was both individual- and population specific, with most of the variation explained by individual host. At the individual level, we found no diversification in microbiome composition between dorsal and ventral body sites, but the degree of intra-individual heterogeneity varied among individuals. To identify how genetic and phenotypic characteristics of fish hosts impact the rate and nature of intra-individual temporal dynamics of the skin microbiome, and thereby contribute to the host-specific patterns documented here, remains an important task for future research.

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  • 10. Berglund, O
    et al.
    Larsson, Per
    Lund university.
    Broman, D
    Organochlorine accumulation and stable isotopes in an Atlantic salmon (Salmo salar) population from the Baltic Sea – effects of omnivory and reproductive strategies2001In: Science of the total environment, Vol. 281, p. 141-151Article in journal (Refereed)
  • 11. Berglund, O
    et al.
    Larsson, Per
    Lund university.
    Brönmark, C
    Greenberg, L
    Eklöf, A
    Okla, L
    Factors influencing organochlorine uptake in age-0 brown trout (Salmo trutta) in lotic environments1997In: Canadian journal of fisheries and aquatic sciences, Vol. 54, p. 2767-2774Article in journal (Refereed)
  • 12. Berglund, O
    et al.
    Larsson, Per
    Lund university.
    Ewald, G
    Okla, L
    Bioaccumulation and differential partitioning of PCBs in freshwater, planktonic food webs2000In: Canadian journal of fisheries and aquatic sciences, Vol. 57, p. 1160-1168Article in journal (Refereed)
  • 13. Berglund, O
    et al.
    Larsson, Per
    Lund university.
    Ewald, G
    Okla, L
    Influence of trophic status on PCB dynamics in lake sediments and biota2000In: Environmental pollution, Vol. 113, p. 199-210Article in journal (Refereed)
  • 14. Berglund, O
    et al.
    Larsson, Per
    Lund university.
    Ewald, G
    Okla, L
    The effect of lake trophy on lipid content and PCB concentrations in planktonic food webs2001In: Ecology, Vol. 82, p. 1078-1088Article in journal (Refereed)
  • 15. Berglund, O
    et al.
    Nyström, P
    Larsson, Per
    Lund university.
    Persistent organic pollutants (POPs) in river food webs – influence of trophic position and degree of heterotrophy2005In: Canadian journal of fisheries and aquatic sciences, Vol. 62, p. 2021-2032Article in journal (Refereed)
  • 16.
    Bergström, Kristofer
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nordahl, Oscar
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Söderling, Peter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Koch-Schmidt, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Borger, Tobias
    County Administration Board Kalmar County, Sweden.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Linnaeus University, Linnaeus Knowledge Environments, Water.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Exceptional longevity in northern peripheral populations of Wels catfish (Siluris glanis)2022In: Scientific Reports, E-ISSN 2045-2322, Vol. 12, no 1, article id 8070Article in journal (Refereed)
    Abstract [en]

    Studies of life-history variation across a species range are crucial for ecological understanding and successful conservation. Here, we examined the growth and age of Wels catfish (Silurus glanis) in Sweden, which represent the northernmost populations in Europe. A total of 1183 individuals were captured, marked and released between 2006 and 2020. Mark-recapture data from 162 individuals (size range: 13-195 cm) were used to estimate von Bertalanffy growth curve parameters which revealed very slow growth rates compared to catfish within the core distribution area (central Europe). The fitted von Bertalanffy growth curve predicted a 150 cm catfish to be around 40 years old, while the largest recaptured individual (length 195 cm) was estimated to be 70 (95% CI 50-112) years old. This was substantially older than the previously documented maximum age of a catfish. The weight at length relationships in these northern peripheral populations were similar to those documented for catfish in central Europe indicating that resources did not constrain growth. This indicates that the slow growth and exceptional high age in the northern catfish populations are the result of lower temperatures and/or local adaptations.

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  • 17.
    Bernes, Claes
    et al.
    Royal Swedish Academy of Sciences.
    Carpenter, Stephen
    University of Wisconsin, USA.
    Gårdmark, Anna
    Swedish University of Agricultural Sciences.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Persson, Lennart
    Umeå University.
    Skov, Christian
    Technical University of Denmark, Denmark.
    Speed, James
    Norwegian University of Science and Technology, Norway.
    Van Donk, Ellen
    Netherlands Institute of Ecology, Netherlands.
    What is the influence of a reduction of planktivorous and benthivorous fish on water quality in temperate eutrophic lakes?  A systematic review2015In: Environmental Evidence, E-ISSN 2047-2382, Vol. 4, p. 1-28, article id 7Article in journal (Refereed)
    Abstract [en]

    Background

    In recent decades, many attempts have been made to restore eutrophic lakes through biomanipulation. Reducing the populations of planktivorous and benthivorous fish (either directly or through stocking of piscivorous fish) may induce ecosystem changes that increase water transparency and decrease the risk of algal blooms and fish kills, at least in the short term. However, the generality of biomanipulation effects on water quality across lake types and geographical regions is not known. Therefore, we have undertaken a systematic review of such effects in eutrophic lakes in temperate regions throughout the world.

    Methods

    Searches for literature were made using online publication databases, search engines, specialist websites and bibliographies of literature reviews. Search terms were developed in English, Danish, Dutch and Swedish. Identified articles were screened for relevance using inclusion criteria set out in an a priori protocol. To reduce the risk of bias, we then critically appraised the combined evidence found on each biomanipulation. Data were extracted on outcomes such as Secchi depth and chlorophyll a concentration before, during and/or after manipulation, and on effect modifiers such as lake properties and amounts of fish removed or stocked.

    Results

    Our searches identified more than 14,500 articles. After screening for relevance, 233 of them remained. After exclusions based on critical appraisal, our evidence base included useful data on 128 biomanipulations in 123 lakes. Of these interventions, 85% had been made in Europe and 15% in North America. Meta-analysis showed that removal of planktivores and benthivores (with or without piscivore stocking) leads to increased Secchi depth and decreased chlorophyll a concentration during intervention and the first three years afterwards. Piscivore stocking alone has no significant effect. The response of chlorophyll a levels to biomanipulation is stronger in lakes where fish removal is intense, and in lakes which are small and/or have high pre-manipulation concentrations of total phosphorus.

    Conclusions

    Our review improves on previous reviews of biomanipulation in that we identified a large number of case studies from many parts of the world and used a consistent, repeatable process to screen them for relevance and susceptibility to bias. Our results indicate that removal of planktivorous and benthivorous fish is a useful means of improving water quality in eutrophic lakes. Biomanipulation tends to be particularly successful in relatively small lakes with short retention times and high phosphorus levels. More thorough fish removal increases the efficacy of biomanipulation. Nonetheless successes and failures have occurred across a wide range of conditions.

  • 18.
    Bernes, Claes
    et al.
    Royal Swedish Academy of Sciences, Sweden.
    Carpenter, Stephen R.
    Univ Wisconsin, USA.
    Gardmark, Anna
    Swedish University of Agricultural Sciences, Sweden.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Persson, Lennart
    Umeå University, Sweden.
    Skov, Christian
    Tech Univ Denmark, Denmark.
    Van Donk, Ellen
    Netherlands Inst Ecol, Netherlands.
    What is the influence on water quality in temperate eutrophic lakes of a reduction of planktivorous and benthivorous fish?: A systematic review protocol2013In: Environmental Evidence, E-ISSN 2047-2382, Vol. 2, no 1, article id 9Article, review/survey (Refereed)
    Abstract [en]

    Background: In lakes that have become eutrophic due to sewage discharges or nutrient runoff from land, problems such as algal blooms and oxygen deficiency often persist even when nutrient supplies have been reduced. One reason is that phosphorus stored in the sediments can exchange with the water. There are indications that the high abundance of phytoplankton, turbid water and lack of submerged vegetation seen in many eutrophic lakes may represent a semi-stable state. For that reason, a shift back to more natural clear-water conditions could be difficult to achieve. In some cases, though, temporary mitigation of eutrophication-related problems has been accomplished through biomanipulation: stocks of zooplanktivorous fish have been reduced by intensive fishing, leading to increased populations of phytoplankton-feeding zooplankton. Moreover, reduction of benthivorous fish may result in lower phosphorus fluxes from the sediments. An alternative to reducing the dominance of planktivores and benthivores by fishing is to stock lakes with piscivorous fish. These two approaches have often been used in combination. The implementation of the EU Water Framework Directive has recently led to more stringent demands for measures against eutrophication, and a systematic review could clarify whether biomanipulation is efficient as a measure of that kind. Methods: The review will examine primary field studies of how large-scale biomanipulation has affected water quality and community structure in eutrophic lakes or reservoirs in temperate regions. Such studies can be based on comparison between conditions before and after manipulation, on comparison between treated and nontreated water bodies, or both. Relevant outcomes include Secchi depth, concentrations of oxygen, nutrients, suspended solids and chlorophyll, abundance and composition of phytoplankton, zooplankton and fish, and coverage of submerged macrophytes.

  • 19.
    Blenckner, Thorsten
    et al.
    Stockholm University.
    Österblom, Henrik
    Stockholm University.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Andersson, Agneta
    Umeå University.
    Elmgren, Ragnar
    Stockholm University.
    Baltic Sea ecosystem-based management under climate change: Synthesis and future challenges2015In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, no Supplement 3, p. S507-S515Article in journal (Refereed)
    Abstract [en]

    Ecosystem-based management (EBM) has emerged as the generally agreed strategy for managing ecosystems, with humans as integral parts of the managed system. Human activities have substantial effects on marine ecosystems, through overfishing, eutrophication, toxic pollution, habitat destruction, and climate change. It is important to advance the scientific knowledge of the cumulative, integrative, and interacting effects of these diverse activities, to support effective implementation of EBM. Based on contributions to this special issue of AMBIO, we synthesize the scientific findings into four components: pollution and legal frameworks, ecosystem processes, scale-dependent effects, and innovative tools and methods. We conclude with challenges for the future, and identify the next steps needed for successful implementation of EBM in general and specifically for the Baltic Sea.

  • 20. Bremle, G
    et al.
    Larsson, Per
    Lund university.
    Long-term variation of PCB in the water of a river in relation to precipitation and internal sources1997In: Environmental science and technology, Vol. 31, p. 3232-3237Article in journal (Refereed)
  • 21. Bremle, G
    et al.
    Larsson, Per
    Lund university.
    PCB concentration in fish in a river system after remediation of contaminated sediment1998In: Environmental science and technology, Vol. 32, p. 3491-3495Article in journal (Refereed)
  • 22. Bremle, G
    et al.
    Larsson, Per
    Lund university.
    PCB in Emån River ecosystem1998In: Ambio, Vol. 27, p. 384-392Article in journal (Refereed)
  • 23. Bremle, G
    et al.
    Larsson, Per
    Lund university.
    PCB in the air during landfilling of a contaminated lake sediment1998In: Atmospheric environment, Vol. 32, p. 1011-1019Article in journal (Refereed)
  • 24. Bremle, G
    et al.
    Larsson, Per
    Lund university.
    Hammar, T
    Helgee, A
    Troedsson, B
    PCB in a river system during sediment remediation1998In: Water, air, and soil pollution, Vol. 107, p. 237-250Article in journal (Refereed)
  • 25. Bremle, G
    et al.
    Okla, L
    Larsson, Per
    Lund university.
    PCB in water and sediment of a lake after remediation of contaminated sediment1998In: Ambio, Vol. 27, p. 398-403Article in journal (Refereed)
  • 26. Bremle, G
    et al.
    Okla, L
    Larsson, Per
    Lund university.
    Uptake of PCBs in fish in a contaminated river system - Bioconcentration factors measured in the field1995In: Environmental science and technology, Vol. 29, p. 2010-2015Article in journal (Refereed)
  • 27. Eklöv, A
    et al.
    Greenberg, L
    Brönmark, C
    Larsson, Per
    Lund university.
    Berglund, O
    Influence of water quality, habitat and species richness on brown trout, Salmo trutta, L., populations1999In: Journal of fish biology, Vol. 54, p. 33-43Article in journal (Refereed)
  • 28. Eklöv, A
    et al.
    Greenberg, L
    Brönmark, C
    Larsson, Per
    Lund university.
    Berglund, O
    Response to stream fishes to improved water quality: A comparison between the 1960s and 1990s1998In: Freshwater biology, Vol. 40, p. 771-782Article in journal (Refereed)
  • 29.
    Engstedt, Olof
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Engkvist, Roland
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Larsson, Per
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Elemental fingerprinting in otoliths reveals natal homing of anadromous Baltic Sea pike (Esox lucius L.)Manuscript (preprint) (Other academic)
    Abstract [en]

    Northern pike (Esox lucius) inhabit the coastal areas of the Baltic Sea. A large part of the fishes show anadromous

    behaviour and spawn in streams and rivers but spend most of the time foraging in the sea. We examined

    spawning migration in four streams in the southwest part of the Baltic, situated within a radius of 50 km. Using

    juvenile pike in the streams as references, otolith analysis by microPIXE revealed unique elemental patterns (Sr,

    Zn, Br, Co and Mn) for the juveniles in each of the four different streams. The strontium signal in the otolith

    of the juveniles was used as an indicator of freshwater origin and the time spent in the stream (size of juveniles).

    Adult marked pike in their migrating spawning phase were caught in each of the streams and otoliths were

    analysed. Defining earlier freshwater origin by the Sr signal from the otolith core to the increase in Sr when the

    fish as juvenile pike migrated to the sea, element composition was determined. A principal component analysis

    showed that the elemental fingerprint during the freshwater phase several years back was similar for adult fish

    and juveniles inhabiting the stream today. The results indicated native homing of the adults to a specific stream,

    a process further corroborated by results from electronic marking (Pit-tags) with the return of adult individuals

    over several consecutive years. We interpret the results as evidence that pike in the Baltic Sea consists of several

    sub-populations and are developed by homing to specific spawning streams. The results of the study may have

    implications for fishery management as pike in the Baltic Sea cannot be seen as homogenous “stock“, but instead

    consists of different, unique populations similar to the pattern demonstrated in salmon (Salmo salar).

  • 30.
    Engstedt, Olof
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Engkvist, Roland
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Elemental fingerprinting in otoliths reveals natal homing of anadromous Baltic Sea pike (Esox lucius L.)2014In: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633, Vol. 23, no 3, p. 313-321Article in journal (Refereed)
    Abstract [en]

    We examined the element pattern in the otoliths of a migratory fish species that inhabit the coastal areas in the brackish of the Baltic Sea. The northern pike (Esox lucius) show migratory behaviour, spawning in streams and rivers and foraging in the sea. We examined spawning migration in four nearby streams in the south-west part of the Baltic. Otolith analysis by microPIXE revealed unique elemental patterns (Sr, Zn, Br, Co and Mn) for the juveniles in each of the different streams. The strontium signal in the otolith of the juveniles was used as an indicator of freshwater origin and the time spent in the stream. Adult pike in their migrating spawning phase were caught in each of the streams. The elemental composition in otoliths in their freshwater phase (using juvenile pike in the streams as references) was determined. A principal component analysis showed that the elemental fingerprint during the freshwater phase several years back in time was similar for the adult fish and for juveniles inhabiting the stream today. The results indicated natal homing of the adults to a specific stream, a conclusion that was strengthened by the fact that marked fish returned to spawn over consecutive years. Anadromous pike in the Baltic Sea may thus be divided in subpopulations. The results of the study may have implications for fishery management, as pike in the Baltic Sea cannot be seen as homogenous population.

  • 31.
    Engstedt, Olof
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Koch-Schmidt, Per
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Larsson, Per
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Experimental validation of Sr uptake in juvenile pike (Esox Lucius L.) otoliths – from water and food.Manuscript (preprint) (Other academic)
    Abstract [en]

    Strontium (Sr) or Sr:Ca ratios in otoliths have been widely used in the last decade to describe migration histories

    of fish between fresh and marine waters. However, reference experimental studies on particular species and

    waters are necessary to confirm the underlying assumption and evaluate the usefulness of this tool for field data.

    We conducted an experiment with the aim to answer these questions for anadromous pike (Esox lucius L.) in

    the Baltic Sea. Juvenile pike were reared in successively increasing salinities (10 steps from 0 to 7 ‰) for 110

    days, and then in constant maximum salinity (7 ‰) for an additional 50 days. Pikes in the experiment were

    divided into two food treatments, given prey fish from brackish environments (7 ‰) and fish from freshwater

    lakes. Sr:Ca in pike otoliths were positively related to Sr in water (i.e salinity) in both treatments, suggesting

    that Sr:Ca ratios may be used to describe migration histories between rivers and the Baltic Sea.

    A significant difference in Sr.Ca ratios was found between the food treatments, showing that differences in diet

    may contribute to variation in otolith Sr:Ca, at least for pike in the Baltic Sea. Maximum Sr:Ca values for pike

    given marine food corresponded with field collected fish from the Baltic Sea.

  • 32.
    Engstedt, Olof
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Koch-Schmidt, Per
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Larsson, Per
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Strontium (Sr) uptake from water and food in otoliths of juvenile pike (Esox lucius L.)2012In: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 418-419, p. 69-74Article in journal (Refereed)
    Abstract [en]

    The strontium (Sr) or Sr:Ca ratio in otoliths has been widely used in the last decade to describe the migration histories of fish between fresh and marine waters. However, reference experimental studies of particular species and waters are necessary to confirm the underlying assumptions and evaluate the applicability of this tool to field data. Laboratory experiments indicated that juvenile, anadromous pike (Esox lucius L) from the Baltic Sea reared in successively increasing salinities (from 0 to 7 parts per thousand) for 110 d accumulated Sr in their otoliths according to a positive relationship with waterborne Sr. When the pike were given prey fish from brackish (7 parts per thousand) environments, the otolith Sr:Ca ratio increased more than in fish given prey from freshwater lakes. Pike held at constant salinity (7 parts per thousand) and given prey fish from the same salinity environment had an Sr:Ca ratio of 6.9 x 10(-3). The ratio decreased successively for fish given prey from freshwater (4.4 x 10(-3)) or kept in freshwater and given food from brackish water (3.1 x 10(-3)). Fish exposed to freshwater and given prey fish from freshwater displayed no increase in Sr:Ca ratio (1.6 x 10(-3)). The experiments demonstrated that the Sr:Ca ratio may be used to describe the migration history of pike between rivers and the Baltic Sea. The maximum Sr:Ca value for pike given marine-origin food corresponded to those of fish collected from the Baltic Sea.

  • 33.
    Engstedt, Olof
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Larsson, Per
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Koch-Schmidt, Per
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Skov, Christian
    Danish Institute for Fisheries Research, Department of Inland Fisheries, Vejlsøvej 39,8600 Silkeborg, Denmark.
    Tibblin, Petter
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nilsson, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Borger, Tobias
    County Administrative Board of Kalmar, 391 86 Kalmar.
    Stenroth, Patrik
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Annual spawning migration of anadromous pike (Esox lucius L.) in streams entering the Baltic SeaManuscript (preprint) (Other academic)
    Abstract [en]

    The movement of pike (n = 3415) was investigated in four streams entering the Baltic Sea in the Kalmar Sound

    region, Sweden. Migration patterns were monitored during spawning in three of the streams and during the

    whole year in the forth stream using passive integrated transponders and outer tags. The study was conducted

    yearly between 2006 and 2010. Mature pike returned (22 – 45%) to the same streams year after year and some

    fish returned to the same regions of the streams. No incidence of fish visiting another stream than the one

    where they were marked was recorded and no fish missed the spawning season to return the next year. These

    results indicated that the reason for fish not returning was due to mortality. The proportions of returning fish

    indicated homing and the spawning ground fidelity (stream) was high. Return rates were influenced by size

    of fish, sex and stream identity. We also investigated if sex, size or individual behaviour influenced timing of

    arrival, departure or duration of stay in freshwater. Diurnal activity was examined in one year in each stream

    suggesting activity peaks in the morning and evening. The results show that pike in the Baltic Sea are anadromous

    and that the migration behavior is likely to create barriers for gene flow. The separation in populations

    by spawning are similar to salmonid species and the management of pike in the Baltic Sea must consider this

    process in strategies and plans of fishing.

  • 34.
    Engstedt, Olof
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nilsson, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Habitat restoration: A sustainable key to management2018In: Biology and Ecology of Pike / [ed] Christian Skov and Anders Nilsson, Boca Ratón: CRC Press, 2018, 1, p. 248-268Chapter in book (Refereed)
  • 35.
    Engstedt, Olof
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Stenroth, Patrik
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Larsson, Per
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Ljunggren, Lars
    Fiskeriverket.
    Elfman, Mikael
    Lunds universitet, Kärnfysik.
    Assessment of natal origin of pike (Esox lucius) in the Baltic Sea using Sr:Ca in otoliths2010In: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 89, p. 547-555Article in journal (Refereed)
    Abstract [en]

    Spawning habitat of pike (Esox lucius) in the Baltic Sea include brackish water bays, brooks and rivers. Elevated salinity concentrations are one of several stressors that might increase the use and importance of freshwater habitats for spawning. In the Baltic Sea, one of the largest brackish seas in the world, freshwater species like pike, perch (Perca fluviatilis), whitefish (Coregonus sp), bream (Abramis brama), ide (Leuciscus idus), roach (Rutilus rutilus) and burbot (Lola iota) all undertake spawning migrations to freshwater. However, over the last decades populations densities of these species have declined, and recruitment failure has been argued to be at least part of the problem. The importance of brooks and rivers as spawning areas for these species have not been quantified and set in relation to spawning success in brackish bays. In this study, we collected 175 adult pike (Esox lucius) on their foraging grounds in the sea. Fish were collected in two regions on the Baltic coast, more than 600 km apart. Subsequently we determined their origin (freshwater or marine) using otolith chemistry. Sagittal otoliths were analysed for strontium using the PIXE-method. The results show that 80 of the 175 pike were recruited in freshwater, and several of the larger specimens showed reoccurring migration behaviour. Data show that freshwater is an important recruitment habitat for Baltic Sea pike, suggesting that habitat improvements in rivers entering the Baltic Sea might significantly contribute to population restoration.

  • 36. Ewald, G
    et al.
    Larsson, Per
    Lund university.
    Partitioning of 14C-labelled 2,2’,4,4’-tetrachlorobiphenyl between water and fish lipids1994In: Environmental toxicology and chemistry, Vol. 13, p. 1577-1580Article in journal (Refereed)
  • 37. Ewald, G
    et al.
    Larsson, Per
    Lund university.
    Linge, H
    Okla, L
    Szarzi, N
    Biotransport of organic pollutants to an inland Alaska lake by migrating sockey salmon (Onchrynchus nerka)1998In: Arctic, Vol. 51, p. 40-47Article in journal (Refereed)
  • 38.
    Flink, Henrik
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nordahl, Oscar
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Hall, Marcus
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Rarysson, Anton
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Bergström, Kristofer
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Petersson, Erik
    Swedish University of agricultural sciences, Sweden.
    Merilä, Juha
    University of Helsinki, Finland;University of Hong Kong, China.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Linnaeus University, Linnaeus Knowledge Environments, Water. University of Helsinki, Finland.
    Examining the effects of authentic C&R on the reproductive potential of Northern pike2021In: Fisheries Research, ISSN 0165-7836, E-ISSN 1872-6763, Vol. 243, article id 106068Article in journal (Refereed)
    Abstract [en]

    The practice within recreational fisheries to release captured fish back to the wild, known as catch-and-release (C&R), is an increasingly important strategy to protect fish stocks from overexploitation. However, C&R is a stressor and since animal reproduction is particularly sensitive to stress there is reason to suspect that such a practice induces sublethal fitness consequences. Here, we investigated whether and how C&R fishing influenced the reproductive potential in an anadromous population of Northern pike (Esox lucius). First, female pike were exposed to authentic C&R using rod-and-reel fishing in a coastal foraging habitat prior to the spawning period. Next, we observed the migration to the freshwater spawning habitat and compared both the timing of arrival and maturity stage between C&R-treated and control individuals. Finally, to evaluate effects on the quality and viability of eggs we stripped captured control and recaptured C&R-treated females, measured egg dry mass to assess nutrient content, conducted artificial fertilisations and incubated eggs in a controlled laboratory experiment. We found no evidence of C&R causing alterations in either arrival time, maturity stage, or the quality and viability of fertilised eggs. In combination, our results suggest that long-term effects of C&R-induced stress on key reproductive traits of pike, if any, are minor.

  • 39.
    Forsman, Anders
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Berggren, Hanna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Åström, Mats E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    To what extent can existing research help project climate change impacts on biodiversity in aquatic environments?: A review of methodological approaches2016In: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 4, no 4, article id 75Article, review/survey (Refereed)
    Abstract [en]

    It is broadly accepted that continued global warming will pose a major threat to biodiversity in the 21st century. But how reliable are current projections regarding consequences of future climate change for biodiversity? To address this issue, we review the methodological approaches in published studies of how life in marine and freshwater environments responds to temperature shifts. We analyze and compare observational field surveys and experiments performed either in the laboratory or under natural conditions in the wild, the type of response variables considered, the number of species investigated, study duration, and the nature and magnitude of experimental temperature manipulations. The observed patterns indicate that, due to limitations of study design, ecological and evolutionary responses of individuals, populations, species, and ecosystems to temperature change were in many cases difficult to establish, and causal mechanism(s) often remained ambiguous. We also discovered that the thermal challenge in experimental studies was 10,000 times more severe than reconstructed estimates of past and projections of future warming of the oceans, and that temperature manipulations also tended to increase in magnitude in more recent studies. These findings raise some concerns regarding the extent to which existing research can increase our understanding of how higher temperatures associated with climate change will affect life in aquatic environments. In view of our review findings, we discuss the trade-off between realism and methodological tractability. We also propose a series of suggestions and directions towards developing a scientific agenda for improving the validity and inference space of future research efforts.

  • 40.
    Forsman, Anders
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Berggren, Hanna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nordahl, Oscar
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Koch-Schmidt, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Pike Esox lucius as an emerging model organism for studies in ecology and evolutionary biology: a review.2015In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 87, no 2, p. 472-479Article, review/survey (Refereed)
    Abstract [en]

    The pikeEsox luciusis a large, long-lived, iteroparous, top- predator fish species with a circumpolardistribution that occupies a broad range of aquatic environments. This study reports on a literaturesearch and demonstrates that the publication rate ofE. luciusresearch increases both in absolute termsand relative to total scientific output, and that the focus of investigation has changed over time frombeing dominated by studies on physiology and disease to being gradually replaced by studies on ecol-ogy and evolution.Esox luciuscan be exploited as a model in future research for identifying causes andconsequences of phenotypic and genetic variation at the levels of individuals, populations and speciesas well as for investigating community processes.

  • 41.
    Fridolfsson, Emil
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Augustsson, Anna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Forss, Jörgen
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Linnaeus University, Linnaeus Knowledge Environments, Water.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Linnaeus University, Linnaeus Knowledge Environments, Water.
    Witthöft, Cornelia M.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Linnaeus University, Linnaeus Knowledge Environments, Sustainable Health.
    Hylander, Samuel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Linnaeus University, Linnaeus Knowledge Environments, Water.
    Förstudie kring hållbar vattenförsörjning i södra Sverige2021Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    Dricksvatten är vårt viktigaste livsmedel men detta rena vatten används även för bevattningsändamål, i vårt avloppssystem och inom industrin. Våra samlade vattenresurser ger dessutom ekosystemtjänster i form av fiske, rekreationsvärde m.m. (Bergek m. fl., 2017). Trots att Sverige är ett mycket vattenrikt land sett ur ett internationellt perspektiv har vattenbrist uppstått i flera delar av landet under senare år. Vidare förväntas pågående och kommande klimatförändringar, befolkningstillväxt och urbanisering påverka vattenkvaliteten negativt samt öka konkurrensen om vatten ytterligare (IPCC, 2014; SMHI, 2020a). Med ökad konkurrens uppstår dessutom målkonflikter mellan olika viktiga samhällsfunktioner. Det finns således ett stort behov av tvärsektoriell forskning samt policyutveckling för att säkerställa en hållbar framtida vattenförsörjning.

    Denna rapport syftar till att sammanställa kunskapsläget vad gäller förutsättningarna för en hållbar vattenförsörjning i Kronobergs län. Först beskrivs tillgång och uttag av dricksvatten i Kronoberg i jämförelse med Kalmar och Skåne län samt förutsättningarna för god framtida vattenkvalitet med Bolmen som exempel. Därefter fokuserar vi på de målkonflikter som kan förväntas uppstå kring dricksvattnet och diskuterar slutligen de kunskapsluckor samt det behov av tvärsektoriell forskning och samhällsutveckling som behövs för en hållbar vattenförsörjning.

    Download full text (pdf)
    Förstudie kring hållbar vattenförsörjning i södra Sverige
  • 42.
    Hall, Marcus
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Koch-Schmidt, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Linnaeus University, Linnaeus Knowledge Environments, Water.
    Yildirim, Yeserin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Sunde, Johanna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Reproductive homing and fine-scaled genetic structuring of anadromous Baltic Sea perch (Perca fluviatilis)2022In: Fisheries Management and Ecology, ISSN 0969-997X, E-ISSN 1365-2400, Vol. 29, no 5, p. 586-596Article in journal (Refereed)
    Abstract [en]

    To investigate the population dynamics of anadromous Baltic Sea perch Perca fluviatilis (Linnaeus), we studied the migratory behaviour (arrival to spawning location) and population structure (genetic structure and differentiation) of three closely located (<50 km) populations. Spawning migration lasted for 32-80 days, and passive integrated transponder tag (PIT-tag) data indicated that anadromous perch displayed reproductive homing. Populations were differentiated, despite low levels of gene flow (3%-5%), and differentiation increased with increasing geographic distance. This fine-scaled spatial structuring was likely, at least partly, explained by homing behaviour. Analyses of temporal within-stream substructuring yielded inconclusive results, so further studies are required to evaluate this. Taken together, our findings highlight the potential for fine-scaled genetic structuring in anadromous perch and indicate that multiple mechanisms, such as isolation by distance, homing, and reproductive timing could contribute to this pattern. This illustrates the importance of considering cryptic barriers to accurately identify reproductive units, and points to the need for local management of anadromous perch.

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    fulltext
  • 43.
    Hall, Marcus
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nordahl, Oscar
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Linnaeus University, Linnaeus Knowledge Environments, Water.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Linnaeus University, Linnaeus Knowledge Environments, Water.
    Intra-population variation in reproductive timing covaries with thermal plasticity of offspring performance in perch Perca fluviatilis2021In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 90, no 10, p. 2236-2347Article in journal (Refereed)
    Abstract [en]

    Life history theory posits that organisms should time their reproduction to coincide with environmental conditions that maximize their fitness. Population-level comparisons have contributed important insights on the adaptive value of reproductive timing and its association to environmental variation. Yet, despite its central role to ecology and evolution, the causes and consequences of variation in reproductive timing among individuals within populations are poorly understood in vertebrates other than birds. Using a combination of observational field studies and a split-brood experiment, we investigated whether differences in breeding time were associated with changes in hatching success, reproductive allocation and reaction norms linking offspring performance to temperature within an anadromous Baltic Sea population of perch Perca fluviatilis. Field observations revealed substantial variation in reproductive timing, with the breeding period lasting almost 2 months and occurring in temperatures ranging from 10 to 21celcius. The hatching success of perch decreased as the reproductive season progressed. At the same time, the reproductive allocation strategy changed over the season, late breeders (the offspring of which were introduced into a high resource environment and increased predation pressure) produced more and smaller eggs that resulted in smaller larvae, compared with early breeders. The split-brood experiment in which eggs were incubated in different temperatures (10, 12, 15, 18 degrees C) showed that differences in reproductive timing were associated with a change in the shape of the reaction norm linking offspring performance to water temperature indicative of adaptive phenotypic plasticity, with the offspring of early breeders performing best in low temperatures and the offspring of late breeders performing best in high temperatures. The seasonal changes in reproductive traits and the shape of the thermal performance suggest time-dependent adaptive differences among individuals within the population. Management actions aimed at preserving and restoring variation in the timing of reproductive events will thus likely also influence variation in associated life history traits and thermal performance curves, which could safeguard populations against environmental challenges and changes associated with exploitation and global warming.

  • 44. Hammar, J
    et al.
    Larsson, Per
    Lund university.
    Klavins, M
    Persistent pollutants in normal and dwarf forms of an Arctic Char population (Salvelinus alpinus L.)1993In: Canadian journal of fisheries and aquatic sciences, Vol. 12, p. 2574-2580Article in journal (Refereed)
  • 45. Hansson, M C
    et al.
    Persson, M E
    Larsson, Per
    Lund university.
    Kjellman, C
    von Schantz, T
    PCB load, aryl hydrocarbon receptor (AhR) and CYP1A1 gene transcription in a wild population of Atlantic salmon (Salmo salar L.) in the Baltic Sea2006In: Environmental toxicology and chemistry, Vol. 25, p. 2197-2207Article in journal (Refereed)
  • 46. Hansson, Maria C.
    et al.
    Persson, Maria E.
    Larsson, Per
    University of Kalmar, School of Pure and Applied Natural Sciences.
    von Schantz, Torbjörn
    Polychlorinated biphenyl (PCB) load, lipid reserves and biotransformation activity in migrating Atlantic salmon from River Mörrum, Sweden2009In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 157, no 12, p. 3396-3403Article in journal (Refereed)
    Abstract [en]

    Atlantic salmon accumulate high levels of contaminants such as polychlorinated biphenyls (PCBs) in their lipids during the adult growth phase spent at sea. The lipids are later utilized during migration for swimming and biological adaptations. We hypothesize that migrating salmons' biotransformation processes are affected by the high levels of built-up PCBs compared to salmon that in a pre-migrational stage. For these analyses we sampled adult Atlantic salmon during migration in the Swedish River Morrum and measured the 21 most common PCB congeners (Sigma PCB) and lipid levels in muscle tissue, aryl hydrocarbon receptor (AHR2) and cytochrome P4501A1(CYP1A1) transcript levels as well as ethoxyresorufin-O-deethylase activity (EROD) in liver. We also determined which AHR2 genotypes the salmon carried. We show that EROD activity is correlated to CYP1A1 level but not to Sigma PCB concentration. Sigma PCB concentration does not predict levels of neither the AHR2 nor CYP1A1 genes. We find no associations between specific AHR2 transcription levels and AHR2 genotypes or a correlation between AHR2 and CYP1A1 transcription levels, which is in direct contrast to pre-migrational adult salmon from the Baltic Sea. When we compare River Morrum to salmon we have previously sampled in the Baltic Sea we show that migrating salmon have significantly lower lipid levels in their muscles; higher muscle concentrations of Sigma PCB on a lipid basis; and significantly lower CYP1A1 and EROD levels compared to salmon from the Baltic Sea. Also, transcript levels of three out of four AHR2 genes are significantly different. In conclusion, migrating Swedish Atlantic salmon carry higher concentrations of PCBs in their lipids compared to salmon in the Baltic Sea, but have lower activation of biotransformation genes and enzymes. Our results indicate that accumulated pollutants from the Baltic Sea are deactivated inside the migrating salmon's lipid tissues and increase in concentration when migration is initiated thereby limiting their impact on biotransformation processes.

  • 47. Holmqvist, N
    et al.
    Stenroth, Patrik
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Berglund, O
    Granéli, W.
    Nyström, P
    Larsson, Per
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Persistent organic pollutants (POPs) in a benthic omnivore – A comparison between lake and stream crayfish populations2007In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 66, p. 1070-1078Article in journal (Refereed)
  • 48. Holmqvist, N
    et al.
    Stenroth, Patrik
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Berglund, O
    Granéli, W.
    Nyström, P
    Larsson, Per
    Lund university.
    The importance of lake trophic status on bioaccumulation of PCBs in benthic organisms – a comparison between littoral and profundal invertebrates2005In: Canadian journal of fisheries and aquatic sciences, Vol. 62, p. 1201-1209Article in journal (Refereed)
  • 49. Holmqvist, N
    et al.
    Stenroth, Patrik
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Berglund, O
    Nyström, P
    Olsson, K
    Jellyman, D
    McIntosh, A R
    Larsson, Per
    Lund university.
    Low levels of persistent organic pollutans (POPs) in New Zealand eels reflect isolation from atmospheric sources2006In: Environmental pollution, Vol. 141, p. 532-538Article in journal (Refereed)
  • 50. J. Tranvik, Lars
    et al.
    Larsson, Per
    Limnology, Department of Ecology, University of Lund .
    Okla, L
    Regnell, O
    In situ mineralization of chlorinated phenols by pelagic bacteria in lakes of differing humic content1991In: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 10, no 2, p. 195-200Article in journal (Refereed)
    Abstract [en]

    The microbial mineralization of phenol and three chlorinated phenols (3,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the water column of 23 pristine, oligotrophic lakes of different humic content was investigated. During short-term (∼2 d) in situ incubations of water samples amended with 14C-labeled phenolic compounds, the fraction of the added pollutant mineralized to 14CO2 was positively correlated with water color (an estimate of humic content) and the total organic carbon concentration of the water. The rate of mineralization per bacterial cell was not correlated with humic content, due to increased bacterial abundance with increasing humic content. Hence, the higher mineralization rate in humic lakes than in clear-water lakes was probably a result of higher bacterial abundance rather than being an effect of bacterial cells having a higher potential for the degradation of such compounds. 

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