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  • 1.
    Bignert, Anders
    et al.
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Danielsson, Sara
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Ek, Caroline
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Faxneld, Suzanne
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Nyberg, Elisabeth
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Comments Concerning the National Swedish Contaminant Monitoring Programme in Marine Biota, 20172017Report (Other academic)
  • 2.
    Ek, Caroline
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Towards understanding stable isotope signatures in stressed systems2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Stable isotope analysis (SIA) is a valuable tool in ecotoxicology because δ13C and δ15N may provide insights into the trophic transfer of contaminants in a food web. The relationship between a species’ trophic position (TP, determined from δ15N) and internal concentration of biomagnifying contaminants can be established and used for regulatory purposes. However, the exposure of organisms to xenobiotics incurs physiological costs, and the stable isotope signature of a consumer reflects not only diet but also a physiological state. The latter raises questions regarding the interpretation of stable isotope signatures in contaminated areas. Therefore, the aim of this Thesis was to evaluate the behaviour of consumers’ stable isotope signatures in stressed systems, with a primary focus on the effects of environmental contaminants.

    In paper I, the physiological costs of chemical exposure were found to alter incorporation rates of dietary nitrogen and carbon in a consumer by influencing both growth and metabolic turnover, with resulting changes in isotope signatures relative to a control system. In paper II, the diet-consumer discrimination factors for 15N and 13C were confirmed to increase under chemical exposure mediated via increased metabolic costs. However, the physiological response was low and translated into only minor shifts in the δ13C and δ15N. The predictability of exposure effects on the stable isotope signature was demonstrated in paper III, in which animals exposed to a chemical with a known mode of action presented expected effects on elemental composition, body size, biomarkers of oxidative stress and the stable isotope signatures. Moreover, consumers’ oxidative balance was found to be related to their δ15N values, thus providing evidence of the kinetic isotope effect on the oxidative status. However, despite the alterations in stable isotope signatures observed in laboratory settings (papers I-III), the effect of xenobiotics on the TP estimates was nil or minor in the field-collected animals. Moreover, the TP values were not significantly different between the animals in the contaminated and the reference habitats because of the high overall uncertainties in the TP estimates (paper IV). Also, the TP estimates based on δ15N in bulk material were more similar between the contaminated and the reference systems than TP estimates based on δ15N values in amino acids. Therefore, the latter method appears more sensitive towards xenobiotics (and, possibly, other environmental stressors) and thus less suitable for TP assessment in contaminated areas.

    This Thesis improved the overall understanding of the applicability of SIA in stressed systems by establishing relationships between various exposure regimes, physiological responses and the stable isotope signatures in consumers. In model species at low trophic levels, the exposure to xenobiotics was found to significantly affect δ13C and δ15N values, which can be expected whenever physiological responses are detected. However, because of the overall high uncertainty in TP estimates, no significant differences between contaminated and control systems were detected, although the estimated TP were consistently higher in the contaminated systems. Future research should focus on higher trophic levels, in which effects of a greater magnitude can be expected. Moreover, the effects in entire food webs should be addressed rather than single prey–consumer relationships as well as other environmental variables that may contribute to the stable isotope variability in and among systems under various environmental pressures.

  • 3.
    Ek, Caroline
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Gerdes, Zandra
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Garbaras, Andrius
    Adolfsson-Erici, Margaretha
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Gorokhova, Elena
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Growth Retardation and Altered Isotope Composition As Delayed Effects of PCB Exposure in Daphnia magna2016In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, no 15, p. 8296-8304Article in journal (Refereed)
    Abstract [en]

    Trophic magnification factor (TMF) analysis employs stable isotope signatures to derive biomagnification potential for environmental contaminants. This approach relies on species delta N-15 values aligning with their trophic position (TP). This, however, may not always be true, because toxic exposure can alter growth and isotope allocation patterns. Here, effects of PCB exposure (mixture of PCB18, PCB40, PCB128, and PCB209) on delta N-15 and delta C-13 as well as processes driving these effects were explored using the cladoceran Daphnia magna. A two-part experiment assessed effects of toxic exposure during and after exposure; juvenile daphnids were exposed during 3 days (accumulation phase) and then allowed to depurate for 4 days (depuration phase). No effects on survival, growth, carbon and nitrogen content, and stable isotope composition were observed after the accumulation phase, whereas significant changes were detected in adults after the depuration phase. In particular, a significantly lower nitrogen content and a growth inhibition were observed, with a concomitant increase in delta N-15 (+0.1 parts per thousand) and decrease in delta C-13 (-0.1 parts per thousand). Although of low magnitude, these changes followed the predicted direction indicating that sublethal effects of contaminant exposure can lead to overestimation of TP and hence underestimated TMF.

  • 4.
    Ek, Caroline
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Holmstrand, Henry
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Mustajärvi, Lukas
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Garbaras, Andrius
    Bariseviciute, Ruta
    Sapolaite, Justina
    Sobek, Anna
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Gorokhova, Elena
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Karlson, Agnes M. L.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Using compound-specific and bulk stable isotope analysis for trophic positioning of bivalves in contaminated Baltic sediments: a field evaluationManuscript (preprint) (Other academic)
  • 5.
    Ek, Caroline
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Karlson, Agnes M. L.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Hansson, Sture
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Garbaras, Andrius
    Gorokhova, Elena
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Stable Isotope Composition in Daphnia Is Modulated by Growth, Temperature, and Toxic Exposure: Implications for Trophic Magnification Factor Assessment2015In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 49, no 11, p. 6934-6942Article in journal (Refereed)
    Abstract [en]

    The potential for using stable isotope analysis in risk assessment of environmental contaminants is crucially dependent on the predictability of the trophic transfer of isotopes in food webs. The relationship between contaminant levels and trophic position of consumers is widely used to assess biomagnification properties of various pollutants by establishing trophic magnification factors (TMF). However, contaminant-induced variability of the isotopic composition in biota is poorly understood. Here, we investigated effects of toxic exposure on delta N-15 and delta C-13 values in a consumer, with a main hypothesis that these effects would be largely mediated via growth rate and metabolic turnover of the test animals. The cladoceran Daphnia magna was used in two experiments that were conducted to manipulate growth and body condition (assayed as C:N ratio) by food availability and temperature (Experiment 1) and by toxic exposure to the pesticide lindane (Experiment 2). We found a significant negative effect of growth rate and a positive effect of temperature on the consumer-diet discrimination factor for delta N-15 and delta C-13, with no effects on the C:N ratio (Experiment 1). In lindane-exposed daphnids, a significant growth inhibition was observed, with concomitant increase in metabolic costs and significantly elevated size-specific delta N-15 and delta C-13 values. Moreover, a significantly higher incorporation of carbon relative to nitrogen, yet a concomitant decrease in C:N ratio was observed in the exposed animals. Together, these results have methodological implications for determining trophic positions and TMF in polluted environments, where elevated delta N-15 values would translate into overestimated trophic positions and underestimated TMF. Furthermore, altered delta C-13 values may lead to erroneous food-chain assignment of the consumer in question.

  • 6.
    Ek, Caroline
    et al.
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Sundbom, Marcus
    Stockholms universitet, Institutionen för miljövetenskap och analytisk kemi (ACES) .
    Danielsson, Sara
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Faxneld, Suzanne
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Evaluation of different stable isotope methods to estimate trophic position of perch (Perca fluviatilis) in Swedish lakes2019Report (Other academic)
    Abstract [en]

    The Water Framework Directive (WFD) requires member states to implement a strategy to meet the environmental quality standards (EQS) set by the WFD for a number of priority substances. Since the EQSs listed in the WFD are derived to protect the most sensitive species in the ecosystem, often top predators or humans, it has been decided that for certain priority substances the quality standards should be compared to a monitoring species with a trophic position (TP) similar to the diet of the most sensitive species. To enable such adjustment require both knowledge about the monitoring species TP in the food web as well as the relationship between contaminant concentration and trophic position. In this study, we focus on finding a suitable method for TP estimates of perch in Swedish lakes by evaluating both traditional stable isotope analysis in bulk samples (BSIA) using different baseline matrices and the more recent development of compound-specific stable isotope analysis in amino acids (CSIA-AA). For this, three representative monitoring lakes were selected in which perch together with potential baseline matrices (bivalves, gastropods and sediment) were sampled. We applied triple-isotope analyses, d15N, d13C and d34S, of bulk material of all sampled matrices, and in addition d15N in perch using CSIA-AA. Results showed that TP estimates derived from CSIA-AA were significantly (p<0.001) lower compared to all the BSIA-derived methods and further that the BSIA-derived TP estimates using gastropods as a baseline were significantly higher (p<0.001) than all other TP estimates. Since no statistical differences could be detected between TP estimates based on bivalves, sediment or a ‘mixture’ baseline these were assumed to produce similar results and therefore all valid baseline matrices for TP estimates of perch in these three lakes. In the present study we also attempted to adjust mercury contaminant data to a specific TP of 3.5 according to the WFD. The adjustment resulted in significantly different concentration for one of the two tested lakes but did not influence the chemical status classification as all lakes were well above the threshold for mercury in freshwater lakes.

  • 7.
    Ek, Caroline
    et al.
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Winkens Pütz, Kerstin
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Danielsson, Sara
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Faxneld, Suzanne
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Screening for pharmaceuticals, phthalates and polycyclic aromatic hydrocarbons (PAHs) in bivalves sampled along the Swedish coast2019Report (Other academic)
    Abstract [en]

    Within the Swedish National Monitoring Programme for Contaminants in marine biota, a selection of the wide array of contaminants that can be found in the environment is analysed. Analysing the samples for all possible contaminants would hardly be feasible, however, screening for different substance groups is a way to investigate if and where new substances arise and may pose a threat to wildlife and humans. In this report, data from a spatial screening study is presented, which aimed to densify the ongoing Swedish National Monitoring Programme for Contaminants in marine biota with regard to pharmaceuticals, phthalates and polycyclic aromatic hydrocarbons (PAHs). The study includes 16 sampling sites along the Swedish coast, from where two different species of bivalves, Limecola balthica and Mytilus edulis, were collected. All applied sampling material in this screening study originates from the Swedish Environmental Specimen Bank of the Swedish Museum of Natural History. The screening included a total of 100 pharmaceuticals, out of which 17 were detected and quantified in at least one sampling site. Risperidone was the pharmaceutical detected at most sites (10 of 13). The only detected phthalate was di(2-ethylhexyl) phthalate (DEHP), which was found in the samples from 3 of 13 sampling sites. Among the PAHs, Benzo(a)pyrene was the substance quantified at most sites (14 out of 16). No geographical patterns could be identified for the detected contaminants, besides for the PAHs. However, this pattern could also be due to a difference in species rather than due to location. PAHs could be detected in the Bothnian Sea and the Sea of Åland, where to date no mussel sampling sites exist within the Swedish National Monitoring Programme for Contaminants in marine biota. The Baltic clam might be a good additional monitoring species besides the Blue mussel, due to their difference in feeding strategy and the potential higher PAH uptake from contaminated sediments rather than the water phase.

  • 8.
    Ek, Caroline
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Yu, Zhenyang
    Garbaras, Andrius
    Oskarsson, Hanna
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Eriksson Wiklund, Ann-Kristin
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Kumblad, Linda
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Gorokhova, Elena
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Metabolic alterations in Gammarus spp. exposed to the beta-blocker propranolol: what causes the increase in stable isotope ratios?Manuscript (preprint) (Other academic)
  • 9.
    Nyberg, Elisabeth
    et al.
    Swedish Museum of Natural History, Department of Environmental research and monitoring. Naturvårdsverket.
    Bignert, Anders
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Danielsson, Sara
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Ek, Caroline
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Faxneld, Suzanne
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Winkens Pütz, Kerstin
    Swedish Museum of Natural History, Department of Environmental research and monitoring.
    Sundbom, Marcus
    Stockholms universitet, Instituionen för miljövetenskap och analytisk kemi.
    Adjustments for confounders in individual and pooled samples from the Swedish national monitoring of contaminants in freshwater fish2019Report (Other academic)
    Abstract [en]

    Within the Swedish National Monitoring Programme for Contaminants in Freshwater Biota, perch, pike and Arctic char are being analysed from 32 lakes distributed all over Sweden. One of the main objectives of the monitoring has been to detect temporal trends in different areas and for different contaminants. However, the measured concentrations in biota can be affected by biological factors such as age, length, trophic position (TP), fat or dry weight content. A change in one or several of these variables over time, or even among specimens taken within the same year, is likely to result in an increased variation of the measured concentrations and hence in a lower chance of detecting a trend. The purpose of this study was to evaluate if an adjustment of contaminant time trends by primarily stable isotopes, but also other confounding factors can:  A) reduce the individual and between-year variation and hence B) improve the likelihood of detecting temporal trends in time series for metals and organic contaminants. The study revealed an improvement in the likelihood of detecting a contaminant trend after adjustment of the data for almost all lakes and for all tested substances. For some lakes and substances, this improvement was substantial. Age seems to be an important confounding factor for metals and per- and polyfluoroalkyl substances. For lipophilic substances, fat content also appears to be an important factor in some lakes together with adjustments for carbon and nitrogen isotope ratios (d13C and d15N), which all reduced the variation in contaminant data. This suggests that there is a benefit of adjusting data on a regular basis in contaminant monitoring programmes in the future.

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