| 1. |
|
|
| 2. |
- Bastias, Elliot, et al.
(author)
-
Chemical and optical properties of leachates from different riparian particulate organic matter sources influence instream microbial activity
- 2020
-
In: Freshwater Science. - : University of Chicago Press. - 2161-9549 .- 2161-9565. ; 39:4, s. 812-823
-
Journal article (peer-reviewed)abstract
- The release of soluble compounds (i.e., leachates) from allochthonous coarse particulate organic matter (CPOM) into stream water can be an important source of dissolved organic matter (DOM) and nutrients for instream microbial activity. Here, we assessed variability in the chemistry and the composition of DOM of leachates from different CPOM sources and examined how these characteristics influenced the activity of microbial assemblages in streams. Specifically, we considered leaf litter from 6 tree species that are broadly distributed in riparian zones of the Mediterranean region, a mixture of fruits from some of these species, and a mixture of twigs. We analyzed the leachates from each CPOM source for the concentration of dissolved forms of carbon, nitrogen, and phosphorus, as well as for the composition of DOM based on optical indices associated with the degree of aromaticity and molecular weight. Under laboratory conditions, we used the Resazurin–Resorufin system to estimate the microbial metabolic activity associated with each leachate type. Microbial metabolic activity varied among leachates from different CPOM sources and was positively related to the degree of aromaticity and the NO3– concentration of leachates. Hence, certain types of riparian CPOM inputs can constitute sources of high-quality DOM and dissolved nutrients for instream microbial assemblages. Thus, management of riparian vegetation should consider variation in leachate properties among plant species, as they can influence dissolved organic carbon and nutrient dynamics and heterotrophic activity in stream ecosystems.
|
|
| 3. |
- Bastias, Elliot, et al.
(author)
-
Landscape regulation of microbial use of terrestrial carbon in boreal streams
- 2024
-
In: Aquatic Sciences. - : Springer Science+Business Media B.V.. - 1015-1621 .- 1420-9055. ; 86:2
-
Journal article (peer-reviewed)abstract
- Microbes decomposing leaf litter in aquatic ecosystems are exposed to two major sources of carbon (C), namely, particulate organic C (POC) and dissolved organic C (DOC). The use of DOC relative to POC during litter decomposition likely depends on the availability of DOC, which in turn is regulated by the characteristics of the surrounding landscape, although this extrinsic indirect control of DOC use remains largely unexplored. We have investigated how variations in stream physical and chemical characteristics, distribution of major landscape elements (i.e., forest, mires, and lakes), and riparian vegetation community composition (i.e., relative cover of deciduous vs. coniferous tree species) influence DOC use by leaf-associated microbes (LAM). Specifically, in a boreal stream network of ten first- to third-order streams, we related in-stream characteristics, landscape elements, and riparian vegetation community composition to DOC/POC respiration ratios (i.e., the amount of CO2 produced by LAM respiration of DOC + POC divided by the amount of leaf C mass lost through decomposition). The results showed that DOC/POC respiration ratios were > 1 in most of the study sites, indicating that LAM use a substantial amount of DOC during leaf litter decomposition. This microbial reliance on DOC varied with in-stream DOC and nutrient concentrations, proportional mire and forest cover, and riparian vegetation community composition. In particular, high mire and coniferous cover increased DOC use by LAM. As such, landscape configuration and how it is modified by land use and climate change must be considered in order to understand microbial turnover of terrestrial C in boreal streams.
|
|
| 4. |
- Bastias, Elliot, et al.
(author)
-
Seasonal variation in the coupling of microbial activity and leaf litter decomposition in a boreal stream network
- 2022
-
In: Freshwater Biology. - : John Wiley & Sons. - 0046-5070 .- 1365-2427. ; 67:5, s. 812-827
-
Journal article (peer-reviewed)abstract
- Most stream networks are characterised by spatial and temporal variability in the physico-chemical conditions that regulate microbial processing of particulate organic matter. How these patterns control the turnover of particulate organic matter via altered activity of leaf-associated microbes has rarely been studied in high-latitude landscapes, particularly throughout long (i.e., up to 6 months) ice- and snow-covered periods.We investigated development of fungal biomass, enzyme activity, microbial respiration, and birch leaf litter decomposition from autumn to early summer in 11 nested streams in a boreal catchment that encompass a gradient in wetland (mire) cover.We observed relatively low variability in decomposition rates across the network, despite differences in key physical and chemical variables (e.g. temperature, pH, and dissolved organic carbon [DOC] concentrations) over time and space.Microbial enzymatic activity and respiration were positively related to leaf litter decomposition rates during early stages of decomposition (i.e., up to c. 30% loss of initial ash-free dry mass). Thereafter, variation in microbial activity and respiration was decoupled from leaf litter mass loss, as enzymatic activity and respiration instead became positively related to DOC concentrations and upstream mire (wetland) cover among streams.Our results suggest that leaf-associated microbes increase their reliance on external sources of energy over time. This switch in resource use was more evident in streams with higher DOC concentration, which in boreal landscapes is largely determined by mire cover. Hence, variation in DOC concentration, linked to landscape configuration, or from intensified land use and climate change, could affect how different carbon sources are used by stream microbial communities, with consequences for overall carbon cycling in boreal headwaters.
|
|
| 5. |
- Brodin, Tomas, et al.
(author)
-
Dilute concentrations of a psychiatric drug alter behavior of fish from natural populations
- 2013
-
In: Science. - : The American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 339:6121, s. 814-815
-
Journal article (peer-reviewed)abstract
- Environmental pollution by pharmaceuticals is increasingly recognized as a major threat to aquatic ecosystems worldwide. A variety of pharmaceuticals enter waterways by way of treated wastewater effluents and remain biochemically active in aquatic systems. Several ecotoxicological studies have been done, but generally, little is known about the ecological effects of pharmaceuticals. Here we show that a benzodiazepine anxiolytic drug (oxazepam) alters behavior and feeding rate of wild European perch (Perca fluviatilis) at concentrations encountered in effluent-influenced surface waters. Individuals exposed to water with dilute drug concentrations (1.8 micrograms liter–1) exhibited increased activity, reduced sociality, and higher feeding rate. As such, our results show that anxiolytic drugs in surface waters alter animal behaviors that are known to have ecological and evolutionary consequences.
|
|
| 6. |
- Brodin, Tomas, et al.
(author)
-
Ecological effects of pharmaceuticals in aquatic systems-impacts through behavioural alterations
- 2014
-
In: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 369:1656, s. 20130580-
-
Research review (peer-reviewed)abstract
- The study of animal behaviour is important for both ecology and ecotoxicology, yet research in these two fields is currently developing independently. Here, we synthesize the available knowledge on drug-induced behavioural alterations in fish, discuss potential ecological consequences and report results from an experiment in which we quantify both uptake and behavioural impact of a psychiatric drug on a predatory fish (Perca fluviatilis) and its invertebrate prey (Coenagrion hastulatum). We show that perch became more active while damselfly behaviour was unaffected, illustrating that behavioural effects of pharmaceuticals can differ between species. Furthermore, we demonstrate that prey consumption can be an important exposure route as on average 46% of the pharmaceutical in ingested prey accumulated in the predator. This suggests that investigations of exposure through bioconcentration, where trophic interactions and subsequent bioaccumulation of exposed individuals are ignored, underestimate exposure. Wildlife may therefore be exposed to higher levels of behaviourally altering pharmaceuticals than predictions based on commonly used exposure assays and pharmaceutical concentrations found in environmental monitoring programmes.
|
|
| 7. |
- Burrows, Ryan M., et al.
(author)
-
Interactive effects of light and nutrients on stream algal growth modified by forest management in boreal landscapes
- 2021
-
In: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 492
-
Journal article (peer-reviewed)abstract
- Boreal forests account for 30% of the world's total forest cover and in many places are subject to intensive forest management, which often involves complete removal of overstory vegetation by clear-cutting. However, we still do not fully understand how forest management affects aquatic ecosystems in these landscapes. Here we asked how forest management-induced changes in environmental conditions, such as incident light and nutrient availability, affect benthic algal growth and nutrient limitation in boreal headwater streams of northern Sweden. We answered this question using a combination of correlative and experimental approaches across a range of forested streams spanning a gradient of site (e.g. canopy openness and water chemistry) and catchment-level (e.g. age of forest regrowth) parameters, with variation among the study streams influenced by different forest management histories and underlying natural variation. We found that benthic algal growth in these forested streams was largely driven by local interactions between dissolved inorganic nitrogen (N) availability and incident light reaching benthic surfaces. Greater water temperature and shallower depths were also associated with greater algal growth. Although high dissolved organic carbon (DOC) concentrations often play a role in reducing light availability to autotrophs in boreal aquatic systems, it was not an important predictor of algal growth in small forested streams despite a large DOC concentration gradient (5 – 32 mg/L). Results from experimental nutrient additions supported the role of N as a key limiting nutrient, but also revealed both spatial and seasonal factors that modulate the effects of altered nutrient availability. Overall, our results suggest that differences in how light regimes and nutrient loading respond to forest management generate small-scale variation in the controls over stream primary productivity, which likely shift in relative importance at the time scale of a forest rotation (60 to 100 years).
|
|
| 8. |
- Burrows, Ryan, et al.
(author)
-
Nitrogen limitation of heterotrophic biofilms in boreal streams
- 2015
-
In: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 60:7, s. 1237-1251
-
Journal article (peer-reviewed)abstract
- Nutrient limitation of the biofilm is fundamental to stream ecosystem processes, as microbial activity shapes the biological availability and biogeochemical cycling of carbon and nutrients. We used nutrient-diffusing substrata (NDS) to investigate heterotrophic nutrient limitation of microbial respiration (MR) across 20 streams draining boreal landscapes in northern Sweden. We also explored variation in microbial biomass and community structure of biofilms that developed on NDS using phospholipid fatty acid (PLFA) biomarkers. Limitation was determined as a significant response of MR and biomass production on cellulose surfaces to enrichment with nitrogen (N), phosphorus (P) or N+P, relative to controls. Microbial respiration was N-limited, with an average 3.3-fold increase on N-amended NDS. Nitrogen limitation decreased, and control rates of MR increased, with greater background concentrations of inorganic N across the sites. In contrast to MR, microbial biomass was primarily N-limited but was greatest for the N+P NDS. Accordingly, differences in respiratory versus biomass responses to nutrient addition resulted in significantly greater biomass-specific MR on N-amended NDS compared to all other treatments. In addition, PLFA biomarkers indicated distinct microbial communities on N and N+P NDS compared to controls and/or P NDS. Greater MR and biomass, and the development of distinct microbial communities, when supplied with inorganic N suggest that factors which alter aquatic N loading during autumn may have important implications for ecosystem processes and the biogeochemistry of boreal streams and rivers. Our findings add to a growing body of evidence that the productivity of Fennoscandian boreal landscapes is constrained by N availability.
|
|
| 9. |
|
|
| 10. |
- Fahlman, Johan, et al.
(author)
-
Impacts of Oxazepam on Perch (Perca fluviatilis) Behavior : Fish Familiarized to Lake Conditions Do Not Show Predicted Anti-anxiety Response
- 2021
-
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 55:6, s. 3624-3633
-
Journal article (peer-reviewed)abstract
- A current theory in environmental science states that dissolved anxiolytics (oxazepam) from wastewater effluents can reduce anti-predator behavior in fish with potentially negative impacts on prey fish populations. Here, we hypothesize that European perch (Perca fluviatilis) populations being exposed to oxazepam in situ show reduced anti-predator behavior, which has previously been observed for exposed isolated fish in laboratory studies. We tested our hypothesis by exposing a whole-lake ecosystem, containing both perch (prey) and northern pike (Esox lucius; predator), to oxazepam while tracking fish behavior before and after exposure in the exposed lake as well as in an unexposed nearby lake (control). Oxazepam concentrations in the exposed lake ranged between 11 and 24 μg L-1, which is >200 times higher than concentrations reported for European rivers. In contrast to our hypothesis, we did not observe an oxazepam-induced reduction in anti-predator behavior, inferred from perch swimming activity, distance to predators, distance to conspecifics, home-range size, and habitat use. In fact, exposure to oxazepam instead stimulated anti-predator behavior (decreased activity, decreased distance to conspecifics, and increased littoral habitat use) when using behavior in the control lake as a reference. Shoal dynamics and temperature changes may have masked modest reductions in anti-predator behavior due to oxazepam. Although we cannot fully resolve the mechanism(s) behind our observations, our results indicate that the effects of oxazepam on perch behavior in a familiar natural ecosystem are negligible in comparison to the effects of other environmental conditions.
|
|
| 11. |
- Fahlman, Johan, et al.
(author)
-
Six common behavioral trials and their relevance for perch performance in natural lakes
- 2020
-
In: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 732
-
Journal article (peer-reviewed)abstract
- Behavioral traits measured in laboratory settings are commonly used when predicting ecological effects and evolutionary outcomes in natural systems. However, uncertainties regarding the relevance of simplified lab-based behavioral tests for complex natural environments have created doubts about the use of these tests within aquatic ecology and ecotoxicology. In this study, we scrutinize the assumption that fish performance in six commonly applied behavioral assays has relevance for in situ behavior, by comparing individual behavior tracked in both artificial laboratory settings as well as in two natural lakes. We show that: i) commonly measured behavioral traits of individual fish (Perca fluviatilis) have low predictive power for within-lake behaviors if interpreted alone, but that; ii) composite variables synthesized from several (six) behavioral assays explain important in situ measures such as swimming activity, dispersion, home-range size, and habitat preference. While our findings support recent criticisms against the use of single behavioral tests for predicting environmental effects, we provide empirical evidences suggesting that fish performances in multiple laboratory assays are highly relevant for fish behavior in nature.
|
|
| 12. |
- Fahlman, Johan, et al.
(author)
-
Using laboratory incubations to predict the fate of pharmaceuticals in aquatic ecosystems
- 2018
-
In: Environmental Chemistry. - : CSIRO Publishing. - 1448-2517 .- 1449-8979. ; 15:8, s. 463-471
-
Journal article (peer-reviewed)abstract
- Environmental contextEnvironmental persistence of excreted pharmaceuticals in aquatic ecosystems is usually predicted using small-scale laboratory experiments assumed to simulate natural conditions. We studied five pharmaceuticals comparing their removal rates from water under laboratory conditions and under natural environmental conditions existing in a large pond. We found that the laboratory conditions did not fully capture the complexity within the pond, which led to different removal rates in the two systems. AbstractEnvironmental persistence is a key property when evaluating risks with excreted pharmaceuticals in aquatic ecosystems. Such persistence is typically predicted using small-scale laboratory incubations, but the variation in aquatic environments and scarcity of field studies to verify laboratory-based persistence estimates create uncertainties around the predictive power of these incubations. In this study we: (1) assess the persistence of five pharmaceuticals (diclofenac, diphenhydramine, hydroxyzine, trimethoprim and oxazepam) in laboratory experiments under different environmental conditions; and (2) use a three-month-long field study in an aquatic ecosystem to verify the laboratory-based persistence estimates. In our laboratory assays, we found that water temperature (TEMP), concentrations of organic solutes (TOC), presence of sediment (SED), and solar radiation (SOL) individually affected dissipation rates. Moreover, we identified rarely studied interaction effects between the treatments (i.e. SOLxSED and TEMPxSOL), which affected the persistence of the studied drugs. Half-lives obtained from the laboratory assays largely explained the dissipation rates during the first week of the field study. However, none of the applied models could accurately predict the long-term dissipation rates (month time-scale) from the water column. For example, the studied antibioticum (trimethoprim) and the anti-anxiety drug (oxazepam) remained at detectable levels in the aquatic environment long after (similar to 150 days) our laboratory based models predicted complete dissipation. We conclude that small-scale laboratory incubations seem sufficient to approximate the short-term (i.e. within a week) dissipation rate of drugs in aquatic ecosystems. However, this simplistic approach does not capture interacting environmental processes that preserve a fraction of the dissolved pharmaceuticals for months in natural water bodies.
|
|
| 13. |
- Fick, Jerker, et al.
(author)
-
Screening of benzodiazepines in thirty European rivers
- 2017
-
In: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 176, s. 324-332
-
Journal article (peer-reviewed)abstract
- Pharmaceuticals as environmental contaminants have received a lot of interest over the past decade but, for several pharmaceuticals, relatively little is known about their occurrence in European surface waters. Benzodiazepines, a class of pharmaceuticals with anxiolytic properties, have received interest due to their behavioral modifying effect on exposed biota. In this study, our results show the presence of one or more benzodiazepine(s) in 86% of the analyzed surface water samples (n = 138) from 30 rivers, representing seven larger European catchments. Of the 13 benzodiazepines included in the study, we detected 9, which together showed median and mean concentrations (of the results above limit of quantification) of 5.4 and 9.6 ng L-1, respectively. Four benzodiazepines (oxazepam, temazepam, clobazam, and bromazepam) were the most commonly detected. In particular, oxazepam had the highest frequency of detection (85%) and a maximum concentration of 61 ng L-1. Temazepam and clobazam were found in 26% (maximum concentration of 39 ng L-1) and 14% (maximum concentration of 11 ng L-1) of the samples analyzed, respectively. Finally, bromazepam was found only in Germany and in 16 out of total 138 samples (12%), with a maximum concentration of 320 ng L-1. This study clearly shows that benzodiazepines are common micro-contaminants of the largest European river systems at ng L-1 levels. Although these concentrations are more than a magnitude lower than those reported to have effective effects on exposed biota, environmental effects cannot be excluded considering the possibility of additive and sub-lethal effects.
|
|
| 14. |
- Frangou, Sophia, et al.
(author)
-
Cortical thickness across the lifespan : Data from 17,075 healthy individuals aged 3-90 years
- 2022
-
In: Human Brain Mapping. - : John Wiley & Sons. - 1065-9471 .- 1097-0193. ; 43:1, s. 431-451
-
Journal article (peer-reviewed)abstract
- Delineating the association of age and cortical thickness in healthy individuals is critical given the association of cortical thickness with cognition and behavior. Previous research has shown that robust estimates of the association between age and brain morphometry require large-scale studies. In response, we used cross-sectional data from 17,075 individuals aged 3-90 years from the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Consortium to infer age-related changes in cortical thickness. We used fractional polynomial (FP) regression to quantify the association between age and cortical thickness, and we computed normalized growth centiles using the parametric Lambda, Mu, and Sigma method. Interindividual variability was estimated using meta-analysis and one-way analysis of variance. For most regions, their highest cortical thickness value was observed in childhood. Age and cortical thickness showed a negative association; the slope was steeper up to the third decade of life and more gradual thereafter; notable exceptions to this general pattern were entorhinal, temporopolar, and anterior cingulate cortices. Interindividual variability was largest in temporal and frontal regions across the lifespan. Age and its FP combinations explained up to 59% variance in cortical thickness. These results may form the basis of further investigation on normative deviation in cortical thickness and its significance for behavioral and cognitive outcomes.
|
|
| 15. |
- Gamfeldt, Lars, 1975, et al.
(author)
-
Higher levels of multiple ecosystem services are found in forests with more tree species
- 2013
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 4
-
Journal article (peer-reviewed)abstract
- Forests are of major importance to human society, contributing several crucial ecosystem services. Biodiversity is suggested to positively influence multiple services but evidence from natural systems at scales relevant to management is scarce. Here, across a scale of 400,000km2, we report that tree species richness in production forests shows positive to positively hump-shaped relationships with multiple ecosystem services. These include production of tree biomass, soil carbon storage, berry production and game production potential. For example, biomass production was approximately 50% greater with five than with one tree species. In addition, we show positive relationships between tree species richness and proxies for other biodiversity components. Importantly, no single tree species was able to promote all services, and some services were negatively correlated to each other. Management of production forests will therefore benefit from considering multiple tree species to sustain the full range of benefits that the society obtains from forests.
|
|
| 16. |
- Hellström, Gustav, et al.
(author)
-
Environmentally relevant concentrations of the common anxiolytic pharmaceutical oxazepam do not have acute effect on spawning behavior in mature male Atlantic salmon (Salmo salar) parr
- 2020
-
In: Journal of Applied Ichthyology. - : John Wiley & Sons. - 0175-8659 .- 1439-0426. ; 36:1, s. 105-112
-
Journal article (peer-reviewed)abstract
- Low concentrations of psychiatric drugs are commonly found in surface waters around the world, and their ability to alter behaviors in aquatic fauna has raised concerns about ecological effects. One critical effect that contamination can have in aquatic systems is modifications of reproductive behaviors. In this study, we hypothesized that oxazepam, a common anxiolytic drug and aquatic contaminant previously shown to induce anti-anxiety behavior in salmonids, also affects the reproductive behavior of Atlantic salmon (Salmo salar). To test this hypothesis, small sexually mature Atlantic salmon males (mature parr) were exposed to concentrations of oxazepam comparable to that of effluent water (1.9 mu g/L). After 5 days of exposure, their reproductive behavior was compared with that of unexposed control individuals. Behavior was monitored in a large-scale flume aquarium that also contained a large male and a female to mimic natural spawning conditions for Atlantic salmon. Three behaviors were quantified for the mature parr; (a) amount of courting behavior towards female, (b) proximity to female, and (c) amount of attacks received from the large male. In contrast to our hypothesis, no difference in either courting behavior, proximity to female, or received aggression could be found between exposed and control male parr. Hence, our results indicate that there is no acute effect of the highest levels of oxazepam concentration reported for urban environments on spawning behavior of mature male parr, although chronic effects could not be ruled out.
|
|
| 17. |
- Hellström, Gustav, et al.
(author)
-
GABAergic anxiolytic drug in water increases migration behaviour in salmon
- 2016
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
-
Journal article (peer-reviewed)abstract
- Migration is an important life-history event in a wide range of taxa, yet many migrations are influenced by anthropogenic change. Although migration dynamics are extensively studied, the potential effects of environmental contaminants on migratory physiology are poorly understood. In this study we show that an anxiolytic drug in water can promote downward migratory behaviour of Atlantic salmon (Salmo salar) in both laboratory setting and in a natural river tributary. Exposing salmon smolt to a dilute concentration of a GABAA receptor agonist (oxazepam) increased migration intensity compared with untreated smolt. These results implicate that salmon migration may be affected by human-induced changes in water chemical properties, such as acidification and pharmaceutical residues in wastewater effluent, via alterations in the GABAA receptor function.
|
|
| 18. |
- Hellström, Gustav, et al.
(author)
-
Upscaling behavioural studies to the field using acoustic telemetry
- 2016
-
In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 170, s. 384-389
-
Journal article (peer-reviewed)abstract
- Laboratory-based behavioural assays are often used in ecotoxicological studies to assess the environmental risk of aquatic contaminants. While results from such laboratory-based risk assessments may be difficult to extrapolate to natural environments, technological advancements over the past decade now make it possible to perform risk assessments through detailed studies of exposed individuals in natural settings. Acoustic telemetry is a technology to monitor movement and behaviour of aquatic organism in oceans, lakes, and rivers. The technology allows for tracking of multiple individuals simultaneously with very high temporal and spatial resolution, with the option to incorporate sensors to measure various physiological and environmental parameters. Although frequently used in fisheries research, aquatic ecotoxicology has been slow to adopt acoustic telemetry as a tool in field-based studies. This mini-review intends to introduce acoustic telemetry to aquatic ecotoxicologists, focusing on the potential of the technology to bridge the gap between laboratory assays and natural behaviours when making toxicological risk assessments.
|
|
| 19. |
- Heynen, Martina, et al.
(author)
-
Effect of bioconcentration and trophic transfer on realized exposure to oxazepam in 2 predators, the dragonfly larvae (Aeshna grandis) and the Eurasian perch (Perca fluviatilis)
- 2016
-
In: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 35:4, s. 930-937
-
Journal article (peer-reviewed)abstract
- Psychoactive substances are used worldwide and constitute one of the most common groups of pharmaceutical contaminants in surface waters. Although these pharmaceuticals are designed to be efficiently eliminated from the human body, very little is known about their trophic-transfer potential in aquatic wildlife. Therefore, the goal of the present study was to quantify and compare uptake of an anxiolytic (oxazepam) from water (bioconcentration) and via the consumption of contaminated diet (trophic transfer) in 2 common freshwater predators: Eurasian perch (Perca fluviatilis) and the dragonfly larvae Aeshna grandis. Bioconcentration and trophic transfer of oxazepam were found in both predator species. However, higher bioconcentrations were observed for perch (bioconcentration factor [BCF], 3.7) than for dragonfly larvae (BCF, 0.5). Perch also retained more oxazepam from consumed prey (41%) than dragonfly larvae (10%), whereas the relative contribution via prey consumption was 14% and 42% for perch and dragonflies, respectively. In addition, bioconcentration was negatively correlated with perch weight, indicating that exposure levels in natural contaminated environments differ between individuals of different size or between different developmental stages. Hence, trophic transfer of pharmaceuticals may indeed occur, and estimates of environmental exposures that do not consider intake via food or size-dependent bioconcentration may therefore lead to wrongful estimations of realized exposure levels in natural contaminated ecosystems. (C) 2016 SETAC
|
|
| 20. |
- Heynen, Martina, et al.
(author)
-
Home alone : the effects of isolation on uptake of a pharmaceutical contaminant in a social fish
- 2016
-
In: Aquatic Toxicology. - : Elsevier. - 0166-445X .- 1879-1514. ; 180, s. 71-77
-
Journal article (peer-reviewed)abstract
- A wide range of biologically active pharmaceutical residues is present in aquatic systems worldwide. As uptake potential and the risk of effects in aquatic wildlife are directly coupled, the aim of this study was to investigate the relationships between stress by isolation, uptake and effects of the psychiatric pharmaceutical oxazepam in fish. To do this, we measured cortisol levels, behavioral stress responses, and oxazepam uptake under different stress and social conditions, in juvenile perch (Percafluviatilis) that were either exposed (1.03 mu gl(-1)) or not exposed to oxazepam. We found single exposed individuals to take up more oxazepam than individuals exposed in groups, likely as a result of stress caused by isolation. Furthermore, the bioconcentration factor (BCF) was significantly negatively correlated with fish weight in both social treatments. We found no effect of oxazepam exposure on body cortisol concentration or behavioral stress response. Most laboratory experiments, including standardized bioconcentration assays, are designed to minimize stress for the test organisms, however wild animals experience stress naturally. Hence, differences in stress levels between laboratory and natural environments can be one of the reasons why predictions from artificial laboratory experiments largely underestimate uptake of oxazepam, and other pharmaceuticals, in the wild.
|
|
| 21. |
- Heynen, Martina, et al.
(author)
-
Tissue-specific uptake of the benzodiazepine oxazepam in adult Eurasian perch (Perca fluviatilis)
- 2016
-
In: Environmental Chemistry. - 1448-2517 .- 1449-8979. ; 13:5, s. 849-853
-
Journal article (peer-reviewed)abstract
- Psychoactive substances are used worldwide and constitute one of the common groups of pharmaceutical contaminants in surface waters. Typically, in field surveys and laboratory studies, muscle or whole - body homogenates are used to quantify pharmaceutical concentrations in biota, although uptake of pharmaceuticals may be tissue - specific. Therefore, the aim of this study was to investigate the tissue - specific (muscle, liver, brain and blood plasma) uptake of the anxiolytic oxazepam in adult Eurasian perch (Perca fluviatilis). In laboratory experiments, perch were exposed to four different concentrations (2, 4, 12 and 20 mu g L-1) of oxazepam for 6 days, and muscle, liver, brain tissue and blood plasma were sampled to determine tissue - specific bioconcentration. We found that the tissue - specific bioconcentration was independent of oxazepam concentration. However, among tissue types, bioconcentration was significantly different, with the concentration in muscle, liver = brain, blood plasma. Hence, it is important to consider the type of tissue used to quantify pharmaceutical uptake in fish, for predictions of species - specific sensitivity and comparisons across studies. Furthermore, our results indicate a somewhat lower transportability (brain/plasma ratio 0.54) of oxazepam from blood to brain in fish compared with in mammals, which should be kept in mind when employing 'read - across' approaches.
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
- Jonsson, Bert, Professor, 1961-, et al.
(author)
-
A learning method for all : The testing effect is independent of cognitive ability
- 2021
-
In: Journal of Educational Psychology. - : American Psychological Association (APA). - 0022-0663 .- 1939-2176. ; 113:5, s. 972-985
-
Journal article (peer-reviewed)abstract
- The testing effect, defined as the positive effect of retrieval practice (i.e., self-testing) on long-term memory retention relative to other ways to support learning, is a robust empirical phenomenon. Despite substantial scientific evidence for the testing effect, less is known about its effectiveness in relation to individual differences in cognitive ability. In the present study, we examine whether the effect of retrieval practice is beneficial independent of cognitive ability using behavioral and brain imaging data. In a within-subject design, upper-secondary students learned Swahili–Swedish word pairs through retrieval practice and study. The testing effects were assessed at a direct test and for a subsample after 1- and 4-weeks retention intervals, respectively. Another subsample performed the 1-week retention test during functional MRI (fMRI). Memory retention was analyzed in relation to an educationally relevant composite score dividing participants into low, intermediate, and high cognitive-ability groups. We provide behavioral evidence that the testing effect is independent of cognitive ability. The fMRI findings confirmed a general effectiveness of retrieval practice by showing that brain regions associated with successful retrieval of conceptual representations and semantic processing were more strongly engaged after retrieval practice in all cognitive-ability groups. It is argued that the advantages of retrieval practice should be conveyed to all teachers and students.
|
|
| 25. |
- Jonsson, Micael
(author)
-
A solution to the accelerated-predator-satiety Lotka-Volterra predator-prey problem using Boubaker polynomial expansion scheme
- 2010
-
In: Journal of Theoretical Biology. - : Elsevier BV. - 0022-5193 .- 1095-8541. ; 264, s. 154-160
-
Journal article (peer-reviewed)abstract
- In this study, an analytical method is introduced for the identification of predator-prey populations time-dependent evolution in a Lotka-Volterra predator-prey model which takes into account the concept of accelerated-predator-satiety.Oppositely to most of the predator-prey problem models, the actual model does not suppose that the predation is strictly proportional to the prey density. In reference to some recent experimental results and particularly to the conclusions of May (1973) about predators which are 'never not hungry', an accelerated satiety function is matched with the initial conventional equations. Solutions are plotted and compared to some relevant ones. The obtained trends are in good agreement with many standard Lotka-Volterra solutions except for the asymptotic behaviour. (C) 2010 Elsevier Ltd. All rights reserved.
|
|
