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1.
  • Woin, Per, 1958-, et al. (author)
  • Effects of metsulfuron methyl and cypermethrin exposure on freshwater model ecosystems
  • 2003
  • In: Aquatic Toxicology. - Amsterdam : Elsevier. - 0166-445X .- 1879-1514. ; 63:3, s. 243-256
  • Journal article (peer-reviewed)abstract
    • The aim of this study was to investigate the short-term (2 weeks) effects of the herbicide metsulfuron methyl alone and in combination with the insecticide cypermethrin in freshwater enclosures (80 l). We used a factorial design with four levels of herbicide (0, 1, 5, 20 mg/l) and two levels of insecticide (0 and 0.05 mg/l). The root growth of the macrophyte species Elodea canadensis and Myriophyllum spicatum decreased following exposure to the lowest concentration of metsulfuron methyl tested. Metsulfuron methyl exposure resulted in a decreased pH in the aquatic enclosure at the lowest concentration tested, which is most likely a further indication of decreased macrophyte primary production. The biomass of periphytic algae growing on the leaves of M. spicatum increased in the enclosures exposed to metsulfuron methyl. The species composition of the periphytic algae differed significantly from the controls in the enclosures exposed to 20 mg/l of the herbicide. The increased biomass of periphytic algae on the leaves of the macrophytes is probably an indirect effect of the herbicide exposure. The exposure to metsulfuron methyl possibly induced a leakage of nutrients from the macrophyte leaves, which promoted an increased algal growth. The exposure to metsulfuron methyl did not alter the biomass or the species composition of the phytoplankton community. The zooplankton communities in the enclosures were dominated by rotifers, which were not affected by the exposure to cypermethrin. However, a cypermethrin exposure of 0.05 mg/l initially decreased the abundance of copepod nauplii. Ten days after exposure, the abundance of nauplii was significantly higher in the insecticide-exposed enclosures compared with the non-exposed enclosures. This might be an indication of a sub-lethal stress response, which either increased the number of offspring produced or induced an increased hatching of copepod resting stages. No combined effects of the herbicide and insecticide exposure, either direct or indirect, were observed in the enclosure study. Significant effects on the macrophytes were observed following exposure to 1 mg metsulfuron methyl per litre in the enclosure study. Furthermore, a single species laboratory assay indicated that the shoot elongation of E. canadensis decreased following exposure to ]/0.1 mg metsulfuron methyl per litre. These concentrations are well within the range of expected environmental concentrations, thus this study shows that aquatic ecosystems, in particular those which are macrophyte- dominated, may be affected by metsulfuron methyl at concentrations that may well occur in water bodies adjacent to agricultural land.
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2.
  • Woin, Per, 1958-, et al. (author)
  • Effects of the pyrethroid insecticide cypermethrin on a freshwater community studied under field conditions : II. Direct and indirect effects on the species composition
  • 2003
  • In: Aquatic Toxicology. - Amsterdam : Elsevier. - 0166-445X .- 1879-1514. ; 63:4, s. 373-389
  • Journal article (peer-reviewed)abstract
    • The effects of cypermethrin, a commonly used pyrethroid insecticide, were studied in small in situ enclosures situatedin an eutrophic lake over an 11-day period. The experimental design used a regression principle that included threeuntreated controls and a gradient of six unreplicated cypermethrin concentrations, ranging from 0.01 to 6 mg/l. Thispaper is the second in a series of two and describes the effects on the species composition of the crustacean, rotifer,periphyton and phytoplankton communities. Multivariate ordination technique (redundancy analysis (RDA) combinedwith Monte Carlo permutation tests) showed that exposure to cypermethrin caused significant changes in the speciescomposition of the communities. Changes in the structure of the communities were observed following exposure to anominal concentration of 0.13 mg cypermethrin per litre above. The direct acute effect of exposure to cypermethrin wasa rapid decrease of many species of crustacean zooplankton. The alterations in crustacean species composition wereprobably due to variations in susceptibility to the direct toxic effects of cypermethrin. No effects concentration (NEC)for individual zooplankton species were calculated using inverse regression and revealed that copepod nauplii were themost sensitive (NEC /0.01 mg/l) of the crustacean groups examined. The observed alterations of the speciescomposition of the autotrophic communities as well as of the rotifers were most likely caused indirectly bycypermethrin, mediated through the direct negative effects of the insecticide on the crustacean grazers. The results ofthis experiment provide further knowledge about the direct and indirect effects of pesticide stress on the ecosystem level.They also show that there is a variation in sensitivity between different species of zooplankton under natural conditionsand thus exemplify the necessity of multispecies approaches in the risk assessment of pesticides.
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3.
  • Woin, Per, 1958-, et al. (author)
  • Effects of the pyrethroid insecticide, cypermethrin, on a freshwater community studied under field conditions : I. Direct and indirect effects on abundance measures of organisms at different trophic levels.
  • 2003
  • In: Aquatic Toxicology. - Amsterdam : Elsevier. - 0166-445X .- 1879-1514. ; 63:4, s. 357-371
  • Journal article (peer-reviewed)abstract
    • The effects of the pyrethroid insecticide cypermethrin on a natural freshwater community were studied in small in situenclosures over an 11-day period. The experiment was conducted in a eutrophic lake using a regression design thatincluded three untreated controls and a gradient of six unreplicated cypermethrin concentrations, ranging from 0.01 to6.1 mg/l. This paper is the first in a series of two, and describes the fate of cypermethrin and its effects on the abundanceof crustaceans, rotifers, protozoans (cilliates and heterotrophic nanoflagellates (HNF)) and bacteria and the biomass ofperiphytic and planktonic algae. The concentration of cypermethrin decreased quickly during the experiment, with ahalf-life of 48 h for the total and 25 h for the dissolved fractions of cypermethrin, respectively. Cypermethrin proved tobe acutely toxic to crustaceans in enclosures receiving nominal cypermethrin concentrations of ]/0.13 mg/l. No EffectConcentration (NEC) and median Effect Concentration (EC50) for the total crustacean community and cladoceran andcopepod subgroups ranged between 0.02 /0.07 and 0.04 /0.17 mg/l, respectively, with copepods being less sensitive thancladocerans. The abundance of rotifers, protozoans and bacteria and the chlorophyll-a concentration of planktonic andperiphytic algae was significantly related to the concentration of cypermethrin. All groups proliferated within 2 /7 daysafter the cypermethrin application in those enclosures where the abundance of crustaceans was seriously affected bycypermethrin (i.e. ]/0.13 mg/l). We hypothesise that the proliferation of rotifers, protozoans, bacteria and algae was dueto a reduced grazer control from crustaceans and thereby mediated indirectly by cypermethrin. The results of thisexperiment provide knowledge on how an entire microplankton community may respond to pyrethroids in nature, andthe indirect effects observed on the community clearly demonstrates the necessity of multispecies field experiments inecotoxicological risk assessment
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4.
  • Bjerselius, R, et al. (author)
  • Male goldfish reproductive and physiology are severely affected by exogenous exposure to 17b-estradiol
  • 2001
  • In: Aquatic Toxicology. - 0166-445X .- 1879-1514. ; 53:2, s. 139-152
  • Journal article (peer-reviewed)abstract
    • Mature male goldfish were exposed to different concentrations of the natural hormone 17beta-estradiol (E2). Two methods of exposure were employed, via ingestion at 0, 1, 10 and 100 microg/g food and via the water at 0, 1 and 10 microg/l. The fish were exposed for 24-28 days during the spawning period. The males were then paired with an artificially induced, spawning female and their sexual behaviour was observed during a 15 min period. The physiological status of the fish was also examined with respect to GSI, presence of milt and spawning tubercles and the blood plasma concentration of E2. Despite the relatively short exposure period, exposure to physiological levels of E2 was shown to severely affect the male goldfish reproductive behaviour and physiology. In conclusion, the results from this study and the ability to interpret the effects on this well-studied species, show that the effects of E2, and possibly other estrogenic EDCs, have severe effects at several vital levels of male goldfish reproduction. The results also suggests that the hormone E2 can act as an endocrine disrupting chemical (EDC) in the environment.PMID: 11311390 [PubMed - indexed for MEDLINE]
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5.
  • Bjerselius, Rickard, et al. (author)
  • Male goldfish reproductive behaviour and physiology are severely affected by exogenous exposure to 17 beta-estradiol
  • 2001
  • In: Aquatic Toxicology. - 0166-445X .- 1879-1514. ; 53:2, s. 139-152
  • Journal article (peer-reviewed)abstract
    • Mature male goldfish were exposed to different concentrations of the natural hormone 17 beta -estradiol (El). Two methods of exposure were employed, via ingestion at 0, 1, 10 and 100 ug/g food and via the water at 0, 1 and 10 mug/l. The fish were exposed fur 74-28 days during the spawning period. The males were then paired with an artificially induced, spawning female and their sexual behaviour was observed during a 15 min period. The physiological status of the fish was also examined with respect to GSI. presence of milt and spawning tubercles and the blood plasma concentration of E-2. Despite the relatively short exposure period. exposure to physiological levels of E-2 was shown to severely affect the male goldfish reproductive behaviour and physiology. In conclusion, the results from this study and the ability to interpret the effects on this well-studied species, show that the effects of E-2, and possibly other estrogenic EDCs have severe effects at several vital levels of male goldfish reproduction. The results also suggests that the hormone E-2 can act as an endocrine disrupting chemical (EDC) in the environment.
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6.
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7.
  • Engwall, Magnus, 1965-, et al. (author)
  • Cytochrome P450IA induction by a coplanar PCB, a PAH mixture, and PCB-contaminated sediment extracts following microinjection of rainbow trout sac-fry
  • 1994
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 30:4, s. 311-324
  • Journal article (peer-reviewed)abstract
    • The 7-ethoxyresorufin-O-deethylase (EROD)-inducing potencies of a coplanar polychlorinated biphenyl (PCB) (3,3',4,3',5-pentachlorobiphenyl, IUPAC No. 126), a mixture of five polycyclic aromatic hydrocarbons (benzo(k)fluoranthene, benz(a)anthracene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene and chrysene), and lipophilic compounds extracted from the sediments in a PCB-contaminated lake and from sediments in lakes up- and downstream, were studied in rainbow trout sac-fry in a 43-day study. The compounds/extracts were injected into the yolk sacs of newly hatched sac-fry and hepatic EROD activities and mortality rates were measured at various times after the injections. Five livers from each group were also examined by transmission electron microscopy. All the compounds/extracts induced hepatic EROD activities in the sac-fry. Ten days after injection the EROD activity caused by PCB No. 126 (1.3 ng per embryo) was 40-fold compared to the control activity. This was the highest induction rate observed in the experiment. For the sediment extracts, the highest induction rates were observed at the first sampling occasion, which for these groups was on day 24. The extract from the Lake Jarnsjon sediment was more potent as an EROD inducer than the extracts of sediments from the lakes up- and downstream from Lake Jarnsjon. None of the sediment extracts caused any significant mortality. In sac-fry injected with the PAH mixture, EROD was only slightly induced. The highest dose of PAHs (10 mu g per embryo) caused about 90% mortality by 24 days after injection. When the livers were examined by transmission electron microscopy, morphological alterations (e.g. hepatocyte degeneration and hypertrophy) were seen in the groups injected with Lake Jarnsjon sediment extract, PCB No. 126 and the highest dose of the PAH mixture (10 mu g per embryo).
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8.
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9.
  • Larsson, D. G. Joakim, 1969, et al. (author)
  • Ethinyloestradiol – an undesired fish contraceptive?
  • 1999
  • In: Aquatic Toxicology. - 0166-445X .- 1879-1514. ; 45:2-3, s. 91-97
  • Journal article (peer-reviewed)abstract
    • Environmental oestrogens are natural or synthetic substances present in the environment, which imitate the effects of endogenous oestrogen. Oestrogenic substances were identified by gas chromatography/mass spectrometry in effluent water from a Swedish sewage treatment works receiving mainly domestic wastewater. Substances found include the synthetic oestrogen used in contraceptives 17 alpha-ethinyloestradiol (4.5 ng l(-1)), the natural oestrogens oestrone (5.8 ng l(-1)) and 17 beta-oestradiol (1.1 ng l(-1)), and the weaker non-steroidal oestrogens 4-nonylphenol (840 ng l(-1)) and bisphenol A (490 ng l(-1)). Ethinyloestradiol exceeded levels shown to be oestrogenic to fish by 45 times. The oestrogenicity of the effluent water was investigated by introducing juvenile rainbow trout (Oncorhynchus mykiss) in cages downstream of the sewage treatment works. After 2 weeks, all oestrogens indicated were present in the bile of the fish, and the oestrogen inducible protein, vitellogenin, was found in large amounts in the plasma (1.5 mg ml(-1)), as determined by enzyme-linked immunosorbent assay and Western blotting. Thus, a widely used synthetic oestrogen affects the endocrine systems of fish exposed to sewage effluent water.
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10.
  • Skarpheoinsdottir, H, et al. (author)
  • Tissue differences, dose-response relationship and persistence of DNA adducts in blue mussels (Mytilus edulis L.) exposed to benzo[a]pyrene
  • 2003
  • In: Aquatic Toxicology. - 0166-445X .- 1879-1514. ; 62:2, s. 165-177
  • Journal article (peer-reviewed)abstract
    • Baltic Sea blue mussels Mytilus edulis) were experimentally exposed to the genotoxic model substance benzo[a]pyrene (B[a]P) to study DNA adduct formation. The specific aims were (a) to examine where in the mussels the DNA adducts were formed, in gills or digestive glands (b) to study the dose-response relationship between B[a]P exposure and DNA adduct formations and (c) to examine the persistence of the formed adducts. A Scope for growth (SFG) study was also run to compare physiological responses of the mussels with the degree of DNA adduct formation. In an initial dose-response experiment, the mussels were exposed to 0.5, 50, and 100 mug/l of tritium labelled B[a]P under semi-static conditions for 4 days, and thereafter the bioaccumulation of B[a]P and DNA adduct formation in different tissues was determined using liquid scintillation counting and P-32-postlabelling analysis. respectively. In a following exposure-depuration experiment, mussels were exposed to 17 mug/l of radiolabelled B[a]P under semi-static conditions for 6 days. B[a]P accumulation and DNA adduct formation were determined during the exposure, and B[a]P elimination and persistence of DNA adducts were studied during 28 days of depuration in uncontaminated water, The results revealed large tissue differences in DNA adduct formation. DNA adduct levels were not elevated in the digestive gland of the mussels at any exposure concentration (0-100 mug/l). even though the highest B[a]P tissue concentrations were found in the digestive gland (1.0+/-0.1 mg B[a]P/g tissue dry wt at 100 mug/l, mean+/-SE. n = 12). DNA adducts were on the other hand formed in the gills, with the highest levels found in mussels exposed to 50 and 100 mug B[a]P/l. and a dose dependent increase in adduct levels (from 1.6 to 5.9 nmol adducts/mol nucleotides) from 0 to 50 mug B[a]P/l, In gills, DNA adduct levels increased with time during the 6-day exposure period in the exposure-depuration experiment, and then persisted for at least 2 weeks after exposure cessation while B[a]P tissue levels exhibited a rapid decrease (half-life of 8 days). No significant differences were observed in SFG between the control and exposed groups. Since DNA adducts exhibited a relatively high persistence in gills compared to B[a]P tissue concentrations, they seem to be a more integrated measure of genotoxic exposure than only chemical analysis of the contaminant bioaccumulation. The results also suggest that if using analysis of DNA adducts in H. edulis for monitoring purposes. analysis of gills in addition to the more commonly used digestive gland should be taken into consideration.
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11.
  • Tedengren, Michael, et al. (author)
  • Heat pretreatment increase cadmium resistance and HSP 70 levels in Baltic Sea mussels
  • 2000
  • In: Aquatic Toxicology. - 0166-445X .- 1879-1514. ; 48:1, s. 1-12
  • Journal article (peer-reviewed)abstract
    • The effects of heat treatment and cadmium exposure on the synthesis of a major stress inducible protein (hsp 70) and on the metabolism of the blue mussel Mytilus edulis L. from the Baltic Sea, were studied in a laboratory experiment. The mussels were kept in sea water of ambient salinity (6.3‰) and temperature (4°C). The effects of cadmium (20 μg l−1), measured as changes in physiological rates (oxygen consumption, ammonia excretion, clearance rates and scope for growth) and hsp 70 expression were studied at 4°C and in combination with a rapid rise in temperature to 20°C. Relatively low levels of hsp 70 were detected but the negative effect was reflected in a reduction of scope for growth of the exposed mussels compared to controls. This effect was more pronounced at 20°C. Mussels not exposed to cadmium in the first experiment were used in a second set of experiments. Heat shocked mussels were allowed to reacclimatise to 4°C for 5 days and then, along with the mussels already at 4°C, exposed to cadmium (20 μg l−1). The results clearly indicated that the mussels exposed to 20°C in the first experiment more rapidly induced synthesis of hsp 70 after cadmium exposure in the second experiment. Also the reacclimatised mussels exposed to heat shock but not to cadmium in the first experiment, induced some hsp 70 in the second experiment. This suggests that the rate of induction of heat shock or stress proteins in Baltic mussels is slower than what has been described for mussels from more marine environments. The mussels kept at 4°C throughout the experiment and exposed to cadmium showed low levels of hsp 70, again indicating a low rate of induction. The increasing levels of hsp 70 correlated well with a maintained level of physiological fitness, in terms of scope for growth, although the mussels showed increasing body burdens of cadmium.
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12.
  • Abrahamson, Alexandra, et al. (author)
  • Gill EROD in monitoring of CYP1A inducers in fish : A study in rainbow trout (Oncorhynchus mykiss) caged in Stockholm and Uppsala waters
  • 2007
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 85:1, s. 1-8
  • Journal article (peer-reviewed)abstract
    • The gill filament 7-ethoxyresorufin O-deethylase (EROD) assay was evaluated as a monitoring tool for waterborne cytochrome P4501 A (CYP1A) inducers using rainbow trout (Oncorhynchus mykiss) caged in urban area waters in Sweden. To compare the CYP1A induction response in different tissues, EROD activity was also analyzed in liver and kidney microsomes. Immunohistochemistry was used to localize CYP1A protein in gill and kidney. In two separate experiments fish were caged at sites with fairly high expected polyaromatic hydrocarbon (PAH) contamination. In the first experiment, gill EROD activities were analyzed in fish exposed for 1-21 days in a river running through Uppsala. The reference site was upstream of Uppsala. In the second, gill, liver and kidney EROD activities were analyzed in fish exposed for 1-5 days in fresh or brackish waters of Stockholm and in a reference lake 60 km north of Stockholm. Fish exposed for 5 days followed by 2 days of recovery in tap water in the laboratory were also examined. The gill consistently showed a higher EROD induction compared with the liver and the kidney. After I day of caging, gill EROD activity was markedly induced (6-17-fold) at all sites examined. Induction in gill was pronounced (5-7-fold) also in fish caged at the reference sites. In the 21-day exposure study gill EROD activity remained highly induced throughout the experiment (26-fold at most) and the induced CYP1A protein was exclusively confined to the gill secondary lamellae. In the 5-day exposure experiment, EROD activity peaked after I day and then declined in both gill and liver, while CYP1A immunostaining in the gill remained intense over the 5-day period. In the kidney, CYP1A staining was weak or absent. We conclude that gill EROD activity is a more sensitive biomarker of exposure to waterborne CYP1A inducers than EROD activity in liver and kidney.
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13.
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14.
  • Aksmann, Anna, et al. (author)
  • The mechanism of anthracene interaction with photosynthetic apparatus : A study using intact cells, thylakoid membranes and PS II complexes isolated from Chlamydomonas reinhardtii
  • 2011
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 104:3-4, s. 205-210
  • Journal article (peer-reviewed)abstract
    • Intact cells of Chlamydomonas reinhardtii as well as isolated thylakoid membranes and photosystem II complexes were used to examine a possible mechanism of anthracene (ANT) interaction with the photosynthetic apparatus. Since ANT concentrations above 1 mM were required to significantly inhibit the rate of oxygen evolution in PS II membrane fragments it may indicate that the toxicant did not directly interact with this photosystem. On the other hand, stimulation of oxygen uptake by ANT-treated thylakoids suggested that ANT could either act as an artificial electron acceptor in the photosynthetic electron transport chain or function as an uncoupler. Electron transfer from excited chlorophyll to ANT is impossible due to the very low reduction potential of ANT and therefore we propose that toxic concentrations of ANT increase the thylakoid membrane permeability and thereby function as an uncoupler, enhancing electron transport in vitro. Hence, its unspecific interference with photosynthetic membranes in vitro suggests that the inhibitory effect observed on intact cell photosynthesis is caused by uncoupling of phosphorylation. 
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15.
  • Albertsson, Eva, 1979, et al. (author)
  • Induction of hepatic carbonyl reductase/20beta-hydroxysteroid dehydrogenase mRNA in rainbow trout downstream from sewage treatment works--possible roles of aryl hydrocarbon receptor agonists and oxidative stress.
  • 2010
  • In: Aquatic toxicology (Amsterdam, Netherlands). - : Elsevier BV. - 1879-1514 .- 0166-445X. ; 97:3, s. 243-9
  • Journal article (peer-reviewed)abstract
    • Carbonyl reductase/20beta-hydroxysteroid dehydrogenase (CR/20beta-HSD) serves both as a key enzyme in the gonadal synthesis of maturing-inducing hormone in salmonids, and as an enzyme protecting against certain reactive oxygen species. We have previously shown that mRNA of the hepatic CR/20beta-HSD B isoform is increased in rainbow trout caged downstream from a Swedish sewage treatment plant. Here, we report an increase of both the A as well as B form in fish kept downstream from a second sewage treatment plant. The two mRNAs were also induced in fish hepatoma cells in vitro after exposure to effluent extract. This indicates that the effects observed in vivo could be a direct effect on the liver, i.e. the mRNA induction does not require a signal from any other organ. When fish were exposed in vivo to several effluents treated with more advanced methods (ozone, moving bed biofilm reactor or membrane bioreactor) the expression of hepatic mRNA CR/20beta-HSD A and B was significantly reduced. Their abundance did not parallel the reduction of estrogen-responsive transcripts, in agreement with our previous observations that ethinylestradiol is not a potent inducer. Treatment with norethisterone, methyltestosterone or hydrocortisone in vivo did not induce the hepatic CR/20beta-HSD A and B mRNA expression. In contrast, both isoforms were markedly induced by the aryl hydrocarbon receptor agonist beta-naphthoflavone as well as by the pro-oxidant herbicide paraquat. We hypothesize that the induction of CR/20beta-HSD A and B by sewage effluents could be due to anthropogenic contaminants stimulating the aryl hydrocarbon receptor and/or causing oxidative stress.
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16.
  • Alfonso, Sébastien, et al. (author)
  • Examining multi- and transgenerational behavioral and molecular alterations resulting from parental exposure to an environmental PCB and PBDE mixture
  • 2019
  • In: Aquatic Toxicology. - : Elsevier. - 0166-445X .- 1879-1514. ; 208, s. 29-38
  • Journal article (peer-reviewed)abstract
    • Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants extensively used during the 20th century and still present in aquatic environments despite their ban. Effects of exposure to these compounds over generations are poorly documented. Therefore, our aims were to characterize behavioral responses and underlying molecular mechanisms in zebrafish exposed to an environmentally relevant mixture of PCBs and PBDEs as well as in four unexposed offspring generations. Zebrafish (F0) were chronically exposed from the first meal onward to a diet spiked with a mixture containing 22 PCB and 7 PBDE congeners in proportions and concentrations reflecting environmental situations (ΣPCBs = 1991 and ΣPBDEs = 411 ng/g). Four offspring generations (F1 to F4) were obtained from this F0 and were not further exposed. Behavior was assessed at both larval and adult stages. Mechanisms related to behavioral defects (habenula maturation and c-fos transcription) and methylation (dnmts transcription) were monitored in larvae. Exposed adult F0 as well as F1 and F3 adults displayed no behavioral change while F2 expressed anxiety-like behavior. Larval behavior was also disrupted, i.e. hyperactive after light to dark transition in F1 or hypoactive in F2, F3 and F4. Behavioral disruptions may be related to defect in habenula maturation (observed in F1) and change in c-fos transcription (observed in F1 and F2). Transcription of the gene encoding DNA methyltransferase (dnmt3ba) was also modified in all generations. Our results lead us to hypothesize that chronic dietary exposure to an environmentally relevant mixture of PCB and PBDE triggers multigenerational and transgenerational molecular and behavioral disruptions in a vertebrate model.
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17.
  • Andersson, Björn, 1985, et al. (author)
  • Differences in metal tolerance among strains, populations, and species of marine diatoms – Importance of exponential growth for quantification
  • 2020
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 226
  • Journal article (peer-reviewed)abstract
    • © 2020 The Author(s) Strains of microalgae vary in traits between species and populations due to adaptation or stochastic processes. Traits of individual strains may also vary depending on the acclimatization state and external forces, such as abiotic stress. In this study we tested how metal tolerance differs among marine diatoms at three organizational levels: species, populations, and strains. At the species level we compared two pelagic Baltic Sea diatoms (Skeletonema marinoi and Thalassiosira baltica). We found that the between-species differences in tolerance (EC50) to the biologically active metals (Cu, Co, Ni, and Zn) was similar to that within-species. In contrast, the two species differed significantly in tolerance towards the non-essential metals, Ag (three-fold higher in T. baltica), Pb and Cd (two and three-fold higher in S. marinoi). At the population level, we found evidence that increased tolerance against Cu and Co (17 and 41 % higher EC50 on average, respectively) had evolved in a S. marinoi population subjected to historical mining activity. On a strain level we demonstrate how the growth phase of cultures (i.e., cellular densities above exponential growth) modulated dose-response relationships to Ag, Cd, Co, Cu, and Zn. Specifically, the EC50's were reduced by 10–60 % in non-exponentially growing S. marinoi (strain RO5AC), depending on metal. For the essential metals these differences were often larger than the average differences between the two species and populations. Consequently, without careful experimental design, interactions between nutrient limitation and metal stress may interfere with detection of small, but evolutionary and ecologically important, differences in tolerance between microalgae. To avoid such artifacts, we outline a semi-continuous cultivation approach that maintains, and empirically tests, that exponential growth is achieved. We argue that such an approach is essential to enable comparison of population or strain differences in tolerance using dose-response tests on cultures of microalgae.
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18.
  • Andersson, Carin, et al. (author)
  • Effects of 17α-ethynylestradiol on EROD activity, spiggin and vitellogenin in three-spined stickleback (Gasterosteus aculeatus)
  • 2007
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 83:1, s. 33-42
  • Journal article (peer-reviewed)abstract
    • The three-spined stickleback (Gasterosteus aculeatus) has quantifiable biomarkers of exposure to estrogens (vitellogenin), androgens (spiggin) and aryl hydrocarbon receptor (AhR) agonists (EROD activity) and is therefore a promising test species for biomonitoring of reprotoxic chemicals in aquatic environments. In this study we evaluated the effects of 17α-ethynylestradiol (EE2) on EROD activity, induction of vitellogenin and spiggin, hepatosomatic index (HSI), ovarian somatic index (OSI) and nephrosomatic index (NSI). Adult male and female three-spined sticklebacks were exposed to concentrations of 0–170 ng EE2/l (measured concentrations) in a flow-through system for 21 days. Exposure to 170 ng EE2/l resulted in a significant 8- and 9-fold induction of gill EROD activity in males and females, respectively. In livers, EROD activity expressed in relation to microsomal protein content was suppressed due to a significant increase in microsomal protein content. Hepatic EROD activity per se expressed as picomol/min was not affected by exposure to EE2. The lowest observed effect concentration for induction of vitellogenin in males was 53.7 ng EE2/l. In females, vitellogenin levels were significantly higher in those exposed to170 ng EE2/l compared to controls. Spiggin production was significantly inhibited and NSI lower in males exposed to 170 ng EE2/l. In both females and males LSI was significantly higher in fish exposed to 170 ng EE2/l than in controls. In females exposed to 170 ng EE2/l, OSI was significantly lower and NSI higher than controls. The observed results from this study show that a synthetic estrogen can affect the well-known biomarker of exposure for dioxin-like compounds, EROD activity, and further that this response can differ between tissues. These findings are important for interpretation of biomonitoring data.
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19.
  • Asker, Noomi, 1968, et al. (author)
  • Hepatic transcriptome profiling indicates differential mRNA expression of apoptosis and immune related genes in eelpout (Zoarces viviparus) caught at Göteborg harbor, Sweden
  • 2013
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 130-131, s. 58-67
  • Journal article (peer-reviewed)abstract
    • The physiology and reproductive performance of eelpout (Zoarces viviparus) have been monitored along the Swedish coast for more than three decades. In this study, transcriptomic profiling was applied for the first time as an exploratory tool to search for new potential candidate biomarkers and to investigate possible stress responses in fish collected from a chronically polluted area. An oligonucleotide microarray with more than 15,000 sequences was used to assess differentially expressed hepatic mRNA levels in female eelpout collected from the contaminated area at Göteborg harbor compared to fish from a national reference site, Fjällbacka. Genes involved in apoptosis and DNA damage (e.g., SMAC/diablo homolog and DDIT4/DNA-damage-inducible protein transcript 4) had higher mRNA expression levels in eelpout from the harbor compared to the reference site, whereas mRNA expression of genes involved in the innate immune system (e.g., complement components and hepcidin) and protein transport/folding (e.g., signal recognition particle and protein disulfide-isomerase) were expressed at lower levels. Gene Ontology enrichment analysis revealed that genes involved biological processes associated with protein folding, immune responses and complement activation were differentially expressed in the harbor eelpout compared to the reference site. The differential mRNA expression of selected genes involved in apoptosis/DNA damage and in the innate immune system was verified by quantitative PCR, using the same fish in addition to eelpout captured four years later. Thus, our approach has identified new potential biomarkers of pollutant exposure and has generated hypotheses on disturbed physiological processes in eelpout. Despite a higher mRNA expression of genes related to apoptosis (e.g., diablo homolog) in eelpout captured in the harbor there were no significant differences in the number of TUNEL-positive apoptotic cells between sites. The mRNA level of genes involved in apoptosis/DNA damage and the status of the innate immune system in fish species captured in polluted environments should be studied in more detail to lay the groundwork for future biomonitoring studies.
  •  
20.
  • Ašmonaitė, Giedrė, 1989, et al. (author)
  • Behavioral toxicity assessment of silver ions and nanoparticles on zebrafish using a locomotion profilling approach
  • 2016
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 173, s. 143-153
  • Journal article (peer-reviewed)abstract
    • Zebrafish (Danio rerio) is not only a widely used species in the Fish Embryo Toxicity (FET) test but also an emerging model in behavioural ecotoxicology. By using automatic behaviour tracking technology, locomotion of developing zebrafish (ZF) larvae can be accurately recorded and potentially used in an ecotoxicological context to detect toxicant-induced behavioural alterations. In this study, we explored if and how quantitative locomotion data can be used for sub-lethal toxicity testing within the FET framework. We exposed ZF embryos to silver ions and nanoparticles, which previously have been reported to cause neurodevelopmental toxicity and behavioural retardation in early-life stages of ZF. Exposure to a broad range of silver (Ag+ and AgNPs) concentrations was conducted, and developmental toxicity was assessed using FET criteria. For behavioural toxicity assessment, locomotion of exposed ZF eleutheroembryos (120 hpf) was quantified according to a customised behavioural assay in an automatic video tracking system. A set of repeated episodes of dark/light stimulation were used to artificially stress ZF and evoke photo-motor responses, which were consequently utilized for locomotion profiling. Our locomotion-based behaviour profiling approach consisted of (1) dose-response ranking for multiple and single locomotion variables; (2) quantitative assessment of locomotion structure; and (3) analysis of ZF responsiveness to darkness stimulation. We documented that both silver forms caused adverse effects on development and inhibited hatchability and, most importantly, altered locomotion. High Ag+ and AgNPs exposures significantly suppressed locomotion and a clear shift in locomotion towards inactivity was reported. Additionally, we noted that low, environmentally relevant Ag+ concentrations may cause subordinate locomotive changes (hyperactivity) in developing fish. Overall, it was concluded that our locomotion-based behaviour-testing scheme can be used jointly with FET and can provide endpoints for sub-lethal toxicity. When combined with multivariate data analysis, this approach facilitated new insights for handling and analysis of data generated by automatized behavioural tracking systems.
  •  
21.
  •  
22.
  • Behrendt, Lars, et al. (author)
  • Induction of cytochrome P450 1 genes and stress response genes in developing zebrafish exposed to ultraviolet radiation
  • 2010
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 98:1, s. 74-82
  • Journal article (peer-reviewed)abstract
    • Ultraviolet (UV) radiation damages cell molecules, and has been suggested to up-regulate mammalian cytochrome P4501 (CYP1) genes through an aryl hydrocarbon receptor (AHR) mediated mechanism. In this study, embryos and larvae of zebrafish (Danio rerio) were exposed to UV to determine the effects on expression of CYP1 and stress response genes in vivo in these fish. Zebrafish embryos were exposed for varying times to UV on two consecutive days, with exposure beginning at 24 and 48h post-fertilization (hpf). Embryos exposed for 2, 4 or 6h twice over 2 days to UVB (0.62 W/m(2); 8.9-26.7 kJ/m(2)) plus UVA (2.05 W/m(2); 29.5-144.6 kJ/m(2)) had moderately (2.4+/-0.8-fold) but significantly up-regulated levels of CYP1A. UVA alone had no effect on CYP1A expression. Proliferating cellular nuclear antigen (PCNA) and Cu-Zn superoxide dismutase (SOD1) transcript levels were induced (2.1+/-0.2 and 2.3+/-0.5-fold, respectively) in embryos exposed to two 6-h pulses of 0.62 W/m(2) UVB (26.8 kJ/m(2)). CYP1A was induced also in embryos exposed to higher intensity UVB (0.93 W/m(2)) for two 3-h or two 4-h pulses (20.1 or 26.8 kJ/m(2)). CYP1B1, SOD1 and PCNA expression was induced by the two 3-h pulses of the higher intensity UVB, but not after two 4-h pulses of the higher intensity UVB, possibly due to impaired condition of surviving embryos, reflected in a mortality of 34% at that UVB dose. A single 8-h long exposure of zebrafish larvae (8dpf) to UVB at 0.93 W/m(2) (26.8 kJ/m(2)) significantly induced CYP1A and CYP1B1 expression, but other CYP1 genes (CYP1C1, CYP1C2 and CYP1D1) showed no significant increase. The results show that UVB can induce expression of CYP1 genes as well stress response genes in developing zebrafish, and that UVB intensity and duration influence the responses.
  •  
23.
  • Beijer, Kristina, 1980-, et al. (author)
  • Azoles additively inhibit cytochrome P450 1 (EROD) and 19 (aromatase) in rainbow trout (Oncorhynchus mykiss)
  • 2018
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 198, s. 73-81
  • Journal article (peer-reviewed)abstract
    • Antifungal azoles are widely used in medicine, agriculture, and material protection and several antifungal azoles have been found in environmental samples. Although these compounds were designed to inhibit fungal enzymes such as lanosterol-14-demethylase (cytochrome P450 (CYP) 51), it is well established that the inhibitory actions of azoles are not specific for fungal CYP isozymes.We refined a gill filament assay to determine the inhibition of CYP1, measured as reduced 7-ethoxyresorufin-O-deethylase (EROD) activity, in rainbow trout (Oncorhynchus mykiss) gill tissue ex vivo. The advantage of this method is that both induction and inhibition of EROD are performed ex vivo. Among thirteen azoles studied, the five that caused the strongest inhibition of gill EROD activity at a concentration of 5 μM were selected for concentration–response assessment. These compounds (bifonazole, clotrimazole, imazalil, miconazole, and prochloraz) showed IC50 values ranging from 0.1 to 1.5 μM. CYP19 (aromatase) inhibition was measured using microsomes from rainbow trout brains. Concentration-response curves for CYP19 inhibition were determined for letrozole, bifonazole, clotrimazole, imazalil, miconazole and prochloraz, which gave IC50 values ranging from 0.02 to 3.3 μM. It was further found that mixtures of the five most potent azoles reduced both CYP1 and 19 catalytic activity in an additive fashion (IC50 = 0.7 μM and 0.6 μM, in the respective assay). Bifonazole (IC50 = 0.1 μM) is not previously known to inhibit CYP1 activity.The additive inhibition of CYP1 and CYP19 catalytic activity is an important finding of the present study. We conclude that this additive action of azoles could mediate adverse impacts on CYP regulated physiological functions in environmentally exposed fish.
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24.
  • Beijer, Kristina, et al. (author)
  • CYP1A inhibition in fish gill filaments : a novel assay applied on pharmaceuticals and other chemicals
  • 2010
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 96:2, s. 145-150
  • Journal article (peer-reviewed)abstract
    • The gill filament 7-ethoxyresorufin O-deethylase (EROD) assay was originally developed as a biomarker for cytochrome P4501A (CYP1A) induction by Ah-receptor agonists in water. In this study, the assay was adapted to measure inhibition of CYP1A activity in fish gill filaments ex vivo. The experiments were carried out using gill arch filaments from beta-naphthoflavone (betaNF)-exposed three-spined stickleback (Gasterosteus aculeatus). Candidate CYP1A inhibitors were added to the assay buffer. Nine selected pharmaceuticals and five known or suspected CYP1A-modulating chemicals were examined with regard to their ability to reduce EROD activity in gill filaments. Ellipticine, a well characterized CYP1A inhibitor, was the most effective inhibitor of the compounds tested. At a concentration in the assay buffer of 1 microM the antifungal azoles ketoconazole, miconazole and bitertanol, and the plant flavonoid acacetin reduced gill EROD activity by more than 50%, implying IC50 values below 1 microM. These compounds have previously been shown to inhibit EROD activity in liver microsomes from fish and mammals at similar concentrations. The proton pump inhibitor omeprazole reduced the gill EROD activity by 39% at 10 microM. It is concluded that the modified gill filament EROD assay is useful to screen for waterborne pollutants that inhibit catalytic CYP1A activity in fish gills.
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25.
  • Bereketoglu, C., et al. (author)
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) cause male-biased sex differentiation in zebrafish
  • 2020
  • In: Aquatic Toxicology. - : Elsevier. - 0166-445X .- 1879-1514. ; 223
  • Journal article (peer-reviewed)abstract
    • Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used pharmaceuticals to treat pain, fever and inflammation. NSAIDs are also known to have many side effects including adverse effects on reproduction in both humans and animals. As NSAIDs usage is not regulated they are frequently detected at high concentrations in the environment. In order to understand the effect of NSAIDs on zebrafish sex differentiation, we used seven different NSAIDs which were either Cox-1 selective, Cox-1 biased, non-selective or COX-2 selective. We show that at higher concentration, NSAIDs are toxic to zebrafish embryo as they lead to mortality and hatching delay. Gene expression analysis following short term exposure of NSAIDs led to downregulation of female specific genes including zp2, vtg2 foxl2 and wnt4. Long term exposure of larvae to environmentally relevant concentrations of Cox-2 selective and non-selective NSAIDs resulted in male-biased sex ratio which confirmed the qRT-PCR analysis. However, the Cox-1 selective acetylsalicylic acid and the Cox-1 biased ketoprofen did not alter sex ratio. The observed male-biased sex ratio could also be due to induction of apoptosis process as the genes including p21 and casp8 were significantly upregulated following exposure to the Cox-2 selective and the non-selective NSAIDs. The present study indicates that NSAIDs alter sex differentiation in zebrafish, primarily through inhibition of Cox-2. This study clearly demonstrates that the use of NSAIDs and their release into the aquatic environment should be carefully monitored to avoid adverse effects to the aquatic organisms. 
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26.
  • Bernabó, Ilaria, et al. (author)
  • Endosulfan acute toxicity in Bufo bufo gills: ultrastructural changes and nitric oxide synthase localization
  • 2008
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 86:3, s. 447-456
  • Journal article (peer-reviewed)abstract
    • Endosulfan is an organochlorine pesticide used in agriculture for a wide range of crops. Endosulfan concentrations of up to 0.7 mg/L can be found in ponds and streams near sprayed agricultural fields. We investigated the short-term toxicity of endosulfan in common toad (Bufo bufo) tadpoles after 24, 48, and 96 h of exposure. Acute toxicity was evaluated at nominal concentrations ranging from 0.01 to 0.6 mg/L: concentrations that could be found after the application of pesticide. Our results show that 0.43 mg/L of endosulfan caused 50% mortality (LC(50)). The effects of a sublethal endosulfan concentration (0.2mg/L) on gill apparatus morphology were evaluated by scanning and transmission electron microscopy. Immunohistochemical methods were also applied to detect the expression pattern of the inducible isoform of nitric oxide synthase (iNOS) in the gills using the confocal laser scanner microscope. Exposure to 0.2mg/L of endosulfan caused an apparent increase in mucus production, the occurrence of secretory vesicles and lamellar bodies, a widening of intercellular spaces and additionally there was evidence of an inflammatory response in the gill apparatus. The morphological alterations occurred after 24h and were more pronounced after 48 and 96 h of exposure. Altered morphology and increased mucus secretion indicate impaired gas exchange and osmoregulation in the gills. In addition, there was an increase of iNOS expression after 24 and 48 h which may reflect hypoxia and inflammation in the gill epithelium. Our results clearly indicate that short-term exposure to a sublethal concentration of endosulfan, near the high end of the environmental range, disrupts gill morphology and function in B. bufo tadpoles.
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27.
  • Bighiu, Maria Alexandra, et al. (author)
  • Mortality and histopathological effects in harbour-transplanted snails with different exposure histories
  • 2017
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 190, s. 11-20
  • Journal article (peer-reviewed)abstract
    • Contaminants are important stressors in the aquatic environment and may exert selective pressures on organisms. We hypothesized that snails originating from a metal-contaminated habitat (B) would have increased tolerance to harbour contaminants (e.g. metals from antifouling paints), compared to snails originating from a relatively clean habitat (A). We assessed tolerance to metals in terms of survival and histopathological alterations after 2, 4 and 8 weeks of in situ exposure in three Baltic Sea boat harbours and three reference sites. We also hypothesized that any potential tolerance to contaminants would be associated with differences in genetic diversity between the two snail populations (evaluated as mitochondrial cytochrome c oxidase subunit I, COI). The results show that snails from population A survived to a higher extent compared to population B, possibly indicating either a lack of adaptation to metals in snails B or impaired health condition due to contaminant pre-exposure or a higher resilience of snails A. Moreover, the genetic diversity of COI was low within each population and did not differ between populations. In general, 83% of all the types of histopathological alterations (e.g. lysis and necrosis of gonads and digestive gland or granulocytoma and phagocytosis in the storage tissue, among others) had a higher probability of occurrence among harbour-exposed snails compared to reference exposed snails, regardless of snail population origin. The only significant difference in histological effects between the two populations was in the frequency of parasite infestations and shell fouling, both being larger for population A than B. Interestingly, the rate of parasite infestations was higher for males than females from population A, whereas no sexual dichotomy was observed for population B. Our results show that exposure to harbour contaminants causes both lethal and sublethal toxicity to snails, and the association between many of the toxic responses and metals substantiates that antifouling substances contribute to the observed effects, although there is a large proportion of variation in our data that remains unexplained.
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28.
  • Blanc, Mélanie, 1993-, et al. (author)
  • Environmental chemicals differentially affect epigenetic-related mechanisms in the zebrafish liver (ZF-L) cell line and in zebrafish embryos
  • 2019
  • In: Aquatic Toxicology. - : Elsevier. - 0166-445X .- 1879-1514. ; 215
  • Journal article (peer-reviewed)abstract
    • A number of chemicals have been shown to affect epigenetic patterning and functions. Since epigenetic mechanisms regulate transcriptional networks, epigenetic changes induced by chemical exposure can represent early molecular events for long-term adverse physiological effects. Epigenetics has thus appeared as a research field of major interest within (eco)toxicological sciences. The present study aimed at measuring effects on epigenetic-related mechanisms of selected environmental chemicals (bisphenols, perfluorinated chemicals, methoxychlor, permethrin, vinclozolin and coumarin 47) in zebrafish embryos and liver cells (ZFL). Transcription of genes related to DNA methylation and histone modifications was measured and global DNA methylation was assessed in ZFL cells using the LUMA assay. The differences in results gathered from both models suggest that chemicals affect different mechanisms related to epigenetics in embryos and cells. In zebrafish embryos, exposure to bisphenol A, coumarin 47, methoxychlor and permethrin lead to significant transcriptional changes in epigenetic factors suggesting that they can impact early epigenome reprogramming related to embryonic development. In ZFL cells, significant transcriptional changes were observed upon exposure to all chemicals but coumarin 47; however, only perfluorooctane sulfonate induced significant effects on global DNA methylation. Notably, in contrast to the other tested chemicals, perfluorooctane sulfonate affected only the expression of the histone demethylase kdm5ba. In addition, kdm5ba appeared as a sensitive gene in zebrafish embryos as well. Taken together, the present results suggest a role for kdm5ba in regulating epigenetic patterns in response to chemical exposure, even though mechanisms remain unclear. To confirm these findings, further evidence is required regarding changes in site-specific histone marks and DNA methylation together with their long-term effects on physiological outcomes.
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29.
  • Boyi, Joy Ometere, et al. (author)
  • Relationships between gene transcription and contaminant concentrations in Baltic ringed seals : A comparison between tissue matrices
  • 2022
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 242
  • Journal article (peer-reviewed)abstract
    • Ringed seals (Pusa hispida) are slowly recovering in the eastern and northern parts of the Baltic Sea after years of hunting pressure and contaminant exposure. Still, consequences of anthropogenic activities such as contaminant exposure and increasing temperatures are stressors that continue to have deleterious effects on their habitat and health. Transcription profiles of seven health-related genes involved in xenobiotic metabolism, endocrine disruption and stress were evaluated in blood, blubber, and liver of Baltic ringed seals in a multi-tissue approach. Selected persistent organic pollutants and total mercury concentrations were measured in blubber and liver, and muscle and liver of these animals, respectively. Concentrations of contaminants varied across tissues on a lipid weight basis but not with sex. mRNA transcript levels for all seven target genes did not vary between sexes or age classes. Transcript levels of thyroid hormone receptor alpha (TR alpha), retinoic acid receptor alpha (RAR alpha) and heat shock protein 70 (HSP70) correlated with levels of persistent organic pollutants. TR alpha transcript levels also correlated positively with mercury concentrations in the liver. Of the three tissues assessed in this multi-tissue approach, blubber showed highest transcription levels of aryl hydrocarbon receptor nuclear translocator (ARNT), thyroid stimulating hormone receptor beta (TSH beta), oestrogen receptor alpha (ESR1) and peroxisome proliferator activated receptor alpha (PPAR alpha). The wide range of genes expressed highlights the value of minimally invasive sampling (e.g. biopsies) for assessing health endpoints in free-ranging marine wildlife and the importance of identifying optimal matrices for targeted gene expression studies. This gene transcript profile study has provided baseline information on transcript levels of biomarkers for early on-set health effects in ringed seals and will be a useful guide to assess the impacts of environmental change in Baltic pinnipeds for conservation and management.
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30.
  • Bradshaw, Clare, et al. (author)
  • Joint effects of gamma radiation and cadmium on subcellular-, individual-and population-level endpoints of the green microalga Raphidocelis subcapitata
  • 2019
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 211, s. 217-226
  • Journal article (peer-reviewed)abstract
    • Interpreting and predicting the combined effects of toxicants in the environment is an important challenge in ecotoxicology. How such effects are connected across different levels of biological organisation is an additional matter of uncertainty. Such knowledge gaps are particularly prominent with regards to how ionising radiation interacts with contaminants. We assessed the response of twelve endpoints at the subcellular, individual and population level in a green microalga when exposed singly and jointly to gamma radiation and cadmium (Cd). We used a fully factorial experimental design where observed effects were compared to those predicted by the Independent Action (IA) model for mixture toxicity to determine whether they deviated from additivity. Subcellular endpoints (e.g., catalase, thiamine diphosphate, xanthophyll cycle pigments) showed an increased antioxidant and/or photoprotective response. However, our results indicate that this protection was not sufficient to prevent lipid peroxidation, which also increased with dose. At ecologically relevant doses, most interactions between gamma radiation and Cd regarding subcellular-, individual- and population-level endpoints were additive as predicted by the IA model. However, exposure to binary mixtures displayed antagonistic interactions between gamma radiation and Cd at the higher end of the tested dose spectrum. No correlations were observed between subcellular endpoints and higher-level endpoints, but there were linkages between individual and population endpoints. Our results suggest that antagonistic interactions between gamma radiation and Cd can occur at higher doses and that these interactions seem to disseminate from subcellular and individual to population level. Possible consequences for aquatic primary production and food-web interactions are discussed.
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31.
  • Broman, Elias, et al. (author)
  • Denitrification responses to increasing cadmium exposure in Baltic Sea sediments
  • 2019
  • In: Aquatic Toxicology. - : Elsevier. - 0166-445X .- 1879-1514. ; 217
  • Journal article (peer-reviewed)abstract
    • Benthic ecosystems have come under intense pressure, due to eutrophication-driven oxygen decline and industrial metal contamination. One of the most toxic metals is Cadmium (Cd), which is lethal to many aquatic organisms already at low concentrations. Denitrification by facultative anaerobic microorganisms is an essential process to transform, but also to remove, excess nitrate in eutrophied systems. Cd has been shown to decrease denitrification and sequester free sulfide, which is available when oxygen is scarce and generally inhibits complete denitrification (i.e. N2O to N2). In polluted sediments, an interaction between oxygen and Cd may influence denitrification and this relationship has not been studied. For example, in the Baltic Sea some sediments are double exposed to both Cd and hypoxia. In this study, we examined how the double exposure of Cd and fluctuations in oxygen affects denitrification in Baltic Sea sediment. Results show that oxygen largely regulated N2O and N2 production after 21 days of exposure to Cd (ranging from 0 to 500 μg/L, 5 different treatments, measured by the isotope pairing technique (IPT)). In the high Cd treatment (500 μg/L) the variation in N2 production increased compared to the other treatments. Increases in N2 production are suggested to be an effect of 1) enhanced nitrification that increases NO3 − availability thus stimulating denitrification, and 2) Cd successfully sequestrating sulfide (yielding CdS), which allows for full denitrification to N2. The in situ field sediment contained initially high Cd concentrations in the pore water (∼10 μg/L) and microbial communities might already have been adapted to metal stress, making the effect of low Cd levels negligible. Here we show that high levels of cadmium pollution might increase N2 production and influence nitrogen cycling in marine sediments. © 2019 The Authors
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32.
  • Brunelli, Elvira, et al. (author)
  • Environmentally Relevant Concentrations of Endosulfan Impair Development, Metamorphosis and Behaviour in Bufo bufo Tadpoles
  • 2009
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 91:2, s. 135-142
  • Journal article (peer-reviewed)abstract
    • Endosulfan is a widely used organochlorine pesticide with well-documented neurotoxic effects in both humans and laboratory animals (mammals and fish). Neurotoxicity has been implied also in amphibians after short-term exposure to endosulfan. Little is known about effects of chronic exposure of endosulfan in amphibians. Previously, we examined the short-term toxicity of endosulfan in common toad (Bufo bufo) tadpoles and determined the LC50 value to 0.43 mg/L. In the present study, we investigated the effects of endosulfan on B. bufo tadpoles after chronic exposure to ecologically relevant concentrations. Tadpoles were exposed in a static renewal test, from shortly after hatching (Gosner stage 25) to completed metamorphosis, to 0.01, 0.05 and 0.1 mg endosulfan/L (nominal). The exposure period lasted 43–52 days. Mortality, larval growth (mass), development (reached Gosner stage at various times and deformities presence), metamorphosis and behaviour (swimming activity) were monitored regularly over the entire course of larval development. Our results show that 0.05 and 0.1 mg endosulfan/L caused impaired behaviour, prolonged time to metamorphosis, increased incidences of mouth and skeletal malformations as well as mortality, and reduced body weight (observed also at 0.01 mg/L) in B. bufo tadpoles. Behavioural effects occurred at exposure day 4, before any other effects occurred, indicating a neurotoxic effect. Endosulfan levels found in groundwater and surface water range from 0.1 to 100 μg/L and after extraordinary runoff events, concentrations exceed 0.5 mg/L in surface water.
  •  
33.
  • Bundschuh, Mirco (author)
  • Effects of current-use fungicides and their mixtures on the feeding and survival of the key shredder Gammarus fossarum
  • 2014
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 150, s. 133-143
  • Journal article (peer-reviewed)abstract
    • Fungicides are frequently applied in agriculture and are subsequently detected in surface waters in total concentrations of up to several tens of micrograms per liter. These concentrations imply potential effects on aquatic communities and fundamental ecosystem functions such as leaf litter breakdown. In this context, the present study investigates sublethal and lethal effects of organic (azoxystrobin, carbendazim, cyprodinil, quinoxyfen, and tebuconazole) and inorganic (three copper (Cu)-based substances and sulfur) current-use fungicides and their mixtures on the key leaf-shredding invertebrate Gammarus fossarum. The feeding activity of fungicide-exposed gammarids was quantified as sublethal endpoint using a static (organic fungicides; 7 d test duration) or a semi-static (inorganic fungicides; 6 d test duration with a water exchange after 3 d) approach (n = 30). EC50-values of organic fungicides were generally observed at concentrations resulting in less than 20% mortality, with the exception of carbendazim. With regard to feeding, quinoxyfen was the most toxic organic fungicide, followed by cyprodinil, carbendazim, azoxystrobin, and tebuconazole. Although all tested organic fungicides have dissimilar (intended) modes of action, a mixture experiment revealed a synergistic effect on gammarids' feeding at high concentrations when using "independent action" as the reference model (similar to 35% deviation between predicted and observed effect). This may be explained by the presence of a synergizing azole fungicide (i.e. tebuconazole) in this mixture. Furthermore, lethal concentrations of all Cu-based fungicides assessed in this study were comparable amongst one another. However, they differed markedly in their effective concentrations when using feeding activity as the endpoint, with Cu-sulfate being most toxic, followed by Cu-hydroxide and Cu-octanoate. In contrast, sulfur neither affected survival nor the feeding activity of gammarids (up to similar to 5 mg/L) but reduced Cu-sulfate's toxicity when applied in a binary mixture. Sulfur-related metabolic processes which reduce the physiological availability of Cu may explain this antagonistic effect. For both fungicide mixtures, the present study thus uncovered deviations from the appropriate reference model, while ecotoxicological effects were observed at field relevant (total) fungicide concentrations. Additionally, for more than half of the tested single substances, a potential risk for Gammarus and thus for the ecological function mediated by these organisms was evident at concentrations measured in agriculturally influenced surface waters. These results suggest that risks to the fundamental ecosystem function of leaf litter breakdown posed by fungicides may not be adequately considered during the regulation of these compounds, which makes further experimental efforts necessary. (C) 2014 Elsevier B.V. All rights reserved.
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34.
  • Bundschuh, Mirco (author)
  • Effects of salinity on leaf breakdown: Dryland salinity versus salinity from a coalmine
  • 2016
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 177, s. 425-432
  • Journal article (peer-reviewed)abstract
    • Salinization of freshwater ecosystems as a result of human activities represents a global threat for ecosystems' integrity. Whether different sources of salinity with their differing ionic compositions lead to variable effects in ecosystem functioning is unknown. Therefore, the present study assessed the impact of dryland- (50 mu S/cm to 11,000 mu S/cm) and coalmine-induced (100 mu S/cm to 2400 mu S/cm) salinization on the leaf litter breakdown, with focus on microorganisms as main decomposer, in two catchments in New South Wales, Australia. The breakdown of Eucalyptus camaldulensis leaves decreased with increasing salinity by up to a factor of three. Coalmine salinity, which is characterised by a higher share of bicarbonates, had a slightly but consistently higher breakdown rate at a given salinity relative to dry land salinity, which is characterised by ionic proportions similar to sea water. Complementary laboratory experiments supported the stimulatory impact of sodium bicarbonates on leaf breakdown when compared to sodium chloride or artificial sea salt. Furthermore, microbial inoculum from a high salinity site (11,000 mu S/cm) yielded lower leaf breakdown at lower salinity relative to inoculum from a low salinity site (50 mu S/cm). Conversely, inoculum from the high salinity site was less sensitive towards increasing salinity levels relative to inoculum from the low salinity site. The effects of the different inoculum were the same regardless of salt source (sodium bicarbonate, sodium chloride and artificial sea salt). Finally, the microorganism-mediated leaf litter breakdown was most efficient at intermediate salinity levels (approximate to 500 mu S/cm). The present study thus points to severe implications of increasing salinity intensities on the ecosystem function of leaf litter breakdown, while the underlying processes need further scrutiny. Crown Copyright (C) 2016 Published by Elsevier B.V. All rights reserved.
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35.
  • Bundschuh, Mirco (author)
  • Exposure pathway dependent effects of titanium dioxide and silver nanoparticles on the benthic amphipod Gammarus fossarum
  • 2019
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 212, s. 47-53
  • Journal article (peer-reviewed)abstract
    • The increasing production of engineered inorganic nanoparticles (EINPs) elevates their release into aquatic ecosystems raising concerns about associated environmental risks. Numerous investigations indicate sediments as the final sink, facilitating the exposure of benthic species to EINPs. Although reports of sub-lethal EINP effects on benthic species are increasing, the importance of exposure pathways (either waterborne or dietary) is poorly understood. This study investigates the influence of two EINPs, namely titanium dioxide (nTiO(2)) and silver (nAg), on the benthic model organism Gammarus fossarum specifically addressing the relative relevance of these pathways. For each type of EINP an individual 30-day long bioassay was conducted, applying a two-factorial test design. The factors include the presence or absence of the EINPs (nTiO(2): similar to 80 nm, 4 mg/L or nAg: similar to 30 nm, 0.125 mg/L; n = 30) in the water phase (waterborne), combined with a preceding 6-day long aging of their diet (black alder leaves) also in presence or absence of the EINPs (dietary). Response variables were mortality, food consumption, feces production and energy assimilation. Additionally, the physiological fitness was examined using lipid content and dry weight of the organisms as measures. Results revealed a significantly reduced energy assimilation (up to similar to 30%) in G. fossarum induced by waterborne exposure towards nTiO(2). In contrast, the dietary exposure towards nAg significantly increased the organisms' energy assimilation (up to similar to 50%). Hence, exposure pathway dependent effects of EINPs cannot be generalized and remain particle specific resting upon their intrinsic properties affecting their potential to interact with the surrounding environment. As a result of the different properties of the EINPs used in this study, we clearly demonstrated variations in type and direction of observed effects in G. fossarum. The results of the present study are thus supporting current approaches for nanospecific grouping that might enable an enhanced accuracy in predicting EINP effects facilitating their environmental risk assessment.
  •  
36.
  • Bundschuh, Mirco (author)
  • Mixture effects of a fungicide and an antibiotic: Assessment and prediction using a decomposer-detritivore system
  • 2021
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 232
  • Journal article (peer-reviewed)abstract
    • Antimicrobials, such as fungicides and antibiotics, pose a risk for microbial decomposers (i.e., bacteria and aquatic fungi) and invertebrate detritivores (i.e., shredders) that play a pivotal role in the ecosystem function of leaf litter breakdown. Although waterborne toxicity and diet-related effects (i.e., dietary exposure and microorganism-mediated alterations in food quality for shredders) of fungicides and antibiotics on decomposer-detritivore systems have been increasingly documented, their joint effect is unknown. We therefore assessed waterborne and dietary effects of an antimicrobial mixture consisting of the fungicide azoxystrobin (AZO) and the antibiotic ciprofloxacin (CIP) on microbial decomposers and the shredder Gammarus fossarum using a tiered approach. We compared effect sizes measured in the present study with model predictions (i.e., independent action) based on published data. During a 7-day feeding activity assay quantifying waterborne toxicity in G. fossarum, the leaf consumption of gammarids was reduced by similar to 60 % compared to the control when subjected to the mixture at concentrations of each component causing a 20 % reduction in the same response variable when applied individually. Moreover, the selective feeding of gammarids during the food choice assay indicated alterations in food quality induced by the antimicrobial mixture. The food selection and, in addition, the decrease in microbial leaf decomposition is likely linked to changes in leaf-associated bacteria and fungi. During a long-term assay, energy processing, growth and energy reserves of gammarids were increased in presence of 15 and 500 mu g/L of AZO and CIP, respectively, through the dietary pathway. These physiological responses were probably driven by CIP-induced alterations in the gut microbiome or immune system of gammarids. In general, model predictions matched observed effects caused by waterborne exposure on the leaf consumption, energy processing and growth of gammarids during short- and long-term assays, respectively. However, when complex horizontal (bacteria and aquatic fungi) and vertical (leaf-associated microorganisms and shredders) interactions were involved, model predictions partly over- or underestimated mixture effects. Therefore, the present study identifies uncertainties of mixture effect predictions for complex biological systems calling for studies targeting the underlying processes and mechanisms.
  •  
37.
  • Bundschuh, Mirco (author)
  • Multiple exposure routes of a pesticide exacerbate effects on a grazing mayfly
  • 2016
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 178, s. 190-196
  • Journal article (peer-reviewed)abstract
    • Hydrophobic pesticides such as pyrethroid insecticides tend to occur in their soluble form mainly as transient pulses in streams. In addition, they are regularly detected in significant quantities adsorbed to stream sediments and other organic in-stream structures. Consequently, stream biota is likely subjected to pesticide exposure via multiple routes. In this study we aimed at investigating the influence of exposure routes for the pyrethroid insecticide lambda-cyhalothrin on the grazing mayfly Heptagenia sulphurea. Therefore, H. sulphurea was exposed to lambda-cyhalothrin via single- (water or biofilm) or biphasic exposure (water and biofilm) at environmentally realistic concentrations (0, 0.1, 1 mu g L-1) and exposure duration (2 h) in a full factorial design (n = 5). Mortality, moulting frequency, and biofilm accrual (proxy for feeding rate) were recorded subsequent to a 7 d post exposure period. Mortality significantly increased and moulting frequency significantly decreased with increasing concentrations of lambda-cyhalothrin in the water phase whereas exposure via biofilm prompted no significant effects on these endpoints (alpha=0.05). Effect predictions systematically underestimated and overestimated effects for mortality and moulting frequency, respectively. Similarly, mayfly feeding rate was significantly reduced by water phase exposure whereas pre-exposed biofilm did not significantly affect this variable. However, we found a significant but non-systematic interaction between water phase and biofilm exposure on mayfly feeding rate. Our results show that exposure to the same pesticide via multiple exposure routes may increase the magnitude of effects beyond the level predicted from single phase exposures which has clear implications for the aquatic risk assessment of hydrophobic pesticides. However, our results additionally reveal that interactions between pesticide exposure routes may vary between selected dependent variables. We emphasize that unravelling the underlying mechanisms causing these discrepancies in interactive effects between exposure routes is a major aspect that should receive further attention in future research. (C) 2016 Elsevier B.V. All rights reserved.
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38.
  • Bundschuh, Mirco (author)
  • Nanoparticle toxicity in Daphnia magna reproduction studies: The importance of test design
  • 2013
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 126, s. 163-168
  • Journal article (peer-reviewed)abstract
    • The increasing use of titanium dioxide nanoparticles (nTiO(2)) inevitably results in their release into the environment, raising concerns about potential adverse effects in wildlife. By following standard test protocols, several studies investigated the ecotoxicity of nTiO(2) among others to Daphnia magna. These studies indicated a large variability - several orders of magnitude - in the response variables. However, other factors, like nanoparticle characteristics and test design, potentially triggering these differences, were largely ignored. Therefore, the present study assessed the chronic ecotoxicity of two nTiO(2) products with varying crystalline structure (A-100; P25) to D. magna. A semi-static and a flow-through exposure scenario were compared, ensuring that both contained environmentally relevant concentrations of dissolved organic carbon. Utilizing the semi-static test design, a concentration as low as 0.06 mg/L A-100 (similar to 330 nm) significantly reduced the reproduction of daphnia indicating environmental risk. In contrast, no implication in the number of released offspring was observed during the flow-through experiment with A-100 (similar to 140 nm). Likewise, P25 (similar to 130 nm) did not adversely affect reproduction irrespective of the test design utilized. Given the present study's results, the particle size, the product composition, i.e. the crystalline structure, and the accumulation of nTiO(2) at the bottom of the test vessel - the latter is relevant for a semi-static test design - may be suggested as factors potentially triggering differences in nTiO(2) toxicity to D. magna. Hence, these factors should be considered to improve environmental risk assessment of nanoparticles. (c) 2012 Elsevier B.V. All rights reserved.
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39.
  • Bundschuh, Mirco (author)
  • Oxidized Carbo-Iron causes reduced reproduction and lower tolerance of juveniles in the amphipod Hyalella azteca
  • 2016
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 181, s. 94-103
  • Journal article (peer-reviewed)abstract
    • For in situ remediation of groundwater contaminated by halogenated hydrocarbons Carbo-Iron, a composite of microscale activated carbon and nano Fe, was developed. Against the background of intended release of Carbo-Iron into the environment in concentrations in the g/L-range, potential ecotoxicological consequences were evaluated in the present study. The nano Fei(0) in Carbo-Iron acts as reducing agent and is oxidized in aqueous systems by chlorinated solvents, groundwater constituents (e.g. dissolved oxygen) and anaerobic corrosion. As Carbo-Iron is generally oxidized rapidly after application into the environment, the oxidized state is environmentally most relevant, and Carbo-Iron was used in its oxidized form in the ecotoxicological tests. The amphipod Hyalella azteca was selected as a surrogate test species for functionally important groundwater crustaceans. Effects of Carbo-Iron on H. azteca were determined in a 10-d acute test, a 7-d feeding activity test and a 42-d chronic test. Additionally, a 56-d life cycle test was performed with a modified design to further evaluate effects of Carbo-Iron on adult H. azteca and their offspring. The size of Carbo-Iron particles in stock and test suspensions was determined via dynamic light scattering. Potential uptake of particles into test organisms was investigated using transmission and scanning electron microscopy. At the termination of the feeding and acute toxicity test (i.e. after 7 and 10 d of exposure, respectively), Carbo-Iron had a significant effect on the weight, length and feeding rate of H. azteca at the highest test concentration of 100 mg/L. While an uptake of Carbo-Iron into the gut was observed, no passage into the surrounding tissue was detected. In both chronic tests, the number of offspring was the most sensitive endpoint and significant effects were recorded at concentrations >= 50 mg/L (42-d experiment) and >= 12.5 mg/L (56-d experiment). Parental exposure to oxidized Carbo-Iron significantly exacerbated the acute effects of the nanocomposite on the subsequent generation of H. azteca by a factor >10. The present study indicates risks for groundwater species at concentrations in the mg/L range. Carbo-Iron may exceed these effect concentrations in treated aquifers, but the presence of the pollutant has most likely impaired the quality of this habitat already. The benefit of remediation has to be regarded against the risk of ecological consequences with special consideration of the observed increasing sensitivity of juvenile H. azteca. (C) 2016 Elsevier B.V. All rights reserved.
  •  
40.
  • Bundschuh, Mirco (author)
  • The importance of diet-related effects of the antibiotic ciprofloxacin on the leaf-shredding invertebrate Gammarus fossarum (Crustacea; Amphipoda)
  • 2020
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 222
  • Journal article (peer-reviewed)abstract
    • Antibiotics may constitute a risk for aquatic detritivorous macroinvertebrates (i.e., shredders) via waterborne and dietary antibiotic exposure. In addition, antibiotics can alter the food quality for shredders mediated by shifts in leaf-associated decomposer (i.e., aquatic fungi and bacteria) communities. However, little is known about the relative importance of the waterborne and dietary effect pathway. Therefore, we followed a tiered testing approach aimed at assessing the relative importance of these effect pathways. We employed the antibiotic ciprofloxacin (CIP) and the shredder Gammarus fossarum as model stressor and test species, respectively. In a first step, we assessed the short-term waterborne toxicity of CIP using survival and leaf consumption of G. fossarum as response variables. Alterations in the leaf-associated decomposer community, which may be reflected by their palatability, were assessed using food choice assays. Finally, we conducted a 2 x 2-factorial experiment over 24 days assessing the pathways individually and combined using energy processing (i.e., leaf consumption and feces production), growth and energy storage (i.e., neutral lipid fatty acids) as variables. Short term waterborne exposure indicated low toxicity with LC50 and EC50 values of 13.6 and 6.4 mg CIP/L, respectively. At the same time, shredders did not prefer any leaf material during the food choice assay. However, the fungal community was significantly affected in the highest CIP-treatments (0.5 and 2.5 mg/L) suggesting an altered food quality for shredders. This assumption is supported by the results of the long-term assay. At 0.5 mg CIP/L, gammarids' leaf consumption, growth and energy storage were increased when subjected via the dietary pathway, which was linked to changes in the leaf-associated microbial community. Our data highlight the importance of dietary effect pathways for effects on shredders, potentially impacting energy dynamics in detritus-based stream ecosystems.
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41.
  • Bundschuh, Mirco (author)
  • Tracer or toxicant: Does stable isotope labeling affect central processes in aquatic food webs?
  • 2023
  • In: Aquatic Toxicology. - 0166-445X .- 1879-1514. ; 259
  • Journal article (peer-reviewed)abstract
    • Stable isotope analysis (SIA) is an elementary technique in food web ecology, but its insights become increasingly ambiguous in complex systems. One approach to elevate the utility of SIA in such systems is the use of heavy isotope tracers (i.e., labeling). However, the fundamental assumption that the addition of such tracers does not affect in situ conditions has been challenged. This study tests if labeling is suitable for autotrophy-based and detritus-based aquatic food webs. For the former, the survival and reproduction of Daphnia magna fed with phytoplankton cultured at different levels of 15N addition were assessed. For the latter, the microbial decom-position of leaf litter was assessed at the same tracer levels. While no significant differences were observed, effect patterns were comparable to a previous study, supporting the isotopic redundancy hypothesis that postulates discrete quantum mechanical states at which the reaction speeds of metabolic processes are altered. Although physiology (reproduction) and activity (microbial decomposition) might not be altered to an ecologically sig-nificant level, labeling with heavy stable isotopes could potentially affect isotopic fractionation in biochemical processes and bias conclusions drawn from resulting SI ratios.
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42.
  • Bundschuh, Mirco (author)
  • Waterborne and diet-related effects of inorganic and organic fungicides on the insect leaf shredder Chaetopteryx villosa (Trichoptera)
  • 2019
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 206, s. 33-42
  • Journal article (peer-reviewed)abstract
    • It is well-documented that fungicides can affect crustacean leaf shredders via two effect pathways, namely waterborne exposure and their diet (i.e., via dietary uptake of fungicides adsorbed to leaf material and an altered microorganism-mediated food quality). As a consequence of different life history strategies, the relevance of these effect pathways for aquatic shredders belonging to other taxonomic classes, for instance insects, remains unclear. Therefore, we investigated waterborne and diet-related effects in larvae of the caddisfly leaf shredder Chaetopteryx villosa (Insecta: Trichoptera) and compared our observations to previous reports on effects in adults of the crustacean leaf shredder Gammarus fossarum (Malacostraca: Amphipoda). We assessed acute waterborne effects of an organic fungicide mixture (OFM) and the inorganic fungicide copper (Cu) on the leaf consumption (n = 30) of the fourth-/fifth-instar larvae of C. villosa and their food choice (n = 49) when offered leaf material, which was either conditioned in presence or in absence of the respective fungicide(s). Moreover, the larval leaf consumption (n = 50) and physiological fitness (i.e., growth as well as lipid and protein content) were examined after subjecting C. villosa for 24 days towards the combination of both effect pathways at environmentally relevant concentrations. G. fossarum and C. villosa exhibited similar sensitivities and the same effect direction when exposed to the OFM (either waterborne or dietary pathways). Both shredders also showed the same effect direction when exposed to dietary Cu, while with regards to mortality and leaf consumption C. villosa was less sensitive to waterborne Cu than G. fossarum. Finally, as observed for G. fossarum, the combined exposure to OFM over 24 days negatively affected leaf consumption and the physiology (i.e., growth and lipid reserves) of C. villosa. While no combined Cu effects were observed for larval leaf consumption, contrasting to the observations for G. fossarum, the physiology of both shredders was negatively affected, despite partly differing effect sizes and directions. Our results suggest that C. villosa and G. fossarum are of comparable sensitivity towards waterborne and diet-related organic fungicide exposure, whereas the trichopteran is less sensitive to Cubased waterborne fungicide exposure. However, when both pathways act jointly, organic and inorganic fungicides can affect the physiology of shredder species with completely different life history strategies. As caddisflies represent a subsidy for terrestrial consumers, these observations indicate that fungicide exposure might not only affect aquatic ecosystem functioning but also the flux of energy across ecosystem boundaries.
  •  
43.
  • Bundschuh, Mirco (author)
  • Waterborne toxicity and diet-related effects of fungicides in the key leaf shredder. Gammarus fossarum (Crustacea: Amphipoda)
  • 2015
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 169, s. 105-112
  • Journal article (peer-reviewed)abstract
    • Animals involved in leaf litter breakdown (i.e., shredders) play a central role in detritus-based stream food webs, while their fitness and functioning can be impaired by anthropogenic stressors. Particularly fungicides can affect shredders via both waterborne exposure and their diet, namely due to co-ingestion of adsorbed fungicides and shifts in the leaf-associated fungal community, on which shredders' nutrition heavily relies. To understand the relevance of these effect pathways, we used a full 2 x 2-factorial test design: the leaf material serving as food was microbially colonized for 12 days either in a fungicide-free control or exposed to a mixture of five current-use fungicides (sum concentration of 62.5 mu g/L). Similarly, the amphipod shredder Gammarus fossarum was subjected to the same treatments but for 24 days. Waterborne exposure reduced leaf consumption by 20%, which did not fully explain the reduction in feces production (similar to 30%), indicating an enhanced utilization of food to compensate for detoxification mechanisms. This may also explain the reduced feces production (similar to 10%) of gammarids feeding on fungicide-exposed leaves. The reduction may, however, also be caused by a decreased nutritious quality of the leaves indicated by a reduced species richness (similar to 40%) of leaf-associated fungi. However, compensation for these effects by Gammarus was seemingly incomplete, since both waterborne exposure and the consumption of the fungicide-affected diet drastically reduced gammarid growth (similar to 110% and similar to 40%, respectively). Our results thus indicate that fungicide mixtures have the potential for detrimental implications in aquatic ecosystem functioning by affecting shredders via both effect pathways. (C) 2015 Elsevier B.V. All rights reserved.
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44.
  • Carlsson, Gunnar, et al. (author)
  • Toxicity of 15 veterinary Pharmaceuticals in zebrafish (Danio rerio) embryos
  • 2013
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 126, s. 30-41
  • Journal article (peer-reviewed)abstract
    • Extensive use of veterinary pharmaceuticals may result in contamination of water bodies adjacent to pasture land or areas where animal manure has been applied. In order to evaluate the potential risk to fish embryos 15 veterinary pharmaceuticals were investigated by use of an extended zebrafish embryo toxicity test. Chemical analysis of the exposure medium was performed by solid phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) for 11 of the compounds and potential metabolism by the embryos was studied for albendazole, febantel, fenbendazole and oxfendazole. Newly fertilized zebrafish eggs were exposed under static conditions in 96-well plates for 6 days to the pharmaceuticals: 5 antibacterials and 10 antiparasitics. Endpoints including mortality, malformations and other sublethal responses were recorded at 24, 48 and 144 h post fertilization (hpf). The pharmaceuticals causing the highest toxicity were antiparasitics whereas the tested antibacterials, danofloxacin, enrofloxacin, tylosine, trimethoprim and oxytetracyclin had a much lower toxic potency in zebrafish embryos. Most toxic were fenbendazole, albendazole and flumethrin with no observed effect concentrations (NOECs) around 0.02 mg/L. The overall NOEC was determined by lethality for the following pharmaceuticals: albendazole, fenbendazole and oxfendazole. Sublethal endpoints, including malformations, side-laying embryos, tremors, reduced movements and altered heart rate increased the sensitivity of the tests and determined the overall NOECs for febantel, doramectin, ivermectin, flumethrin and toltrazuril. Exposure to doramectin and ivermectin caused a decrease in movements at 24 hpf and a decrease in heart rate at 48 hpf. Flumethrin exposure resulted in decreased time to hatching, except at the highest concentrations, and caused an increase in heart rate at 48 hpf. In contrast, toltrazuril caused an increased time to hatching and a decrease in heart rate. Chemical analysis of the exposure medium after the tests revealed great differences between nominal and measured concentrations, emphasizing the need of including analysis of the actual exposure concentrations. The results indicated that metabolism of albendazole into its sulfoxide protected the embryos from toxicity. Albendazole was metabolized efficiently into albendazole sulfoxide at lower exposure concentrations, resulting in reduced toxicity. At higher concentrations, an increasing proportion of albendazole remained unmetabolized and embryo mortality occurred. Metabolism by the embryos of febantel into fenbendazole and oxfendazole and of fenbendazole into oxfendazole was demonstrated. It is suggested that the toxic effect of febantel in zebrafish embryos is due to metabolism into fenbendazole.
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45.
  • Chen, Huihui, et al. (author)
  • Molecular, behavioral, and growth responses of juvenile yellow catfish ( Tachysurus fulvidraco ) exposed to carbamazepine
  • 2024
  • In: Aquatic Toxicology. - : Elsevier. - 0166-445X .- 1879-1514. ; 271
  • Journal article (peer-reviewed)abstract
    • Carbamazepine (CBZ) is an anticonvulsant medication used to treat epilepsy and bipolar disorder. Due to its persistence and low removal rate in wastewater treatment plants, it is frequently detected in the environment, raising concerns regarding its potential adverse effects on aquatic organisms and ecosystems. In this study, we aimed to assess the impact of CBZ on the behavior and growth of juvenile yellow catfish Tachysurus fulvidraco , a native and economically important species in China. Fish were exposed to CBZ at three concentrations of 1, 10, or 100 mu g/L for 14 days. The fish exposed to 10 and 100 mu g/L of CBZ exhibited decreased feeding, and a significant increase in cannibalistic tendencies was observed in fish exposed to 100 mu g/L CBZ. Acetylcholinesterase activity was increased in the brain of fish exposed to 100 mu g/L CBZ. CBZ also inhibited the growth of yellow catfish. To better elucidate mechanisms of toxicity, transcriptomics was conducted in both the brain and liver. In the brain, gene networks associated with neurotransmitter dysfunction were altered by CBZ, as well as networks associated with mitochondrial dysfunction and metabolism. In the liver, gene networks associated with the immune system were altered by CBZ. The current study improves comprehension of the sub-lethal effects of CBZ and reveals novel insight into molecular and biochemical pathways disrupted by CBZ, identifying putative key events associated with reduced growth and altered behavior. This study emphasizes the necessity for improved comprehension of the effects of pharmaceutical contaminants on fish at environmentally relevant levels.
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46.
  • Dawoud, Mohab, et al. (author)
  • Interactive effects of an insecticide and a fungicide on different organism groups and ecosystem functioning in a stream detrital food web
  • 2017
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 186, s. 215-221
  • Journal article (peer-reviewed)abstract
    • Freshwater ecosystems are often affected by cocktails of multiple pesticides targeting different organism groups. Prediction and evaluation of the ecosystem-level effects of these mixtures is complicated by the potential not only for interactions among the pesticides themselves, but also for the pesticides to alter biotic interactions across trophic levels. In a stream microcosm experiment, we investigated the effects of two pesticides targeting two organism groups (the insecticide lindane and fungicide azoxystrobin) on the functioning of a model stream detrital food web consisting of a detritivore (Ispoda: Asellus aquaticus) and microbes (an assemblage of fungal hyphomycetes) consuming leaf litter. We assessed how these pesticides interacted with the presence and absence of the detritivore to affect three indicators of ecosystem functioning - leaf decomposition, fungal biomass, fungal sporulation - as well as detritivore mortality. Leaf decomposition rates were more strongly impacted by the fungicide than the insecticide, reflecting especially negative effects on leaf processing by detritivores. This result most like reflects reduced fungal biomass and increased detritivore mortality under the fungicide treatment. Fungal sporulation was elevated by exposure to both the insecticide and fungicide, possibly representing a stress-induced increase in investment in propagule dispersal. Stressor interactions were apparent in the impacts of the combined pesticide treatment on fungal sporulation and detritivore mortality, which were reduced and elevated relative to the single stressor treatments, respectively. These results demonstrate the potential of trophic and multiple stressor interactions to modulate the ecosystem-level impacts of chemicals, highlighting important challenges in predicting, understanding and evaluating the impacts of multiple chemical stressors on more complex food webs in situ. (C) 2017 Elsevier B.V. All rights reserved.
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47.
  • Deng, Jun, et al. (author)
  • Hexabromocyclododecane-induced developmental toxicity and apoptosis in zebrafish embryos
  • 2009
  • In: Aquatic Toxicology. - : Elsevier. - 0166-445X .- 1879-1514. ; 93:1, s. 29-36
  • Journal article (peer-reviewed)abstract
    • Hexabromocyclododecane (HBCD) is widely used as a brominated flame retardant, and has been detected in the aquatic environment, wild animals, and humans. However, details of the environmental health risk of HBCD are not well known. In this study, zebrafish embryos were used to assess the developmental toxicity of the chemical. Four-hour post-fertilization (hpf) zebrafish embryos were exposed to various concentrations of HBCD (0, 0.05, 0.1, 0.5, and 1.0 mg L-1) until 96 h. Exposure to 0.1, 0.5, and 1.0 mg L-1 HBCD significantly increased the malformation rate and reduced survival in the 0.5 and 1.0 mg L-1 HBCD exposure groups. Acridine orange (AO) staining showed that HBCD exposure resulted in cell apoptosis. Reactive oxygen species (ROS) was significantly induced at exposures of 0.1, 0.5, and 1.0 mg L-1 HBCD. To test the apoptotic pathway, several genes related to cell apoptosis, such as p53, Puma, Apaf-1, caspase-9, and caspase-3, were examined using real-time PCR. The expression patterns of these genes were up-regulated to some extent. Two anti-apoptotic genes, Mdm2 (antagonist of p53) and Bcl-2 (inhibitor of Bax), were down-regulated, and the activity of capspase-9 and caspase-3 was significantly increased. The overall results demonstrate that waterborne HBCD is able to produce oxidative stress and induce apoptosis through the involvement of caspases in zebrafish embryos. The results also indicate that zebrafish embryos can serve as a reliable model for the developmental toxicity of HBCD.
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48.
  • dos Anjos, Talles Bruno Oliveira, et al. (author)
  • Assessing the effects of a mixture of hydrophobic contaminants on the algae Rhodomonas salina using the chemical activity concept
  • 2023
  • In: Aquatic Toxicology. - : Elsevier. - 0166-445X .- 1879-1514. ; 265
  • Journal article (peer-reviewed)abstract
    • The production and release of chemicals from human activities are on the rise. Understanding how the aquatic environment is affected by the presence of an unknown number of chemicals is lacking. We employed the chemical activity concept to assess the combined effects of hydrophobic organic contaminants on the phyto-plankton species Rodomonas salina. Chemical activity is additive, and refers to the relative saturation of a chemical in the studied matrix. The growth of R. salina was affected by chemical activity, following a chemical activity-response curve, resulting in an Ea50 value of 0.078, which falls within the baseline toxicity range observed in earlier studies. The chlorophyll a content exhibited both increases and decreases with rising chemical activity, with the increase possibly linked to an antioxidant mechanism. Yet, growth inhibition provided more sensitive and robust responses compared to photosynthesis-related endpoints; all measured endpoints correlated with increased chemical activity. Growth inhibition is an ecologically relevant endpoint and integrates ther-modynamic principles such as membrane disruption. Our study utilized passive dosing, enabling us to control exposure and determine activities in both the medium and the algae. The concept of chemical activity and our results can be extended to other neutral chemical groups as effects of chemical activity remain independent of the mixture composition.
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49.
  • Ek, Helene, 1976, et al. (author)
  • Tentative biomarkers for 2,4,6-trinitrotoluene (TNT) in fish (Oncorhynchus mykiss)
  • 2005
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 72:3, s. 221-230
  • Journal article (peer-reviewed)abstract
    • 2,4,6-Trinitrotoluene (TNT) is the major explosive in ammunition dumped into lakes and the sea after World War II. To identify useful biomarkers of TNT-exposure for forthcoming fish monitoring studies at ammunition dumping sites, rainbow trout (Oncorhynchus mykiss) were intraperitoneal (i.p.) injected with TNT in peanut oil at doses of 0, 100, 200 or 400 mg TNT/kg body weight and sampled 72 h later. The study covered blood parameters, and hepatic antioxidant and detoxifying enzymes. Fish treated with TNT had an increased glutathione S-transferase (GST) activity and glutathione reductase (GR) activity, and a decreased percentage of oxidised glutathione (%GSSG) compared to the control group. In addition to increased methemoglobin, the increased glutathione and glutathione dependent enzyme activities indicate that TNT oxidises macromolecules and activates antioxidant defence systems which may be useful as general biomarkers of TNT-exposure. The fish bile was analysed for TNT and its metabolites by gas chromatography-mass spectrometry (GC-MS), and the toxicity of the bile was determined with the cladoceran Ceriodaphnia dubia. A dose-dependent increase in TNT, 2-amino-4,6-dinitrotoluene (2-ADNT) and 4-amino-2,6-dinitrotoluene (4-ADNT) was found in the hydrolysed bile of the TNT-treated fish. These results indicate that the fish are able to detoxify and excrete TNT and suggest that the detection of TNT, 2-ADNT and 4-ADNT in bile may be suitable as a direct marker of exposure to TNT. (c) 2005 Elsevier B.V. All rights reserved.
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50.
  • Ericson, Hanna, et al. (author)
  • Physiological effects of diclofenac, ibuprofen and propranolol on Baltic Sea blue mussels
  • 2010
  • In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 99:2, s. 223-231
  • Journal article (peer-reviewed)abstract
    • Pharmaceuticals are constantly dispersed into the environment and little is known of the effects on non-target organisms. This is an issue of growing concern. In this study, Baltic Sea blue mussels, Mytilus edulis trossulus, were exposed to diclofenac, ibuprofen and propranolol, three pharmaceuticals that are produced and sold in large quantities and have a widespread occurrence in aquatic environments. The mussels were exposed to pharmaceuticals in concentrations ranging from 1 to 10,000 mu g l(-1). The pharmaceuticals were added both separately and in combination. Mussels exposed to high concentrations of pharmaceuticals showed a clear response compared to controls. Firstly, they had a significantly lower scope for growth, which indicates that the organisms had a smaller part of their energy available for normal metabolism, and secondly, they had lower byssus strength and lower abundance of byssus threads, resulting in reduced ability to attach to the underlying substrate. Mussels exposed to lower concentrations showed tendencies of the same results. The concentration of diclofenac and propranolol was quantified in the mussels using both liquid chromatography coupled to mass spectrometry (LC-MS). The measurements showed a significantly higher concentration in the organisms as compared to the water the mussels were exposed to; the uptake reached concentrations two orders of magnitudes higher than found in sewage treatment plant effluents. This study showed that common pharmaceuticals are taken up and negatively affect the physiology of a non-target species at levels of two to three orders of magnitudes higher than found in sewage treatment plant effluents.
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