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  • 1.
    Urrutia-Cordero, Pablo
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap. Univ Autonoma Madrid, Dept Biol, Madrid 28049, Spain..
    Agha, Ramsy
    Univ Autonoma Madrid, Dept Biol, Madrid 28049, Spain..
    Cires, Samuel
    Univ Autonoma Madrid, Dept Biol, Madrid 28049, Spain..
    Angeles Lezcano, Maria
    Univ Autonoma Madrid, Dept Biol, Madrid 28049, Spain..
    Sanchez-Contreras, Maria
    Univ Autonoma Madrid, Dept Biol, Madrid 28049, Spain..
    Waara, Karl-Otto
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Utkilen, Hans
    Norwegian Inst Publ Hlth, Dept Water Hyg, N-0403 Oslo, Norway..
    Quesada, Antonio
    Univ Autonoma Madrid, Dept Biol, Madrid 28049, Spain..
    Effects of harmful cyanobacteria on the freshwater pathogenic free-living amoeba Acanthamoeba castellanii2013Inngår i: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 130, s. 9-17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Grazing is a major regulating factor in cyanobacterial population dynamics and, subsequently, considerable effort has been spent on investigating the effects of cyanotoxins on major metazoan grazers. However, protozoan grazers such as free-living amoebae can also feed efficiently on cyanobacteria, while simultaneously posing a major threat for public health as parasites of humans and potential reservoirs of opportunistic pathogens. In this study, we conducted several experiments in which the freshwater amoeba Acanthamoeba castellanii was exposed to pure microcystin-LR (MC-LR) and six cyanobacterial strains, three MC-producing strains (MC-LR, MC-RR, MC-YR, MC-WR, [Dha7] MC-RR) and three strains containing other oligopeptides such as anabaenopeptins and cyanopeptolins. Although the exposure to high concentrations of pure MC-LR yielded no effects on amoeba, all MC-producing strains inflicted high mortality rates on amoeba populations, suggesting that toxic effects must be mediated through the ingestion of toxic cells. Interestingly, an anabaenopeptin-producing strain caused the greatest inhibition of amoeba growth, indicating that toxic bioactive compounds other than MCs are of great importance for amoebae grazers. Confocal scanning microscopy revealed different alterations in amoeba cytoskeleton integrity and as such, the observed declines in amoeba densities could have indeed been caused via a cascade of cellular events primarily triggered by oligopeptides with protein-phosphatase inhibition capabilities such as MCs or anabaenopeptins. Moreover, inducible-defense mechanisms such as the egestion of toxic, MC-producing cyanobacterial cells and the increase of resting stages (encystation) in amoebae co-cultivated with all cyanobacterial strains were observed in our experiments. Consequently, cyanobacterial strains showed different susceptibilities to amoeba grazing which were possibly influenced by the potentiality of their toxic secondary metabolites. Hence, this study shows the importance of cyanobacterial toxicity against amoeba grazing and, that cyanobacteria may contain a wide range of chemical compounds capable of negatively affect free-living, herbivorous amoebae. Moreover, this is of high importance for understanding the interactions and population dynamics of such organisms in aquatic ecosystems. (c) 2012 Elsevier B.V. All rights reserved.

  • 2.
    Woin, Per
    et al.
    Department of Ecology, Chemical Ecology and Ecotoxicology, University of Lund, Lund, Sweden.
    Christoffersen, Kirsten
    Freshwater Biological Laboratory, University of Copenhagen, Hillerød, Denmark.
    Friberg-Jensen, Ursula
    Freshwater Biological Laboratory, University of Copenhagen, Hillerød, Denmark.
    Wendt-Rasch, Lina
    Department of Ecology, Chemical Ecology and Ecotoxicology, University of Lund, Lund, Sweden.
    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.2003Inngår i: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 63, nr 4, s. 357-371Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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

  • 3.
    Woin, Per
    et al.
    Department of Ecology, Chemical Ecology and Ecotoxicology, Lund University, Lund, Sweden.
    Wendt-Rasch, Lina
    Department of Ecology, Chemical Ecology and Ecotoxicology, Lund University, Lund, Sweden.
    Friberg-Jensen, Ursula
    Freshwater Biological Laboratory, Hillerød, Denmark.
    Christoffersen, Kirsten
    Freshwater Biological Laboratory, Hillerød, Denmark.
    Effects of the pyrethroid insecticide cypermethrin on a freshwater community studied under field conditions: II. Direct and indirect effects on the species composition2003Inngår i: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 63, nr 4, s. 373-389Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 4.
    Woin, Per
    et al.
    Department of Ecology, Chemical Ecology and Ecotoxicology, Lund University, Lund, Sweden.
    Wendt-Rasch, Lina
    Department of Ecology, Chemical Ecology and Ecotoxicology, Lund University, Lund, Sweden.
    Pirzadeh, P.
    Department of Ecology, Chemical Ecology and Ecotoxicology, Lund University, Lund, Sweden.
    Effects of metsulfuron methyl and cypermethrin exposure on freshwater model ecosystems2003Inngår i: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 63, nr 3, s. 243-256Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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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