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  • Wiley (CrossRef)  (93)
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  • 1
    In: Freshwater Biology, June 2013, Vol.58(6), pp.1116-1125
    Description: 1. Most European crayfish species are strongly threatened, mainly as a result of the introduced pathogen, , transmitted by invasive North American crayfish. Long‐term coexistence of American and European crayfish species is therefore regarded as almost impossible, even though some coexisting populations have been observed. 2. In this study, crayfish were collected from presently coexisting populations of the introduced spiny‐cheek crayfish () and the native noble crayfish () from nine standing waters in central Europe. Our aim was to resolve whether the coexistence resulted from reduced virulence in local strains of , increased immunity in the native crayfish or an absence of the pathogen in these populations. We used highly sensitive ‐specific real‐time PCR to evaluate the crayfish latent carrier status, combined with transmission experiments to further validate the molecular results. 3. From the total of 523 crayfish tested (490 spiny‐cheek crayfish, 33 noble crayfish), none positive for was detected. Transmission experiments confirmed these results: No abnormal mortality or behavioural changes were seen in noble crayfish kept together with American crayfish from the coexisting populations. If we assume a very low prevalence of of 10% in a carrier population, there is a 98% probability of disease being absent in five of the nine coexisting populations tested. Hence, a consistent absence, or an extremely low prevalence, of seems to allow the coexistence of European and American crayfish in these central European populations. 4. The results are important for native crayfish conservation and management and demonstrate that disease transmission risk may vary substantially between the different populations of spiny‐cheek crayfish in central Europe.
    Keywords: Coexistence ; Crayfish Plague ; Invasive Species ; Real‐Time Pcr ; Transmission Experiment
    ISSN: 0046-5070
    E-ISSN: 1365-2427
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  • 2
    In: Freshwater Biology, April 2014, Vol.59(4), pp.761-776
    Description: Reconstructing the phylogeographic history of a species can aid in defining areas of conservation priority. For freshwater species, historical river structure plays a significant role in explaining genetic differentiation and population structure. However, human‐induced translocations can erase the natural genetic structure, especially for species of commercial interest such as the noble crayfish (Astacus astacus). Our aim was to reconstruct the current genetic structure of the endangered noble crayfish in central Europe to identify refugial areas that are hotspots of genetic diversity. We analysed a fragment of the mitochondrial cytochrome oxidase subunit I, and the 16S rRNA from 540 noble crayfish specimens from 156 sampling sites distributed around five European sea basins. Additionally, we conducted a microsatellite analysis of 289 individuals from 22 sites. Both mitochondrial and nuclear markers revealed genetically relatively homogenous populations in central Europe that had been influenced by anthropogenic translocations. However, some areas (Eider catchment in northern Germany and Rhineland‐Palatinate in south‐western Germany) show a distinct genetic structure with endemic haplotypes and private alleles indicating (i) that these areas were refugia for A. astacus in central Europe and (ii) that these populations have not been subject to anthropogenic translocations. Further, we found the highest genetic diversity in the Black Sea basin and particularly high differentiation between populations from the western Balkans and the remaining Black Sea populations. The split between Western Balkan and the remaining European populations is estimated to have occurred approximately 700 k years before present, whereas remaining differentiations occurred within the last 450 k years. Using migration modelling, we detected that the North Sea basin and the Baltic Sea basin were colonised independently via different colonisation paths from the eastern Black Sea basin, while the western Balkans did not contribute to this colonisation. Our results suggest the existence of at least two refugial areas in south‐eastern Europe. To conserve maximum genetic diversity, conservation priorities for noble crayfish should focus on the south‐eastern European genetic hotspots and on populations in central Europe that hold an autochthonous genetic structure (e.g. Langsee in the Eider catchment area). We further propose that each river catchment should form a separate management unit to reduce anthropogenic genetic homogenisation.
    Keywords: Human‐Mediated Translocation ; Microsatellite Analysis ; Migration Model ; Mitochondrial ; Refugial Areas
    ISSN: 0046-5070
    E-ISSN: 1365-2427
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  • 3
    In: Freshwater Biology, December 2014, Vol.59(12), pp.2645-2655
    Description: Biodiversity is globally threatened by the replacement of native species by invasive species and ensuing changes in ecosystem functioning. Although trophic linkages between aquatic and terrestrial ecosystems have received attention, effects of aquatic invasive species on the flow of resource subsidies have been considered only recently. We examined how the effects of one of the most invasive macroinvertebrate species in European waterways, the amphipod Dikerogammarus villosus, extend from streams to the terrestrial food web. We quantified aquatic emergence and the contribution of aquatic resources to the diets of two riparian spider taxa in relation to the density of D. villosus. Our results indicated that the effects of this invasive species carry over to the terrestrial system via cross‐ecosystem flow of resource subsidy. The contribution of aquatic resources to the diet of the terrestrial web‐building spider Tetragnatha decreased from 60% at low densities of D. villosus to 10% at a D. villosus density 〉5000 individuals m−2. This correlates with a decreasing emergence rate of merolimnic midges (species with an aquatic larval phase) from 12 to 〈3 mg dry biomass m−2 day−1 at the respective densities of D. villosus. The magnitude of biomass flow from the aquatic to the terrestrial ecosystem is most likely decreased by D. villosus, and this decrease extends to the diet of riparian web‐building spiders. Effects of this aquatic invader may also extend to a decoupling of the terrestrial ecosystem from the aquatic ecosystem in terms of subsidy flux.
    Keywords: Aquatic–Terrestrial Interaction ; Dikerogammarus Villosus ; Riparian Spider ; Stable Isotopes ; Tetragnatha
    ISSN: 0046-5070
    E-ISSN: 1365-2427
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  • 4
    In: Freshwater Biology, December 2016, Vol.61(12), pp.2185-2196
    Description: Ecotoxicology is often criticised for its simplistic approach, which does not normally consider the complexity of field conditions. Simple laboratory experiments can still be useful, however, especially for assessing effects of emerging stressors such as nanoparticles, which exhibit fates, exposure profiles and modes of action substantially different from those of traditional chemicals. Here we argue that it is important to understand the potential effects of environmental conditions (e.g. UV radiation, dissolved organic matter, chemical stressors) on the fate and ecotoxicological potential of nanoparticles by using simple and well‐controlled experiments, while aiming to mimic realistic environmental conditions as closely as possible. The observation that increasingly complex test systems may yield lower effect thresholds for nanoparticles than standardised tests suggests that current approaches require modification. Specifically, research is encouraged on interactions among trophic levels, community composition and ecosystem and evolutionary processes, so that effects observed in complex environmental settings can be explained mechanistically. We highlight recent discoveries in ecotoxicology and ecology that suggest nanoparticle‐induced consequences on evolutionary and ecosystem processes as well as their potential transfer across ecosystem boundaries. These insights may encourage further research on nanoparticle effects informed by ecological theory.
    Keywords: Environmental Variables ; Mechanism Of Toxicity ; Mixture Toxicity ; Nanomaterial ; Trophic Interaction
    ISSN: 0046-5070
    E-ISSN: 1365-2427
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  • 5
    In: Journal of Applied Ecology, August 2014, Vol.51(4), pp.958-967
    Description: Molecular genetic methods continuously uncover cryptic lineages harboured by various species. However, from an applied perspective, it remains unclear whether and to which extent such a genetic diversity affects biological traits (e.g. ecological, behavioural and physiological characteristics) and environmental management. We assessed potential deviations regarding the trait ‘environmental stress tolerance’ using individuals from five field populations of each of two cryptic lineages (called A and B) comprised under the nominal species Gammarus fossarum. We used ammonia as a chemical stressor while assessing the feeding rate on leaf discs as a measure of sublethal response. In this context, we established a restriction fragment length polymorphism assay to allow a rapid identification of the lineages. We observed a biologically meaningful and statistically significant twofold higher overall tolerance of one cryptic lineage, lineage B, over the other. Confounding factors that may have the potential to influence the test results, such as life stage, sex, season of collection, parasitism, physiological status of organisms and upstream land‐use patterns of the river catchments, were either controlled for or displayed only minor deviations between lineages. Synthesis and applications. The trait differences observed in the present study seem to be mainly explained by the considerable genetic differentiation between cryptic lineages of one nominal species. Although traits other than tolerance have been minimally investigated in this context, this study indicates implications in the reliability and quality of environmental monitoring and management if cryptic lineage complexes are ignored. The trait differences observed in the present study seem to be mainly explained by the considerable genetic differentiation between cryptic lineages of one nominal species. Although traits other than tolerance have been minimally investigated in this context, this study indicates implications in the reliability and quality of environmental monitoring and management if cryptic lineage complexes are ignored.
    Keywords: Environmental Management ; Gammarus ; Genetic Differentiation ; Leaf Litter Breakdown ; Nominal Species ; Rflp ; Sensitivity
    ISSN: 0021-8901
    E-ISSN: 1365-2664
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  • 6
    In: Journal of Applied Ecology, April 2015, Vol.52(2), pp.310-322
    Description: The application of fungicides is considered an indispensable measure to secure crop production. These substances, however, may unintentionally enter surface waters via run‐off, potentially affecting the microbial community. To assess such risks adequately, authorities recently called for suitable test designs involving relevant aquatic micro‐organisms. We assessed the structural and functional responses of leaf‐associated microbial communities, which play a key role in the breakdown of allochthonous leaf material in streams, towards the inorganic fungicides copper (Cu) and elemental sulphur (S). These substances are of particular interest as they are authorized for both conventional and organic farming in many countries of the world. We used the food choice of the amphipod shredder Gammarus fossarum (indicative for micro‐organism‐mediated leaf palatability) as well as microbial leaf decomposition as functional endpoints. Moreover, the leaf‐associated microbial communities were characterized by means of bacterial density, fungal biomass and community composition facilitating mechanistic understanding of the observed functional effects. While Gammarus preferred Cu‐exposed leaves over unexposed ones, microbial leaf decomposition was reduced by both Cu and S (up to 30%). Furthermore, Cu exposure decreased bacterial densities (up to 60%), stimulated the growth of leaf‐associated fungi (up to 100%) and altered fungal community composition, while S did not affect any of the assessed structural endpoints. Synthesis and applications. We observed both structural and functional changes in leaf‐associated microbial communities at inorganic fungicide concentrations realistic for surface water bodies influenced by conventional and organic farming. Our data hence justify a careful re‐evaluation of the environmental safety of the agricultural use of these compounds. Moreover, inclusion of an experimental design similar to the one used in this study in lower tier environmental risk assessments of antimicrobial compounds may aid to safeguard the integrity of aquatic microbial communities and the functions they provide. We observed both structural and functional changes in leaf‐associated microbial communities at inorganic fungicide concentrations realistic for surface water bodies influenced by conventional and organic farming. Our data hence justify a careful re‐evaluation of the environmental safety of the agricultural use of these compounds. Moreover, inclusion of an experimental design similar to the one used in this study in lower tier environmental risk assessments of antimicrobial compounds may aid to safeguard the integrity of aquatic microbial communities and the functions they provide.
    Keywords: Antagonistic Effect ; Antimicrobial ; Aquatic Hyphomycetes ; Bacteria ; Biofilm ; Ecosystem Functioning ; Environmental Risk Assessment ; Heavy Metal ; Leaf Litter Breakdown ; Mixture Toxicity
    ISSN: 0021-8901
    E-ISSN: 1365-2664
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  • 7
    Language: English
    In: Integrated Environmental Assessment and Management, October 2011, Vol.7(4), pp.612-623
    Description: The quantification of risk (the likelihood and extent of adverse effects) is a prerequisite in regulatory decision making for plant protection products and is the goal of the Xplicit project. In its present development stage, realism is increased in the exposure assessment (EA), first by using real‐world data on, e.g., landscape factors affecting exposure, and second, by taking the variability of key factors into account. Spatial and temporal variability is explicitly addressed. Scale dependencies are taken into account, which allows for risk quantification at different scales, for example, at landscape scale, an overall picture of the potential exposure of nontarget organisms can be derived (e.g., for all off‐crop habitats in a given landscape); at local scale, exposure might be relevant to assess recovery and recolonization potential; intermediate scales might best refer to population level and hence might be relevant for risk management decisions (e.g., individual off‐crop habitats). The Xplicit approach is designed to comply with a central paradigm of probabilistic approaches, namely, that each individual case that is derived from the variability functions employed should represent a potential real‐world case. This is mainly achieved by operating in a spatiotemporally explicit fashion. Landscape factors affecting the local exposure of habitats of nontarget species (i.e., receptors) are derived from geodatabases. Variability in time is resolved by operating at discrete time steps, with the probability of events (e.g., application) or conditions (e.g., wind conditions) defined in probability density functions (PDFs). The propagation of variability of parameters into variability of exposure and risk is done using a Monte Carlo approach. Among the outcomes are expectancy values on the realistic worst‐case exposure (predicted environmental concentration [PEC]), the probability that the PEC exceeds the ecologically acceptable concentration (EAC) for a given fraction of habitats, and risk curves. The outcome can be calculated at any ecologically meaningful organization level of receptors. An example application of Xplicit is shown for a hypothetical risk assessment for nontarget arthropods (NTAs), demonstrating how the risk quantification can be improved compared with the standard deterministic approach. Integr Environ Assess Manag 2011;7:612–623. © 2011 SETAC
    Keywords: Probabilistic Risk Assessment ; Plant Protection Products ; Spray Drift ; Monte Carlo ; Landscape Level
    ISSN: 1551-3777
    E-ISSN: 1551-3793
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  • 8
    Language: English
    In: Integrated Environmental Assessment and Management, January 2013, Vol.9(1), pp.172-173
    Description: Byline: Alexander Feckler, Ralf Schulz, Mirco Bundschuh ***** No abstract is available for this article. ***** Author Affiliation: Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Germany
    Keywords: Environmental Sciences;
    ISSN: 1551-3777
    E-ISSN: 1551-3793
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  • 9
    In: Global Change Biology, February 2018, Vol.24(2), pp.e402-e415
    Description: Ecosystem functions in streams (e.g., microbially mediated leaf litter breakdown) are threatened globally by the predicted agricultural intensification and its expansion into pristine areas, which is associated with increasing use of fertilizers and pesticides. However, the ecological consequences may depend on the disturbance history of microbial communities. To test this, we assessed the effects of fungicides and nutrients (four levels each) on the structural and functional resilience of leaf‐associated microbial communities with differing disturbance histories (pristine vs. previously disturbed) in a 2 × 4 × 4‐factorial design (=6) over 21 days. Microbial leaf breakdown was assessed as a functional variable, whereas structural changes were characterized by the fungal community composition, species richness, biomass, and other factors. Leaf breakdown by the pristine microbial community was reduced by up to 30% upon fungicide exposure compared with controls, whereas the previously disturbed microbial community increased leaf breakdown by up to 85%. This significant difference in the functional response increased in magnitude with increasing nutrient concentrations. A pollution‐induced community tolerance in the previously disturbed microbial community, which was dominated by a few species with high breakdown efficacies, may explain the maintained function under stress. Hence, the global pressure on pristine ecosystems by agricultural expansion is expected to cause a modification in the structure and function of heterotrophic microbial communities, with microbially mediated leaf litter breakdown likely becoming more stable over time as a consequence of fungal community adaptions. Agricultural land use is projected to expand and intensify globally, with elevated chemical stress release to adjacent streams. We assessed if leaf‐associated microbial communities adapt to a combination of two agricultural stressors, namely fungicides and nutrients. Under fungicide stress, previously disturbed communities showed an even stimulated rate of leaf litter breakdown, while microbial communities from a pristine site were negatively affected. Nutrients induced positive effects on leaf litter breakdown, which was stronger for the previously disturbed community. These observations are likely explained by a dominance of tolerant and effective fungal decomposers that were able to maintain their biomass and sporulation.
    Keywords: Agricultural Intensification ; Aquatic Hyphomycetes ; Bacteria ; Biofilm ; Ecosystem Function ; Fungicides ; Land Use ; Nutrients
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 10
    Language: English
    In: Environmental Toxicology and Chemistry, October 2012, Vol.31(10), pp.2384-2390
    Description: Traditional risk assessment guidelines employ acute or chronic toxicity tests for a maximum of one generation of organisms. These tests are usually performed in the laboratory at a constant standard temperature, although in the field organisms may experience different temperatures, which may be a source of additional stress. Climate change–related temperature shifts may have serious impacts on ectotherm populations that are key components of the aquatic food chains, particularly in combination with the exposure of pollutants affecting their development. Here, a chronic full life‐cycle test with from the first‐instar larvae in the parental (P) generation until emergence in the subsequent F1 generation was conducted at different temperatures (16 and 24°C), testing the effect of the insect growth regulator pyriproxyfen at 1, 3, 10, 30, and 100 µg/L. The emergence ratios were significantly affected by the interaction of temperature, chemical treatment, and generation, showing that, at lower temperatures, the negative effects of pyriproxyfen exposure were significantly greater in the F1 generation than in the P generation. The development rate showed that the effects of the interactions were significant in the F1 generation, underscoring the importance of extended exposure as a useful amendment to the risk assessment of those agrochemicals potentially influencing developmental and reproductive parameters in intact organisms. Moreover, results demonstrated that any difference from the standard temperature of 20°C might result in additional stress, leading to disruption of biological functions in , highlighting the interaction among different global climate change‐related variables. Environ. Toxicol. Chem. 2012; 31: 2384–2390. © 2012 SETAC
    Keywords: Full Life‐Cycle Test ; Interaction Effect ; Ectotherms ; Temperature Shift ; Organisms' Sensibility
    ISSN: 0730-7268
    E-ISSN: 1552-8618
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