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  • Risk Assessment
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  • 1
    Language: English
    In: Ecotoxicology and Environmental Safety, 2010, Vol.73(7), pp.1674-1680
    Description: Current aquatic environmental risk assessment of plant protection products or biocides does not consider effects on organisms involved in leaf litter breakdown, a fundamental ecosystem process in streams. Therefore, direct ecotoxicological implications of tebuconazole, a frequently used triazole fungicide, on the leaf-shredding amphipod , were assessed. While acute toxicity was low (96h-LC =1347 μg/L), feeding rate, a sublethal endpoint, was significantly reduced after seven days of exposure to 600 μg/L. At the same concentration, but during a three week exposure under semi-static conditions, gammarids showed significant reductions in feeding, but also in assimilation and growth. At 200 μg/L, however, only assimilation was significantly affected. As these endpoints can be used to evaluate the ecotoxicity of a broad range of chemicals and to deduce possible implications in the functioning of ecosystems, the inclusion of similar experimental set-ups might further improve aquatic environmental risk assessment.
    Keywords: Gammarus ; Shredder ; Triazole Fungicide ; Sublethal Endpoints ; Environmental Risk Assessment ; Confidence Interval Testing ; Ecology ; Public Health
    ISSN: 0147-6513
    E-ISSN: 1090-2414
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  • 2
    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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  • 3
    Language: English
    In: Environmental Pollution, 2015, Vol.205, pp.16-22
    Description: Copper (Cu) exposure can increase leaf-associated fungal biomass, an important food component for leaf-shredding macroinvertebrates. To test if this positive nutritional effect supports the physiological fitness of these animals and to assess its importance...
    Keywords: Other Biological Topics ; Annan Biologi
    ISSN: 0269-7491
    E-ISSN: 18736424
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  • 4
    Language: English
    In: Environmental Science and Pollution Research, 2013, Vol.20(10), pp.7341-7347
    Description: Although generally misunderstood, the p value is the probability of the test results or more extreme results given H 0 is true: it is not the probability of H 0 being true given the results. To obtain directly useful insight about H 0 , the positive predictive value (PPV) and the negative predictive value (NPV) may be useful extensions of null hypothesis significance testing (NHST). They provide information about the probability of statistically significant and non-significant test outcomes being true based on an a priori defined biologically meaningful effect size. The present study explores the utility of PPV and NPV in an ecotoxicological context by using the frequently applied Daphnia magna reproduction test (OECD guideline 211) and the chemical stressor lindane as a model system. The results indicate that especially the NPV deviates meaningfully between a test design strictly following the guideline and an experimental procedure controlling for α and β at the level of 0.05. Consequently, PPV and NPV may be useful supplements to NHST that inform the researcher about the level of confidence warranted by both statistically significant and non-significant test results. This approach also reinforces the value of considering α , β , and a biologically meaningful effect size a priori.
    Keywords: Sample size ; Bayesian ; Power analysis ; Effect size ; Type I error rate ; Type II error rate
    ISSN: 0944-1344
    E-ISSN: 1614-7499
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  • 5
    Language: English
    In: Environmental science & technology, 07 February 2017, Vol.51(3), pp.1785-1794
    Description: Systemic neonicotinoid insecticides are increasingly used as a crop protection measure to suppress insect pests on trees. However, senescent foliage falling from treated trees represents a rarely studied pathway through which neonicotinoids may enter nontarget environments, e.g., surface waters. To estimate risk posed by this pathway, neonicotinoid residues were analyzed in foliage from black alder trees treated with one of three neonicotinoid insecticides (imidacloprid, thiacloprid, or acetamiprid) at five concentrations, each ranging from 0.0375-9.6 g active ingredient/cm trunk diameter at breast height (n = 3). Foliar residues measured at the time of leaf fall were used as input parameters for a model predicting imidacloprid water concentrations over a 100-m-long stream stretch as a consequence of remobilization from introduced foliage (input: 600 g foliage/m containing 80 μg imidacloprid/g). The water concentration (up to ∼250 ng/L) predicted by the model exceeded the recently proposed Maximum Permissible Concentration of 8.3 ng/L for ∼6.5 days. Moreover, dietary uptake was identified as an additional exposure route for aquatic organisms. The alternative pathway (i.e., introduction via leaf fall) and exposure route (i.e., dietary uptake) associated with the systemic nature of neonicotinoids should be accounted for during their registration process in order to safeguard ecosystem integrity.
    Keywords: Rivers ; Trees -- Metabolism
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 6
    Language: English
    In: Environmental Toxicology and Chemistry, December 2011, Vol.30(12), pp.2718-2724
    Description: Leaf litter breakdown is a fundamental process in aquatic ecosystems that is realized by microbial decomposers and invertebrate detritivores. Although this process may be adversely affected by fungicides, among other factors, no test design exists to assess combined effects on such decomposer–detritivore systems. Hence, the present study assessed effects of the model fungicide tebuconazole (65 µg/L) on the conditioning of leaf material (by characterizing the associated microbial community) as well as the combined effects (i.e., direct toxicity and food quality‐related effects (=indirect)) on the energy processing of the leaf‐shredding amphipod using a five‐week semistatic test design. Gammarids exposed to tebuconazole produced significantly less feces (∼20%), which in turn significantly increased their assimilation (∼30%). Moreover, a significantly reduced lipid content (∼20%) indicated lower physiological fitness. The conditioning process was altered as well, which was indicated by a significantly reduced fungal biomass (∼40%) and sporulation (∼30%) associated with the leaf material. These results suggest that tebuconazole affects both components of the investigated decomposer‐detritivore system. However, adverse effects on the level of detritivores cannot be explicitly attributed to direct or indirect pathways. Nevertheless, as the endpoints assessed are directly related to leaf litter breakdown and associated energy transfer processes, the protectiveness of environmental risk assessment for this ecosystem function may be more realistically assessed in future studies by using this or comparable test designs. Environ. Toxicol. Chem. 2011;30:2718–2724. © 2011 SETAC
    Keywords: Combined Effects ; Environmental Risk Assessment ; Leaf Litter Breakdown ; Microbial Community ; Shredder
    ISSN: 0730-7268
    E-ISSN: 1552-8618
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  • 7
    Language: English
    In: Archives of Environmental Contamination and Toxicology, 2011, Vol.60(3), pp.437-443
    Description: A 125-mile reach of the South River, Virginia, was contaminated with mercury during the first half of the 20th century. As increased concentrations of mercury have persisted, researchers have carefully studied its distribution in the river biota and estimated associated risks. The present study evaluated the influence of mercury on feeding rate and uptake by the amphipod Hyalella azteca . The test organisms were exposed for 7 days with leaf discs to reference and contaminated field sediment during the preliminary experiment and additionally to Sedimite (a commercial mercury-sequestering agent) amended sediments during the final experiment. The preliminary experiment demonstrated a decreased feeding rate (approximately 35%) of H. azteca in sediment from a contaminated site relative to sediment from a reference site. The test design of the final experiment took advantage of the knowledge gained in the preliminary experiment by increasing the number of replicates, which decreased the type II error rate. First, the results of the final experiment confirmed the results of the preliminary experiment by again demonstrating differences in the feeding rate of approximately 35% between reference and contaminated sediment. Second, the results indicated a lower feeding rate in reference sediment in the presence of Sedimite. Third, an opposite tendency, although not significant, was apparent for Sedimite-amended contaminated sediment. Thus, Sedimite appears to decrease sediment quality, whereas this conclusion is based on the feeding rate of H. azteca . However, Sedimite and its value as a mercury-sequestering agent requires further evaluation.
    Keywords: Sediments (Geology);
    ISSN: 0090-4341
    E-ISSN: 1432-0703
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  • 8
    Language: English
    In: Aquatic Toxicology, 2011, Vol.104(1), pp.32-37
    Description: The energy stored in coarse particulate organic matter, e.g. leaf litter, is released to aquatic ecosystems by breakdown processes involving microorganisms and leaf shredding invertebrates. The palatability of leaves and thus the feeding of shredders on leaf material are highly influenced by microorganisms. However, implications in the colonization of leaves by microorganisms (=conditioning) caused by chemical stressors are rarely studied. Our laboratory experiments, therefore, investigated for the first time effects of a fungicide on the conditioning process of leaf material by means of food-choice experiments using (Crustacea: Amphipoda). Additionally, microbial analyses were conducted to facilitate the mechanistic understanding of the observed behavior. Gammarids significantly preferred control leaf discs over those conditioned in presence of the fungicide tebuconazole at concentrations of 50 and 500 μg/L. Besides the decrease of fungal biomass with increasing fungicide concentration, also the leaf associated fungal community composition showed that species preferred by gammarids, such as , , or , were more frequent in the control. , however, which is rejected by gammarids, was abundant in all treatments suggesting an increasing importance of this species for the lower leaf palatability – as other more palatable fungal species were almost absent – in the fungicide treatments. Hence, the food-choice behavior of seems to be a suitable indicator for alterations in leaf associated microbial communities, especially fungal species composition, caused by chemical stressors. Finally, this or similar test systems may be a reasonable supplement to the environmental risk assessment of chemicals in order to achieve its protection goals, as on the one hand, indirect effects may occur far below concentrations known to affect gammarids directly, and on the other hand, the observed shifts in leaf associated microbial communities may have perpetuating implications in leaf shredding invertebrates.
    Keywords: Fungal Community ; Leaf Litter Decomposition ; Confidence Interval Testing ; Aquatic Hyphomycetes ; Azole Fungicide ; Bacteria ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 9
    Language: English
    In: Ecotoxicology and Environmental Safety, 01 September 2013, Vol.95, pp.137-143
    Description: The present study investigated sublethal effects of a field relevant pesticide mixture (one herbicide, three fungicides, five insecticides) on by considering different peak exposure scenarios, which may be generated by the inherent properties of vegetated ditches. Additional experiments aimed at the identification of germane exposure pathways (food and water). Therefore, were exposed in independent experiments to three scenarios, which differed besides in the peak concentration of the pesticide mixture also in the mixture's composition and exposure duration ( =20 per treatment). The exposure duration of 12 or 120 min was followed by a seven-day post-exposure observation period. At a constant concentration–time product, a lower exposure duration in concert with a proportionally higher peak concentration caused a substantially elevated ecotoxicity compared to a treatment with a longer exposure duration at a lower peak concentration. Given the importance of the insecticide lambda-cyhalothrin for the mixture's ecotoxicity it may be concluded that the fast mode of action of pyrethroids mainly explains this observation. Moreover, field relevant concentrations of the pesticide mixture applied at an exposure duration of 120 min resulted in reduced gammarids' feeding rate, which may be indicative for shifts in the ecosystem function of leaf litter breakdown and hence the provision of energy for local and downstream communities. Finally, the present study indicated that both pathways of exposure, namely via food or water, reduce gammarids' feeding rate synergistically. This suggests that both exposure pathways should be considered for compounds exhibiting a high K (e.g. pyrethroids) during the risk assessment of single substances and mixtures.
    Keywords: Feeding ; Mixture Toxicity ; Herbicide ; Insecticide ; Fungicide ; Peak Exposure ; Ecology ; Public Health
    ISSN: 0147-6513
    E-ISSN: 1090-2414
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  • 10
    Language: English
    In: Scientific Reports, 01 November 2017, Vol.7(1), pp.1-10
    Description: Abstract Systemic neonicotinoids are commonly used in forest pest management programs. Senescent leaves containing neonicotinoids may, however, fall from treated trees into nearby streams. There, leaf-shredding invertebrates are particularly exposed due to their diet (feeding on neonicotinoid-contaminated leaves) or collaterally via the water phase (leaching of a neonicotinoid from leaves) – a fact not considered during aquatic environmental risk assessment. To unravel the relevance of these pathways we used leaves from trees treated with the neonicotinoid thiacloprid to subject the amphipod shredder Gammarus fossarum for 21 days (n = 40) either to dietary, waterborne or a combined (dietary + waterborne) exposure. Dietary exposure caused – relative to the control – similar reductions in gammarids’ leaf consumption (~35%) and lipid content (~20%) as observed for the waterborne exposure pathway (30 and 22%). The effect sizes observed under combined exposure suggested additivity of effects being largely predictable using the reference model “independent action”. Since gammarids accumulated – independent of the exposure pathway – up to 280 ng thiacloprid/g, dietary exposure may also be relevant for predators which prey on Gammarus. Consequently, neglecting dietary exposure might underestimate the environmental risk systemic insecticides pose for ecosystem integrity calling for its consideration during the evaluation and registration of chemical stressors.
    Keywords: Biology
    E-ISSN: 2045-2322
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