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  • Ecology
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  • 1
    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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  • 2
    Language: English
    In: Chemosphere, 2011, Vol.85(10), pp.1563-1567
    Description: ► Effects of nTiO and ambient UV-irradiation affect representatives of detrital food webs. ► Accumulation of nTiO at the bottom of the test vessel seems to affect ecotoxicity. ► nTiO and ambient UV-irradiation increases ecotoxicity due to the formation of ROS. Production and use of engineered nanoparticles, such as titanium dioxide nanoparticles (nTiO ), is increasing worldwide, enhancing their probability to enter aquatic environments. However, direct effects of nTiO as well as ecotoxicological consequences due to the interactions of nTiO with environmental factors like ultraviolet (UV) irradiation on representatives of detrital food webs have not been assessed so far. Hence, the present study displayed for the first time adverse sublethal effects of nTiO at concentrations as low as 0.2 mg L on the leaf shredding amphipod both in presence and absence of ambient UV-irradiation following a 7-d exposure. In absence of UV-irradiation, however, the effects seemed to be driven by accumulation of nTiO at the bottom of the test vessels to which the gammarids were potentially exposed. The adverse sublethal and lethal effects on gammarids caused by the combined application of nTiO and ambient UV-irradiation are suggested to be driven by the formation of reactive oxygen species. In conclusion, both the accumulation of nTiO at the bottom of the test vessel and the UV induced formation of reactive oxygen species clearly affected its ecotoxicity, which is recommended for consideration in the environmental risk assessment of nanoparticles.
    Keywords: Nanoparticle ; Titanium Dioxide ; Ultraviolet Irradiation ; Gammarus Fossarum ; Accumulation ; Reactive Oxygen Species ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 3
    Language: English
    In: Environmental Pollution, January 2015, Vol.196, pp.276-283
    Description: Interactions with environmental parameters may alter the ecotoxicity of nanoparticles. The present study therefore assessed the (in)direct effects of nanoparticulate titanium dioxide (nano-TiO ) towards , considering nano-TiO 's photocatalytic properties at ambient UV-intensities. Gammarids' habitat selection was investigated using its feeding preference on leaf discs either exposed to or protected from UV-irradiation in presence of nano-TiO as proxy (  = 49). UV-irradiation alone induced a significant preference for UV-protected habitats, which was more pronounced in simultaneous presence of nano-TiO . This behaviour may be mainly explained by the UV-induced formation of reactive oxygen species (ROS) by nano-TiO . Besides their direct toxicity, ROS may have lowered the leaf-quality in UV-exposed areas contributing (approximately 30%) to the observed behavioural pattern. Since the predicted no effect concentration of nano-TiO in combination with UV-irradiation falls below the predicted environmental concentration this study underpins the importance of considering environmental parameters during the risk assessment of nanoparticles. Results revealed for the first time a PNEC of nano-TiO falling below the PEC indicating a substantial risk for aquatic ecosystems already nowadays.
    Keywords: Gammarus ; Uv-Irradiation ; Interaction Effect ; Reactive Oxygen Species ; Behavioural Response ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 4
    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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  • 5
    Language: English
    In: Aquatic Toxicology, 15 January 2013, Vol.126, pp.163-168
    Description: ► nTiO concentrations one order of magnitude above the PEC caused adverse chronic effects. ► Particle size and product composition, i.e. crystalline structure, trigger differences in nTiO toxicity. ► nTiO accumulation at the bottom of the test vessel is an important effect pathway. ► Dissolved organic carbon influences fate and finally nTiO toxicity. The increasing use of titanium dioxide nanoparticles (nTiO ) 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 among others to . 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 products with varying crystalline structure (A-100; P25) to . 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 (∼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 (∼140 nm). Likewise, P25 (∼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 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 toxicity to . Hence, these factors should be considered to improve environmental risk assessment of nanoparticles.
    Keywords: Inorganic Nanoparticles ; Reproduction ; Growth ; Flow-through ; Crustacea ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 6
    Language: English
    In: Ecotoxicology and Environmental Safety, January 2015, Vol.111, pp.263-270
    Description: Studies assessing the acute and chronic toxicity of silver nanoparticle (nAg) materials rarely consider potential implications of environmental variables. In order to increase our understanding in this respect, we investigated the acute and chronic effects of various nAg materials on . Thereby, different nanoparticle size classes with a citrate coating (20-, ~30-, 60- as well as 100-nm nAg) and one size class without any coating (140 nm) were tested, considering at the same time two pH levels (6.5 and 8.0) as well as the absence or presence of dissolved organic matter (DOM; 〈0.1 or 8.0 mg total organic carbon/L). Results display a reduced toxicity of nAg in media with higher pH and the presence of DOM as well as increasing initial particle size, if similarly coated. This suggests that the associated fraction of Ag species 〈2 nm (including Ag ) is driving the nAg toxicity. This hypothesis is supported by normalizing the 48-h EC -values to Ag species 〈2 nm, which displays comparable toxicity estimates for the majority of the nAg materials assessed. It may therefore be concluded that a combination of both the particle characteristics, i.e. its initial size and surface coating, and environmental factors trigger the toxicity of ion-releasing nanoparticles.
    Keywords: Nanomaterial ; Silver ; Acute Toxicity ; Crustacean ; Environmental Conditions ; Ecology ; Public Health
    ISSN: 0147-6513
    E-ISSN: 1090-2414
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  • 7
    In: Environmental Toxicology and Chemistry, July 2016, Vol.35(7), pp.1766-1774
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://onlinelibrary.wiley.com/doi/10.1002/etc.3325/abstract Byline: Ricki R. Rosenfeldt, Frank Seitz, Ann-Cathrin Haigis, Johanna Hoger, Jochen P. Zubrod, Ralf Schulz, Mirco Bundschuh Abstract Titanium dioxide nanoparticles (TiO.sub.2-NPs) adsorb co-occurring heavy metals in surface waters, modulating their toxicity for freshwater invertebrates. The processes triggering this interaction may be influenced by several environmental parameters; however, their relative importance remains unclear. The present study assessed the implications of aging on the joint acute toxicity of copper (Cu) and TiO.sub.2-NPs for Daphnia magna over a duration of up to 72h. The influences of aging duration as well as ionic strength, pH, and presence of different qualities of organic matter during aging were assessed. The results indicated that the presence of TiO.sub.2-NPs often reduced the Cu-induced toxicity for daphnids after aging (albeit with varying extent), which was displayed by up to 3-fold higher EC50 (50% effective concentration) values compared to the absence of TiO.sub.2-NPs. Moreover, the Cu speciation, influenced by the ionic composition and the pH as well as the presence of organic additives in the medium, strongly modulated the processes during aging, with partly limited implications of the aging duration on the ecotoxicological response of D. magna. Nonetheless, the present study underpins the potential of TiO.sub.2-NPs to modify toxicity induced by heavy metals in freshwater ecosystems under various environmental conditions. This pattern, however, needs further verification using heavy metal ions with differing properties in combination with further environmental factors, such as ultraviolet irradiation. Environ Toxicol Chem 2016;35:1766-1774. [c] 2015 SETAC Supporting information: Additional Supporting Information may be found in the online version of this article This article includes online-only Supplemental Data. CAPTION(S): Supporting Information.
    Keywords: Environmental Parameter ; Adsorption ; Mixture Toxicity ; Factorial Approach ; Crustacean
    ISSN: 0730-7268
    E-ISSN: 1552-8618
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  • 8
    Language: English
    In: Aquatic Toxicology, August 2015, Vol.165, pp.154-159
    Description: In aquatic ecosystems, titanium dioxide nanoparticles (nano-TiO ) may adsorb co-occurring chemical stressors, such as copper (Cu). This interaction has the potential to reduce the concentration of dissolved Cu due to surface binding to the nanoparticles. The subsequent sedimentation of nano-TiO agglomerates may increase the exposure of benthic species towards the associated Cu. This scenario was assessed by employing the amphipod as model species and taking advantage of a 2 × 2-factorial design investigating absence and presence of 2 mg nano-TiO /L and 40 μg Cu/L ( = 45; = 24 d) in darkness, respectively. Nano-TiO alone did not affect mortality and leaf consumption, whereas Cu alone caused high mortality (〉70%), reduced leaf consumption (25%) and feces production (30%) relative to the control. In presence of nano-TiO , Cu-induced toxicity was largely eliminated. However, independent of Cu, nano-TiO decreased the gammarids’ assimilation and weight. Hence, nano-TiO may be applicable as Cu-remediation agent, while its potential long-term effects need further attention.
    Keywords: Heavy Metal ; Benthic Invertebrates ; Energy Processing ; Remediation ; Combined Toxicity ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 9
    In: Environmental Toxicology and Chemistry, August 2017, Vol.36(8), pp.2178-2189
    Description: Byline: Jochen P. Zubrod, Dominic Englert, Jakob Wolfram, Ricki R. Rosenfeldt, Alexander Feckler, Rebecca Bundschuh, Frank Seitz, Marco Konschak, Patrick Baudy, Simon Luderwald, Patrick Fink, Andreas Lorke, Ralf Schulz, Mirco Bundschuh Abstract Leaf litter is a major source of carbon and energy for stream food webs, while both leaf-decomposing microorganisms and macroinvertebrate leaf shredders can be affected by fungicides. Despite the potential for season-long fungicide exposure for these organisms, however, such chronic exposures have not yet been considered. Using an artificial stream facility, effects of a chronic (lasting up to 8 wk) exposure to a mixture of 5 fungicides (sum concentration 20I1/4g/L) on leaf-associated microorganisms and the key leaf shredder Gammarus fossarum were therefore assessed. While bacterial density and microorganism-mediated leaf decomposition remained unaltered, fungicide exposure reduced fungal biomass ([less than or equal to]71%) on leaves from day 28 onward. Gammarids responded to the combined stress from consumption of fungicide-affected leaves and waterborne exposure with a reduced abundance ([less than or equal to]18%), which triggered reductions in final population biomass (18%) and in the number of precopula pairs ([less than or equal to]22%) but could not fully explain the decreased leaf consumption (19%), lipid content ([less than or equal to]43%; going along with an altered composition of fatty acids), and juvenile production (35%). In contrast, fine particulate organic matter production and stream respiration were unaffected. Our results imply that long-term exposure of leaf-associated fungi and shredders toward fungicides may result in detrimental implications in stream food webs and impairments of detrital material fluxes. These findings render it important to understand decomposer communities' long-term adaptational capabilities to ensure that functional integrity is safeguarded. Environ Toxicol Chem 2017;36:2178-2189. [c] 2017 SETAC Supporting information: Additional Supporting Information may be found in the online version of this article This article includes online-only Supplemental Data. CAPTION(S): Supporting Data.
    Keywords: Aquatic Hyphomycetes ; Chronic Exposure ; Gammarus Fossarum ; Leaf Litter Breakdown ; Population Development
    ISSN: 0730-7268
    E-ISSN: 1552-8618
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  • 10
    Language: English
    In: Aquatic Toxicology, July 2019, Vol.212, pp.47-53
    Description: 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 ) and silver (nAg), on the benthic model organism 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 : ∼80 nm, 4 mg/L or nAg: ∼30 nm, 0.125 mg/L;  = 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 ∼30%) in induced by waterborne exposure towards nTiO . In contrast, the dietary exposure towards nAg significantly increased the organisms’ energy assimilation (up 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 . The results of the present study are thus supporting current approaches for nano-specific grouping that might enable an enhanced accuracy in predicting EINP effects facilitating their environmental risk assessment.
    Keywords: Nanomaterial ; Titanium Dioxide ; Silver ; Exposure Pathway ; Chronic Toxicity ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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