Kooperativer Bibliotheksverbund

Language: English

In: Environmental Pollution, March 2017, Vol.222, pp.458-464

Description: Leaf-shredding amphipods play a critical role in the ecosystem function of leaf litter breakdown, a key process in many low order streams. Fungicides, however, may adversely influence shredders' behavior and the functions they provide, while there is only limited knowledge concerning effects on their reproductive performance. To assess the latter, a semi-static 56-day partial life-cycle bioassay using the model shredder (  = 30) was performed applying two environmentally relevant concentrations of a model fungicide mixture (i.e., 5 and 25 μg/L) composed of five fungicides with different modes of toxic action. Variables related to the food processing (leaf consumption and feces production), growth (body length and dry weight), energy reserves (lipid content), and reproduction (amplexus pairs, number and length of offspring) were determined to understand potential implications in the organisms' energy budget. While the fungicides did not affect leaf consumption, both fungicide treatments significantly reduced amphipods' feces production (∼20%) compared to the control. This observation suggests an increased food utilization to counteract the elevated and stress-related energy demand: although growth as well as energy reserves were unaffected, amplexus pairs were less frequently observed in both fungicide treatments (∼50–100%) suggesting a tradeoff regarding energy allocation favoring the maintenance of fundamental functions at the organism level over reproduction. As a result, the time to release of first offspring was delayed in both fungicide treatments (7 and 14 days) and the median number of offspring was significantly lower in the 25-μg/L treatment (100%), whereas offspring length remained unaffected. The results of this study thus indicate that chronic fungicide exposures can negatively impact shredders' reproductive performance. This may translate into lower abundances and thus a reduced contribution to leaf litter breakdown in fungicide-impacted streams with potentially far-reaching consequences for detritus-based food webs. Chronic exposure to environmentally relevant fungicide concentrations can negatively impact leaf-shredders' reproductive performance.

Keywords: Shredder ; Fungicide ; Mixture ; Energy Allocation ; Reproduction ; Engineering ; Environmental Sciences ; Anatomy & Physiology

ISSN: 0269-7491

E-ISSN: 1873-6424

DOI: 10.1016/j.envpol.2016.11.079

URL: View record in ScienceDirect (Access to full text may be restricted)

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

DOI: 10.1111/gcb.13859

Language: English

In: Environmental Pollution, October 2018, Vol.241, pp.549-556

Description: Waterborne exposure towards fungicides is known to trigger negative effects in aquatic leaf-associated microbial decomposers and leaf-shredding macroinvertebrates. We expected similar effects when these organisms use leaf material from terrestrial plants that were treated with systemic fungicides as a food source since the fungicides may remain within the leaves when entering aquatic systems. To test this hypothesis, we treated black alder ( ) trees with a tap water control or a systemic fungicide mixture (azoxystrobin, cyprodinil, quinoxyfen, and tebuconazole) at two worst-case application rates. Leaves of these trees were used in an experiment targeting alterations in two functions provided by leaf-associated microorganisms, namely the decomposition and conditioning of leaf material. The latter was addressed via the food-choice response of the amphipod shredder . During a second experiment, the potential impact of long-term consumption of leaves from trees treated with systemic fungicides on was assessed. Systemic fungicide treatment altered the resource quality of the leaf material resulting in trends of increased fungal spore production and an altered community composition of leaf-associated fungi. These changes in turn caused a significant preference of for microbially conditioned leaves that had received the highest fungicide treatment over control leaves. This higher food quality ultimately resulted in a higher gammarid growth (up to 300% increase) during the long-term feeding assay. Although the underlying mechanisms still need to be addressed, the present study demonstrates a positive indirect response in aquatic organisms due to systemic pesticide application in a terrestrial system. As the effects from the introduction of plant material treated with systemic fungicides strongly differ from those mediated via other pathways (e.g., waterborne exposure), our study provides a novel perspective of fungicide-triggered effects in aquatic detritus-based food webs. Leaves from trees treated with systemic fungicides cause positive effects in an aquatic decomposer-detritivore system.

Keywords: Aquatic Hyphomycetes ; Gammarus Fossarum ; Resource Quality ; Systemic Pesticides ; Engineering ; Environmental Sciences ; Anatomy & Physiology

ISSN: 0269-7491

E-ISSN: 1873-6424

DOI: 10.1016/j.envpol.2018.05.069

URL: View record in ScienceDirect (Access to full text may be restricted)

Language: English

In: Environmental science & technology, 20 January 2015, Vol.49(2), pp.1173-81

Description: The level of protection provided by the present environmental risk assessment (ERA) of fungicides in the European Union for fungi is unknown. Therefore, we assessed the structural and functional implications of five fungicides with different modes of action (azoxystrobin, carbendazim, cyprodinil, quinoxyfen, and tebuconazole) individually and in mixture on communities of aquatic hyphomycetes. This is a polyphyletic group of fungi containing key drivers in the breakdown of leaf litter, governing both microbial leaf decomposition and the palatability of leaves for leaf-shredding macroinvertebrates. All fungicides impaired leaf palatability to the leaf-shredder Gammarus fossarum and caused structural changes in fungal communities. In addition, all compounds except for quinoxyfen altered microbial leaf decomposition. Our results suggest that the European Union’s first-tier ERA provides sufficient protection for the tested fungicides, with the exception of tebuconazole and the mixture, while higher-tier ERA does not provide an adequate level of protection for fungicides in general. Therefore, our results show the need to incorporate aquatic fungi as well as their functions into ERA testing schemes to safeguard the integrity of aquatic ecosystems.

Keywords: Ecosystem ; Fungi -- Drug Effects ; Fungicides, Industrial -- Analysis ; Plant Leaves -- Metabolism ; Water Pollutants, Chemical -- Analysis

ISSN: 0013936X

E-ISSN: 1520-5851

DOI: 10.1021/es5050453

URL: View this record in MEDLINE/PubMed

Language: English

In: Aquatic Toxicology, 2015, Vol.169, pp.105-112

Description: 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...

Keywords: Other Biological Topics ; Annan Biologi

ISSN: 0166-445X

E-ISSN: 18791514

DOI: 10.1016/j.aquatox.2015.10.008

URL: View source record

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

DOI: 10.1002/etc.3756