| 1. |
- Audet, Joachim, et al.
(författare)
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Forest streams are important sources for nitrous oxide emissions - Nitrous oxide emissions from Swedish streams
- 2020
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 26, s. 629-641
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Tidskriftsartikel (refereegranskat)abstract
- Streams and river networks are increasingly recognized as significant sources for the greenhouse gas nitrous oxide (N2O). N2O is a transformation product of nitrogenous compounds in soil, sediment and water. Agricultural areas are considered a particular hotspot for emissions because of the large input of nitrogen (N) fertilizers applied on arable land. However, there is little information on N2O emissions from forest streams although they constitute a major part of the total stream network globally. Here, we compiled N2O concentration data from low-order streams (~1,000 observations from 172 stream sites) covering a large geographical gradient in Sweden from the temperate to the boreal zone and representing catchments with various degrees of agriculture and forest coverage. Our results showed that agricultural and forest streams had comparable N2O concentrations of 1.6 +/- 2.1 and 1.3 +/- 1.8 mu g N/L, respectively (mean +/- SD) despite higher total N (TN) concentrations in agricultural streams (1,520 +/- 1,640 vs. 780 +/- 600 mu g N/L). Although clear patterns linking N2O concentrations and environmental variables were difficult to discern, the percent saturation of N2O in the streams was positively correlated with stream concentration of TN and negatively correlated with pH. We speculate that the apparent contradiction between lower TN concentration but similar N2O concentrations in forest streams than in agricultural streams is due to the low pH (<6) in forest soils and streams which affects denitrification and yields higher N2O emissions. An estimate of the N2O emission from low-order streams at the national scale revealed that ~1.8 x 10(9) g N2O-N are emitted annually in Sweden, with forest streams contributing about 80% of the total stream emission. Hence, our results provide evidence that forest streams can act as substantial N2O sources in the landscape with 800 x 10(9) g CO2-eq emitted annually in Sweden, equivalent to 25% of the total N2O emissions from the Swedish agricultural sector.
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| 2. |
- Bundschuh, Mirco, et al.
(författare)
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How toxicants influence organic matter decomposition in streams
- 2021
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Ingår i: The Ecology of Plant Litter Decomposition in Stream Ecosystems. - Cham : Springer International Publishing. - 9783030728533 ; , s. 379-410
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Bokkapitel (refereegranskat)abstract
- The ecosystem process of organic matter decomposition (OMD) in fresh waters is realised by a complex interaction among different groups of microorganisms (including bacteria and fungi) and detritivorous animals. As a consequence of this multi-level interaction, biotic (e.g., competition, predation) and abiotic (e.g., flow, temperature, toxicants) factors may influence the performance of either (micro)organism group with potential feedback to detritivores, and in turn OMD. In this chapter, we discuss how the abiotic factor toxicants affects OMD. We organised the chapter along a conceptual model that pinpoints groups of organisms and their interactions, which are critical for OMD. We focus on four toxicant classes (i.e., fungicides, antibiotics, insecticides and metals) that specifically affect fungi, bacteria or detritivorous invertebrates or have a broad activity spectrum. We summarize the effects caused by these toxicant classes on relevant groups of organisms, which are often determined by the toxicant mode of action. On this basis, we develop effect pathways leading to alterations in OMD dynamics. Finally, we discuss whether and how these effect pathways may support the interpretation of effect patterns observed under (semi-)field conditions and highlight research gaps we suggest addressing in order to improve understanding and prediction power.
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| 3. |
- Bundschuh, Mirco, et al.
(författare)
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Nanoparticles transported from aquatic to terrestrial ecosystems via emerging aquatic insects compromise subsidy quality
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticle contaminants enter aquatic ecosystems and are transported along the stream network. Here, we demonstrate a novel pathway for the return of nanoparticles from aquatic to terrestrial ecosystems via cross-boundary subsidies. During their emergence, trichopteran caddisflies carried titanium dioxide and gold nanoparticles into their terrestrial life stages. Moreover, their emergence was delayed by <= 30 days, and their energy reserves were depleted by <= 25%. Based on worst case estimates, it is suggested that terrestrial predators, such as bats feeding on aquatic prey, may ingest up to three orders of magnitude higher gold levels than anticipated for humans. Additionally, terrestrial predator species may suffer from alterations in the temporal availability and nutritional quality of their prey. Considering the substantial transfer of insect biomass to terrestrial ecosystems, nanoparticles may decouple aquatic and terrestrial food webs with important (meta-)ecosystem level consequences.
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| 4. |
- Feckler, Alexander, et al.
(författare)
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A blessing in disguise? Natural organic matter reduces the UV light-induced toxicity of nanoparticulate titanium dioxide
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 663, s. 518-526
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Tidskriftsartikel (refereegranskat)abstract
- Besides their economic value, engineered inorganic nanoparticles (EINPs) may pose a risk for the integrity of ecosystems. Among EINPs, titanium dioxide (nTiO(2)) is frequently used and released into surface waters in the mu g range. There, nTiO(2) interacts with environmental factors, influencing its potential to cause adverse effects on aquatic life. Although factors like ultra violet (UV) light and natural organic matter (NOM) are considered as ubiquitous, their joint impact on nTiO(2)-induced toxicity is poorly understood. This study addressed the acute toxicity of nTiO(2) (P25; 0.00-64.00 mg/L; similar to 60 nm) at ambient UV light (0.00-5.20 WUVA/m(2)) and NOM levels (seaweed extract; 0.00-4.00 mg TOC/L), using the immobility of Daphnia magna as response variable. Confirming previous studies, effects caused by nTiO(2) were elevated with increasing UV radiation (up to similar to 280 fold) and mitigated by higher NOM levels (up to similar to 12 fold), possibly due to reduced reactive oxygen species (ROS; measured as (OH)-O-center dot radicals) formation at lower UV intensities. However, contradicting to former studies, nTiO(2)-mediated ROS formation was not proportional to increasing NOM levels: lower concentrations (0.04-0.40 mg TOC/L) slightly diminished, whereas a higher concentration (4.00 mg TOC/L) promoted the ROS quantity, irrespective of UV intensity. Measured ROS levels do not fully explain the observed nTiO(2)-induced toxicity, whereas increasing acetylcholinesterase and glutathione-S-transferase activities in daphnids (in presence of 8.00 mg/L nTiO(2) and elevated UV intensity) point towards neurotoxic and oxidative stress as a driver for the observed effects. Hence, despite higher (OH)-O-center dot levels in the treatments where 4.00 mg TOC/L were present, NOM was still capable of reducing nTiO(2)-induced stress and ultimately adverse effects in aquatic life. (C) 2019 Elsevier B.V. All rights reserved.
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| 5. |
- Feckler, Alexander, et al.
(författare)
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A glance into the black box: Novel species-specific quantitative real-time PCR assays to disentangle aquatic hyphomycete community composition
- 2019
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Ingår i: Fungal Ecology. - : Elsevier BV. - 1754-5048 .- 1878-0083. ; 42
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Tidskriftsartikel (refereegranskat)abstract
- Aquatic hyphomycetes (AH) are ubiquitous fungi playing a key role in the decomposition of leaf litter in streams. Though their functional performance is modulated by their community composition, this ecological relationship remains poorly investigated due to a lack of suitable methods to identify the biomass-contribution of individual species to AH communities. We, therefore, designed and validated TaqMan (R) probe-based qPCR assays targeting ten AH species common in temperate regions, allowing detection and quantification of these species within complex communities. In a further step, we compared qPCR-obtained DNA levels to concentrations of the traditional fungal biomass proxy ergosterol. We demonstrate that the qPCR assays are valid for use and that DNA and ergosterol concentrations were significantly positively correlated, suggesting DNA levels as a suitable species-specific biomass proxy. Accordingly, the use of these assays may facilitate multi-species experiments to address major research issues in stress and community ecology including biodiversity-ecosystem functioning relationships. (C) 2019 Elsevier Ltd and British Mycological Society. All rights reserved.
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| 6. |
- Feckler, Alexander, et al.
(författare)
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Blinded by the light: Increased chlorophyll fluorescence of herbicide-exposed periphyton masks unfavorable structural responses during exposure and recovery
- 2018
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 203, s. 187-193
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Tidskriftsartikel (refereegranskat)abstract
- In surface waters within agricultural catchments, periphyton - i.e., biofilms containing algae, heterotrophs, and associated detritus - is subjected to multiple stressors including herbicides. Although herbicide effects on periphyton are frequently studied, the focus has been on photosynthesis-inhibiting herbicides while other modes of toxic action have received little attention. Against this background, a 21-days-lasting bioassay was conducted, during which mature periphytic communities were exposed to the carotenoid-biosynthesis-inhibiting herbicide diflufenican for 12 days (up to 10 mu g/L; n = 4), followed by a 9-days-lasting recovery phase in herbicide-free medium. Variables related to periphytic functioning (photosynthetic efficiency and non-photochemical quenching) and structure (pigment concentrations, biomass, and algal community structure) were quantified every third day during both experimental phases. Exposure to >= 0.2 mu g diflufenican/L resulted in 20-25% and 25-30% lowered carotenoid and chlorophyll a concentrations, respectively, likely explained by a reduced algal biovolume as well as diflufenican's mode of toxic action and thus a shift towards a higher heterotrophy of the communities. Despite these adverse effects on the photosynthetic apparatus, the photosynthetic efficiency increased by up to similar to 15% under diflufenican exposure judged on higher chlorophyll fluorescence. This may be explained by an up to similar to 60% reduced non-photochemical quenching as well as binding of diflufenican to the pigment-protein membrane complex of the photosystem II, two processes causing higher chlorophyll fluorescence. Additionally, phototrophs may have actively increased energy assimilation to cope with higher energy demands under chemical stress. Although periphyton showed some recovery potential following the exposure phase, observed as increasing chlorophyll a concentrations and non-photochemical quenching, periphyton may not be able to quickly recover from stress given the persistent increase in the photosynthetic efficiency. While the processes underlying the observed effects yet remain speculative, the results suggest a shift towards a higher degree of heterotrophy in periphytic communities ultimately increasing the importance of heterotrophic ecosystem functions at impacted sites over the long term.
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| 7. |
- Feckler, Alexander, et al.
(författare)
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Cryptic lineages - same but different?
- 2013
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Ingår i: Integrated Environmental Assessment and Management. - : Wiley. - 1551-3777 .- 1551-3793. ; 9, s. 172-173
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Feckler, Alexander, et al.
(författare)
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Cryptic species diversity: an overlooked factor in environmental management?
- 2014
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 51, s. 958-967
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Tidskriftsartikel (refereegranskat)abstract
- 1. 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.2. 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.3. 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.4. 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.
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| 9. |
- Feckler, Alexander, et al.
(författare)
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Decoupled structure and function of leaf-associated microorganisms under anthropogenic pressure: Potential hurdles for environmental monitoring
- 2020
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Ingår i: Freshwater Science. - : University of Chicago Press. - 2161-9549 .- 2161-9565. ; 39, s. 652-664
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Tidskriftsartikel (refereegranskat)abstract
- Legal frameworks that assess stream ecological integrity rely mostly on structural metrics and implicitly assume that good structure will result in good function. This assumption may, however, be challenged. The results of our literature screening show that the structure and function of leaf-associated microbial assemblages can be decoupled, meaning that structure and function are not similarly affected by anthropogenic pressures. This decoupling can be characterized by microbially-mediated leaf litter decomposition remaining stable, increasing, or exhibiting a U-shaped response as structural metrics (e.g., taxonomic diversity) change gradually. When these types of decoupling occur, stream ecological integrity may be misinterpreted when solely based on structural metrics. This misinterpretation may be driven by a structurally-simplified microbial assemblage (e.g., fewer taxa) effectively decomposing leaf litter, which may limit the contribution of structurally-simplified assemblages to further ecosystem level processes (e.g., nutrition of food webs). At the same time, structurally-simplified microbial assemblages may exhibit reduced ecological resilience against pressures. Therefore, we suggest that incorporating both structural and functional metrics will improve stream biomonitoring by increasing our ability to determine the consequences of anthropogenic pressures. Additional use of molecular biological methods and information on microbial traits should improve the assessment of stream ecological integrity.
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| 10. |
- Feckler, Alexander, et al.
(författare)
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Detritivore physiology and growth benefit from algal presence during microbial leaf colonization
- 2024
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Ingår i: Limnology and Oceanography. - 0024-3590 .- 1939-5590. ; 69, s. 848-860
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Tidskriftsartikel (refereegranskat)abstract
- In headwater streams, riparian leaf litter is the primary food source for detritivores. While it is well known that aquatic fungi improve the nutritious quality of leaves, our understanding on whether and how benthic algae influence this process remains limited. Here, we hypothesized that the interplay between algae and fungi, termed "algal priming", further enhances food quality. In a 40-d microcosm experiment, we fed Gammarus fossarum of two size classes with Fagus sylvatica leaves of varying qualities: pure leaves (low quality), leaves colonized by fungi (intermediate quality), and leaves colonized by fungi in the presence of a diatom (high quality). Our results revealed that Gammarus' ingestion rates increased (55-164%) with food quality, spurring accelerated growth (4-14%), regardless of the size class. Furthermore, we observed a tendency for Gammarus' overall fatty acid (FA) quantity to rise with higher-quality food (12-318%), with the FA profile exhibiting increased proportions of specific polyunsaturated FAs that are essential for detritivores. These observations can likely be attributed to leaf-associated fungi, which are more readily assimilated than the leaves and are known as a source of FA. This enhancing effect by fungi was further amplified in the presence of diatoms, presumably through the positive effect of algal-derived labile organic carbon, which supports fungal growth. Despite reduced autochthonous primary production in shaded headwater streams, the experimental findings from this study indicate a potential of enhanced secondary production and energy transfer to higher trophic levels within the aquatic ecosystem.
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