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Sökning: WFRF:(Friberg Nikolai)

  • Resultat 1-7 av 7
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  • Bergfur, Jenny, et al. (författare)
  • Trade-offs between fungal and bacterial respiration along gradients in temperature, nutrients and substrata: Experiments with stream derived microbial communities
  • 2012
  • Ingår i: Fungal ecology. - : Elsevier. - 1754-5048 .- 1878-0083. ; 5:1, s. 46-52
  • Tidskriftsartikel (refereegranskat)abstract
    • We examined the effects of temperature, nutrients and substrata on microbial respiration rates. Leaves of alder and oak were incubated in a natural stream. Leaf discs were incubated in antibiotics to manipulate the ratio of fungi to bacteria with three treatments: antifungal, antibacterial, and combined antifungal and antibacterial treatment in addition to controls. Discs were subsequently incubated in different nutrient set-ups and temperature regimes. Significant effects of temperature, nutrients, microbial treatment and leaf type on respiration rates were found. However, temperature did not significantly add to the effect of eutrophication on microbial respiration rates. A stronger effect of temperature on fungal mediated respiration than on bacterial mediated respiration was found. In streams where leaf litter constitutes the main energy source, fungi constitute the dominant microbial decomposer. Our results indicate that increased temperature due to global warming might have serious implications for ecosystem functioning when leaf litter constitutes the main energy source.
  • Friberg, Nikolai, et al. (författare)
  • Changing Northern catchments: Is altered hydrology, temperature or both going to shape future stream communities and ecosystem processes?
  • 2013
  • Ingår i: Hydrological Processes. - 0885-6087 .- 1099-1085. ; 27:5, s. 734-740
  • Tidskriftsartikel (refereegranskat)abstract
    • Global change is predicted to increase temperature substantially in the North as well as altering run-off regimes with less synchronicity as the importance of snow melt declines. River biota and ecosystem processes will be influenced across all levels of organization, both in concert and individually. It is of vital importance that the impacts, and their likely magnitude, can be identified in order to deploy suitable adaptation strategies at the catchment scale. In this paper, we re-analyse four data sets from studies conducted in Greenland (66–69oN), Iceland (64oN), Sweden (60oN) and Denmark (55–57oN) to try and tease out the likely impacts of water temperature and hydrology in shaping the stream communities and ecosystem processes in high-latitude catchments. Water temperature was the environmental variable that best explained macroinvertebrate community composition across latitudes. In contrast, no significant relationship between macroinvertebrate community composition and measures of hydraulic stability (or nutrients) was found. We found a strong linear relationship between decay rate of leaf litter and water temperature (r2 = 0.68; p < 0.0001) independent of latitudes. Our study suggests that temperature could be the primary driver of ecosystem change in future with northern catchments likely to be especially vulnerable.
  • Lento, Jennifer, et al. (författare)
  • Temperature and spatial connectivity drive patterns in freshwater macroinvertebrate diversity across the Arctic
  • 2021
  • Ingår i: Freshwater Biology. - : John Wiley & Sons. - 0046-5070 .- 1365-2427.
  • Tidskriftsartikel (refereegranskat)abstract
    • Warming in the Arctic is predicted to change freshwater biodiversity through loss of unique taxa and northward range expansion of lower latitude taxa. Detecting such changes requires establishing circumpolar baselines for diversity, and understanding the primary drivers of diversity. We examined benthic macroinvertebrate diversity using a circumpolar dataset of >1,500 Arctic lake and river sites. Rarefied α diversity within catchments was assessed along latitude and temperature gradients. Community composition was assessed through region-scale analysis of β diversity and its components (nestedness and turnover), and analysis of biotic–abiotic relationships. Rarefied α diversity of lakes and rivers declined with increasing latitude, although more strongly across mainland regions than islands. Diversity was strongly related to air temperature, with the lowest diversity in the coldest catchments. Regional dissimilarity was highest when mainland regions were compared with islands, suggesting that connectivity limitations led to the strongest dissimilarity. High contributions of nestedness indicated that island regions contained a subset of the taxa found in mainland regions. High Arctic rivers and lakes were predominately occupied by Chironomidae and Oligochaeta, whereas Ephemeroptera, Plecoptera, and Trichoptera taxa were more abundant at lower latitudes. Community composition was strongly associated with temperature, although geology and precipitation were also important correlates. The strong association with temperature supports the prediction that warming will increase Arctic macroinvertebrate diversity, although low diversity on islands suggests that this increase will be limited by biogeographical constraints. Long-term harmonised monitoring across the circumpolar region is necessary to detect such changes to diversity and inform science-based management.
  • Moss, Brian D., et al. (författare)
  • Climate change and the future of freshwater biodiversity in Europe : a primer for policy-makers
  • 2009
  • Ingår i: Freshwater Reviews. - 1755-084X. ; 2:2, s. 103-130
  • Tidskriftsartikel (refereegranskat)abstract
    • Earth's climate is changing, and by the end of the 21st century in Europe, average temperatures are likely to have risen by at least 2 °C, and more likely 4 °C with associated effects on patterns of precipitation and the frequency of extreme weather events. Attention among policy-makers is divided about how to minimise the change, how to mitigate its effects, how to maintain the natural resources on which societies depend and how to adapt human societies to the changes. Natural systems are still seen, through a long tradition of conservation management that is largely species-based, as amenable to adaptive management, and biodiversity, mostly perceived as the richness of plant and vertebrate communities, often forms a focus for planning. We argue that prediction of particular species changes will be possible only in a minority of cases but that prediction of trends in general structure and operation of four generic freshwater ecosystems (erosive rivers, depositional floodplain rivers, shallow lakes and deep lakes) in three broad zones of Europe (Mediterranean, Central and Arctic-Boreal) is practicable. Maintenance and rehabilitation of ecological structures and operations will inevitably and incidentally embrace restoration of appropriate levels of species biodiversity. Using expert judgement, based on an extensive literature, we have outlined, primarily for lay policy makers, the pristine features of these systems, their states under current human impacts, how these states are likely to alter with a warming of 2 °C to 4 °C and what might be done to mitigate this. We have avoided technical terms in the interests of communication, and although we have included full referencing as in academic papers, we have eliminated degrees of detail that could confuse broad policy-making  
  • O'Gorman, Eoin J., et al. (författare)
  • Impacts of Warming on the Structure and Functioning of Aquatic Communities : Individual-to Ecosystem-Level Responses
  • 2012
  • Ingår i: Advances in Ecological Research, Vol 47. - : Elsevier. - 9780123983152 ; , s. 81-176
  • Bokkapitel (refereegranskat)abstract
    • Environmental warming is predicted to rise dramatically over the next century, yet few studies have investigated its effects in natural, multi-species systems. We present data collated over an 8-year period from a catchment of geothermally heated streams in Iceland, which acts as a natural experiment on the effects of warming across different organisational levels and spatiotemporal scales. Body sizes and population biomasses of individual species responded strongly to temperature, with some providing evidence to support temperature size rules. Macroinvertebrate and meiofaunal community composition also changed dramatically across the thermal gradient. Interactions within the warm streams in particular were characterised by food chains linking algae to snails to the apex predator, brown trout These chains were missing from the colder systems, where snails were replaced by much smaller herbivores and invertebrate omnivores were the top predators. Trout were also subsidised by terrestrial invertebrate prey, which could have an effect analogous to apparent competition within the aquatic prey assemblage. Top-down effects by snails on diatoms were stronger in the warmer streams, which could account for a shallowing of mass-abundance slopes across the community. This may indicate reduced energy transfer efficiency from resources to consumers in the warmer systems and/or a change in predator-prey mass ratios. All the ecosystem process rates investigated increased with temperature, but with differing thermal sensitivities, with important implications for overall ecosystem functioning (e.g. creating potential imbalances in elemental fluxes). Ecosystem respiration rose rapidly with temperature, leading to increased heterotrophy. There were also indications that food web stability may be lower in the warmer streams.
  • Song, You, et al. (författare)
  • High-throughput analyses and Bayesian network modeling highlight novel epigenetic Adverse Outcome Pathway networks of DNA methyltransferase inhibitor mediated transgenerational effects
  • 2021
  • Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 408
  • Tidskriftsartikel (refereegranskat)abstract
    • A number of epigenetic modulating chemicals are known to affect multiple generations of a population from a single ancestral exposure, thus posing transgenerational hazards. The present study aimed to establish a high-throughput (HT) analytical workflow for cost-efficient concentration-response analysis of epigenetic and phenotypic effects, and to support the development of novel Adverse Outcome Pathway (AOP) networks for DNA methyltransferase (DNMT) inhibitor-mediated transgenerational effects on aquatic organisms. The model DNMT inhibitor 5-azacytidine (5AC) and the model freshwater crustacean Daphnia magna were used to generate new experimental data and served as prototypes to construct AOPs for aquatic organisms. Targeted HT bioassays (DNMT ELISA, MS-HRM and qPCR) in combination with multigenerational ecotoxicity tests revealed concentration-dependent transgenerational (F0-F3) effects of 5AC on total DNMT activity, DNA promoter methylation, gene body methylation, gene transcription and reproduction. Top sensitive toxicity pathways related to 5AC exposure, such as apoptosis and DNA damage responses were identified in both F0 and F3 using Gaussian Bayesian network modeling. Two novel epigenetic AOP networks on DNMT inhibitor mediated one-generational and transgenerational effects were developed for aquatic organisms and assessed for the weight of evidence. The new HT analytical workflow and AOPs can facilitate future ecological hazard assessment of epigenetic modulating chemicals.
  • Tiegs, Scott D., et al. (författare)
  • Global patterns and drivers of ecosystem functioning in rivers and riparian zones
  • 2019
  • Ingår i: Science Advances. - Washington : American Association of Advancement in Science. - 2375-2548. ; 5:1
  • Tidskriftsartikel (refereegranskat)abstract
    • River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth's biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented "next-generation biomonitoring" by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.
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  • Resultat 1-7 av 7

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