| 1. |
- Belle, Simon, et al.
(författare)
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Climate-induced changes in carbon flows across the plant-consumer interface in a small subarctic lake
- 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
- Reconstructions of past food web dynamics are necessary for better understanding long-term impacts of climate change on subarctic lakes. We studied elemental and stable isotopic composition of sedimentary organic matter, photosynthetic pigments and carbon stable isotopic composition of Daphnia (Cladocera; Crustacea) resting eggs (delta C-13(Clado)) in a sediment record from a small subarctic lake. We examined how regional climate and landscape changes over the last 5800 years affected the relative importance of allochthonous and autochthonous carbon transfer to zooplankton. Overall, delta C-13(Clado) values were well in line with the range of theoretical values of aquatic primary producers, confirming that zooplankton consumers in subarctic lakes, even in the long-term perspective, are mainly fuelled by autochthonous primary production. Results also revealed greater incorporations of benthic algae into zooplankton biomass in periods that had a warmer and drier climate and clearer water, whereas a colder and wetter climate and lower water transparency induced higher contributions of planktonic algae to Daphnia biomass. This study thus emphasizes long-term influence of terrestrial-aquatic linkages and in-lake processes on the functioning of subarctic lake food webs.
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| 2. |
- Bighiu, Maria, et al.
(författare)
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Assessing microbial contamination and antibiotic resistant bacteria using zebra mussels (Dreissena polymorpha)
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 650, s. 2141-2149
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Tidskriftsartikel (refereegranskat)abstract
- Aquatic pollution with faecal bacteria and subsequent consumption of contaminated water or food is a worldwide issue that causes severe health effects (e.g. meningitis, salmonellosis, dysentery). In addition, the excessive use of antibiotics in animal husbandry and human medicine has enhanced the selective pressure on pathogenic bacteria, further increasing human health risks and detrimental effects on natural microbial communities. This urges the need to monitor faecal contamination using a time-integrated approach, as grab water samples can miss pathogen peaks. We tested the ability of zebra mussels (Dreissena polymorpha) to take up and depurate faecal indicator bacteria such as Escherichia coli and intestinal enterococci. Furthermore, we quantified the frequency of antibiotic resistant bacteria in water and mussels both in controlled laboratory tests and under in situ conditions downstream of a sewage treatment plant (STP). Laboratory results show that bacterial indicators in mussels were 132 times higher than their concentration in water, and that mussels retained bacteria up to 2 days after pulse exposure. Field results show decreasing bacterial concentrations in both water and mussels downstream the STP, with maximum E. coli concentrations ranging 173-9 cfu mL(-1) in water and 2970-330 cfu g(-1) in mussels. Similarly, enterococci ranged 59-4 cfu mL(-1) and 1450-240 cfu g(-1) in water and mussels, respectively. High proportions of antibiotic resistant E. coli were found in mussels (72%) and water (65%), and slightly lower proportion of resistant enterococci was found in mussels (47%) and in water (34%). Moreover, 33% of the bacteria isolated from mussels were resistant to multiple antibiotics, which emphasizes that resistance is a common feature in surface waters and highlights the need for safe water management. Our results show that zebra mussels provide an efficient, time-integrating tool for quantifying faecal indicators, including resistant and multidrug resistant bacteria. (C) 2018 The Authors. Published by Elsevier B.V.
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| 3. |
- Bundschuh, Mirco, et al.
(författare)
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The mode of bioturbation triggers pesticide remobilization from aquatic sediments
- 2016
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Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier BV. - 0147-6513 .- 1090-2414. ; 130, s. 171-176
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Tidskriftsartikel (refereegranskat)abstract
- After their release into the aquatic environment, contaminants may - depending on the physicochemical properties - adsorb to sediments. From there these contaminants can either be buried or remobilised by abiotic factors (e.g., resuspension) as well as by the bioturbating activity of sediment dwelling invertebrates. Little is, however, know about the effects of bioturbation on the fate of pesticides. Therefore, the present study quantified the impact of the bioturbation mode of benthic invertebrate species (bio-diffusor vs. bio-irrigation), the invertebrate density (i.e. 0-8 individuals per replicate), and the substance inherent properties (i.e. hydrophobicity, water solubility) on the remobilization of sediment-associated pesticides in a laboratory-based set-up over 13 days. We found that both the bioturbation mode (i.e., species identity) and species density, as well as pesticide properties (i.e., hydrophobicity) affected the direction and magnitude of remobilisation of sediment-bound pesticides. The oligochaeta Lumbriculus variegatus showed a density-dependent effect on the remobilization of lindane to the water phase, whereas those with the amphipod Monoporeia affinis and larvae of the midge Chironomus riparius did not. Although these findings show that sediments not per definition are a sink for pesticides, the rates of pesticide remobilization are limited. This observation, thus, suggests that the risk for aquatic communities posed by the remobilization of pesticides from the sediment due to bioturbation is low. (C) 2016 Published by Elsevier Inc.
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| 4. |
- Dawoud, Mohab, et al.
(författare)
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Interactive effects of an insecticide and a fungicide on different organism groups and ecosystem functioning in a stream detrital food web
- 2017
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 186, s. 215-221
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Tidskriftsartikel (refereegranskat)abstract
- Freshwater ecosystems are often affected by cocktails of multiple pesticides targeting different organism groups. Prediction and evaluation of the ecosystem-level effects of these mixtures is complicated by the potential not only for interactions among the pesticides themselves, but also for the pesticides to alter biotic interactions across trophic levels. In a stream microcosm experiment, we investigated the effects of two pesticides targeting two organism groups (the insecticide lindane and fungicide azoxystrobin) on the functioning of a model stream detrital food web consisting of a detritivore (Ispoda: Asellus aquaticus) and microbes (an assemblage of fungal hyphomycetes) consuming leaf litter. We assessed how these pesticides interacted with the presence and absence of the detritivore to affect three indicators of ecosystem functioning - leaf decomposition, fungal biomass, fungal sporulation - as well as detritivore mortality. Leaf decomposition rates were more strongly impacted by the fungicide than the insecticide, reflecting especially negative effects on leaf processing by detritivores. This result most like reflects reduced fungal biomass and increased detritivore mortality under the fungicide treatment. Fungal sporulation was elevated by exposure to both the insecticide and fungicide, possibly representing a stress-induced increase in investment in propagule dispersal. Stressor interactions were apparent in the impacts of the combined pesticide treatment on fungal sporulation and detritivore mortality, which were reduced and elevated relative to the single stressor treatments, respectively. These results demonstrate the potential of trophic and multiple stressor interactions to modulate the ecosystem-level impacts of chemicals, highlighting important challenges in predicting, understanding and evaluating the impacts of multiple chemical stressors on more complex food webs in situ. (C) 2017 Elsevier B.V. All rights reserved.
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| 5. |
- Feckler, Alexander, et al.
(författare)
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Exposure pathway-dependent effects of the fungicide epoxiconazole on a decomposer-detritivore system
- 2016
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 571, s. 992-1000
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Tidskriftsartikel (refereegranskat)abstract
- Shredders play a central role in the breakdown of leaf material in aquatic systems. These organisms and the ecological function they provide may, however, be affected by chemical stressors either as a consequence of direct waterborne exposure or through alterations in food-quality (indirect pathway). To unravel the biological relevance of these effect pathways, we applied a 2 x 2-factorial test design. Leaf material was microbially colonized for 10 days in absence or presence of the fungicide epoxiconazole (15 mu g/L) and subsequently fed to the shredder Asellus aquaticus under exposure to epoxiconazole (15 mu g/L) or in fungicide-free medium over a 28-day period (n = 40). Both effect pathways caused alterations in asselids' food processing, physiological fitness, and growth, although not always statistically significantly: assimilation either increased or remained at a similar level relative to the control suggesting compensatory behavior of A. aquaticus to cope with the enhanced energy demand for detoxification processes and decreased nutritional quality of the food. The latter was driven by lowered microbial biomasses and the altered composition of fatty acids associated with the leaf material. Even with increased assimilation, direct and indirect effects caused decreases in the growth and lipid (fatty acid) content of A. aquaticus with relative effect sizes between 10 and 40%. Moreover, the concentrations of two essential polyunsaturated fatty acids (i.e., arachidonic acid and eicosapentaenoic acid) were non-significantly reduced (up to similar to 15%) in asselids. This effect was, however, independent of the exposure pathway. Although waterborne effects were generally stronger than the diet-related effects, results suggest impaired functioning of A. aquaticus via both effect pathways. (C) 2016 Elsevier B.V. All rights reserved.
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| 6. |
- Feckler, Alexander, et al.
(författare)
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History matters: Heterotrophic microbial community structure and function adapt to multiple stressors
- 2018
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 24, s. E402-E415
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Tidskriftsartikel (refereegranskat)abstract
- 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 2x4x4-factorial design (n=6) over 21days. 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.
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| 7. |
- Gardeström, Johanna, et al.
(författare)
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Disturbance history influences stressor impacts : effects of a fungicide and nutrients on microbial diversity and litter decomposition
- 2016
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Ingår i: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 61:12, s. 2171-2184
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Tidskriftsartikel (refereegranskat)abstract
- Streams draining agricultural catchments are severely degraded by multiple stressors, including nutrient enrichment and pesticides. The understanding of how such stressors interact to alter ecosystem structure and function, and how responses of biota reflect their longer-term disturbance history, remains limited. We conducted a multifactorial stream microcosm experiment to investigate how elevated nutrients and a fungicide (azoxystrobin) interact to affect multiple variables associated with leaf decomposition: the biomass, sporulation rate and diversity of aquatic hyphomycete decomposers, litter decomposition rates and detritivore growth. We further manipulated decomposer species composition by using three distinct fungal assemblages drawn from streams with contrasting histories of agricultural disturbance: a forest stream, a mixed land-use stream subject to nutrient enrichment but little pesticide use, and an agricultural stream subjected to both intensive nutrient and pesticide use. We also varied the presence of the detritivorous isopod Asellus aquaticus. The fungicide azoxystrobin reduced both biomass and diversity of aquatic hyphomycetes and growth of A.aquaticus, and had negative knock-on effects on leaf decomposition and fungal sporulation. These impacts further varied with nutrient concentration. Impacts of the fungicide differed markedly among the three fungal assemblages. The agricultural assemblages were dominated by tolerant species and showed some capacity for maintaining processes under pesticide exposure, whereas diversity and functioning were strongly suppressed in the forest stream assemblage, which was dominated by stress-intolerant species. Pesticides, in interaction with other agricultural stressors, can impact microbial diversity and key ecosystem processes underlying the delivery of ecosystem services from streams. The extent of such impacts vary according to the longer-term disturbance history of the biota, and might be most acute when agricultural activity expands into previously uncultivated catchments, as is currently occurring in many regions of the world.
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| 8. |
- Goedkoop, Willem, et al.
(författare)
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Assessing the effects of field-relevant pesticide mixtures for their compliance with the concentration addition model - An experimental approach with Daphnia magna
- 2018
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 644, s. 342-349
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Tidskriftsartikel (refereegranskat)abstract
- The environmental risk assessment of pesticides is mainly performed on individual active ingredients. In surface waters within the agricultural landscape, however, contamination is usually characterized by complex pesticide mixtures. To estimate the joint effects caused by these complex mixtures, mathematical models have been proposed. Among these, the model of concentration addition (CA) is suggested as default model for the risk assessment of chemical mixtures as it is considered protective for mixtures composed of similar and dissimilar acting substances. Here we assessed the suitability of CA predictions for seven field relevant pesticide mixtures using acute (immobility) and chronic (reproduction) responses of the standard test species Daphnia magna. Pesticide mixtures indicated largely additive or less than additive effects when using CA model predictions as a reference. Moreover, we revealed that deviations from CA predictions are lower for chronic (up to 3.2-fold) relative to acute (up to 7.2-fold) response variables. Additionally, CA predictions were in general more accurate for complex mixtures relative to those composed of only a few pesticides. Thus, this study suggests CA models as largely protective for the risk assessment of pesticide mixtures justifying its use as default model. At the same time, extrapolating conclusions about the joint effects of pesticides from acute to chronic responses is uncertain, due to partly large discrepancies with regards to the deviation of model prediction and observed effects between exposure scenarios. (C) 2018 Elsevier B.V. All rights reserved.
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| 9. |
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| 10. |
- Goedkoop, Willem, et al.
(författare)
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CAFF Circumpolar Biodiversity Monitoring Program State of Arctic Freshwater Biodiversity Report
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Arctic freshwater ecosystems (lakes, rivers, and associated wetlands) are threatened by climate change and human development that can affect freshwater biodiversity. Such effects will change not only the distributions and abundances of aquatic species, but also the lives of Arctic Peoples that are dependent on the ecosystem services supplied by lakes and rivers. Thus, the freshwater biodiversity program of the Circumpolar Biodiversity Monitoring Program (Freshwater-CBMP) focuses on lake and river ecosystems and has established a long-term monitoring framework for these Arctic freshwaters. Developed for the Conservation of Arctic Flora and Fauna (CAFF; the biodiversity Working Group of the Arctic Council), this framework facilitates more accurate and rapid detection, communication and response to significant trends in Arctic water quality and biodiversity. Freshwater-CBMP goals are addressed in the “Arctic Freshwater Biodiversity Monitoring Plan”, which describes an integrated, ecosystem-based approach for monitoring Arctic freshwaters.
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| 11. |
- Goedkoop, Willem
(författare)
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Phenanthrene Bioaccumulation in the Nematode Caenorhabditis elegans
- 2015
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49, s. 1842-1850
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Tidskriftsartikel (refereegranskat)abstract
- The contribution of food to the bioaccumulation of xenobiotics and hence toxicity is still an ambiguous issue. It is becoming more and more evident that universal statements cannot be made, but that the relative contribution of food-associated xenobiotics in bioaccumulation depends on species, substance, and environmental conditions. Yet, small-sized benthic or soil animals such as nematodes have largely been disregarded so far. Bioaccumulation of the polycyclic aromatic hydrocarbon phenanthrene in the absence and presence of bacterial food was measured in the nematode Caenorhabditis elegans. Elimination of phenanthrene in the nematodes was biphasic, suggesting that there was a slowly exchanging pool within the nematodes or that biotransformation of phenanthrene took place. Even with food present, dissolved phenanthrene was still the major contributor to bioaccumulated compound in nematode tissues, whereas the diet only contributed about 9%. Toxicokinetic parameters in the treatment without food were different from the ones of the treatment with bacteria, possibly because nematodes depleted their lipid reserves during starvation.
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| 12. |
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| 13. |
- Goedkoop, Willem, et al.
(författare)
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Undersökning av pesticidorsakade effekter på bentiska organismsamhällen i jordbrukspåverkade vattendrag
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Under 2015 och 2016 provtogs sammanlagt 32 respektive 13 vattendrag i jordbruksbygder med avseende paett antal biologiska variabler (pavaxtalger, meiofauna och makroskopisk bottenfauna) bottenfauna och medavseende pa oorganisk vattenkemi (narsalter, metaller, alkalinitet, m.m.). Proverna togs och analyserades avackrediterad personal vid SLU. Backarna ingick i det screeninguppdrag som SLU fick av Naturvardsverket2015–2016, utom 4 som utgor del av det nationella miljoovervakningsprogrammet (M42, N34, O18, E21).Undersokningen en unik mojlighet att fa ett dataunderlag som innefattar bade kvantifieringar av exponeringenmed bekampningsmedel (beraknat som toxiska enheter, ΣTU, med akuta EC50-varden) och den biologiskaresponsen hos olika organismgrupper i jordbrukspaverkade vattendrag.Generellt var det svart att koppla analyser av de biologiska samhallena till exponeringen medbekampningsmedel (ΣTU). Det beror framst pa att toppar med kraftiga fororeningar med bekampningsmedelnoterades endast i enstaka fall. Analyserna visade att exponeringen for alger oftast overskred EU:s uniformprinciples, en regulatorisk koncentration for vilken inga effekter ska forekomma for enskilda substanser.Pavaxtalgerna har dock en kort generationstid och en snabb tillvaxt och torde visa en snabb aterhamtning efteren exponering.Analys av algssamhallena uppvisade en stor variation i biomassa och artsammansattning blandvattendragen. Tradformiga gronalger och tradformiga rodalger var vanligt forekommande, och kiselalger,framforallt arter som lever som enstaka celler, fanns pa alla lokaler. De flesta algtaxa ar typiska for naringsrikavattendrag och vatten med neutralt eller hogt pH. Forekomsten av rodalger tyder pa en mojlig begransningmed ljus i vissa backar, och forekomsten av kiselalgstaxon Diadesmis contenta var. contenta tyder pa starkavattenstandsforandringar i andra. Den ekologiska statusklassningen med fastsittande kiselalger bekraftade attde flesta vattendrag var naringsrika, framforallt rika pa fosfor, samt att nagra aven var mattligt eller starktpaverkade av organiska, syretarande fororeningar. De flesta av vattendragen klassades som mattlig ekologiskstatus. Andelen deformerade kiselalgsskal overskred 1% pa en tredjedel av lokalerna vilket kan tyda pa enpaverkan av miljogifter sasom metaller eller bekampningsmedel. Redundansanalys for kiselalger visade intepa en signifikant paverkan fran herbiciderna. Daremot paverkades kiselalgernas artsammansattning signifikantav aluminium-, jarn- och kvavekoncentrationerna i vattnet.Bottenfaunadata visade att alla vattendrag utom O18 uppnar hog eller god ekologisk status narbedomningen gors med ASPT. For SPEARpesticides-indexet lag samtliga varden utom fyra under 33, vilket i denvetenskapliga litteraturen anges som grans for god-mattlig status, utan att ha en formell sadan status iTyskland. SPEARpesticides visar med andra ord en helt annan bild an ASPT som ingar i de svenskabedomningsgrunderna. Bade ASPT och SPEARpesticides visar dock, liksom i tidigare analyser, ett starktstatistiskt samband (R2 = 0,62). Det starka sambandet tyder pa att de bada indexen i stort satt mater sammapaverkan, fast i olika skalor. Tidigare analyser har ocksa visat att bada indexen visar ett starkt samband medandelen jordbruksmark i vattendragens avrinningsomrade. Varken ASPT eller SPEARpesticides visar ett tydligtsamband med den maximalt uppmatta ΣTUDaphnia under sasongen, vilket kan beror pa de generellt laga vardenfor ΣTUDaphnia.Redundansanalys visade att ΣTUDaphnia inte paverkade bottenfaunasamhallena signifikant. Daremot fannvi att meiofaunasamhallen i biofilmerna pa stenarna signifikant paverkades av ΣTUDaphnia. Resultatet kan beropa att denna mindre fauna lever mer exponerat och att vissa bekampningsmedel kan ackumulera i biofilmerna.Nematodfaunan i biofilmerna visade pa nema-SPEAR-varden under gransen for god status i Kavlingean,Segea och M42. Atta vattendrag hade en sa pass rik nematodfauna med manga fororeningskansliganematodarter att Nema-SPEAR indikerade hog ekologisk status.Analysen visar att vattendrag som erfar en stark jordbrukspaverkan och fysisk paverkan haller enoverraskande god status med avseende pa pavaxtalger och bottenfauna. En kombination av hoganasaltskoncentrationer, en god syresattning som foljd av stromforhallandena, samt en god tillgang till fodakan bidra till att vattendragen far en rik bottenfauna och forhallandevist hoga indexvarden. Aven det faktumatt provtagning gors pa de sparsamma steniga bottnarna (dar mojligt) i de annars sand/lerbottendomineradevattendragen kan bidra till att de visar forhallandevis hog status.
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| 14. |
- Johansson, Karin S L, et al.
(författare)
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Algal blooms increase heterotrophy at the base of boreal lake food webs-evidence from fatty acid biomarkers
- 2016
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590 .- 1939-5590. ; 61:5, s. 1563-1573
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Tidskriftsartikel (refereegranskat)abstract
- Physical defenses and grazer avoidance of the bloom-forming microalga Gonyostomum semen may reduce the direct coupling between phytoplankton and higher trophic levels and result in an increased importance of alternative basal food resources such as bacteria and heterotrophic protozoans. To assess the importance of algal and heterotrophic food resources for zooplankton during G. semen blooms and the effects of zooplankton diets on a higher consumer, we analyzed the fatty acid composition of zooplankton and the invertebrate predator Chaoborus flavicans from eight lakes along a gradient in the predominance of G. semen relative to other algae and the duration of G. semen blooms. The proportion of fatty acids of bacterial origin increased significantly along the G. semen gradient in all consumers studied. In addition, the proportion of polyunsaturated fatty acids (PUFA) decreased in cladocerans. These results suggest that heterotrophic pathways can compensate for a reduced trophic coupling between phytoplankton and filter-feeding zooplankton. The lower PUFA content in cladoceran prey from lakes at the higher end of the G. semen gradient did not affect the PUFA content of the predator C. flavicans, suggesting selective assimilation and retention of PUFA and/or feeding on other, more PUFA-rich prey. © 2016 Association for the Sciences of Limnology and Oceanography
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| 15. |
- Lau, Danny C. P., et al.
(författare)
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Lake responses to long-term disturbances and management practices
- 2017
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Ingår i: Freshwater Biology. - : WILEY. - 0046-5070 .- 1365-2427. ; 62:4, s. 792-806
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Tidskriftsartikel (refereegranskat)abstract
- 1. Long-term human-induced disturbances such as acidification and algal invasions, and management practices such as liming, are known to alter community structure and biodiversity of north temperate lakes. We assessed if they impacted on the trophic ecology and production of apex consumers (i.e. fish) and the overall food-chain length (FCL) of boreal lake ecosystems, and if these functional responses were consistent with the biodiversity changes. We hypothesise that fish production and FCL decrease with decreasing species biodiversity of lake communities, and that long-term environmental perturbations will alter the relative reliance of fish on littoral versus pelagic trophic pathways and their ontogenetic changes in trophic position (TP). 2. We analysed long-term data and stable isotopes of multiple organismal groups - phytoplankton, zooplankton, littoral and sub-littoral/profundal macroinvertebrates, and fish - collected from small boreal lakes that have been subjected to acidification, lime application and/or algal invasion by Gonyostomum semen. Species biodiversity, FCL and fish production (i.e. growth and catch-per-uniteffort) were compared among three lake categories, i.e. acidic, limed and circumneutral (reference) lakes, within each three lakes were selected. Fish TP and their relative littoral versus pelagic reliance were estimated based on stable nitrogen and carbon isotopes respectively. 3. Gonyostomum contributed to 77-98% phytoplankton biovolume in acidic lakes, <1-79% in limed lakes and 0-30% in circumneutral lakes. Its prevalence was correlated with total organic carbon concentration but not with lake pH, alkalinity or any other environmental variable. Diversity and evenness of phytoplankton, macroinvertebrates and fish generally decreased with increasing Gonyostomum biovolume, such that biodiversity was higher in circumneutral and limed lakes than in acidic lakes. 4. Isotopic data revealed that FCL was shortest in limed lakes (3.94 +/- 0.08; least- squares mean +/- SE), intermediate in acidic lakes (4.19 +/- 0.07) and longest in circumneutral lakes (4.38 +/- 0.08). Limed lakes also had the lowest fish growth and CPUE. Overall littoral reliance of fish was higher in acidic lakes (0.53 +/- 0.03) than in limed lakes (0.42 +/- 0.02) and circumneutral lakes (0.30 +/- 0.02), suggesting that fish production and FCL there could have been sustained by the increased littoral reliance when pelagic trophic pathways were hindered by Gonyostomum invasion. European perch (Perca fluviatilis), the most common fish in the lakes, showed faster TP increases in acidic and limed lakes, likely due to their earlier ontogenetic shift from zooplanktivory to zoobenthivory and/or piscivory. 5. Overall, our findings indicate that long-term disturbances (i.e. acidification and algal invasions) and management practices (i.e. liming) can (i) induce contrasting responses in biodiversity, FCL and fish production of boreal lakes; (ii) be the primary driver of FCL variation among small and similar-size ecosystems; and (iii) alter the trophic ecology (i.e. TP change during ontogeny and littoral reliance) of key fish species. The trophic ecology and production of apex consumers and FCL together can provide useful integrated proxies for ecosystem functioning, which can supplement traditional biodiversity measurements for more robust environmental assessments.
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| 16. |
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