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Bergström, Ann-KristinORCID iD iconorcid.org/0000-0001-5102-4289
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Publications (10 of 60) Show all publications
Bergström, A.-K., Karlsson, J., Karlsson, D. & Vrede, T. (2018). Contrasting plankton stoichiometry and nutrient regeneration in northern arctic and boreal lakes. Aquatic Sciences, 80(2), Article ID UNSP 24.
Open this publication in new window or tab >>Contrasting plankton stoichiometry and nutrient regeneration in northern arctic and boreal lakes
2018 (English)In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 80, no 2, article id UNSP 24Article in journal (Refereed) Published
Abstract [en]

Contrasting carbon: nitrogen: phosphorus (C: N: P) stoichiometry between phytoplankton and zooplankton affect consumer growth and phytoplankton nutrient limitation via nutrient recycling by zooplankton. However, no study has assessed how regional differences in terrestrial loadings of organic matter affect plankton N: P stoichiometry and recycling in systems with low N deposition and N-limited phytoplankton. We address this question by using data from 14 unproductive headwater arctic and boreal lakes. We found that boreal lakes had higher lake water-and seston C, N and P concentrations than arctic lakes, whereas seston C: N, C: P and N: P ratios did not differ among regions. Boreal zooplankton were also richer in N and P relative to C, with lower somatic N: P ratios, compared to arctic lakes. Consequently, the estimated N: P imbalances between seston and zooplankton were negative in arctic lakes, indicating zooplankton feeding on phytoplankton of suboptimal N content, resulting in low consumer driven N: P recycling (medians arctic sub-mid and high altitude lakes: 11 and 13). In boreal lakes, estimated N: P imbalance did not differ from zero, with a seston N: P stoichiometry matching the N: P requirements of zooplankton, which resulted in higher consumer driven N: P recycling (median 18). Our results imply that regional climate induced catchment differences, through enhanced terrestrial nutrient inputs, affect plankton stoichiometry by raising consumer N: P recycling ratio and changing zooplankton from being mainly N-(arctic) to NP co-limited (boreal). Browning of lakes, in regions with low N deposition, may therefore promote large-scale regional changes in plankton nutrient limitation with potential feedbacks on pelagic food webs.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Carbon, Nitrogen, Nutrient limitation, Phosphorus, Phytoplankton, Zooplankton
National Category
Oceanography, Hydrology and Water Resources Environmental Sciences Ecology
Identifiers
urn:nbn:se:umu:diva-147316 (URN)10.1007/s00027-018-0575-2 (DOI)000429435600001 ()
Available from: 2018-05-25 Created: 2018-05-25 Last updated: 2018-08-17Bibliographically approved
Creed, I. F., Bergström, A.-K., Trick, C. G., Grimm, N. B., Hessen, D. O., Karlsson, J., . . . Weyhenmeyer, G. A. (2018). Global change-driven effects on dissolved organic matter composition: Implications for food webs of northern lakes. Global Change Biology, 24(8), 3692-3714
Open this publication in new window or tab >>Global change-driven effects on dissolved organic matter composition: Implications for food webs of northern lakes
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2018 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 24, no 8, p. 3692-3714Article, review/survey (Refereed) Published
Abstract [en]

Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial-aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)-the messenger between terrestrial and lake ecosystems-with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
atmospheric change, cyanobacteria, dissolved organic matter, food webs, lake, mercury, northern
National Category
Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-150465 (URN)10.1111/gcb.14129 (DOI)000437284700035 ()29543363 (PubMedID)
Funder
Swedish Research Council, AKB 2010-4675Swedish Research Council, RG 2013-5001
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-08-22Bibliographically approved
Klaus, M., Geibrink, E., Jonsson, A., Bergström, A.-K., Bastviken, D., Laudon, H., . . . Karlsson, J. (2018). Greenhouse gas emissions from boreal inland waters unchanged after forest harvesting. Biogeosciences, 15(18), 5575-5594
Open this publication in new window or tab >>Greenhouse gas emissions from boreal inland waters unchanged after forest harvesting
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2018 (English)In: Biogeosciences, ISSN 1726-4170, Vol. 15, no 18, p. 5575-5594Article in journal (Refereed) Published
Abstract [en]

Forestry practices often result in an increased export of carbon and nitrogen to downstream aquatic systems. Although these losses affect the greenhouse gas (GHG) budget of managed forests, it is unknown if they modify GHG emissions of recipient aquatic systems. To assess this question, air-water fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) were quantified for humic lakes and their inlet streams in four boreal catchments using a before-after control-impact experiment. Two catchments were treated with forest clear-cuts followed by site preparation (18 % and 44 % of the catchment area). GHG fluxes and hydrological and physicochemical water characteristics were measured at multiple locations in lakes and streams at high temporal resolution throughout the summer season over a 4-year period. Both lakes and streams evaded all GHGs. The treatment did not significantly change GHG fluxes in streams or lakes within 3 years after the treatment, despite significant increases of CO2 and CH4 concentrations in hillslope groundwater. Our results highlight that GHGs leaching from forest clear-cuts may be buffered in the riparian zone-stream continuum, likely acting as effective biogeochemical processors and wind shelters to prevent additional GHG evasion via downstream inland waters. These findings are representative of low productive forests located in relatively flat landscapes where forestry practices cause only a limited initial impact on catchment hydrology and biogeochemistry.

Place, publisher, year, edition, pages
Copernicus Gesellschaft, 2018
National Category
Forest Science
Identifiers
urn:nbn:se:umu:diva-152400 (URN)10.5194/bg-15-5575-2018 (DOI)000445040900002 ()
Funder
Swedish Research Council Formas, 210-2012-1461The Kempe Foundations, SMK-1240EU, European Research Council, 725546
Available from: 2018-10-05 Created: 2018-10-05 Last updated: 2018-10-05Bibliographically approved
Myrstener, M., Rocher-Ros, G., Burrows, R. M., Bergström, A.-K., Giesler, R. & Sponseller, R. A. (2018). Persistent nitrogen limitation of stream biofilm communities along climate gradients in the Arctic. Global Change Biology, 24(8), 3680-3691
Open this publication in new window or tab >>Persistent nitrogen limitation of stream biofilm communities along climate gradients in the Arctic
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2018 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 24, no 8, p. 3680-3691Article in journal (Refereed) Published
Abstract [en]

Climate change is rapidly reshaping Arctic landscapes through shifts in vegetation cover and productivity, soil resource mobilization, and hydrological regimes. The implications of these changes for stream ecosystems and food webs is unclear and will depend largely on microbial biofilm responses to concurrent shifts in temperature, light, and resource supply from land. To study those responses, we used nutrient diffusing substrates to manipulate resource supply to biofilm communities along regional gradients in stream temperature, riparian shading, and dissolved organic carbon (DOC) loading in Arctic Sweden. We found strong nitrogen (N) limitation across this gradient for gross primary production, community respiration and chlorophyll-a accumulation. For unamended biofilms, activity and biomass accrual were not closely related to any single physical or chemical driver across this region. However, the magnitude of biofilm response to N addition was: in tundra streams, biofilm response was constrained by thermal regimes, whereas variation in light availability regulated this response in birch and coniferous forest streams. Furthermore, heterotrophic responses to experimental N addition increased across the region with greater stream water concentrations of DOC relative to inorganic N. Thus, future shifts in resource supply to these ecosystems are likely to interact with other concurrent environmental changes to regulate stream productivity. Indeed, our results suggest that in the absence of increased nutrient inputs, Arctic streams will be less sensitive to future changes in other habitat variables such as temperature and DOC loading.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
Arctic, bioassay, biofilm, climate change, colimitation, nitrogen limitation, nutrient addition, stream productivity
National Category
Environmental Sciences Ecology
Identifiers
urn:nbn:se:umu:diva-150651 (URN)10.1111/gcb.14117 (DOI)000437284700034 ()29516598 (PubMedID)2-s2.0-85045398289 (Scopus ID)
Funder
Swedish Research Council, 2013-5001Swedish Research Council Formas, 2013-5001; 217-2012-1418
Available from: 2018-08-29 Created: 2018-08-29 Last updated: 2018-08-29Bibliographically approved
Isles, P. D. F., Creed, I. F. & Bergström, A.-K. (2018). Recent Synchronous Declines in DIN:TP in Swedish Lakes. Global Biogeochemical Cycles, 32(2), 208-225
Open this publication in new window or tab >>Recent Synchronous Declines in DIN:TP in Swedish Lakes
2018 (English)In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 32, no 2, p. 208-225Article in journal (Refereed) Published
Abstract [en]

Declining atmospheric nitrogen (N) deposition in northern Europe and parts of North America, coupled with ongoing changes in climate, has the potential to alter the nutrient limitation status of freshwater ecosystems. In this study we compared time series data of atmospheric N deposition, air temperature, and precipitation with corresponding estimates of dissolved inorganic nitrogen (DIN), total phosphorus (TP), DIN: TP, and total organic carbon from 78 headwater streams and 95 nutrient-poor lakes in Sweden from 1998 to 2013 to assess trends in, and potential drivers of, lake N:P ratios. We found that trends in nutrients were variable at the scale of individual lakes but were highly synchronous at the regional scale, suggesting underlying control by broad-scale environmental drivers mediated by site-specific characteristics. Widespread declines in lake DIN throughout Sweden were correlated with declines in atmospheric N deposition, particularly in northern areas. TP did not have strong directional trends, but interannual variability was synchronous at regional scales, implying that broad-scale climate drivers were affecting these trends. Overall, we observed a significant decline in DIN:TP throughout Sweden over the monitoring period. At the beginning of the study period, 32% of lakes were N limited and 45% colimited by N and P. Proportions increased to 63% of lakes N limited and 20% colimited by N and P at the end of the study period. These results suggest that N limitation is likely to become more widespread in subarctic and boreal areas of Europe in the future if recent trends continue. Plain Language Summary This article examines the way in which changes in the amount of nitrogen from the atmosphere being delivered to lakes (as a result of fossil fuel combustion) are interacting with global climate change to affect nutrient availability in Swedish lakes. Nitrogen can act as fertilizer in lakes, supporting increased growth of algae and aquatic plants. The amount of nitrogen relative to other important elements such as phosphorus can help to determine which groups of plants and algae dominate lake ecosystems, as well as how much living biomass lakes can sustain. We find that declines in atmospheric deposition of nitrogen, which have resulted from the adoption of policies controlling emissions from fossil fuel combustion, have caused declines in nitrogen concentrations in lakes throughout Sweden. This has changed the balance of nitrogen and phosphorus, which may result in changes to the structure of lake biological communities. At the same time, variability in climate also has subtle but widespread affects on lake nutrient concentrations, suggesting that the availability of nutrients in lakes at northern latitudes is likely to change in the future as the climate warms.

Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2018
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-146166 (URN)10.1002/2017GB005722 (DOI)000426773600004 ()
Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2018-08-20Bibliographically approved
Klaus, M., Bergström, A.-K., Jonsson, A., Deininger, A., Geibrink, E. & Karlsson, J. (2018). Weak response of greenhouse gas emissions to whole lake N enrichment. Limnology and Oceanography, 63, S340-S353
Open this publication in new window or tab >>Weak response of greenhouse gas emissions to whole lake N enrichment
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2018 (English)In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, p. S340-S353Article in journal (Refereed) Published
Abstract [en]

Global warming and land use scenarios suggest increased 21st century nitrogen (N) inputs to aquatic systems. Nitrogen affects in-lake processing and, potentially, atmospheric exchange of greenhouse gases, probably being most relevant in unproductive systems. Here, we test for the first time the effect of a whole-lake experimental increase (threefold) in external nitrate loads on the atmospheric exchange of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from N-limited unproductive boreal lakes. Nitrate enrichment effects were assessed within a paired Before/After-Control/Impact framework based on 2-hourly to biweekly surface-water sampling of dissolved gas concentrations, and monthly whole-lake inventory surveys, carried out over 4 yrs in six lakes. Nitrate enrichment did not affect gas exchange during summer stratification and whole-lake gas inventories during summer and winter stratification. This finding specifically emphasizes the modest role of internal carbon fixation for the CO2 dynamics of unproductive boreal lakes. A global synthesis of 52 published studies revealed a wide range of nutrient fertilization effects, both in systems similar to our experimental lakes, and other more productive systems. Effects depended mainly on the spatiotemporal scale of the study and became more pronounced when N enrichment was combined with phosphorous. Conclusively, although short-term and habitat-specific effects can occur, changes in N supply have only weak whole-ecosystem effects on greenhouse gas emissions from unproductive boreal lakes.

National Category
Physical Geography
Identifiers
urn:nbn:se:umu:diva-135002 (URN)10.1002/lno.10743 (DOI)000427077300023 ()
Note

Originally included in thesis in manuscript form

Available from: 2017-05-15 Created: 2017-05-15 Last updated: 2018-06-09Bibliographically approved
Soares, A. R. A., Bergström, A.-K., Sponseller, R. A., Moberg, J. M., Giesler, R., Kritzberg, E. S., . . . Berggren, M. (2017). New insights on resource stoichiometry: assessing availability of carbon, nitrogen, and phosphorus to bacterioplankton. Biogeosciences, 14(6), 1527-1539
Open this publication in new window or tab >>New insights on resource stoichiometry: assessing availability of carbon, nitrogen, and phosphorus to bacterioplankton
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2017 (English)In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 14, no 6, p. 1527-1539Article in journal (Refereed) Published
Abstract [en]

Boreal lake and river ecosystems receive large quantities of organic nutrients and carbon (C) from their catchments. How bacterioplankton respond to these inputs is not well understood, in part because we base our understanding and predictions on "total pools", yet we know little about the stoichiometry of bioavailable elements within organic matter. We designed bioassays with the purpose of exhausting the pools of readily bioavailable dissolved organic carbon (BDOC), bioavailable dissolved nitrogen (BDN), and bioavailable dissolved phosphorus (BDP) as fast as possible. Applying the method in four boreal lakes at base-flow conditions yielded concentrations of bioavailable resources in the range 105-693 mu g CL-1 for BDOC (2% of initial total DOC), 24-288 mu g NL-1 for BDN (31% of initial total dissolved nitrogen), and 0.2-17 mu g PL-1 for BDP (49% of initial total dissolved phosphorus). Thus, relative bioavailability increased from carbon (C) to nitrogen (N) to phosphorus (P). We show that the main fraction of bioavailable nutrients is organic, representing 80% of BDN and 61% of BDP. In addition, we demonstrate that total C : N and C: P ratios are as much as 13-fold higher than C : N and C: P ratios for bioavailable resource fractions. Further, by applying additional bioavailability measurements to seven widely distributed rivers, we provide support for a general pattern of relatively high bioavailability of P and N in relation to C. Altogether, our findings underscore the poor availability of C for support of bacterial metabolism in boreal C-rich fresh-waters, and suggest that these ecosystems are very sensitive to increased input of bioavailable DOC.

National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-133745 (URN)10.5194/bg-14-1527-2017 (DOI)000398193100004 ()
Available from: 2017-05-09 Created: 2017-05-09 Last updated: 2018-06-09Bibliographically approved
Deininger, A., Faithfull, C. & Bergström, A.-K. (2017). Nitrogen effects on the pelagic food web are modified by dissolved organic carbon. Oecologia, 184(4), 901-916
Open this publication in new window or tab >>Nitrogen effects on the pelagic food web are modified by dissolved organic carbon
2017 (English)In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 184, no 4, p. 901-916Article in journal (Refereed) Published
Abstract [en]

Global environmental change has altered the nitrogen (N) cycle and enhanced terrestrial dissolved organic carbon (DOC) loadings to northern boreal lakes. However, it is still unclear how enhanced N availability affects pelagic food web efficiency (FWE) and crustacean zooplankton growth in N limited boreal lakes. Here, we performed in situ mesocosm experiments in six unproductive boreal Swedish lakes, paired across a DOC gradient, with one lake in each pair fertilized with N (2011: reference year; 2012, 2013: impact years). We assessed how zooplankton growth and FWE were affected by changes in pelagic energy mobilization (PEM), food chain length (phytoplankton versus bacterial production based food chain, i.e. PP:BP), and food quality (seston stoichiometry) in response to N fertilization. Although PP, PEM and PP:BP increased in low and medium DOC lakes after N fertilization, consumer growth and FWE were reduced, especially at low DOC-potentially due to reduced phytoplankton food quality [increased C: phosphorus (P); N:P]. At high DOC, N fertilization caused modest increases in PP and PEM, with marginal changes in PP:BP and phytoplankton food quality, which, combined, led to a slight increase in zooplankton growth and FWE. Consequently, at low DOC (<12 mg L-1), increased N availability lowers FWE due to mismatches in food quality demand and supply, whereas at high DOC this mismatch does not occur, and zooplankton production and FWE may increase. We conclude that the lake DOC level is critical for predicting the effects of enhanced inorganic N availability on pelagic productivity in boreal lakes.

Place, publisher, year, edition, pages
SPRINGER, 2017
Keywords
Boreal lakes, Global change, Nitrogen availability, Trophic transfer efficiency, Zooplankton
National Category
Ecology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-142883 (URN)10.1007/s00442-017-3921-5 (DOI)000408003400015 ()
Available from: 2017-12-13 Created: 2017-12-13 Last updated: 2018-06-09Bibliographically approved
Deininger, A., Faithfull, C. L., Karlsson, J., Klaus, M. & Bergström, A.-K. (2017). Pelagic food web response to whole lake N fertilization. Limnology and Oceanography, 62(4), 1498-1511
Open this publication in new window or tab >>Pelagic food web response to whole lake N fertilization
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2017 (English)In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 62, no 4, p. 1498-1511Article in journal (Refereed) Published
Abstract [en]

Anthropogenic activities are increasing inorganic nitrogen (N) loadings to unproductive boreal lakes. In many of these lakes phytoplankton are N limited, consequently N fertilization may affect ecosystem productivity and consumer resource use. Here, we conducted whole lake inorganic N fertilization experiments with six small N limited unproductive boreal lakes (three control and three N enriched) in an area receiving low N deposition with one reference and two impact years. Our aim was to assess the effects of N fertilization on pelagic biomass production and consumer resource use. We found that phytoplankton primary production (PP) and biomass, and the PP: bacterioplankton production ratio increased after fertilization. As expected, the relative contribution of phytoplankton derived resources (autochthony) that supported the crustacean zooplankton community increased. Yet, the response in the consumer community was modest with autochthony only increasing in one of the three major zooplankton groups and with no effect on zooplankton biomass. In conclusion, our findings imply that newly available phytoplankton energy derived from N fertilization was not efficiently transferred up to zooplankton, indicating a mismatch between producer energy supply and consumer energy use with potential accumulation of phytoplankton biomass as the result.

Keywords
autochthony, basal production, boreal, dissolved organic carbon, limitation, nitrate, phytoplankton, zooplankton
National Category
Ecology Environmental Sciences
Research subject
Limnology
Identifiers
urn:nbn:se:umu:diva-130332 (URN)10.1002/lno.10513 (DOI)000404993100013 ()
Funder
Swedish Research Council, 621-2010-4675
Available from: 2017-01-17 Created: 2017-01-17 Last updated: 2018-06-09Bibliographically approved
Deininger, A., Faithfull, C. L. & Bergström, A.-K. (2017). Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon. Ecology, 98(4), 982-994
Open this publication in new window or tab >>Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon
2017 (English)In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 98, no 4, p. 982-994Article in journal (Refereed) Published
Abstract [en]

Global change has increased inorganic nitrogen (N) and dissolved organic carbon (DOC; i.e. ‘browning’) inputs to northern hemisphere boreal lakes. However, we do not know how phytoplankton in nutrient poor lake ecosystems of different DOC concentration respond to increased N availability. Here, we monitored changes in phytoplankton production, biomass and community composition in response to whole lake inorganic N fertilization in six boreal unproductive Swedish lakes divided into three lake pairs (control, N enriched) at three DOC levels (low, medium, high), with one reference year (2011) and two impact years (2012, 2013). We found that phytoplankton biomass and production decreased with DOC concentration before N fertilization. Further, phytoplankton community composition also differed with respect to DOC, with a dominance of non-flagellated autotrophs at low DOC towards an increasing dominance of flagellated autotrophs with increased lake DOC concentration. The N fertilization increased phytoplankton biomass and production in all lakes, but did not affect phytoplankton community composition. However, the net response in biomass and production to N fertilization declined with increasing DOC, implying that the lake DOC concentration is critical in order to infer phytoplankton responses to N fertilization, and that the system switches from being primarily nutrient limited to becoming increasingly light limited with increased DOC concentration. In conclusion, our results show that browning will reduce phytoplankton production and biomass and influence phytoplankton community composition, whereas increased inorganic N loadings from deposition, forestry or other land use will primarily enhance phytoplankton biomass and production. Together, any change in the landscape that enhances inorganic N availability will increase phytoplankton production and biomass, but the positive effects of N will be much weaker or even neutralized in browner lakes as caused by light limitation.

Keywords
boreal lakes, climate change, DOC, N deposition, N limitation, phytoplankton community composition, phytoplankton production, whole lake enrichment experiment
National Category
Ecology Environmental Sciences
Research subject
Limnology
Identifiers
urn:nbn:se:umu:diva-130336 (URN)10.1002/ecy.1758 (DOI)000398175200011 ()28144934 (PubMedID)
Funder
Swedish Research Council, 621-2010-4675
Available from: 2017-01-17 Created: 2017-01-17 Last updated: 2018-06-09Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-5102-4289

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