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Hauptmann, D. & Myrstener, M. (2023). Spatial and temporal patterns of stream nutrient limitation in an Arctic catchment. Hydrobiologia, 850(7), 1699-1713
Open this publication in new window or tab >>Spatial and temporal patterns of stream nutrient limitation in an Arctic catchment
2023 (English)In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 850, no 7, p. 1699-1713Article in journal (Refereed) Published
Abstract [en]

Arctic stream biofilm responses to ongoing climate-related changes in physical and chemical conditions have major implications for stream food webs and biogeochemical cycles. Yet, such effects have rarely been studied outside summer months or at sub-catchment scales in the Arctic. We used deployments of nutrient diffusing substrates (NDS) to assess the spatial (20 deployments) and seasonal patterns (10 deployments) and physical and chemical drivers of nutrient limitation within an Arctic stream catchment. Results show that nutrient limitation of autotrophic processes was common during summer, but that light inhibited biomass accrual under the ice in winter. Alongside single N, P and C responses, co-limitation dominated the overall pattern of limitation over time and across the catchment. However, the primary limiting nutrient to autotrophs changed from N to P in parts of the catchment with higher N concentrations. As Arctic studies are often conducted at individual sites during summer, these may miss shifts in the drivers of stream productivity that arise from variable nutrient, temperature, and light regimes. Our results caution against focusing on one single most important limiting nutrient, as we found that this can shift seasonally and over small spatial scales in this Arctic catchment.

Place, publisher, year, edition, pages
Springer Science+Business Media B.V., 2023
Keywords
Arctic ecosystems, Biofilm, Climate change, Nutrient limitation, Resource limitation, Seasonality
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-205794 (URN)10.1007/s10750-023-05178-7 (DOI)000948786600001 ()2-s2.0-85149752013 (Scopus ID)
Funder
Swedish Research Council Formas, 217-2012-1418
Available from: 2023-03-28 Created: 2023-03-28 Last updated: 2024-07-02Bibliographically approved
Myrstener, M., Fork, M. L., Bergström, A.-K., Puts, I., Hauptmann, D., Isles, P. D. F., . . . Sponseller, R. A. (2022). Resolving the Drivers of Algal Nutrient Limitation from Boreal to Arctic Lakes and Streams. Ecosystems (New York. Print), 25, 1682-1699
Open this publication in new window or tab >>Resolving the Drivers of Algal Nutrient Limitation from Boreal to Arctic Lakes and Streams
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2022 (English)In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 25, p. 1682-1699Article in journal (Refereed) Published
Abstract [en]

Nutrient inputs to northern freshwaters are changing, potentially altering aquatic ecosystem functioning through effects on primary producers. Yet, while primary producer growth is sensitive to nutrient supply, it is also constrained by a suite of other factors, including light and temperature, which may play varying roles across stream and lake habitats. Here, we use bioassay results from 89 lakes and streams spanning northern boreal to Arctic Sweden to test for differences in nutrient limitation status of algal biomass along gradients in colored dissolved organic carbon (DOC), water temperature, and nutrient concentrations, and to ask whether there are distinct patterns and drivers between habitats. Single nitrogen (N) limitation or primary N-limitation with secondary phosphorus (P) limitation of algal biomass was the most common condition for streams and lakes. Average response to N-addition was a doubling in biomass; however, the degree of limitation was modulated by the distinct physical and chemical conditions in lakes versus streams and across boreal to Arctic regions. Overall, algal responses to N-addition were strongest at sites with low background concentrations of dissolved inorganic N. Low temperatures constrained biomass responses to added nutrients in lakes but had weaker effects on responses in streams. Further, DOC mediated the response of algal biomass to nutrient addition differently among lakes and streams. Stream responses were dampened at higher DOC, whereas lake responses to nutrient addition increased from low to moderate DOC but were depressed at high DOC. Our results suggest that future changes in nutrient availability, particularly N, will exert strong effects on the trophic state of northern freshwaters. However, we highlight important differences in the physical and chemical factors that shape algal responses to nutrient availability in different parts of aquatic networks, which will ultimately affect the integrated response of northern aquatic systems to ongoing environmental changes.

Place, publisher, year, edition, pages
Springer-Verlag New York, 2022
Keywords
lake, nitrogen, nutrient limitation, periphyton, phosphorus, phytoplankton, stream
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-194276 (URN)10.1007/s10021-022-00759-4 (DOI)000779217200001 ()2-s2.0-85127656090 (Scopus ID)
Available from: 2022-04-29 Created: 2022-04-29 Last updated: 2024-07-02Bibliographically approved
Myrstener, M., Thomas, S. A., Giesler, R. & Sponseller, R. A. (2021). Nitrogen supply and physical disturbance shapes Arctic stream nitrogen uptake through effects on metabolic activity. Freshwater Biology, 66(8), 1502-1514
Open this publication in new window or tab >>Nitrogen supply and physical disturbance shapes Arctic stream nitrogen uptake through effects on metabolic activity
2021 (English)In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 66, no 8, p. 1502-1514Article in journal (Refereed) Published
Abstract [en]

Climate change in the Arctic is altering the delivery of nutrients from terrestrial to aquatic ecosystems. The impact of these changes on downstream lakes and rivers is influenced by the capacity of small streams to retain such inputs. Given the potential for nutrient limitation in oligotrophic Arctic streams, biotic demand should be high, unless harsh environmental conditions maintain low biomass standing stocks that limit nutrient uptake capacity.

We assessed the drivers of nutrient uptake in two contrasting headwater environments in Arctic Sweden: one stream draining upland tundra and the other draining an alluvial valley with birch forest. At both sites, we measured nitrate (NO3) uptake biweekly using short-term slug releases and estimated rates of gross primary production (GPP) and ecosystem respiration from continuous dissolved oxygen measurements.

Catchment characteristics were associated with distinct stream chemical and biological properties. For example, the tundra stream maintained relatively low NO3 concentrations (average: 46 µg N/L) and rates of GPP (0.2 g O2 m−2 day−1). By comparison, the birch forest stream was more NO3 rich (88 µg N/L) and productive (GPP: 1.7 g O2 m−2 day−1). These differences corresponded to greater areal NO3 uptake rate and increased NO3 use efficiency (as uptake velocity) in the birch forest stream (max 192 µg N m−2 min−1 and 96 mm/hr) compared to its tundra counterpart (max 52 µg N m−2 min−1 and 49 mm/hr) during 2017. Further, different sets of environmental drivers predicted temporal patterns of nutrient uptake at these sites: abiotic factors (e.g. NO3 concentration and discharge) were associated with changes in uptake in the tundra stream, while metabolic activity was more important in the birch forest stream.

Between sites, variation in uptake metrics suggests that the ability to retain pulses of nutrients is linked to nutrient supply regimes controlled at larger spatial and temporal scales and habitat properties that promote biomass accrual and thus biotic demand.

Overall, constraints on biotic potential imposed by the habitat template determined the capacity of these high latitude streams to respond to future changes in nutrient inputs arising from climate warming or human land use.

Place, publisher, year, edition, pages
John Wiley & Sons, 2021
Keywords
Arctic, catchment, metabolism, nutrient uptake, tundra
National Category
Physical Geography
Identifiers
urn:nbn:se:umu:diva-177434 (URN)10.1111/fwb.13734 (DOI)000656619300001 ()2-s2.0-85107359743 (Scopus ID)
Note

Originally included in thesis in manuscript form.

Available from: 2020-12-09 Created: 2020-12-09 Last updated: 2022-01-10Bibliographically approved
Myrstener, M., Gómez-Gener, L., Rocher-Ros, G., Giesler, R. & Sponseller, R. A. (2021). Nutrients influence seasonal metabolic patterns and total productivity of Arctic streams. Limnology and Oceanography, 66(S1), S182-S196
Open this publication in new window or tab >>Nutrients influence seasonal metabolic patterns and total productivity of Arctic streams
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2021 (English)In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 66, no S1, p. S182-S196Article in journal (Refereed) Published
Abstract [en]

The seasonality of gross primary production (GPP) in streams is driven by multiple physical and chemical factors, yet incident light is often thought to be most important. In Arctic tundra streams, however, light is available in saturating amounts throughout the summer, but sharp declines in nutrient supply during the terrestrial growing season may constrain aquatic productivity. Given the opposing seasonality of these drivers, we hypothesized that "shoulder seasons"-spring and autumn-represent critical time windows when light and nutrients align to optimize rates of stream productivity in the Arctic. To test this, we measured annual patterns of GPP and biofilm accumulation in eight streams in Arctic Sweden. We found that the aquatic growing season length differed by 4 months across streams and was determined largely by the timing of ice-off in spring. During the growing season, temporal variability in GPP for nitrogen (N) poor streams was correlated with inorganic N concentration, while in more N-rich streams GPP was instead linked to changes in phosphorus and light. Annual GPP varied ninefold among streams and was enhanced by N availability, the length of ice-free period, and low flood frequency. Finally, network scale estimates of GPP highlight the overall significance of the shoulder seasons, which accounted for 48% of annual productivity. We suggest that the timing of ice off and nutrient supply from land interact to regulate the annual metabolic regimes of nutrient poor, Arctic streams, leading to unexpected peaks in productivity that are offset from the terrestrial growing season.

Place, publisher, year, edition, pages
John Wiley & Sons, 2021
National Category
Oceanography, Hydrology and Water Resources Ecology
Identifiers
urn:nbn:se:umu:diva-176077 (URN)10.1002/lno.11614 (DOI)000574213000001 ()2-s2.0-85091768445 (Scopus ID)
Funder
Swedish Research Council Formas, 2014‐970, 2016‐01412
Available from: 2020-10-23 Created: 2020-10-23 Last updated: 2021-07-07Bibliographically approved
Rocher-Ros, G., Sponseller, R. A., Bergström, A.-K., Myrstener, M. & Giesler, R. (2020). Stream metabolism controls diel patterns and evasion of CO2 in Arctic streams. Global Change Biology, 26(3), 1400-1413
Open this publication in new window or tab >>Stream metabolism controls diel patterns and evasion of CO2 in Arctic streams
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2020 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 26, no 3, p. 1400-1413Article in journal (Refereed) Published
Abstract [en]

Streams play an important role in the global carbon (C) cycle, accounting for a large portion of CO2 evaded from inland waters despite their small areal coverage. However, the relative importance of different terrestrial and aquatic processes driving CO2 production and evasion from streams remains poorly understood. In this study, we measured O-2 and CO2 continuously in streams draining tundra-dominated catchments in northern Sweden, during the summers of 2015 and 2016. From this, we estimated daily metabolic rates and CO2 evasion simultaneously and thus provide insight into the role of stream metabolism as a driver of C dynamics in Arctic streams. Our results show that aquatic biological processes regulate CO2 concentrations and evasion at multiple timescales. Photosynthesis caused CO2 concentrations to decrease by as much as 900 ppm during the day, with the magnitude of this diel variation being strongest at the low-turbulence streams. Diel patterns in CO2 concentrations in turn influenced evasion, with up to 45% higher rates at night. Throughout the summer, CO2 evasion was sustained by aquatic ecosystem respiration, which was one order of magnitude higher than gross primary production. Furthermore, in most cases, the contribution of stream respiration exceeded CO2 evasion, suggesting that some stream reaches serve as net sources of CO2, thus creating longitudinal heterogeneity in C production and loss within this stream network. Overall, our results provide the first link between stream metabolism and CO2 evasion in the Arctic and demonstrate that stream metabolic processes are key drivers of the transformation and fate of terrestrial organic matter exported from these landscapes.

Place, publisher, year, edition, pages
John Wiley & Sons, 2020
Keywords
Arctic, carbon cycle, carbon processing, CO2 evasion, stream metabolism
National Category
Ecology Geosciences, Multidisciplinary
Research subject
Limnology
Identifiers
urn:nbn:se:umu:diva-158880 (URN)10.1111/gcb.14895 (DOI)000499301300001 ()31667979 (PubMedID)2-s2.0-85076165577 (Scopus ID)
Note

Originally included in thesis in manuscript form.

Available from: 2019-05-13 Created: 2019-05-13 Last updated: 2023-03-24Bibliographically approved
Myrstener, M. (2020). The role of nutrients for stream ecosystem function in Arctic landscapes: drivers of productivity under environmental change. (Doctoral dissertation). Umeå: Umeå universitet
Open this publication in new window or tab >>The role of nutrients for stream ecosystem function in Arctic landscapes: drivers of productivity under environmental change
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Arctic and sub-Arctic freshwaters are currently experiencing substantial ecosystem changes due to the effects of global warming. Global warming effects on these freshwaters include increasing water temperatures, altered hydrological patterns, shifts in riparian vegetation and changes in the export of nutrients and carbon from soils. How these alterations to the physical and chemical hab-itat will affect stream ecosystem functioning largely depends on the responses by autotrophic pro-ducers and heterotrophic primary consumers. In this thesis, I explore how key stream ecosystem processes such as metabolic rates and nutrient cycling vary as a function of climate and landscape drivers, particularly light, temperature, and nutrient and carbon availability. To do this I leveraged natural gradients in vegetation, altitude, disturbance, and precipitation throughout the year in northern Sweden, as well as long- and short-term manipulations of nutrient availability. I also synthesized nutrient limitation data from lakes and streams to more holistically assess the re-sponses of boreal to Arctic freshwaters to changes in nutrients and climate variables. I found that nutrient availability, and especially nitrogen (N), is a main driver of spatial and temporal patterns of biofilm productivity, whole system metabolic rates, and short term N uptake in Arctic and sub-Arctic streams. I also show the importance of light and temperature constraints during early spring and late autumn, which set the limit for the aquatic growing season and annual productivity pat-terns. I present a first comparison of combined drivers of lake and stream responses to nutrient addition, which points to a shared importance of N and phosphorus (P) rather than light or tem-perature in driving the magnitude of nutrient limitation across these systems. Ultimately, I pro-pose that across large ranges in habitat variables, widespread nutrient limitation of Arctic fresh-waters constrain other climate change effects on ecosystem functions. The results presented in this thesis will promote better predictions of climate change effects on Boreal to Arctic stream ecosystem functioning.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2020. p. 22
Keywords
Nutrients, Stream, Arctic, Boreal, Primary productivity, Algae, Biofilm, Nutrient limitation, Nitrogen, Phosphorus
National Category
Physical Geography
Identifiers
urn:nbn:se:umu:diva-177439 (URN)978-91-7855-445-4 (ISBN)978-91-7855-446-1 (ISBN)
Public defence
2021-01-22, KBG501, KBC huset, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2020-12-18 Created: 2020-12-09 Last updated: 2020-12-17Bibliographically 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: 2021-06-03Bibliographically approved
Myrstener, M., Jonsson, A. & Bergström, A.-K. (2016). The effects of temperature and resource availability on denitrification and relative N2O production in boreal lake sediments. Journal of Environmental Sciences(China), 47, 82-90
Open this publication in new window or tab >>The effects of temperature and resource availability on denitrification and relative N2O production in boreal lake sediments
2016 (English)In: Journal of Environmental Sciences(China), ISSN 1001-0742, E-ISSN 1878-7320, Vol. 47, p. 82-90Article in journal (Refereed) Published
Abstract [en]

Anthropogenic environmental stressors (like atmospheric deposition, land use change, and climate warming) are predicted to increase inorganic nitrogen and organic carbon loading to northern boreal lakes, with potential consequences for denitrification in lakes. However, our ability to predict effects of these changes is currently limited as northern boreal lakes have been largely neglected in denitrification studies. The aim of this study was therefore to assess how maximum potential denitrification and N2O production rates, and the relationship between the two (relative N2O production), is controlled by availability of nitrate (NO3), carbon (C), phosphorus (P), and temperature. Experiments were performed using the acetylene inhibition technique on sediments from a small, nutrient poor boreal lake in northern Sweden in 2014. Maximum potential denitrification and N2O production rates at 4°C were reached already at NO3 additions of 106–120 μg NO3–N/L, and remained unchanged with higher NO3 amendments. Higher incubation temperatures increased maximum potential denitrification and N2O production rates, and Q10 was somewhat higher for N2O production (1.77) than for denitrification (1.69). The relative N2O production ranged between 13% and 64%, and was not related to NO3 concentration, but the ratio increased when incubations were amended with C and P (from a median of 16% to 27%). Combined, our results suggests that unproductive northern boreal lakes currently have low potential for denitrification but are susceptible to small changes in NO3 loading especially if these are accompanied by enhanced C and P availability, likely promoting higher N2O production relative to N2.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Acetylene, NO3, Carbon, DOC, Nitrous oxide ratio, Sediment
National Category
Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-126746 (URN)10.1016/j.jes.2016.03.003 (DOI)000383932200010 ()27593275 (PubMedID)2-s2.0-84963625764 (Scopus ID)
Available from: 2016-10-19 Created: 2016-10-13 Last updated: 2023-03-24Bibliographically approved
Myrstener, M., Fork, M. L., Callisto Puts, I., Hauptmann, D., Bergström, A.-K. & Sponseller, R. A.Resolving the drivers of aquatic nutrient limitation along boreal to Arctic climate gradients.
Open this publication in new window or tab >>Resolving the drivers of aquatic nutrient limitation along boreal to Arctic climate gradients
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(English)Manuscript (preprint) (Other academic)
National Category
Physical Geography
Identifiers
urn:nbn:se:umu:diva-177438 (URN)
Available from: 2020-12-09 Created: 2020-12-09 Last updated: 2021-05-06
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0943-641x

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