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Wikner, Johan, Docent
Biography [eng]

Role of bacterioplankton respiration in marine oxygen consumption and CO2-emission

Oxygen deficiency of coastal waters and increased emissions of carbon dioxide to the atmosphere constitute major environmental concerns for the biosphere today. Bacterioplankton accounts for more than 50 percent of the flow of carbon and oxygen in aquatic environments. Therefore, improved understanding of the regulation of bacterial respiration is necessary to promote development of adequate models the marine carbon and oxygen cycles. These constitutes the basis for management of oxygen depleted bottom waters and assessments of the human impact on the CO2 -level in the atmosphere.

The project addresses the following questions:

·        Is bacterial maintenance energy driving a significant fraction of bacterial respiration in the deep sea?

·        What metabolic and morphological adaptation are driven by maintenance respiration?

·        Is temperature, DOC substrate or genetic regulation controlling maintenance respiration?

·        Are bacterioplankton dynamics associated with major meteorological events like the North Atlantic Oscillation index?

Biography [swe]

Marina bakteriers roll för uppkomsten av syrefria havsområden och produktion av koldioxid

Min forskning inriktar sig på att förstå vad som kontrollerar bakterieplanktons tillväxt, respiration och förekomst i havet. Speciellt intresserar jag mig för hur ämnen från älvar och vattendrag påverkar bakteriernas aktivitet i havsmiljön.

Ett projekt försöker mäta hur stor bakterieplanktons underhållsrespiration är i naturliga miljöer, hur den varierar mellan olika typer av födosubstrat och arter. Vi vill också förstå hur stor basalrespirationen är av den totala, och vilka konskvenser detta har för vad som bestämmer syresituationen och produktionen av koldioxid i havet.

Tidsserier från miljöövervakningsprogram används för att förstå vad som kontrollerar bakteriell tillväxt och respiration på långa tidskalor. Där ingår också bedömning av klimatförändringars inverkan på bakteriell aktivitet och förekomst.

Publications (10 of 62) Show all publications
Vikström, K. & Wikner, J. (2018). Importance of Bacterial Maintenance Respiration in a Subarctic Estuary: a Proof of Concept from the Field. Microbial Ecology
Open this publication in new window or tab >>Importance of Bacterial Maintenance Respiration in a Subarctic Estuary: a Proof of Concept from the Field
2018 (English)In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

Bacterial respiration contributes to atmospheric carbon dioxide accumulation and development of hypoxia and is a critical, often overlooked, component of ecosystem function. This study investigates the concept that maintenance respiration is a significant proportion of bacterial respiration at natural nutrient levels in the field, advancing our understanding of bacterial living conditions and energy strategies. Two river-sea transects of respiration and specific growth rates were analyzed representing low- and highproductivity conditions (by in situ bacterial biomass production) in a subarctic estuary, using an established ecophysiological linear model (the Pirt model) estimating maintenance respiration. The Pirt model was applicable to field conditions during high, but not low, bacterial biomass production. However, a quadratic model provided a better fit to observed data, accounting for the maintained respiration at low μ. A first estimate of maintenance respiration was 0.58 fmol O2 day−1 cell−1 by the quadratic model. Twenty percent to nearly all of the bacterial respiration was due to maintenance respiration over the observed range of μ (0.21– 0.002 day−1 ). In the less productive condition, bacterial specific respiration was high and without dependence on μ, suggesting enhanced bacterial energy expenditure during starvation. Annual maintenance respiration accounted for 58% of the total bacterioplankton respiration based on μ from monitoring data. Phosphorus availability occasionally, but inconsistently, explained some of the remaining variation in bacterial specific respiration. Bacterial maintenance respiration can constitute a large share of pelagic respiration and merit further study to understand bacterial energetics and oxygen dynamics in the aquatic environment.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Marine, Bacteria, Maintenance, Respiration, Stoichiometry, Model
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-152580 (URN)10.1007/s00248-018-1244-7 (DOI)
Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2019-02-27
Ahlgren, J., Rolff, C., Grimvall, A., Omstedt, A. & Wikner, J. (2017). Orsaker till minskande syrehalter i Bottenhavet. Göteborg
Open this publication in new window or tab >>Orsaker till minskande syrehalter i Bottenhavet
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2017 (Swedish)Report (Refereed)
Abstract [sv]

Resultat från den nationella miljöövervakningen visar att syrehalterna i Bottenhavet har minskat sedan 1970-talet, en minskning som accelererat från 1990. För att ha möjlighet att på något sätt kunna åtgärda denna försämring av den marina miljön är det nödvändigt att identifiera orsakerna till denna syreminskning, eftersom olika orsaker kan kräva olika former av åtgärder. Om orsaken till exempel är ökad syreförbrukning beroende på regional övergödning, skulle detta innebära ökat behov av regionala reningsåtgärder. Målsättningen med projektet var därmed att ge en tillförlitlig förklaring till de sjunkande syrehalterna i Bottenhavet under de senaste 20 åren genom att använda data från de nationella miljöövervakningsprogrammen. De huvudhypoteser som undersöktes som orsaker till de sjunkande syrehalterna var:  • Ökad regional gödning av Bottenhavet och därmed ökad produktion.  • Tillförsel av syrefattigt och fosfatrikt från Egentliga Östersjön.  • Starkare haloklin och försämrad ventilation av Bottenhavets djupvatten.  • Ökad temperatur och ökad tillförsel av löst organiskt kol. Analys av tidsserier och modellanalyser utifrån miljöövervaknings- och forskningsdata visade att den observerade syrehaltsminskningen i Bottenhavets djupvatten främst beror på en ökning av vattentemperaturen och delvis på en ökning av löst organiskt kol i vattnet, samt tillflöde från Egentliga Östersjön. Dataanalysen visade däremot inget tydligt stöd för att ökad produktion av biomassa i Bottenhavet orsakat de minskande syrehalterna. Detta gäller indikatorer för växtplankton, sedimentation och bakterieplankton som alla förväntas öka vid ökad produktion och det finns således inga direkta indicier för att stödja hypotesen om ökad gödning av Bottenhavet.  Sammantaget visar de analyser som gjorts inom projektet att Bottenhavets framtida hälsa främst gynnas av en kombination av åtgärder för att motverka globala klimatförändringar, samt åtgärder för att förbättra vattenkvaliteten i Egentliga Östersjön. Näringstillförsel från Bottenhavets avrinningsområden bedöms främst ha haft betydelse för syresituationen i kustnära vattenförekomster. Den bedöms därför inte i betydande omfattning ha orsakat de minskande syrehalterna i Bottenhavets utsjöområden.  

Place, publisher, year, edition, pages
Göteborg: , 2017. p. 25
Series
Havsmiljöinstitutets rapport ; 2017:5
National Category
Environmental Sciences
Research subject
biology, Environmental Science
Identifiers
urn:nbn:se:umu:diva-143775 (URN)
Available from: 2018-01-09 Created: 2018-01-09 Last updated: 2018-06-09Bibliographically approved
Ahlgren, J., Grimvall, A., Omstedt, A., Rolff, C. & Wikner, J. (2017). Temperature, DOC level and basin interactions explain the declining oxygen concentrations in the Bothnian Sea. Journal of Marine Systems, 170, 22-30
Open this publication in new window or tab >>Temperature, DOC level and basin interactions explain the declining oxygen concentrations in the Bothnian Sea
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2017 (English)In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 170, p. 22-30Article in journal (Refereed) Published
Abstract [en]

Hypoxia and oxygen deficient zones are expanding worldwide. To properly manage this deterioration of the marine environment, it is important to identify the causes of oxygen declines and the influence of anthropogenic activities. Here, we provide a study aiming to explain the declining oxygen levels in the deep waters of the Bothnian Sea over the past 20 years by investigating data from environmental monitoring programmes. The observed decline in oxygen concentrations in deep waters was found to be primarily a consequence of water temperature increase and partly caused by an increase in dissolved organic carbon (DOC) in the seawater (R-Adj(2). = 0.83) as well as inflow from the adjacent sea basin. As none of the tested eutrophication-related predictors were significant according to a stepwise multiple regression, a regional increase in nutrient inputs to the area is unlikely to explain a significant portion of the oxygen decline. Based on the findings of this study, preventing the development of anoxia in the deep water of the Bothnian Sea is dependent on the large-scale measures taken to reduce climate change. In addition, the reduction of the nutrient load to the Baltic Proper is required to counteract the development of hypoxic and phosphate-rich water in the Baltic Proper, which can form deep water in the Bothnian Sea. The relative importance of these sources to oxygen consumption is difficult to determine from the available data, but the results clearly demonstrate the importance of climate related factors such as temperature, DOC and inflow from adjacent basins for the oxygen status of the sea.

Keywords
Oxygen depletion, Hypoxia, Bothnian Sea, Baltic Sea, Climatic changes, Modelling
National Category
Oceanography, Hydrology and Water Resources Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-136048 (URN)10.1016/j.jmarsys.2016.12.010 (DOI)000401211400003 ()
Available from: 2017-06-20 Created: 2017-06-20 Last updated: 2018-06-09Bibliographically approved
Andersson, A. & Wikner, J. (2016). Klimatförändringar kan leda till mindre fisk i havet. In: Havet: om miljötillståndet i i svenska havsområden. 2015/2016 (pp. 25-28). Göteborg: Havs- och vattenmyndigheten
Open this publication in new window or tab >>Klimatförändringar kan leda till mindre fisk i havet
2016 (Swedish)In: Havet: om miljötillståndet i i svenska havsområden. 2015/2016, Göteborg: Havs- och vattenmyndigheten , 2016, p. 25-28Chapter in book (Other academic)
Place, publisher, year, edition, pages
Göteborg: Havs- och vattenmyndigheten, 2016
Series
Havet, ISSN 1654-6741 ; 2015/2016
Keywords
marin, tillståndsbedömning, tidsserier, referensvärden
National Category
Ecology Environmental Sciences Oceanography, Hydrology and Water Resources
Research subject
biology, Environmental Science
Identifiers
urn:nbn:se:umu:diva-128849 (URN)978-91-982291-3-4 (ISBN)978-91-87967-12-2 (ISBN)
Available from: 2016-12-16 Created: 2016-12-16 Last updated: 2018-06-09Bibliographically approved
Båmstedt, U. & Wikner, J. (2016). Mixing depth and allochthonous dissolved organic carbon: controlling factors of coastal trophic balance. Marine Ecology Progress Series, 561, 17-29
Open this publication in new window or tab >>Mixing depth and allochthonous dissolved organic carbon: controlling factors of coastal trophic balance
2016 (English)In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 561, p. 17-29Article in journal (Refereed) Published
Abstract [en]

ABSTRACT: The interacting effects of different mixing depths and increased allochthonous dissolved organic carbon (DOC) on the ratio of heterotrophic to autotrophic production (i.e. trophic balance) was evaluated in a mesocosm study with a stratified water column. An autumn plankton community from the northern Bothnian Sea showed significantly decreased phytoplankton production and somewhat increased bacterial production with added DOC. In addition, increased mixing depth further reduced phytoplankton production. With a deep pycnocline and added DOC, the system became net-heterotrophic, with an average bacteria-to-phytoplankton production ratio of 1.24. With a deep pycnocline without added DOC, the trophic balance was changed to 0.44 (i.e. autotrophic). With a shallow pycnocline, the system remained net-autotrophic irrespective of DOC addition. We propose that increased precipitation in northern Europe due to climate change may result in changed density stratification and increased allochthonous DOC transport to the sea, leading to more heterotrophic coastal aquatic ecosystems. Such a scenario may entail reduced biological production at higher trophic levels and enhanced CO2 emission to the atmosphere.

Place, publisher, year, edition, pages
Oldendorf/Luhe: , 2016
Keywords
marine, ecology, climate, production, plankton, mesocosm, trophic, balance, dissolved organic carbon, stratification
National Category
Ecology Microbiology Botany Zoology
Identifiers
urn:nbn:se:umu:diva-128844 (URN)10.3354/meps11907 (DOI)000391695800002 ()
Available from: 2016-12-16 Created: 2016-12-16 Last updated: 2019-03-06Bibliographically approved
Viitasalo, M., Blenckner, T., Gårdmark, A., Kaartokallio, H., Kautsky, L., Kuosa, H., . . . Wikner, J. (2015). Environmental Impacts—Marine Ecosystems. In: The BACC II Author Team (Ed.), Second Assessment of Climate Change for the Baltic Sea Basin: (pp. 363-380). London: Springer
Open this publication in new window or tab >>Environmental Impacts—Marine Ecosystems
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2015 (English)In: Second Assessment of Climate Change for the Baltic Sea Basin / [ed] The BACC II Author Team, London: Springer, 2015, p. 363-380Chapter in book (Other academic)
Abstract [en]

Increase in sea surface temperature is projected to change seasonal succession and induce dominance shifts in phytoplankton in spring and promote the growth of cyanobacteria in summer. In general, climate change is projected to worsen oxygen conditions and eutrophication in the Baltic Proper and the Gulf of Finland. In the Gulf of Bothnia, the increasing freshwater discharge may increase the amount of dissolved organic carbon (DOC) in the water and hence reduce phytoplankton productivity. In winter, reduced duration and spatial extent of sea ice will cause habitat loss for ice-dwelling organisms and probably induce changes in nutrient dynamics within and under the sea ice. The projected salinity decline will probably affect the functional diversity of the benthic communities and induce geographical shifts in the distribution limits of key species such as bladder wrack and blue mussel. In the pelagic ecosystem, the decrease in salinity together with poor oxygen conditions in the deep basins will negatively influence the main Baltic Sea piscivore, cod. This has been suggested to cause cascading effects on clupeids and zooplankton.

Place, publisher, year, edition, pages
London: Springer, 2015
Series
Regional climate studies, ISSN 1862-0248
Keywords
Baltic Sea, Climate change, Benthic and pelagic communities, Biodiversity, Biogeography, Regime shifts, Cascading effects
National Category
Climate Research
Research subject
biology, Environmental Science
Identifiers
urn:nbn:se:umu:diva-113486 (URN)10.1007/978-3-319-16006-1_19 (DOI)978-3-319-16006-1 (ISBN)978-3-319-16005-4 (ISBN)
Available from: 2015-12-18 Created: 2015-12-18 Last updated: 2018-06-07Bibliographically approved
Andersson, A., Meier, H. M., Ripszam, M., Rowe, O., Wikner, J., Haglund, P., . . . Elmgren, R. (2015). Projected future climate change and Baltic Sea ecosystem management. Ambio, 44(Suppl 3), S345-S356
Open this publication in new window or tab >>Projected future climate change and Baltic Sea ecosystem management
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2015 (English)In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, no Suppl 3, p. S345-S356Article in journal (Refereed) Published
Abstract [en]

Climate change is likely to have large effectson the Baltic Sea ecosystem. Simulations indicate 2–4 Cwarming and 50–80 % decrease in ice cover by 2100.Precipitation may increase *30 % in the north, causingincreased land runoff of allochthonous organic matter(AOM) and organic pollutants and decreased salinity.Coupled physical–biogeochemical models indicate that, inthe south, bottom-water anoxia may spread, reducing codrecruitment and increasing sediment phosphorus release,thus promoting cyanobacterial blooms. In the north,heterotrophic bacteria will be favored by AOM, whilephytoplankton production may be reduced. Extra trophiclevels in the food web may increase energy losses andconsequently reduce fish production. Future managementof the Baltic Sea must consider the effects of climatechange on the ecosystem dynamics and functions, as wellas the effects of anthropogenic nutrient and pollutant load.Monitoring should have a holistic approach, encompassingboth autotrophic (phytoplankton) and heterotrophic (e.g.,bacterial) processes.

Place, publisher, year, edition, pages
Springer, 2015
Keywords
Climate change, Allochthonous organic matter, Primary production, Bacterial production, Food web, Monitoring
National Category
Chemical Sciences Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-98932 (URN)10.1007/s13280-015-0654-8 (DOI)000362290800003 ()26022318 (PubMedID)
Note

Supplement: 3 Special Issue: SI

Available from: 2015-01-28 Created: 2015-01-28 Last updated: 2018-06-07Bibliographically approved
Nydahl, A., Panigrahi, S. & Wikner, J. (2013). Increased microbial activity in a warmer and wetter climate enhances the risk of coastal hypoxia. FEMS Microbiology Ecology, 85(2), 338-347
Open this publication in new window or tab >>Increased microbial activity in a warmer and wetter climate enhances the risk of coastal hypoxia
2013 (English)In: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 85, no 2, p. 338-347Article in journal (Refereed) Published
Abstract [en]

The coastal zone is the most productive area of the marine environment and the area that is most exposed to environmental drivers associated with human pressures in a watershed. In dark bottle incubation experiments, we investigated the short-term interactive effects of changes in salinity, temperature and riverine dissolved organic matter (rDOM) on microbial respiration, growth and abundance in an estuarine community. An interaction effect was found for bacterial growth, where the assimilation of rDOM increased at higher salinities. A 3 °C rise in the temperature had a positive effect on microbial respiration. A higher concentration of DOM consistently enhanced respiration and bacterial abundance, while an increase in temperature reduced bacterial abundance. The latter result was most likely caused by a positive interaction effect of temperature, salinity and rDOM on the abundance of bacterivorous flagellates. Elevated temperature and precipitation, causing increased discharges of rDOM and an associated lowered salinity, will therefore primarily promote bacterial respiration, growth and bacterivore abundance. Our results suggest a positive net outcome for microbial activity under the projected climate change, driven by different, partially interacting environmental factors. Thus, hypoxia in coastal zones may increase due to enhanced respiration caused by higher temperatures and rDOM discharge acting synergistically.

Place, publisher, year, edition, pages
Hoboken: Wiley-Blackwell, 2013
Keywords
bacterioplankton, protozoa, phytoplankton, marine, Baltic Sea
National Category
Microbiology
Research subject
biology
Identifiers
urn:nbn:se:umu:diva-62730 (URN)10.1111/1574-6941.12123 (DOI)000328962900012 ()
Available from: 2012-12-16 Created: 2012-12-16 Last updated: 2018-06-08Bibliographically approved
Wikner, J., Panigrahi, S., Nydahl, A., Lundberg, E., Båmstedt, U. & Tengberg, A. (2013). Precise continuous measurements of pelagic respiration in coastal waters with Oxygen Optodes. Limnology and Oceanography: Methods, 11, 1-15
Open this publication in new window or tab >>Precise continuous measurements of pelagic respiration in coastal waters with Oxygen Optodes
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2013 (English)In: Limnology and Oceanography: Methods, ISSN 1541-5856, E-ISSN 1541-5856, Vol. 11, p. 1-15Article in journal (Refereed) Published
Abstract [en]

An analytical setup for respiration rate measurements was developed and evaluated in pelagic water samples using a commercially available optical oxygen sensor (Optode (TM)). This setup required the development of a gas tight stopper to connect the sensors to a 1 dm(3) glass sample bottle, precise temperature control (+/- 0.05 degrees C), and proper stirring of samples. The detection limit and precision of the method was 0.3 mmol O-2 m(-3) d(-1). This was similar to the detection limit for the high-precision Winkler titration method reported in field studies. When compared with the Winkler method, the Optode sensor enabled operator-independent, high temporal resolution measurement of respiration, better coverage of plankton groups and detection of non-linear oxygen decline, without the need for wet chemistry. Respiration rates measured by the Optodes showed good accuracy when compared with measurements made with the Winkler titration method (3% deviation), followed the expected temperature response (Q(10) = 3.0), were correlated with chlorophyll a and were congruent with earlier reported values in the literature. The main source of uncertainty was a necessary correction for system drift during the incubation period, due to oxygen release from the plastic components. Additionally, less stringent temperature control on board research vessels during rough seas reduced the precision. We conclude that the developed Optode system can be used to measure respiration in productive coastal waters. Samples from cold or deep waters were, however, often below the detection limit.

Place, publisher, year, edition, pages
Association for the Sciences of Limnology and Oceanography, 2013
National Category
Natural Sciences
Identifiers
urn:nbn:se:umu:diva-62731 (URN)10.4319/lom.2013.11.1 (DOI)000317920600001 ()
Available from: 2012-12-16 Created: 2012-12-16 Last updated: 2018-06-08Bibliographically approved
Moksnes, P.-O., Albertsson, J., Elfwing, T., Hansen, J., Lindegarth, M., Nilsson, J., . . . Wikner, J. (2013). Sammanvägd bedömning av miljötillståndet i Havet. Göteborg: Havsmiljöinstitutet
Open this publication in new window or tab >>Sammanvägd bedömning av miljötillståndet i Havet
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2013 (Swedish)Report (Other academic)
Place, publisher, year, edition, pages
Göteborg: Havsmiljöinstitutet, 2013. p. 46
Series
Havsmiljöinstitutets rapport ; 3
National Category
Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-85418 (URN)
Available from: 2014-02-04 Created: 2014-02-04 Last updated: 2018-06-08Bibliographically approved
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