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Wikner, Johan, Professor
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 78) Show all publications
Wikner, J. (2024). Prokaryotic plankton respiration, growth and abundance in the Arctic Ocean 2021. Swedish National Data Service
Open this publication in new window or tab >>Prokaryotic plankton respiration, growth and abundance in the Arctic Ocean 2021
2024 (English)Data set, Primary data
Abstract [en]

The dataset consists of results from measurements of prokaryotic (Bacteria and Archaea) plankton respiration, growth, and abundance in the Arctic Ocean surface (0-500 m) in 2021. Data was collected during the Synoptic Arctic Survey expedition with the Swedish research icebreaker Oden between July 25 and September 20, 2021.

Samples were collected primarily with Niskin-bottles on a rosette-sampler equipped with a CTD probe. Some samples were also taken in the boundary layer between ice and seawater with a Ruttner sampler after a hole to the water surface was drilled.

Process speeds were measured on board within an hour of sampling in a cool laboratory with a temperature of 7°C. Plankton respiration was measured by oxygen optodes in eight simultaneous samples incubated at in situ temperature. For the PROMAC project, all samples were pre-filtered with 1.2 μm filters to specifically measure prokaryotic respiration. Growth of the prokaryotic community was measured by uptake of the DNA base thymidine labeled with tritium incubated at in situ temperature. The presence of prokaryotes was measured by epifluorescence microscopy after labeling with the dye acridine orange. Cell morphology and interactions were also studied via scanning electron microscopy in samples preserved with glutaraldehyde. In the filtered samples, the presence of different prokaryotic taxa was determined by sequencing the 16S RNA gene. In addition, expression of genes from isolated mRNA was measured. For metagenomics and transcriptomics from unfiltered samples, please refer to the OMICS project from the same expedition.

The main projects (“SASIce24h” and “SAS”) aim to contribute knowledge about prokaryotic plankton respiration, growth rate and total biomass to better understand the turnover of carbon in the Arctic Ocean and its regulation. The results from the expedition will also provide a basis for comparison with similar studies in the future to follow climate change. The spatial coverage will increase the understanding of how processes vary in different parts of the ocean. Simultaneous measurements in other parts of the Arctic Ocean by other countries will contribute to a more comprehensive picture. The “PROMAC” project studies the maintenance respiration of prokaryotic plankton and what activities are included there. The temperature sensitivity of plankton respiration is investigated in the “RespirationQ10”-project. Determination of the conversion factor from thymidine uptake to cell growth is carried out in the subproject "TCF". Whether enough of the trace element thymidine was added was investigated in the sub-project ”Isotope dilution”. First results will be published during 2024.

Place, publisher, year
Swedish National Data Service, 2024
National Category
Ecology Oceanography, Hydrology and Water Resources Microbiology
Research subject
biology
Identifiers
urn:nbn:se:umu:diva-220187 (URN)10.5878/6qa4-cn46 (DOI)
Funder
The Kempe Foundations, SMK-1854
Available from: 2024-01-29 Created: 2024-01-29 Last updated: 2024-02-07
Wikner, J. & Vikström, K. (2023). Extensive prokaryotic maintenance respiration in the sea influenced by osmoregulation. Frontiers in Marine Science, 10, Article ID 1070070.
Open this publication in new window or tab >>Extensive prokaryotic maintenance respiration in the sea influenced by osmoregulation
2023 (English)In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 10, article id 1070070Article in journal (Refereed) Published
Abstract [en]

Microbial respiration is the major process consuming oxygen in the biosphere. The relative energy demand from growth of biomass or maintenance activities determines the regulation of respiration with impact on how the development of hypoxia and CO2 emissions is controlled. This coupling is crucial for understanding the life history and associated ecological interactions of microorganisms. However, the knowledge of rate and regulating factors of maintenance respiration in the biosphere is limited. In this study, we demonstrated significant relationships in marine field samples where the prokaryotic specific growth rate predicts cell-specific respiration, in accordance with theory from culture models, over a 10-fold salinity range. This enables the first reported direct estimates of maintenance respiration in nature to show a 6-fold variation between 0.12-0.62 fmol O2 cell-1 d-1, comprising 29-72% of prokaryotic specific respiration. The lowest maintenance respiration occurred at salinity close to physiological osmolarity, suggesting osmoregulation as one of the more energy-consuming maintenance activities. A conservative global estimate of maintenance respiration accounted for 66% of the total prokaryotic respiration in the ocean´s mixed layer. This means that maintenance activities dominate the use of the energy generated by prokaryotic respiration in the sea, where osmoregulation is one significant energy consumer. Consequently, maintenance respiration and its regulation must be included in ecological and biogeochemical models to accurately project and manage the development of hypoxia and CO2 emissions from the ocean.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2023
Keywords
bacterioplankton, CO2, growth, maintenance, oxygen, regulation, respiration, salinity
National Category
Ecology Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:umu:diva-206345 (URN)10.3389/fmars.2023.1070070 (DOI)000955369700001 ()2-s2.0-85150697947 (Scopus ID)
Funder
The Kempe Foundations, SMK-1854Ecosystem dynamics in the Baltic Sea in a changing climate perspective - ECOCHANGE, 224-919-09
Note

Errata: Wikner J and Vikström K (2023) Corrigendum: Extensive prokaryotic maintenance respiration in the sea influenced by osmoregulation. Front. Mar. Sci. 10:1289152. doi: 10.3389/fmars.2023.1289152

Available from: 2023-04-28 Created: 2023-04-28 Last updated: 2024-02-07Bibliographically approved
Verma, A., Amnebrink, D., Pinhassi, J. & Wikner, J. (2023). Prokaryotic maintenance respiration and growth efficiency field patterns reproduced by temperature and nutrient control at mesocosm scale. Environmental Microbiology, 25(3), 721-737
Open this publication in new window or tab >>Prokaryotic maintenance respiration and growth efficiency field patterns reproduced by temperature and nutrient control at mesocosm scale
2023 (English)In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 25, no 3, p. 721-737Article in journal (Refereed) Published
Abstract [en]

The distribution of prokaryotic metabolism between maintenance and growth activities has a profound impact on the transformation of carbon substrates to either biomass or CO2. Knowledge of key factors influencing prokaryotic maintenance respiration is, however, highly limited. This mesocosm study validated the significance of prokaryotic maintenance respiration by mimicking temperature and nutrients within levels representative of winter and summer conditions. A global range of growth efficiencies (0.05–0.57) and specific growth rates (0.06–2.7 d−1) were obtained. The field pattern of cell-specific respiration versus specific growth rate and the global relationship between growth efficiency and growth rate were reproduced. Maintenance respiration accounted for 75% and 15% of prokaryotic respiration corresponding to winter and summer conditions, respectively. Temperature and nutrients showed independent positive effects for all prokaryotic variables except abundance and cell-specific respiration. All treatments resulted in different taxonomic diversity, with specific populations of amplicon sequence variants associated with either maintenance or growth conditions. These results validate a significant relationship between specific growth and respiration rate under productive conditions and show that elevated prokaryotic maintenance respiration can occur under cold and oligotrophic conditions. The experimental design provides a tool for further study of prokaryotic energy metabolism under realistic conditions at the mesocosm scale.

Place, publisher, year, edition, pages
John Wiley & Sons, 2023
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-203123 (URN)10.1111/1462-2920.16300 (DOI)000905378800001 ()36511634 (PubMedID)2-s2.0-85145287538 (Scopus ID)
Available from: 2023-01-16 Created: 2023-01-16 Last updated: 2024-02-07Bibliographically approved
Verma, A. & Amnebrink, D. (2023). Prokaryotic variables from a indoor-mesocosm experiment measured during the winter in the Northern Bothnian Sea.
Open this publication in new window or tab >>Prokaryotic variables from a indoor-mesocosm experiment measured during the winter in the Northern Bothnian Sea
2023 (English)Data set
Abstract [en]

The primary data was collected during the indoor-mesocosm experiment conducted in March 2020 at Umea Marine Science Centre, Umea University, Sweden situated in the Northern Bothnian Sea (63° 34ˈN, 19° 50ˈE). A full factorial experiment was set with temperature and the addition of nutrients as treatment factors with a natural pelagic food web containing all trophic levels except fish. A total of four experimental treatments were set up with three replicates each: C, control (1°C, no additions); N (1°C,+ nutrients); T (10°C, no additions) and TN (10°C, + nutrients). For each treatment, eight different samplings were done in triplicates. The variables in the data include the prokaryotic abundance (PA), growth (PG), respiration (PR), specific prokaryotic respiration (ρ), specific growth rates (µ), growth efficiency (PGE), dissolved organic carbon (DOC), total dissolved phosphorus (TDP) and total dissolved nitrogen (TDN).

National Category
Biological Sciences Ecology Microbiology
Identifiers
urn:nbn:se:umu:diva-220186 (URN)
Funder
The Kempe Foundations, SMK-185
Available from: 2024-01-29 Created: 2024-01-29 Last updated: 2024-02-07
Wikner, J., Vikström, K. & Verma, A. (2023). Regulation of marine plankton respiration: a test of models. Frontiers in Marine Science, 10, Article ID 1134699.
Open this publication in new window or tab >>Regulation of marine plankton respiration: a test of models
2023 (English)In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 10, article id 1134699Article, review/survey (Refereed) Published
Abstract [en]

Plankton respiration is a major process removing oxygen from pelagic environments and constitutes one of the largest oxygen transformations in the sea. Where the O2 supplies due to dissolution, advection and oxygenic photosynthesis are not sufficient, hypoxic, or anoxic waters may result. Coastal waters with limited water exchange are especially prone to have low oxygen levels due to eutrophication and climate change. To support marine environmental management in a period of rapid climate change, we investigated the current knowledge of regulating plankton respiration based on field and experimental studies reported in the literature. Models for regulation of plankton respiration was tested on a three-year field data set. Temperature is the most reported predictor positively influencing plankton respiration (mean r2 = 0.50, n=15). The organic carbon supply driven by primary production has a similar coefficient of determination but fewer reported relationships (mean r2 = 0.52, n=6). Riverine discharges of dissolved organic carbon can override the influence of primary production in estuaries precluding effects of nutrient reductions. The median predictions of respiration regulation produced by current models vary by a factor of 2 from the median of observed values and extreme values varied even more. Predictions by models are therefore still too uncertain for application at regional and local scales. Models with temperature as predictor showed best performance but deviated from measured values in some seasons. The combined dependence of plankton respiration on temperature, phytoplankton production and discharge of riverine organic carbon will probably lead to increased oxygen consumption and reduced oxygen levels with projected climate change. This will be especially pronounced where increased precipitation is expected to enhance riverine discharges of carbon compounds. The biologically mediated transfer of carbon for long-term storage in deeper layers will slow down. Implementation of plankton respiration measurements in long-term ecological monitoring programs at water body and basin scales is advocated, which would enable future multivariate analyses and improvements in model precision across aquatic environments.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2023
Keywords
carbon, climate, effect, oxygen, plankton, regulation, respiration, temperature
National Category
Ecology Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:umu:diva-206939 (URN)10.3389/fmars.2023.1134699 (DOI)000960152600001 ()2-s2.0-85152640439 (Scopus ID)
Funder
Ecosystem dynamics in the Baltic Sea in a changing climate perspective - ECOCHANGE, 224-919- 09The Kempe Foundations, SMK-1854
Available from: 2023-04-28 Created: 2023-04-28 Last updated: 2023-05-02Bibliographically approved
Wikner, J., Ramnefält, R., Simon, K. & de Senerpont Domis, L. N. (2023). Report of the primary data shell status and use for open science primary data collection.
Open this publication in new window or tab >>Report of the primary data shell status and use for open science primary data collection
2023 (English)Report (Other academic)
Abstract [en]

A web-based pilot primary data shell was developed to investigate its potential to support joint archiving of open data by the research community and promote open science. Direct storage of primary data values in a relational data base harmonizes data format, integrates quality assurance routines, and facilitates extraction and re-use of data sets. Combined, this will foster advancement of scientific knowledge and an efficient use of research funding. Based on a questionnaire, project partners’ most prominent concern for implementing joint data archiving was maintaining data integrity and avoidance of miss-use of data. The pilot primary data shell constitutes a web interface where experiments with several treatments and replicates can be entered. Forms for 6 variables of different types have been constructed. 70 variables including import routines still need to be implemented prior to the launch of a fully operational primary data shell. Data integrity is achieved by use of data masks and user authentication. By using both local and central terminals, data administration can comply with national directives and legislation, fostering acceptance by researchers to deliver data. A steering board and scientific advisory group are recommended for administrating an operational data shell on the European scale.

Publisher
p. 34
Series
AQUACOSM-plus ; D4.16
Keywords
data, primary, open, collection, web
National Category
Biological Sciences
Research subject
data science
Identifiers
urn:nbn:se:umu:diva-220180 (URN)
Funder
EU, Horizon 2020, 871081
Note

In Aquacosm-plus Network of Leading Ecosystem Scale Experimental Aquatic Mesocosm Facilities Connecting Rivers, Lakes, Estuaries and Oceans in Europe and Beyond

Available from: 2024-01-29 Created: 2024-01-29 Last updated: 2024-01-29Bibliographically approved
Wikner, J., Larsson, H., Vikström, K., Båmstedt, U., Berger, S. A., Kyle, M. & Nejstgaard, J. (2023). Report on boundary conditions for winter mesocosms.
Open this publication in new window or tab >>Report on boundary conditions for winter mesocosms
Show others...
2023 (English)Report (Other academic)
Abstract [en]

Ongoing climate change is projected to extend the warmer and therefore the biologically productive season, reducing ice cover, ice thickness, and quality, potentially influencing biodiversity, and productivity of aquatic ecosystems. Changed influence of dissolved organic matter is one factor that can contribute to those effects. Winter ecology is little studied, and the advancement of knowledge would benefit from controlled experiments on the mesocosm scale. To investigate the capability of mesocosm experimental infrastructures for winter ecological research, a 5-months long experiment during the sub-arctic winter in 2021/2022 was conducted in Umeå, Sweden. Simultaneously, the performance of an outdoor and indoor mesocosm facility with ice-forming capability at the same site was compared. Boundary conditions for hydrographic, chemical, and biological variables were determined.The facilities were operated successfully over winter and treatments caused similar effects in both systems, despite some differences presented below. Salinity and temperature were similar between the facilities throughout the experiment. Ice was markedly thicker on the sea compared to in the indoor facility. Further the ice inside the outdoor mesocosms, was significantly thicker than on the surrounding natural sea. Light irradiance indoors correlated with the outdoor facility, but light irradiance indoors could not reach the outside values in the lightest months of the experiment (after mid-March). Both dissolved organic carbon and dissolved nitrogen was higher in the outdoor facility, possibly caused by a pump effect increasing organic carbon and nitrogen concentrations. Most other nutrient levels remained similar. Chlorophyll-a was comparable between the facilities, while plankton respiration was twice the rate outdoors compared to indoors. Two substances were used to simulate browning, HuminFeed® (a commercially available leonardite) and soil extract, causing similar treatment effects in both facilities for 75% of measured variables. HuminFeed caused a marked increase in CDOM (coloured dissolved organic matter) and nitrite during spring. Treatment with soil extract resulted in slightly higher phosphorus concentrations.The indoor mesocosm facility was thus comparable to the outdoor facility regarding experimental effects, despite facility differences observed. The organic matter sources HuminFeed and soil extract differ in some experimental effects that need to be considered. These results should provide basic knowledge for improving experimental design in future winter mesocosm studies.

Publisher
p. 36
Series
AQUACOSM-plus ; D8.5
National Category
Ecology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-220182 (URN)
Funder
EU, Horizon 2020, 871081
Note

In Aquacosm-plus Network of Leading Ecosystem Scale Experimental Aquatic Mesocosm Facilities Connecting Rivers, Lakes, Estuaries and Oceans in Europe and Beyond.

Available from: 2024-01-29 Created: 2024-01-29 Last updated: 2024-01-30Bibliographically approved
Vass, M., Eriksson, K., Carlsson-Graner, U., Wikner, J. & Andersson, A. (2022). Co-occurrences enhance our understanding of aquatic fungal metacommunity assembly and reveal potential host–parasite interactions. FEMS Microbiology Ecology, 98(11), Article ID fiac120.
Open this publication in new window or tab >>Co-occurrences enhance our understanding of aquatic fungal metacommunity assembly and reveal potential host–parasite interactions
Show others...
2022 (English)In: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 98, no 11, article id fiac120Article in journal (Refereed) Published
Abstract [en]

Our knowledge of aquatic fungal communities, their assembly, distributions and ecological roles in marine ecosystems is scarce. Hence, we aimed to investigate fungal metacommunities of coastal habitats in a subarctic zone (northern Baltic Sea, Sweden). Using a novel joint species distribution model and network approach, we quantified the importance of biotic associations contributing to the assembly of mycoplankton, further, detected potential biotic interactions between fungi–algae pairs, respectively. Our long-read metabarcoding approach identified 493 fungal taxa, of which a dominant fraction (44.4%) was assigned as early-diverging fungi (i.e. Cryptomycota and Chytridiomycota). Alpha diversity of mycoplankton declined and community compositions changed along inlet–bay–offshore transects. The distributions of most fungi were rather influenced by environmental factors than by spatial drivers, and the influence of biotic associations was pronounced when environmental filtering was weak. We found great number of co-occurrences (120) among the dominant fungal groups, and the 25 associations between fungal and algal OTUs suggested potential host–parasite and/or saprotroph links, supporting a Cryptomycota-based mycoloop pathway. We emphasize that the contribution of biotic associations to mycoplankton assembly are important to consider in future studies as it helps to improve predictions of species distributions in aquatic ecosystems.

Place, publisher, year, edition, pages
Oxford University Press, 2022
Keywords
coastal marine habitats, ecological network, long-read metabarcoding, metacommunity structure, mycoplankton
National Category
Ecology Microbiology
Identifiers
urn:nbn:se:umu:diva-200716 (URN)10.1093/femsec/fiac120 (DOI)000877178200002 ()2-s2.0-85152416670 (Scopus ID)
Funder
Umeå UniversitySwedish Research Council FormasEcosystem dynamics in the Baltic Sea in a changing climate perspective - ECOCHANGESwedish National Infrastructure for Computing (SNIC)Swedish Research Council, 2018–05973
Available from: 2022-11-02 Created: 2022-11-02 Last updated: 2023-04-28Bibliographically approved
Ramnefält, R. & Wikner, J. (2022). Report of centralised data portal launch. European Commission
Open this publication in new window or tab >>Report of centralised data portal launch
2022 (English)Report (Other academic)
Abstract [en]

A pilot version of a web interface primary data shell has been developed. The shell was pre-tested by a selected group of dedicated partners, improved and launched for testing by partners in the whole AQUACOSM-plus community. By a couple of introductory meetings, partners were shown the procedure to enter a mesocosm experiment and add primary data. Partners had the opportunity to test the platform for 2,5 months and give feed-back with suggestions of improvements. Suggestions for improvements were noted from the partners and additional improvements were furthermore identified by the task group itself. No major requirements of changes of the basic structure of the primary data shell were requested. Most suggested improvements for the six prioritized variables are planned to be remedied within the project period. The need of resources to develop a fully operational shell will be presented in the final report from this task.

Place, publisher, year, edition, pages
European Commission, 2022. p. 23
Series
Aquacosm-plus ; D4.9
National Category
Oceanography, Hydrology and Water Resources Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-208736 (URN)
Funder
EU, Horizon 2020, 871081
Available from: 2023-05-30 Created: 2023-05-30 Last updated: 2023-05-31Bibliographically approved
Jürgens, K. & Wikner, J. (2021). [Indirect parameters: Ecosystem] Microbial community and processes. In: Jannica Haldin; Petra Kääriä; H.E. Markus Meier; Jonas Pålsson (Ed.), Climate change in the baltic sea: 2021 fact sheet (pp. 39-39). Helsinki: Helsinki Commission (HELCOM)
Open this publication in new window or tab >>[Indirect parameters: Ecosystem] Microbial community and processes
2021 (English)In: Climate change in the baltic sea: 2021 fact sheet / [ed] Jannica Haldin; Petra Kääriä; H.E. Markus Meier; Jonas Pålsson, Helsinki: Helsinki Commission (HELCOM) , 2021, p. 39-39Chapter in book (Refereed)
Abstract [en]

This overview focuses on bacterioplankton, comprising single-celled prokaryotes, i.e.,small organisms that lack a nucleus (Bacteriaand Archaea), in the water column, consuming organic carbon as an energy and carbonsource. Benthic prokaryotes and protozoa (i.e., unicellular zooplankton and zoobenthos) are also important but not included here. Bacteria are the major transformers of carbon, nitrogen, sulphur, and trace metalcycles in aquatic environments. The supply of organic carbon mainly controls bacterial biomass production. The bacterial community composition changes along the salinity andoxygen gradients of the Baltic Sea. Shifts in, e.g., food sources, temperature, and oxygen concentration result in rapid bacterioplankton community changes, with potential impact also on overall ecosystem functions, such as respiration, carbon consumption, and biomass production.

Place, publisher, year, edition, pages
Helsinki: Helsinki Commission (HELCOM), 2021
Series
Baltic Sea Environment Proceedings, ISSN 0357-2994 ; 180
Keywords
Climate, effects, status, Baltic Sea, weather, meteorologi, hydrography, chemistry, biology, ecosystem
National Category
Ecology Climate Research
Research subject
climate change
Identifiers
urn:nbn:se:umu:diva-192208 (URN)
Available from: 2022-02-04 Created: 2022-02-04 Last updated: 2022-02-07Bibliographically approved
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