Periodic Reporting for period 1 - FlocDOM (A broad ecological approach to study the biological uptake of dissolved organic matter (DOM) and DOM-flocculates in the rapidly changing Arctic coastal ecosystems)
Berichtszeitraum: 2019-02-01 bis 2021-01-31
The Arctic Ocean receives a vast amount of organic carbon via runoff from surrounding glaciers and thawing permafrost soils. This dissolved organic matter (DOM) comprises one of the world’s largest active carbon pools, i.e. can be respired to CO2 by heterotrophic organisms. Yet our understanding of how well this terrestrial carbon is degraded in the marine environment is poor. As recent climate warming accelerates the input of carbon to the coastal Ocean it becomes more urgent to study this matter as it may play a major part in determining whether the Arctic Ocean becomes a sink or a source of CO2 in the future. In the saltwater-freshwater interface of coastal environments, the salinity change causes the charge of the DOM molecules to change causing about 10-20% of this carbon pool to aggregate/flocculate into larger particles. Bacteria are the main degraders of DOM, however, with flocculation, a great proportion of the carbon becomes available to larger heterotrophic organisms, such as pelagic protists and benthic filter feeders. Via these flocs the carbon enters the food web at a higher level and escapes the microbial loop. This path is however rarely considered. The overall aim of this project is to improve the knowledge on the response of heterotrophic organisms to terrestrial organic carbon supply (both from glaciers and soils) with focus on the coastal ecosystems of Greenland. I will track the degradation paths of both DOM and flocculated DOM using a combination of controlled laboratory studies and field studies using radioisotope tracers. The project ‘FlocDOM’ proposes a much-needed effort for a holistic ecological approach to assess the effects of increased runoff in the Arctic and to quantify for the first time the salt-induced aggregation, subsequent mineralization and burial of various terrestrial DOM pools in the Arctic.
The first major activity of the project was my secondment at SAMS in Scotland in March 2019. Here I experimentally created flocculation of DOM and tested whether pelagic protist could feed on the flocs by measuring their net growth. The expertise of my host Professor Mike Zubkov helped be gain important insights on the subject, that have been extremely useful to the following research. Also, it was a fantastic opportunity to work with a sorting flow cytometer and the protists cultures available at the host institution.
The second major activity was establishing a method for quantifying flocculation of DOM. The protocol was established together with Dr. Rachel Sipler, who leads a research group at Memorial University and is the Canada Research Chair in Ocean Biogeochemistry. The technique enables separation of newly formed flocculates and following analysis of both the particulate and the dissolved phase. I coordinated and led cross-Arctic efforts to perform these experiments at 10 different sites in the summer of 2019: multiple sites in Arctic Canada (by Dr. Rachel Sipler), Svalbard (by Dr. Oliver Müller), Western Greenland (Dr. Friederike Gründger), Eastern Greenland (Maria Lund Paulsen) and Arctic Russia (Maria Lund Paulsen).
The third major activity took place in August 2019 when I participated in a very successful field campaign to NE Greenland Young Sound. There I collaborated closely with 4 other young scientists our common aim was to determine the fate of allochthonous material and organic matter (OM) coming from glacial melt water and rivers in Young Sound and its effects on biological communities.
Our specific objectives were:
1. Quantity and quality (bioavailability) of OM and allochthonous matter coming from freshwater sources (Tyroler and Zackenberg river)
2. Quantify the transformation of dissolved to particulate OM (i.e. flocculation) when the freshwater enters the fjord
3. Sediment traps: the sedimentation of autochthonous vs. allochthonous matter along a gradient from the river and its bioavailability
4. Sediment cores: Remineralization and burial of allochthonous material in sediments along a gradient from the river
5. Study the effects of allochthonous material on biological processes (i.e. copepod mortality and bacterial growth/diversity)
The fourth major activity was to complete all laboratory analysis of all samples collected in Greenland and the cross-arctic flocculation experiments. I spend some effort getting experience with the IR-MS (isotopic-ratio mass spec) as this was a new technique for me and I had to run it independently for several months. I learned to use a CytoFlex flow cytometer, on which I ran samples. Further, I developed extensive experience with DNA extraction techniques. I much appreciate expanding my skills in the laboratory.
Now all samples are measured I will spend my remaining time as a MSCA-postdoc on writing papers and outreach activities. Further I am participating in a postdoc training course in Bayesian Statistics.
Dissemination activities of my project has so far included:
1) A scientific talk at Arctic Science Summit Week 2019 in Arkhangelsk.
2) A seminar at the seminar club of The Technical University of Denmark, Section of Aquatic Science.
3) I have published a book chapter: Doi: 10.1002/9781119300762.wsts0199
4) I have published popular science articles:
https://iasc.info/news/iasc-news/502-glacial-runoff-and-coastal-flocculation-of-terrestrial-matter-by-maria-paulsen-2019-marine-working-group-fellow(öffnet in neuem Fenster)
5) I have co-authored a scientific publication on the theme within my WP4:Societal importance of Antarctic negative feedbacks on climate change: blue carbon gains from sea ice, ice shelf and glacier losses.
6) I have supervised 2 PhD students and assisted grad-school studens with assignments on Arctic coastal ecology
The second major activity was establishing a method for quantifying flocculation of DOM. The protocol was established together with Dr. Rachel Sipler, who leads a research group at Memorial University and is the Canada Research Chair in Ocean Biogeochemistry. The technique enables separation of newly formed flocculates and following analysis of both the particulate and the dissolved phase. I coordinated and led cross-Arctic efforts to perform these experiments at 10 different sites in the summer of 2019: multiple sites in Arctic Canada (by Dr. Rachel Sipler), Svalbard (by Dr. Oliver Müller), Western Greenland (Dr. Friederike Gründger), Eastern Greenland (Maria Lund Paulsen) and Arctic Russia (Maria Lund Paulsen).
The third major activity took place in August 2019 when I participated in a very successful field campaign to NE Greenland Young Sound. There I collaborated closely with 4 other young scientists our common aim was to determine the fate of allochthonous material and organic matter (OM) coming from glacial melt water and rivers in Young Sound and its effects on biological communities.
Our specific objectives were:
1. Quantity and quality (bioavailability) of OM and allochthonous matter coming from freshwater sources (Tyroler and Zackenberg river)
2. Quantify the transformation of dissolved to particulate OM (i.e. flocculation) when the freshwater enters the fjord
3. Sediment traps: the sedimentation of autochthonous vs. allochthonous matter along a gradient from the river and its bioavailability
4. Sediment cores: Remineralization and burial of allochthonous material in sediments along a gradient from the river
5. Study the effects of allochthonous material on biological processes (i.e. copepod mortality and bacterial growth/diversity)
The fourth major activity was to complete all laboratory analysis of all samples collected in Greenland and the cross-arctic flocculation experiments. I spend some effort getting experience with the IR-MS (isotopic-ratio mass spec) as this was a new technique for me and I had to run it independently for several months. I learned to use a CytoFlex flow cytometer, on which I ran samples. Further, I developed extensive experience with DNA extraction techniques. I much appreciate expanding my skills in the laboratory.
Now all samples are measured I will spend my remaining time as a MSCA-postdoc on writing papers and outreach activities. Further I am participating in a postdoc training course in Bayesian Statistics.
Dissemination activities of my project has so far included:
1) A scientific talk at Arctic Science Summit Week 2019 in Arkhangelsk.
2) A seminar at the seminar club of The Technical University of Denmark, Section of Aquatic Science.
3) I have published a book chapter: Doi: 10.1002/9781119300762.wsts0199
4) I have published popular science articles:
https://iasc.info/news/iasc-news/502-glacial-runoff-and-coastal-flocculation-of-terrestrial-matter-by-maria-paulsen-2019-marine-working-group-fellow(öffnet in neuem Fenster)
5) I have co-authored a scientific publication on the theme within my WP4:Societal importance of Antarctic negative feedbacks on climate change: blue carbon gains from sea ice, ice shelf and glacier losses.
6) I have supervised 2 PhD students and assisted grad-school studens with assignments on Arctic coastal ecology
Results from this project so far, support the conclusions that flocculation is a mopst significant process in coastal systems and that the process is responsible for a massive carbon transport to the sediment. Results also indicate that the inorganic particles (glacial flour) acts as a catalyst in this process. I have successfully applied for an ASSEMBLE Plus grant to study these interactions further (activities will take place summer 2021 if possible, considering corona restrictions). Long-term incubation studies illustrate the effects of flocculation on the pelagic food web of Arctic fjords. The project has wider societal impacts as it uncovers new insights into the future of the coastal arctic food webs as well as improves our understanding of the global carbon cycle.
The main expected result of the project until the end is the publication of 5 scientific articles in open access journals:
Title: Carbon bioavailability in flocculated vs dissolved Arctic organic matter:
Paulsen, Holding, Laufer-Meiser, Wiedmann, Winding, Sejr, Sipler
Journal: Environ. Sci. Technol.
Title: Riverine input and flocculation potential in five contrasting Arctic rivers
Authors: Paulsen, Holding, Laufer-Meiser, Wiedmann, Winding, Sejr, Sipler
Journal: Environ. Sci. Technol.
Title: Bacterial response to permafrost derived organic matter in contrasting water masses, NW Svalbard
Authors: Paulsen, Stedmon, Müller
Journal: Frontiers or Polar biology
Title: The biogeochemical impact of mineral particle runoff in the Baltic Sea
Authors: Paulsen, Asmala
Journal: Biogeoscience
Further I expect several co-authorships in near future.
The main expected result of the project until the end is the publication of 5 scientific articles in open access journals:
Title: Carbon bioavailability in flocculated vs dissolved Arctic organic matter:
Paulsen, Holding, Laufer-Meiser, Wiedmann, Winding, Sejr, Sipler
Journal: Environ. Sci. Technol.
Title: Riverine input and flocculation potential in five contrasting Arctic rivers
Authors: Paulsen, Holding, Laufer-Meiser, Wiedmann, Winding, Sejr, Sipler
Journal: Environ. Sci. Technol.
Title: Bacterial response to permafrost derived organic matter in contrasting water masses, NW Svalbard
Authors: Paulsen, Stedmon, Müller
Journal: Frontiers or Polar biology
Title: The biogeochemical impact of mineral particle runoff in the Baltic Sea
Authors: Paulsen, Asmala
Journal: Biogeoscience
Further I expect several co-authorships in near future.