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- Broman, Elias, 1985-, et al.
(författare)
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Biotic interactions between benthic infauna and aerobic methanotrophs mediate methane fluxes from coastal sediments
- 2024
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Ingår i: The ISME journal. - 1751-7370 .- 1751-7362. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- Coastal ecosystems dominate oceanic methane (CH4) emissions. However, there is limited knowledge about how biotic interactions between infauna and aerobic methanotrophs (i.e. CH4 oxidizing bacteria) drive the spatial-temporal dynamics of these emissions. Here, we investigated the role of meio- and macrofauna in mediating CH4 sediment-water fluxes and aerobic methanotrophic activity that can oxidize significant portions of CH4. We show that macrofauna increases CH4 fluxes by enhancing vertical solute transport through bioturbation, but this effect is somewhat offset by high meiofauna abundance. The increase in CH4 flux reduces CH4 pore-water availability, resulting in lower abundance and activity of aerobic methanotrophs, an effect that counterbalances the potential stimulation of these bacteria by higher oxygen flux to the sediment via bioturbation. These findings indicate that a larger than previously thought portion of CH4 emissions from coastal ecosystems is due to faunal activity and multiple complex interactions with methanotrophs.
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| 2. |
- Maciute, Adele, et al.
(författare)
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A microsensor-based method for measuring respiration of individual nematodes
- 2021
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Ingår i: Methods in Ecology and Evolution. - 2041-210X. ; 12:10, s. 1841-1847
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Tidskriftsartikel (refereegranskat)abstract
- Meiofauna (invertebrates that pass through a 1-mm mesh sieve, but are retained on a 40-µm mesh) represent the most abundant and diverse animal group on Earth, but empirical evidence of their role in benthic respiration, production and carbon cycling across ecosystems is not well documented. Moreover, how meiofauna respond to changing oxygen conditions is poorly understood. We further developed an incubation system, in which oxygen and temperature conditions are easily controlled and single meiofaunal nematode respiration is resolved in glass capillary tubes, using Clark-type oxygen microsensor. We performed the respiration measurements after exposing nematodes to different ambient oxygen concentrations, which resulted in 3–60µM O2 during hypoxic and 80–210µM O2 during oxic incubations in close proximity to the respective nematodes. Individual nematode respiration rates ranged from 0.02 to 1.30nmol O2 ind.−1day−1 and were 27% lower during hypoxic than oxic incubations. Rates derived from established allometric relations were on average fourfold higher than our direct measurements. The presented method is suitable for single nematode respiration measurements and can be adapted to a wide range of experimental conditions. Therefore, it can be used to assess meiofauna contribution to ecosystem processes and investigate species-specific responses to changing environmental conditions, for example, oxygen stress, increasing water temperature.
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| 5. |
- Polovodova Asteman, Irina, 1980, et al.
(författare)
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Spreading of an alien benthic foraminifer in the North Sea: a reason to be worried?
- 2023
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Ingår i: International Congress FORAMS2023, Perugia, Italy, 25-30th June. - Perugia, Italy : Micropress Europe & The Grzybowski Foundation.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the Skagerrak-Kattegat (eastern North Sea), the alien benthic foraminifer Nonionella sp. T1 (previously referred to as “Nonionella stella”) was reported for the first time in 2011 and 2012 in the Swedish and southern Norwegian fjords, respectively. Based on dated sediment cores its first occurrence can be traced back to the 1980s in the Gullmar Fjord, to the 2000s in the Öresund and to 2010 in the Oslofjord. Since then, Nonionella sp T1 has spread all over the Kattegat and coastal Skagerrak, according to sampling campaigns performed between 2016 and 2022. The species is now highly abundant in the entire Kattegat, including the Öresund, as well as in fjord mouths of the seasonally hypoxic Gullmar Fjord, the oxic Hakefjord and the long-term polluted Idefjord as demonstrated by molecular and morphospecies data. At the same time, Nonionella sp T1 is rare to absent in the Baltic Sea, Skagerrak deep basin and in deep fjords of western and northern Norway. This study shows some preliminary results on the species’ present distribution in the study area and raises questions about the driving factors and potential effects on the local biodiversity.
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| 6. |
- Stief, Peter, et al.
(författare)
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Intracellular nitrate storage by diatoms can be an important nitrogen pool in freshwater and marine ecosystems
- 2022
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Ingår i: Communications Earth and Environment. - : Springer Science and Business Media LLC. - 2662-4435. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Identifying and quantifying nitrogen pools is essential for understanding the nitrogen cycle in aquatic ecosystems. The ubiquitous diatoms represent an overlooked nitrate pool as they can accumulate nitrate intracellularly and utilize it for nitrogen assimilation, dissipation of excess photosynthetic energy, and Dissimilatory Nitrate Reduction to Ammonium (DNRA). Here, we document the global co-occurrence of diatoms and intracellular nitrate in phototrophic microbial communities in freshwater (n = 69), coastal (n = 44), and open marine (n = 4) habitats. Diatom abundance and total intracellular nitrate contents in water columns, sediments, microbial mats, and epilithic biofilms were highly significantly correlated. In contrast, diatom community composition had only a marginal influence on total intracellular nitrate contents. Nitrate concentrations inside diatom cells exceeded ambient nitrate concentrations ∼100–4000-fold. The collective intracellular nitrate pool of the diatom community accounted for <1% of total nitrate in pelagic habitats and 65–95% in benthic habitats. Accordingly, nitrate-storing diatoms are emerging as significant contributors to benthic nitrogen cycling, in particular through Dissimilatory Nitrate Reduction to Ammonium activity under anoxic conditions.
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