| 1. |
- Costello, David M., et al.
(författare)
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Global patterns and controls of nutrient immobilization on decomposing cellulose in riverine ecosystems
- 2022
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Ingår i: Global Biogeochemical Cycles. - : John Wiley & Sons. - 0886-6236 .- 1944-9224. ; 36:3
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Tidskriftsartikel (refereegranskat)abstract
- Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature. Collectively, we demonstrated that exogenous nutrient supply and immobilization are critical control points for decomposition of organic matter.
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| 2. |
- Maasri, Alain, et al.
(författare)
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A global agenda for advancing freshwater biodiversity research
- 2022
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 25:2, s. 255-263
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Tidskriftsartikel (refereegranskat)abstract
- Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation.
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| 3. |
- Tiegs, Scott D., et al.
(författare)
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Global patterns and drivers of ecosystem functioning in rivers and riparian zones
- 2019
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Ingår i: Science Advances. - Washington : American Association of Advancement in Science. - 2375-2548. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth's biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented "next-generation biomonitoring" by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.
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| 4. |
- Arandia-Gorostidi, Nestor, et al.
(författare)
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Efficient carbon and nitrogen transfer from marine diatom aggregates to colonizing bacterial groups
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial degradation of sinking diatom aggregates is key for the availability of organic matter in the deep-ocean. Yet, little is known about the impact of aggregate colonization by different bacterial taxa on organic carbon and nutrient cycling within aggregates. Here, we tracked the carbon (C) and nitrogen (N) transfer from the diatom Leptocylindrus danicus to different environmental bacterial groups using a combination of C-13 and N-15 isotope incubation (incubated for 72 h), CARD-FISH and nanoSIMS single-cell analysis. Pseudoalteromonas bacterial group was the first colonizing diatom-aggregates, succeeded by the Alteromonas group. Within aggregates, diatom-attached bacteria were considerably more enriched in C-13 and N-15 than non-attached bacteria. Isotopic mass balance budget indicates that both groups showed comparable levels of diatom C in their biomass, accounting for 19 +/- 7% and 15 +/- 11%, respectively. In contrast to C, bacteria of the Alteromonas groups showed significantly higher levels of N derived from diatoms (77 +/- 28%) than Pseudoalteromonas (47 +/- 17%), suggesting a competitive advantage for Alteromonas in the N-limiting environments of the deep-sea. Our results imply that bacterial succession within diatom aggregates may largely impact taxa-specific C and N uptake, which may have important consequences for the quantity and quality of organic matter exported to the deep ocean.
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