| 1. |
- Alegria Zufia, Javier, Ph.D. 1992-, et al.
(författare)
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Growth and mortality rates of picophytoplankton in the Baltic Sea Proper
- 2024
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Ingår i: Marine Ecology Progress Series. - Oldendorf : Inter-Research. - 0171-8630 .- 1616-1599. ; 735, s. 63-76
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Tidskriftsartikel (refereegranskat)abstract
- Picophytoplankton (<2 µm diameter), a diverse group of picocyanobacteria and photosynthetic picoeukaryotes, are significant contributors to primary production. Predatory mortality controls picophytoplankton biomass and thereby energy transfer in the marine food web. The 2 major pathways of picophytoplankton mortality are grazing and viral lysis. Grazing passes carbon directly to higher trophic levels, while lysis products are passed into the viral loop. Picophytoplankton are abundant in the Baltic Sea but little is known about their predatory mortality. Using a modification of the dilution approach, we calculated growth and mortality rates of picophytoplankton and studied the effect of predation on community structure during late August and September. The experiments were conducted coinciding with the peak in picophytoplankton abundance (similar to 10(5) cells ml(-1)) at the Linnaeus Microbial Observatory in the Baltic Sea Proper. The results showed that grazing is an important controller of picocyanobacteria and photosynthetic picoeukaryote populations, while no significant viral lysis effect was detected. Grazing on picocyanobacteria was proportional to growth rates, while grazing on photosynthetic picoeukaryotes exceeded growth. Selective grazing of phylogenetically distinct picocyanobacterial clades had a significant effect on community structure, suggesting that grazing has an impact on the seasonal dynamics of co-occurring clades. Picocyanobacteria had a higher carbon transfer contribution to higher trophic levels than photosynthetic picoeukaryotes at the time of the experiments. The study shows that picophytoplankton are important contributors to carbon cycling in the Baltic Sea microbial food web and should be considered for future ecological models.
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| 2. |
- Laber, Christien P., et al.
(författare)
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Colony-forming and single-cell picocyanobacteria nitrogen acquisition strategies and carbon fixation in the brackish Baltic Sea
- 2024
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Ingår i: Limnology and Oceanography. - Hoboken, NJ : John Wiley & Sons. - 0024-3590 .- 1939-5590.
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Tidskriftsartikel (refereegranskat)abstract
- Picocyanobacteria are widespread and globally significant primary producers. In brackish waters, picocyanobacterial populations are composed of diverse species with both single-cell and colony-forming lifestyles. Compared to their marine counterparts, brackish picocyanobacteria are less well characterized and the focus of research has been weighted toward single-cell picocyanobacteria. Here, we investigate the uptake dynamics of single and colony-forming picocyanobacteria using incubations with dual carbon-13 and inorganic (ammonium and nitrate) or organic (urea and amino acids) nitrogen-15 sources during August and September 2020 in the central Baltic Sea. Phytoplankton community and group-specific uptake rates were obtained using an elemental analyzer isotope ratio mass spectrometer (EA-IRMS) and nano secondary-ion mass spectrometry (NanoSIMS). Picocyanobacteria contributed greater than one third of the ammonium, urea, amino acids, and inorganic carbon community uptake/fixation in September but < 10% in August when phytoplankton biomass was higher. Overall, single-cell ammonium and urea uptake rates were significantly higher for single-celled compared to colonial picocyanobacteria. In a 6-yr offshore central Baltic Sea time series (2015-2020), summer abundances of colonial picocyanobacteria reached up to 10(5) cells mL(-1) and represented > 5% of the average phytoplankton biomass, suggesting that they are periodically important for the ecosystem. Colonial strain identification was not distinguishable using 16S rRNA gene amplicon data, highlighting a need for refined tools for identification of colonial forms. This study shows the significance of single-celled brackish picocyanobacteria to nutrient cycling and the importance of considering uptake and lifestyle strategies when assessing the role of picocyanobacteria in aquatic ecosystems.
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| 3. |
- Lindehoff, Elin, et al.
(författare)
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Biomass performance and stability of 5-year outdoor microalgal cultivation for CO2 removal from cement flue gas
- 2024
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Ingår i: Bioresource Technology Reports. - Oxford : Elsevier. - 2589-014X. ; 25, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- The study evaluated removal of industrial CO2 from cement flue gas using algal cultivation. Local polycultures were grown in an up-scaled outdoor photobioreactor over 5 years in northern Europe. Algal biomass was harvested 2–3 times per week and the closed panel system was re-filled with seawater amended with nutrients. Flue gas was fed to the photobioreactor circulatory system in one direction or re-circulated. Removal efficiency of CO2 averaged 9 % in non-recirculation and 17 % in re-circulation modes and reached 20–60 % under best cultivation conditions. Recovery of carbon into algal biomass reached up to 10 g m2d−1 in non-recirculation mode. Biomass performance was explained by circulation mode and shift of polyculture traits. Stability of biomass quality was shown over seasons, with higher relative content of protein in autumn. Toxic elements in biomass were below legal thresholds for upcycling. The study shows feasibility of algal solutions for conversion of waste, applied in temperate climate. © 2023 The Authors
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| 4. |
- Nham, Quyen, et al.
(författare)
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Microalgal production and nutrient recovery under mixotrophic mode using cheese whey permeate
- 2024
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Ingår i: Bioresource Technology. - Amsterdam : Elsevier. - 0960-8524 .- 1873-2976. ; 410, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Mixotrophic microalgal solutions are efficient nutrient recovery methods, with potential to prolong the cultivation seasons in temperate climates. To improve operation sustainability, the study used landfill leachate for nitrogen source and whey permeate for phosphorus and organic carbon. A non-axenic polyculture, dominated by green algae, was cultivated in mixotrophic mode on glucose or whey permeate compared to a photoautotrophic control in outdoor pilot-scaled raceway ponds during Nordic spring and autumn. The whey permeate treatment had the highest algal growth rate and productivity (0.48 d−1, 183.8 mg L−1 d−1), nutrient removal (total nitrogen: 21.71 mg L−1 d−1, total phosphorus: 3.05 mg L−1 d−1) and recovery rate (carbon: 85.19 mg L−1 d−1, nitrogen: 17.01 mg L−1 d−1, phosphorus: 2.58 mg L−1 d−1). When grown in whey permeate, algal cultures demonstrated consistent productivity and biochemical composition in high (spring) and low light conditions (autumn), suggesting the feasibility of year-round production in Nordic conditions. © 2024 The Authors
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| 5. |
- Pérez Blanco, Eva, et al.
(författare)
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Population dynamics of dominant dinoflagellate species in the North Sea : in situ growth rates, photosynthetic potential, and losses due to parasitism
- 2024
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Ingår i: Harmful Algae. - : Elsevier. - 1568-9883 .- 1878-1470. ; 134
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Tidskriftsartikel (refereegranskat)abstract
- In the North Sea, Tripos and Dinophysis are commonly occurring mixotrophic planktonic dinoflagellate genera. In order to understand their bloom dynamics, an occurring bloom dominated by T. furca and D. norvegica was followed for several days. High cell abundances of these species were located to estimate: in situ growth rates from cell cycle analyses, depth distributions, growth rates sustained by photosynthesis, and parasite infection prevalence in all T. furca, T. fusus, D. norvegica and D. acuminata. Cell abundances were over 10000 cells L−1 for T. furca and up to 18000 cells L−1 for D. norvegica. Cells accumulated between 15-25 m depth and presented low specific in situ growth rates of 0.04-0.15 d−1 for T. furca and 0.02-0.16 d−1 for D. norvegica. Photosynthesis could sustain growth rates of 0.01-0.18 d−1 for T. furca and 0.02 to 0.14 d−1 for D. norvegica, suggesting that these species were relying mainly on photosynthesis. Parasite infections where generally low, with occasional high prevalence in D. norvegica (by Parvilucifera sp.) and T. fusus (by Amoebophrya sp.), while both parasites showed comparable prevalence in D. acuminata, which could offset in situ growth rates by parasite-induced host mortality. The restructuring effect of parasites on dinoflagellate blooms is often overlooked and this study elucidates their effect to cell abundances and their growth at the final stages of a bloom.
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| 6. |
- Weissenbach, Julia, et al.
(författare)
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Ploidy levels in diverse picocyanobacteria from the Baltic Sea
- 2024
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Ingår i: Environmental Microbiology Reports. - : John Wiley & Sons. - 1758-2229. ; 16:5
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Tidskriftsartikel (refereegranskat)abstract
- In nature, the number of genome or chromosome copies within cells (ploidy) can vary between species and environmental conditions, potentially influencing how organisms adapt to changing environments. Although ploidy levels cannot be easily determined by standard genome sequencing, understanding ploidy is crucial for the quantitative interpretation of molecular data. Cyanobacteria are known to contain haploid, oligoploid, and polyploid species. The smallest cyanobacteria, picocyanobacteria (less than 2 μm in diameter), have a widespread distribution ranging from marine to freshwater environments, contributing significantly to global primary production. In this study, we determined the ploidy level of genetically and physiologically diverse brackish picocyanobacteria isolated from the Baltic Sea using a qPCR assay targeting the rbcL gene. The strains contained one to four genome copies per cell. The ploidy level was not linked with phylogeny based on the identity of the 16S rRNA gene. The variation of ploidy among the brackish strains was lower compared to what has been reported for freshwater strains and was more similar to what has been reported for marine strains. The potential ecological advantage of polyploidy among picocyanobacteria has yet to be described. Our study highlights the importance of considering ploidy to interpret the abundance and adaptation of brackish picocyanobacteria.
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