| 1. |
- Bunse, Carina, et al.
(author)
-
High Frequency Multi-Year Variability in Baltic Sea Microbial Plankton Stocks and Activities
- 2019
-
In: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 9
-
Journal article (peer-reviewed)abstract
- Marine bacterioplankton are essential in global nutrient cycling and organic matter turnover. Time-series analyses, often at monthly sampling frequencies, have established the paramount role of abiotic and biotic variables in structuring bacterioplankton communities and productivities. However, fine-scale seasonal microbial activities, and underlying biological principles, are not fully understood. We report results from four consecutive years of high-frequency time-series sampling in the Baltic Proper. Pronounced temporal dynamics in most investigated microbial variables were observed, including bacterial heterotrophic production, plankton biomass, extracellular enzyme activities, substrate uptake rate constants of glucose, pyruvate, acetate, amino acids, and leucine, as well as nutrient limitation bioassays. Spring blooms consisting of diatoms and dinoflagellates were followed by elevated bacterial heterotrophic production and abundances. During summer, bacterial productivity estimates increased even further, coinciding with an initial cyanobacterial bloom in early July. However, bacterial abundances only increased following a second cyanobacterial bloom, peaking in August. Uptake rate constants for the different measured carbon compounds varied seasonally and inter-annually and were highly correlated to bacterial productivity estimates, temperature, and cyanobacterial abundances. Further, we detected nutrient limitation in response to environmental conditions in a multitude of microbial variables, such as elevated productivities in nutrient bioassays, changes in enzymatic activities, or substrate preferences. Variations among biotic variables often occurred on time scales of days to a few weeks, yet often spanning several sampling occasions. Such dynamics might not have been captured by sampling at monthly intervals, as compared to more predictable transitions in abiotic variables such as temperature or nutrient concentrations. Our study indicates that high resolution analyses of microbial biomass and productivity parameters can help out in the development of biogeochemical and food web models disentangling the microbial black box.
|
|
| 2. |
- Ejsmond, M. J., et al.
(author)
-
Modeling vitamin B1 transfer to consumers in the aquatic food web
- 2019
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
-
Journal article (peer-reviewed)abstract
- Vitamin B-1 is an essential exogenous micronutrient for animals. Mass death and reproductive failure in top aquatic consumers caused by vitamin B-1 deficiency is an emerging conservation issue in Northern hemisphere aquatic ecosystems. We present for the first time a model that identifies conditions responsible for the constrained flow of vitamin B-1 from unicellular organisms to planktivorous fishes. The flow of vitamin B-1 through the food web is constrained under anthropogenic pressures of increased nutrient input and, driven by climatic change, increased light attenuation by dissolved substances transported to marine coastal systems. Fishing pressure on piscivorous fish, through increased abundance of planktivorous fish that overexploit mesozooplankton, may further constrain vitamin B-1 flow from producers to consumers. We also found that key ecological contributors to the constrained flow of vitamin B-1 are a low mesozooplankton biomass, picoalgae prevailing among primary producers and low fluctuations of population numbers of planktonic organisms.
|
|
| 3. |
- Fridolfsson, Emil, et al.
(author)
-
Förstudie kring hållbar vattenförsörjning i södra Sverige
- 2021
-
Reports (pop. science, debate, etc.)abstract
- Dricksvatten är vårt viktigaste livsmedel men detta rena vatten används även för bevattningsändamål, i vårt avloppssystem och inom industrin. Våra samlade vattenresurser ger dessutom ekosystemtjänster i form av fiske, rekreationsvärde m.m. (Bergek m. fl., 2017). Trots att Sverige är ett mycket vattenrikt land sett ur ett internationellt perspektiv har vattenbrist uppstått i flera delar av landet under senare år. Vidare förväntas pågående och kommande klimatförändringar, befolkningstillväxt och urbanisering påverka vattenkvaliteten negativt samt öka konkurrensen om vatten ytterligare (IPCC, 2014; SMHI, 2020a). Med ökad konkurrens uppstår dessutom målkonflikter mellan olika viktiga samhällsfunktioner. Det finns således ett stort behov av tvärsektoriell forskning samt policyutveckling för att säkerställa en hållbar framtida vattenförsörjning.Denna rapport syftar till att sammanställa kunskapsläget vad gäller förutsättningarna för en hållbar vattenförsörjning i Kronobergs län. Först beskrivs tillgång och uttag av dricksvatten i Kronoberg i jämförelse med Kalmar och Skåne län samt förutsättningarna för god framtida vattenkvalitet med Bolmen som exempel. Därefter fokuserar vi på de målkonflikter som kan förväntas uppstå kring dricksvattnet och diskuterar slutligen de kunskapsluckor samt det behov av tvärsektoriell forskning och samhällsutveckling som behövs för en hållbar vattenförsörjning.
|
|
| 4. |
- Fridolfsson, Emil, et al.
(author)
-
Limited effects of macro-nutrient ratios on thiamin content and transfer in phytoplankton and copepods
- 2023
-
In: Journal of Plankton Research. - : Oxford University Press. - 0142-7873 .- 1464-3774. ; 45:2, s. 360-371
-
Journal article (peer-reviewed)abstract
- Vitamin B-1 (thiamin) is primarily produced by bacteria, phytoplankton and fungi in aquatic food webs and transferred to higher trophic levels by ingestion. However, much remains unknown regarding the dynamics this water-soluble, essential micronutrient; e.g. how it relates to macronutrients (carbon, nitrogen and phosphorous). Nutrient limitation has been found to be related to periods of thiamin deficiency as well as in models. Hence, thiamin transfer to copepods from three phytoplankton species from different taxa was investigated, along with the effect of various nutrient regimes on thiamin content. Nutrient levels did not affect thiamin content of phytoplankton nor the transfer to copepods. Instead, phytoplankton displayed species-specific thiamin and macronutrient contents and whilst a higher thiamin content in the prey lead to higher levels in copepods, the transfer was lower for Skeletonema compared to Dunaliella and Rhodomonas. In all, thiamin transfer to copepods is not only dependent on thiamin content of the prey, but also the edibility and/or digestibility is of importance. Thiamin is essential for all organisms, and this study offers insights into the limited effect of macronutrients on the dynamics and transfer of thiamin in the aquatic food webs.
|
|
| 5. |
- Fridolfsson, Emil, et al.
(author)
-
Multiyear analysis uncovers coordinated seasonality in stocks and composition of the planktonic food web in the Baltic Sea proper
- 2023
-
In: Scientific Reports. - London : Springer Nature. - 2045-2322. ; 13:1
-
Journal article (peer-reviewed)abstract
- The planktonic realm from bacteria to zooplankton provides the baseline for pelagic aquatic food webs. However, multiple trophic levels are seldomly included in time series studies, hampering a holistic understanding of the influence of seasonal dynamics and species interactions on food web structure and biogeochemical cycles. Here, we investigated plankton community composition, focusing on bacterio-, phyto- and large mesozooplankton, and how biotic and abiotic factors correlate at the Linnaeus Microbial Observatory (LMO) station in the Baltic Sea from 2011 to 2018. Plankton communities structures showed pronounced dynamic shifts with recurring patterns. Summarizing the parts of the planktonic microbial food web studied here to total carbon, a picture emerges with phytoplankton consistently contributing > 39% while bacterio- and large mesozooplankton contributed ~ 30% and ~ 7%, respectively, during summer. Cyanophyceae, Actinobacteria, Bacteroidetes, and Proteobacteria were important groups among the prokaryotes. Importantly, Dinophyceae, and not Bacillariophyceae, dominated the autotrophic spring bloom whereas Litostomatea (ciliates) and Appendicularia contributed significantly to the consumer entities together with the more traditionally observed mesozooplankton, Copepoda and Cladocera. Our findings of seasonality in both plankton composition and carbon stocks emphasize the importance of time series analyses of food web structure for characterizing the regulation of biogeochemical cycles and appropriately constraining ecosystem models.
|
|
| 6. |
- Fridolfsson, Emil, et al.
(author)
-
Seasonal variation and species-specific concentrations of the essential vitamin B₁ (thiamin) in zooplankton and seston
- 2019
-
In: Marine Biology. - New York, NY : Springer. - 0025-3162 .- 1432-1793. ; 166:6, s. 1-13
-
Journal article (peer-reviewed)abstract
- Thiamin (vitamin B1) is mainly produced by bacteria and phytoplankton and then transferred to zooplankton and higher trophic levels but knowledge on the dynamics of these processes in aquatic ecosystems is lacking. Hence, the seasonal variation in thiamin content was assessed in field samples of copepods and in pico-, nano- and micro-plankton of two size classes (0.7–3 µm and > 3 µm) collected monthly in the Baltic Sea during 3 years and in the Skagerrak during 1 year. Copepods exhibited species-specific concentrations of thiamin and Acartia sp. had the highest carbon-specific thiamin content, at both locations. Even members of the same genus, but from different systems contained different levels of thiamin, with higher thiamin content per specimen in copepods from the Skagerrak compared to congeners from the Baltic Sea. Furthermore, our results show that the small plankton (0.7–3 µm) had a higher carbon-specific thiamin content compared to the large (> 3 µm). Additionally, there was a large seasonal variation and thiamin content was highly correlated comparing the two size fractions. Finally, there was an overall positive correlation between thiamin content in copepods and plankton. However, for periods of high thiamin content in the two size fractions, this correlation was negative. This suggests a decoupling between thiamin availability in pico-, nano- and micro-plankton and zooplankton in the Baltic Sea. Knowledge about concentrations of this essential micronutrient in the aquatic food web is limited and this study constitutes a foundation for further understanding the dynamics of thiamin in aquatic environments.
|
|
| 7. |
- Fridolfsson, Emil, et al.
(author)
-
Species-specific content of thiamin (vitamin B1) in phytoplankton and the transfer to copepods
- 2020
-
In: Journal of Plankton Research. - : Oxford University Press. - 0142-7873 .- 1464-3774. ; 42:3, s. 274-285
-
Journal article (peer-reviewed)abstract
- Thiamin (vitamin B1) is primarily produced by bacteria and phytoplankton in aquatic food webs and transferred by ingestion to higher trophic levels. However, much remains unknown regarding production, content and transfer of this water-soluble, essential micronutrient. Hence, the thiamin content of six phytoplankton species from different taxa was investigated, along with the effect of thiamin amendment on thiamin content. Furthermore, thiamin transfer to copepods was estimated in feeding experiments. Prey type, not phytoplankton thiamin content per se, was the most important factor for the transfer of thiamin, as it was lowest from filamentous Cyanophyceae and highest from more easily ingested prey like Dunaliella tertiolecta and Rhodomonas salina. Cyanophyceae had the highest thiamin content of the investigated species, eightfold higher than the lowest. Phytoplankton varied in thiamin content related to the supply of thiamin, where thiamin addition enabled higher thiamin content in some species, while copepod thiamin content was less variable. In all, thiamin transfer is not only dependent on the prey thiamin content, but also the edibility and/or digestibility is of importance. Thiamin is essential for all organisms, and this study constitutes an important building block to understanding the dynamics and transfer of thiamin in the aquatic food web.
|
|
| 8. |
- Fridolfsson, Emil, et al.
(author)
-
Thiamin (vitamin B1) content in phytoplankton and zooplankton in the presence of filamentous cyanobacteria
- 2018
-
In: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 63:6, s. 2423-2435
-
Journal article (peer-reviewed)abstract
- Top predators in several aquatic food webs regularly display elevated reproductive failure, caused by thiamin(vitamin B1)deficiency. The reasons for these low-thiamin levels are not understood and information about the transfer of thiamin from the producers (bacteria and phytoplankton) to higher trophic levels is limited. One main concern is whether cyanobacterial blooms could negatively affect thiamin transfer in aquatic systems. Laboratory experiments with Baltic Sea plankton communities and single phytoplankton species were used to study the effect of filamentous cyanobacteria on the transfer of thiamin from phytoplankton to zooplankton. Experiments showed that the thiamin content in copepods was reduced when exposed to elevated levels of cyanobacteria, although filamentous cyanobacteria had higher levels of thiamin than any other analyzed phytoplankton species. Filamentous cyanobacteria also had a negative effect on copepod egg production despite high concentrations of non-cyanobacterial food. Phytoplankton species composition affected overall thiamin concentration with relatively more thiamin available for transfer when the relative abundance of Dinophyceae was higher. Finally, phytoplankton thiamin levels were lower when copepods were abundant, indicating that grazers affect thiamin levels in phytoplankton community, likely by selective feeding. Overall, high levels of thiamin in phytoplankton communities are not reflected in the copepod community. We conclude that presence of filamentous cyanobacteria during summer potentially reduces the transfer of thiamin to higher trophic levels by negatively affecting phytoplankton and copepod thiamin content as well as copepod reproduction, thereby lowering the absolute capacity of the food web to transfer thiamin through copepods to higher trophic levels.
|
|
| 9. |
- Fridolfsson, Emil
(author)
-
Thiamin (vitamin B1) in the aquatic food web
- 2019
-
Doctoral thesis (other academic/artistic)abstract
- Thiamin (vitamin B1) is required for several life-sustaining processes in most organisms and cells, e.g. in the conversion of food to energy. It also serves as an antioxidant and is important for proper nerve signaling. Thiamin is produced predominantly by bacteria and phytoplankton in the aquatic food web. Not all bacteria and phytoplankton, nor any organisms in higher trophic levels can produce thiamin; instead, they rely on a continuous external supply and uptake of this essential compound. Thiamin deficiencies occur episodically in a wide range of taxa, especially in higher trophic levels. In the Baltic Sea, thiamin deficiencies has been most pronounced in salmon (Salmo salar) and recently deficiencies are also reported for other fish species and birds.This thesis focuses on thiamin dynamics in lower trophic levels, covering primary producers as well as primary consumers, as this topic has not received much attention previously. Thiamin content of common phytoplankton and zooplankton species and the transfer between them was investigated in experiments and field studies. The relationship between thiamin deficiency and underlying environmental factors was also investigated using monitoring data.Thiamin content differed among phytoplankton classes, species and even strains. Filamentous Cyanophyceae had considerably higher thiamin content than other classes. However, thiamin transfer to copepods was lower, probably associated with difficulties ingesting the filaments. Moreover, thiamin content in seston varied seasonally, being highest during summer when both Prymnesiophyceae and filamentous Cyanophyceae were more abundant. Thiamin content in the two size fractions correlated strongly and was always higher in the smaller size fraction, illustrating the importance of picoplankton and bacteria in the food web. Also, seston thiamin content was higher in the Baltic Proper than in the Skagerrak. Copepods differed in thiamin content among genera, as well as between locations. Acartia sp. had the highest thiamin content and copepods from the Skagerrak had higher levels than congeners from the Baltic Sea. Thiamin deficiency syndromes in salmon was associated with changes in all trophic levels, as well as changes in several abiotic variables.In all, this thesis provides new insights on thiamin content and seasonal dynamics in various phytoplankton and zooplankton species, the transfer of this vitamin between trophic levels as well as the overall importance of thiamin in the aquatic food web.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- Larisch, Lisa-Marie, et al.
(author)
-
Effects of two randomized and controlled multi-component interventions focusing on 24-hour movement behavior among office workers: A compositional data analysis
- 2021
-
In: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 18
-
Journal article (peer-reviewed)abstract
- Intervention studies aiming at changing movement behavior have usually not accounted for the compositional nature of time-use data. Compositional data analysis (CoDA) has been sug-gested as a useful strategy for analyzing such data. The aim of this study was to examine the effects of two multi-component interventions on 24-h movement behavior (using CoDA) and on cardi-orespiratory fitness among office workers; one focusing on reducing sedentariness and the other on increasing physical activity. Office workers (n = 263) were cluster randomized into one of two 6-month intervention groups, or a control group. Time spent in sedentary behavior, light-intensity, moderate and vigorous physical activity, and time in bed were assessed using accelerometers and diaries, both for 24 h in total, and for work and leisure time separately. Cardiorespiratory fitness was estimated using a sub-maximal cycle ergometer test. Intervention effects were analyzed using linear mixed models. No intervention effects were found, either for 24-h behaviors in total, or for work and leisure time behaviors separately. Cardiorespiratory fitness did not change significantly. Despite a thorough analysis of 24-h behaviors using CoDA, no intervention effects were found, nei-ther for behaviors in total, nor for work and leisure time behaviors separately. Cardiorespiratory fitness did not change significantly. Although the design of the multi-component interventions was based on theoretical frameworks, and included cognitive behavioral therapy counselling, which has been proven effective in other populations, issues related to implementation of and compliance with some intervention components may have led to the observed lack of intervention effect.
|
|
| 13. |
- Legrand, Catherine, et al.
(author)
-
Interannual variability of phyto-bacterioplankton biomass and production in coastal and offshore waters of the Baltic Sea
- 2015
-
In: Ambio. - : Springer. - 0044-7447 .- 1654-7209. ; 44:supplement 3, s. S427-S438
-
Journal article (peer-reviewed)abstract
- The microbial part of the pelagic food web is seldom characterized in models despite its major contribution to biogeochemical cycles. In the Baltic Sea, spatial and temporal high frequency sampling over three years revealed changes in heterotrophic bacteria and phytoplankton coupling (biomass and production) related to hydrographic properties of the ecosystem. Phyto- and bacterioplankton were bottom-up driven in both coastal and offshore areas. Cold winter temperature was essential for phytoplankton to conform to the successional sequence in temperate waters. In terms of annual carbon production, the loss of the spring bloom (diatoms and dinoflagellates) after mild winters tended not to be compensated for by other taxa, not even summer cyanobacteria. These results improve our ability to project Baltic Sea ecosystem response to short- and long-term environmental changes.
|
|
| 14. |
- Majaneva, Sanna, et al.
(author)
-
Deficiency syndromes in top predators associated with large-scale changes in the Baltic Sea ecosystem
- 2020
-
In: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 15:1
-
Journal article (peer-reviewed)abstract
- Vitamin B1 (thiamin) deficiency is an issue periodically affecting a wide range of taxa worldwide. In aquatic pelagic systems, thiamin is mainly produced by bacteria and phytoplankton and is transferred to fish and birds via zooplankton, but there is no general consensus on when or why this transfer is disrupted. We focus on the occurrence in salmon (Salmo salar) of a thiamin deficiency syndrome (M74), the incidence of which is highly correlated among populations derived from different spawning rivers. Here, we show that M74 in salmon is associated with certain large-scale abiotic changes in the main common feeding area of salmon in the southern Baltic Sea. Years with high M74 incidence were characterized by stagnant periods with relatively low salinity and phosphate and silicate concentrations but high total nitrogen. Consequently, there were major changes in phytoplankton and zooplankton, with, e.g., increased abundances of Cryptophyceae, Dinophyceae, Diatomophyceae and Euglenophyceae and Acartia spp. during high M74 incidence years. The prey fish communities also had increased stocks of both herring and sprat in these years. Overall, this suggests important changes in the entire food web structure and nutritional pathways in the common feeding period during high M74 incidence years. Previous research has emphasized the importance of the abundance of planktivorous fish for the occurrence of M74. By using this 27-year time series, we expand this analysis to the entire ecosystem and discuss potential mechanisms inducing thiamin deficiency in salmon.
|
|
| 15. |
- Martínez-García, Sandra, et al.
(author)
-
Seasonal Dynamics in Carbon Cycling of Marine Bacterioplankton Are Lifestyle Dependent
- 2022
-
In: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 13
-
Journal article (peer-reviewed)abstract
- Although free-living (FL) and particle-attached (PA) bacteria are recognized as ecologically distinct compartments of marine microbial food-webs, few, if any, studies have determined their dynamics in abundance, function (production, respiration and substrate utilization) and taxonomy over a yearly cycle. In the Baltic Sea, abundance and production of PA bacteria (defined as the size-fraction >3.0 mu m) peaked over 3 months in summer (6 months for FL bacteria), largely coinciding with blooms of Chitinophagales (Bacteroidetes). Pronounced changes in the growth efficiency (range 0.05-0.27) of FL bacteria (defined as the size-fraction <3.0 mu m) indicated the magnitude of seasonal variability of ecological settings bacteria experience. Accordingly, 16S rRNA gene analyses of bacterial community composition uncovered distinct correlations between taxa, environmental variables and metabolisms, including Firmicutes associated with elevated hydrolytic enzyme activity in winter and Verrucomicrobia with utilization of algal-derived substrates during summer. Further, our results suggested a substrate-controlled succession in the PA fraction, from Bacteroidetes using polymers to Actinobacteria and Betaproteobacteria using monomers across the spring to autumn phytoplankton bloom transition. Collectively, our findings emphasize pronounced seasonal changes in both the composition of the bacterial community in the PA and FL size-fractions and their contribution to organic matter utilization and carbon cycling. This is important for interpreting microbial ecosystem function-responses to natural and human-induced environmental changes.
|
|
| 16. |
- Todisco, Vittoria, et al.
(author)
-
Thiamin dynamics during the adult life cycle of Atlantic salmon (Salmo salar)
- 2024
-
In: Journal of Fish Biology. - : John Wiley & Sons. - 0022-1112 .- 1095-8649. ; 104:3, s. 807-824
-
Journal article (peer-reviewed)abstract
- Thiamin is an essential water-soluble B vitamin known for its wide range of metabolic functions and antioxidant properties. Over the past decades, reproductive failures induced by thiamin deficiency have been observed in several salmonid species worldwide, but it is unclear why this micronutrient deficiency arises. Few studies have compared thiamin concentrations in systems of salmonid populations with or without documented thiamin deficiency. Moreover, it is not well known whether and how thiamin concentration changes during the marine feeding phase and the spawning migration. Therefore, samples of Atlantic salmon (Salmo salar) were collected when actively feeding in the open Baltic Sea, after the sea migration to natal rivers, after river migration, and during the spawning period. To compare populations of Baltic salmon with systems without documented thiamin deficiency, a population of landlocked salmon located in Lake Vanern (Sweden) was sampled as well as salmon from Norwegian rivers draining into the North Atlantic Ocean. Results showed the highest mean thiamin concentrations in Lake Vanern salmon, followed by North Atlantic, and the lowest in Baltic populations. Therefore, salmon in the Baltic Sea seem to be consistently more constrained by thiamin than those in other systems. Condition factor and body length had little to no effect on thiamin concentrations in all systems, suggesting that there is no relation between the body condition of salmon and thiamin deficiency. In our large spatiotemporal comparison of salmon populations, thiamin concentrations declined toward spawning in all studied systems, suggesting that the reduction in thiamin concentration arises as a natural consequence of starvation rather than to be related to thiamin deficiency in the system. These results suggest that factors affecting accumulation during the marine feeding phase are key for understanding the thiamin deficiency in salmonids.
|
|
