| 1. |
- Hall, Marcus, et al.
(författare)
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Reproductive homing and fine-scaled genetic structuring of anadromous Baltic Sea perch (Perca fluviatilis)
- 2022
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Ingår i: Fisheries Management and Ecology. - : John Wiley & Sons. - 0969-997X .- 1365-2400. ; 29:5, s. 586-596
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the population dynamics of anadromous Baltic Sea perch Perca fluviatilis (Linnaeus), we studied the migratory behaviour (arrival to spawning location) and population structure (genetic structure and differentiation) of three closely located (<50 km) populations. Spawning migration lasted for 32-80 days, and passive integrated transponder tag (PIT-tag) data indicated that anadromous perch displayed reproductive homing. Populations were differentiated, despite low levels of gene flow (3%-5%), and differentiation increased with increasing geographic distance. This fine-scaled spatial structuring was likely, at least partly, explained by homing behaviour. Analyses of temporal within-stream substructuring yielded inconclusive results, so further studies are required to evaluate this. Taken together, our findings highlight the potential for fine-scaled genetic structuring in anadromous perch and indicate that multiple mechanisms, such as isolation by distance, homing, and reproductive timing could contribute to this pattern. This illustrates the importance of considering cryptic barriers to accurately identify reproductive units, and points to the need for local management of anadromous perch.
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| 2. |
- Broman, Elias, 1985-, et al.
(författare)
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Cyanophage Diversity and Community Structure in Dead Zone Sediments
- 2021
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Ingår i: mSphere. - : American Society for Microbiology. - 2379-5042. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- Up to 20% of prokaryotic organisms in the oceans are estimated to die every day due to viral infection and lysis. Viruses can therefore alter microbial diversity, community structure, and biogeochemical processes driven by these organisms. Cyanophages are viruses that infect and lyse cyanobacterial cells, adding bioavailable carbon and nutrients into the environment. Cyanobacteria are photosynthesizing bacteria, with some species capable of N-2 fixation, which are known to form large blooms as well as resistant resting cells known as akinetes. Here, we investigated cyanophage diversity and community structure plus cyanobacteria in dead zone sediments. We sampled surface sediments and sequenced DNA and RNA, along an oxygen gradient-representing oxic, hypoxic, and anoxic conditions-in one of the world's largest dead zones located in the Baltic Sea. Cyanophages were detected at all stations and, based on partial genome contigs, had a higher alpha diversity and different beta diversity in the hypoxic-anoxic sediments, suggesting that cyanobacteria in dead zone sediments and/or environmental conditions select for specific cyanophages. Some of these cyanophages can infect cyanobacteria with potential consequences for gene expression related to their photosystem and phosphate regulation. Top cyanobacterial genera detected in the anoxic sediment included Dolichospermum/Anabaena, Synechococcus, and Cyanobium. RNA transcripts classified to cyanobacteria were associated with numerous pathways, including anaerobic carbon metabolism and N-2 fixation. Cyanobacterial blooms are known to fuel oxygen-depleted ecosystems with phosphorus (so-called internal loading), and our cyanophage data indicate the potential for viral lysis of cyanobacteria which might explain the high nutrient turnover in these environments. IMPORTANCE Cyanophages are viruses that target cyanobacteria and directly control their abundance via viral lysis. Cyanobacteria are known to cause large blooms in water bodies, substantially contributing to oxygen depletion in bottom waters resulting in areas called dead zones. Our knowledge of cyanophages in dead zones is very scarce, and so far, no studies have assembled partial cyanophage genomes and investigated their associated cyanobacteria in these dark and anoxic sediments. Here, we present the first study using DNA and RNA sequencing to investigate in situ diversity of cyanophages and cyanobacteria in dead zones. Our study shows that dead zone sediments contain different cyanophages compared to oxic sediments and suggest that these viruses are able to affect cyanobacterial photosystem and phosphate regulation. Furthermore, cyanophage-controlled lysis of cyanobacteria might also increase the turnover of carbon, phosphorus, and nitrogen in these oxygen-free environments at the bottom of the sea.
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| 3. |
- Capo, Eric, et al.
(författare)
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Oxygen-deficient water zones in the Baltic Sea promote uncharacterized Hg methylating microorganisms in underlying sediments
- 2022
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Ingår i: Limnology and Oceanography. - : Wiley. - 1939-5590 .- 0024-3590. ; 67:1
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Tidskriftsartikel (refereegranskat)abstract
- Human-induced expansion of oxygen-deficient zones can have dramatic impacts on marine systems and its resident biota. One example is the formation of the potent neurotoxic methylmercury (MeHg) that is mediated by microbial methylation of inorganic divalent Hg (HgII) under oxygen-deficient conditions. A negative consequence of the expansion of oxygen-deficient zones could be an increase in MeHg production due to shifts in microbial communities in favor of microorganisms methylating Hg. There is, however, limited knowledge about Hg-methylating microbes, i.e., those carrying hgc genes critical for mediating the process, from marine sediments. Here, we aim to study the presence of hgc genes and transcripts in metagenomes and metatranscriptomes from four surface sediments with contrasting concentrations of oxygen and sulfide in the Baltic Sea. We show that potential Hg methylators differed among sediments depending on redox conditions. Sediments with an oxygenated surface featured hgc-like genes and transcripts predominantly associated with uncultured Desulfobacterota (OalgD group) and Desulfobacterales (including Desulfobacula sp.) while sediments with a hypoxic-anoxic surface included hgc-carrying Verrucomicrobia, unclassified Desulfobacterales, Desulfatiglandales, and uncharacterized microbes. Our data suggest that the expansion of oxygen-deficient zones in marine systems may lead to a compositional change of Hg-methylating microbial groups in the sediments, where Hg methylators whose metabolism and biology have not yet been characterized will be promoted and expand.
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| 4. |
- Flink, Henrik, et al.
(författare)
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Examining the effects of authentic C&R on the reproductive potential of Northern pike
- 2021
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Ingår i: Fisheries Research. - : Elsevier. - 0165-7836 .- 1872-6763. ; 243
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Tidskriftsartikel (refereegranskat)abstract
- The practice within recreational fisheries to release captured fish back to the wild, known as catch-and-release (C&R), is an increasingly important strategy to protect fish stocks from overexploitation. However, C&R is a stressor and since animal reproduction is particularly sensitive to stress there is reason to suspect that such a practice induces sublethal fitness consequences. Here, we investigated whether and how C&R fishing influenced the reproductive potential in an anadromous population of Northern pike (Esox lucius). First, female pike were exposed to authentic C&R using rod-and-reel fishing in a coastal foraging habitat prior to the spawning period. Next, we observed the migration to the freshwater spawning habitat and compared both the timing of arrival and maturity stage between C&R-treated and control individuals. Finally, to evaluate effects on the quality and viability of eggs we stripped captured control and recaptured C&R-treated females, measured egg dry mass to assess nutrient content, conducted artificial fertilisations and incubated eggs in a controlled laboratory experiment. We found no evidence of C&R causing alterations in either arrival time, maturity stage, or the quality and viability of fertilised eggs. In combination, our results suggest that long-term effects of C&R-induced stress on key reproductive traits of pike, if any, are minor.
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| 5. |
- Hall, Marcus, et al.
(författare)
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Intra-population variation in reproductive timing covaries with thermal plasticity of offspring performance in perch Perca fluviatilis
- 2021
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Ingår i: Journal of Animal Ecology. - : John Wiley & Sons. - 0021-8790 .- 1365-2656.
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Tidskriftsartikel (refereegranskat)abstract
- Life history theory posits that organisms should time their reproduction to coincide with environmental conditions that maximize their fitness. Population-level comparisons have contributed important insights on the adaptive value of reproductive timing and its association to environmental variation. Yet, despite its central role to ecology and evolution, the causes and consequences of variation in reproductive timing among individuals within populations are poorly understood in vertebrates other than birds.Using a combination of observational field studies and a split-brood experiment, we investigated whether differences in breeding time were associated with changes in hatching success, reproductive allocation and reaction norms linking offspring performance to temperature within an anadromous Baltic Sea population of perch Perca fluviatilis.Field observations revealed substantial variation in reproductive timing, with the breeding period lasting almost 2 months and occurring in temperatures ranging from 10 to 21°C. The hatching success of perch decreased as the reproductive season progressed. At the same time, the reproductive allocation strategy changed over the season, late breeders (the offspring of which were introduced into a high resource environment and increased predation pressure) produced more and smaller eggs that resulted in smaller larvae, compared with early breeders.The split-brood experiment in which eggs were incubated in different temperatures (10, 12, 15, 18°C) showed that differences in reproductive timing were associated with a change in the shape of the reaction norm linking offspring performance to water temperature indicative of adaptive phenotypic plasticity, with the offspring of early breeders performing best in low temperatures and the offspring of late breeders performing best in high temperatures.The seasonal changes in reproductive traits and the shape of the thermal performance suggest time-dependent adaptive differences among individuals within the population. Management actions aimed at preserving and restoring variation in the timing of reproductive events will thus likely also influence variation in associated life history traits and thermal performance curves, which could safeguard populations against environmental challenges and changes associated with exploitation and global warming.
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| 6. |
- Theorell, Töres, et al.
(författare)
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A systematic review of studies in the contributions of the work environment to ischaemic heart disease development
- 2016
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Ingår i: European Journal of Public Health. - : Oxford University Press. - 1101-1262 .- 1464-360X. ; 26:3, s. 470-477
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Forskningsöversikt (refereegranskat)abstract
- Background: There is need for an updated systematic review of associations between occupational exposures and ischaemic heart disease (IHD), using the GRADE system. Methods: Inclusion criteria: (i) publication in English in peer-reviewed journal between 1985 and 2014, (ii) quantified relationship between occupational exposure (psychosocial, organizational, physical and other ergonomic job factors) and IHD outcome, (iii) cohort studies with at least 1000 participants or comparable case-control studies with at least 50 + 50 participants, (iv) assessments of exposure and outcome at baseline as well as at follow-up and (v) gender and age analysis. Relevance and quality were assessed using predefined criteria. Level of evidence was then assessed using the GRADE system. Consistency of findings was examined for a number of confounders. Possible publication bias was discussed. Results: Ninety-six articles of high or medium high scientific quality were finally included. There was moderately strong evidence (grade 3 out of 4) for a relationship between job strain and small decision latitude on one hand and IHD incidence on the other hand. Limited evidence (grade 2) was found for iso-strain, pressing work, effort-reward imbalance, low support, lack of justice, lack of skill discretion, insecure employment, night work, long working week and noise in relation to IHD. No difference between men and women with regard to the effect of adverse job conditions on IHD incidence. Conclusions: There is scientific evidence that employees, both men and women, who report specific occupational exposures, such as low decision latitude, job strain or noise, have an increased incidence of IHD.
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| 7. |
- Tibblin, Petter, et al.
(författare)
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Higher abundance of adult pike in Baltic Sea coastal areas adjacent to restored wetlands compared to reference bays
- 2023
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Ingår i: Hydrobiologia. - : Springer. - 0018-8158 .- 1573-5117. ; 850, s. 2049-2060
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Tidskriftsartikel (refereegranskat)abstract
- The abundance of pike, a keystone top-predator, have declined dramatically in the Baltic Sea since the 1990s likely owing to recruitment failure. It has been proposed that wetland restoration can aid the recovery of the pike stock by increasing the number of recruits produced by anadromous populations. Yet, no previous studies have addressed whether wetland restorations are associated with higher abundances of adult pike in the coastal habitat. To address this, we performed standardised rod-and-reel survey fishing in paired bays with and without wetlands across three coastal areas and 3 years. To estimate dispersal and the contribution of wetland pike to the coastal stock, we tagged captured pike with passive integrated responders (PIT) and employed PIT reader stations in wetland inlets. The results showed that pike abundances were on average 90% higher in bays with an adjacent wetland although the effect varied among areas. Moreover, PIT-data uncovered that wetland pike constituted a high proportion of the pike found in adjacent coastal habitats and that some wetland fish dispersed up to 10 km. These results support that wetland restoration is a valuable tool to aid the coastal pike stock and ultimately restore the function and services of the coastal ecosystem.
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