| 1. |
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| 2. |
- Ahlgrim, C., et al.
(författare)
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Comparison of Molecular Multiplex and Singleplex Analysis of IgE to Grass Pollen Allergens in Untreated German Grass Pollen-Allergic Patients
- 2015
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Ingår i: Journal of investigational allergology & clinical immunology. - 1018-9068 .- 1698-0808. ; 25:3, s. 190-195
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Tidskriftsartikel (refereegranskat)abstract
- Background: The ImmunoCAP ISAC 112 platform is the only commercially available molecular allergy IgE multiplex test. Data on the comparison of this rather novel test with the molecular singleplex ImmunoCAP IgE platform are lacking. Objective:To compare the multiplex ISAC 112 platform and the singleplex ImmunoCAP platform in regard to IgE to grass pollen allergens in untreated grass pollen allergic patients in Germany. Methods: Serum samples from 101 adults with grass pollen allergy were analyzed for specific IgE (sIgE) to 8 allergenic molecules from timothy grass pollen and to the 112 allergenic molecules included in the ISAC panel. The results for the multiplex and singleplex tests were subsequently analyzed statistically. Results: Comparison of sIgE to grass pollen allergens detected by ISAC 112 and the singleplex ImmunoCAP assay revealed the following correlation coefficients: 0.88 (rPhl p1), 0.96 (rPhl p2), 0.70 (nPhl p4), 0.94 (rPhl p5b), 0.92 (rPhl p6), 0.85 (rPhl p11), and 0.78 (rPhl p12). Conclusion: Molecular testing with ISAC 112 correlates well with the ImmunoCAP platform for respective molecular timothy grass pollen allergens.
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| 3. |
- Bell, Olivia, et al.
(författare)
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The effects of eutrophication and browning on prey availability and body growth of the three-spined stickleback (Gasterosteus aculeatus)
- 2022
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Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 267
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Tidskriftsartikel (refereegranskat)abstract
- Shallow coastal areas often have high productivity and diversity, in part due to the high availability of light and nutrients. At the same time, they are exposed to multiple environmental pressures, such as browning and eutrophication. Browning is mainly caused by runoff bringing coloured dissolved organic matter (CDOM), reducing light availability in waters, whereas eutrophication is caused by high nutrient loading, leading to eutrophication symptoms such as algal blooms. Existing variation and further change in light and nutrients of coastal areas could have large implications for aquatic food webs, including fish. For instance, reduced light might alter food availability and reduce foraging abilities, whereas increased nutrient supply might, depending on the extent, increase food availability. In this study, we performed a mesocosm experiment, including benthic and pelagic communities, together with young-of-the-year three-spined stickleback (Gasterosteus aculeatus) as predators. The three-spined stickleback is not only a common model organism but also an increasingly common and important mesopredator in the Baltic Sea. We examined the extent to which browning and nutrient enrichment, alone and in combination, influenced the density, biomass, and composition of stickleback prey, and diet choice, body growth and condition of the stickleback. Stickleback body growth was positively affected by nutrient-enrichment, probably because of a positive bottom-up effect with increased primary production, as evident in the much higher chlorophyll -a concentrations in the pelagic habitat, and increased food availability. In contrast, there was a marginal negative effect of browning on stickleback body growth and condition, most likely due to negative effects of reduced visibility on feeding rates. We also found that prey availability increased with nutrient-enrichment but not with browning. Interestingly, nutrient-enrichment counteracted the negative effects of browning when combined. Our findings add novel understandings about the potential for both eutrophication and browning to affect coastal food webs and fish body growth in the Baltic Sea.
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| 4. |
- Bergström, Lena, et al.
(författare)
-
Klimatförändringar och biologisk mångfald : Slutsatser från IPCC och IPBES i ett svenskt perspektiv.
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- De stora miljö- och samhällsproblemen kommer inte ensamma. De är sammankopplade på olika sätt. Detta innebär utmaningar men ger också möjligheter att utveckla åtgärder och lösningar. Det gäller både för klimatfrågan och frågan om att motverka förlusten av biologisk mångfald och ekosystem. Kunskapens betydelse för att hantera dessa och andra aspekter är ovärderlig, såväl kring specifika frågeställningar som kring omständigheter och förutsättningar för åtgärdsarbetet.Den här kunskapssammanställningen har gjorts av forskare från Lunds universitet och Sveriges lantbruksuniversitet på uppdrag av Naturvårdsverket och SMHI. Forskarna har tagit avstamp i de omfattande kunskapsutvärderingar som gjorts av den mellanstatliga klimatpanelen (IPCC) och den mellanstatliga plattformen för biologisk mångfald (IPBES). Slutsatserna från IPCC och IPBES sätts i ett svenskt perspektiv, bland annat genom utvalda exempel vilka fungerar som aktuella illustrationer av hur klimatförändringar påverkar biologisk mångfald och ekosystem i Sverige.
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| 5. |
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| 6. |
- Byström, Pär, et al.
(författare)
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Ontogenetic constraints and diet shifts in Perch (Perca fluviatilis) : mechanisms and consequences for intra-cohort cannibalism
- 2012
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Ingår i: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 57:4, s. 847-857
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Tidskriftsartikel (refereegranskat)abstract
- 1. In many populations, sufficient size variation to allow for cannibalism may develop not only among age cohorts but also within them. Here, we used data on resource dynamics, consumer body size distribution and gape size limitation to unravel mechanisms promoting cannibalism within cohorts of young-of-the-year (YOY) perch (Perca fluviatilis). 2. Perch are strongly gape limited when feeding on large zooplankton during early ontogeny. As a consequence, only initially large fish were able to shift to feeding on abundant large invertebrates, necessary to sustain fast growth. 3. We suggest that a combination of high initial size variation and exclusive access to resources for individuals with an initial size advantage is a prerequisite for the development of a size distribution sufficient for intra-cohort cannibalism to occur. 4. During the time when cannibalism was observed, growth of the largest individuals in YOY perch cohorts was faster than that of smaller individuals. However, the energy gain from cannibalism did not increase growth rate enough to reach a size necessary to feed on more abundant size classes of victims, and therefore, the effect of cannibalism on overall cohort density was minor. 5. In addition to a high energy gain from cannibalism allowing for fast growth, strong resource limitation and slow growth rates of small individuals (i.e. potential victims) are a prerequisite not only for the development of intra-cohort cannibalism but also for its persistence.
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| 7. |
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| 8. |
- Ekström, Andreas, 1979, et al.
(författare)
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Cardiorespiratory adjustments to chronic environmental warming improve hypoxia tolerance in European perch (Perca fluviatilis).
- 2021
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Ingår i: The Journal of experimental biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 224:6
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Tidskriftsartikel (refereegranskat)abstract
- Aquatic hypoxia will become increasingly prevalent in the future as a result of eutrophication combined with climate warming. While short-term warming typically constrains fish hypoxia tolerance, many fishes cope with warming by adjusting physiological traits through thermal acclimation. Yet, little is known about how such adjustments affect tolerance to hypoxia. We examined European perch (Perca fluviatilis) from the Biotest enclosure (23°C, Biotest population), a unique ∼1km2 ecosystem artificially warmed by cooling water from a nuclear power plant, and an adjacent reference site (16-18°C, reference population). Specifically, we evaluated how acute and chronic warming affect routine oxygen consumption rate (ṀO2,routine) and cardiovascular performance in acute hypoxia, alongside assessment of the thermal acclimation of the aerobic contribution to hypoxia tolerance (critical O2 tension for ṀO2,routine: Pcrit) and absolute hypoxia tolerance (O2 tension at loss of equilibrium; PLOE). Chronic adjustments (possibly across lifetime or generations) alleviated energetic costs of warming in Biotest perch by depressing ṀO2,routine and cardiac output, and by increasing blood O2 carrying capacity relative to reference perch acutely warmed to 23°C. These adjustments were associated with improved maintenance of cardiovascular function and ṀO2,routine in hypoxia (i.e. reduced Pcrit). However, while Pcrit was only partially thermally compensated in Biotest perch, they had superior absolute hypoxia tolerance (i.e. lowest PLOE) relative to reference perch irrespective of temperature. We show that European perch can thermally adjust physiological traits to safeguard and even improve hypoxia tolerance during chronic environmental warming. This points to cautious optimism that eurythermal fish species may be resilient to the imposition of impaired hypoxia tolerance with climate warming.
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| 9. |
- Faithfull, Carolyn, 1982-, et al.
(författare)
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Bottom–up carbon subsidies and top–down predation pressure interact to affect aquatic food web structure
- 2011
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Ingår i: Oikos. - : John Wiley. - 0030-1299 .- 1600-0706. ; 120:2, s. 311-320
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Tidskriftsartikel (refereegranskat)abstract
- Human impacts such as eutrophication, overexploitation and climate change currently threaten future global food and drinking water supplies. Consequently, it is important that we understand how anthropogenic resource (bottom–up) and consumer (top–down) manipulations affect aquatic food web structure and production. Future climate changes are predicted to increase the inputs of terrestrial dissolved organic carbon to lakes. These carbon subsidies can either increase or decrease total basal production in aquatic food webs, depending on bacterial competition with phytoplankton for nutrients. This study examines the effects of carbon subsidies (bottom–up) on a pelagic community exposed to different levels of top–down predation. We conducted a large scale mesocosm experiment in an oligotrophic clear water lake in northern Sweden, using a natural plankton community exposed to three levels of glucose addition (0, 420 and 2100 mg C l–1 total added glucose) and three levels of young-of-the-year perch Perca fluviatilis density (0, 0.56 and 2 individuals m–3). Bacterioplankton production doubled with glucose addition, but phytoplankton production was unaffected, in contrast to previous studies that have manipulated carbon, nutrients or light simultaneously. This suggests that carbon addition alone is not sufficient to reduce autotrophic production, at least in an oligotrophic lake dominated by mixotrophic phytoplankton. Larval perch grazing did not produce a classical trophic cascade, but substantially altered the species composition of crustacean zooplankton and ciliate trophic levels. Glucose addition increased the biomass of rotifers, thus potentially increasing energy transfer through the heterotrophic pathway, but only when fish were absent. This study illustrates that changes in community structure due to selective feeding by top-predators can determine the influence of bottom–up carbon subsidies.
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| 10. |
- Faithfull, Carolyn, 1982-, et al.
(författare)
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Transfer of bacterial production based on labile carbon to higher trophic levels in an oligotrophic pelagic system
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- It is debatable whether bacterial production (BP) based on labile carbon (C) is an important energy subsidy for higher trophic levels in the pelagic zone of lakes. Increased BP may reduce phytoplankton and basal production through competition for phosphorus. However, enhanced BP can also be regarded as an additional basal food resource used directly by unselective filter feeding (cladocerans) or indirectly through grazing on the microbial food web (cladocerans and copepods). In a mesocosm experiment we traced the contribution of BP to crustacean zooplankton and planktivorous fish using stable isotopes and labile glucose-C as a biomarker. BP increased with glucose-C addition and all zooplankton and fish incorporated some glucose-C. Although cladocerans incorporated the most glucose-C, increased BP did not affect cladoceran biomass. Instead, calanoid copepod biomass increased with glucose addition. This suggests that the ability to select high quality food such as bacterial grazing protists capable of trophic upgrading (i.e. de novo synthesis of fatty acids), had a stronger positive effect on calanoids, than unselective grazing on bacteria and protists had on cladoceran biomass. Higher BP was associated with increased survival and population growth of young-of-the-year perch when stocked at high densities, which suggested that BP had a density dependant effect on fish growth. Although the total amount of energy mobilized did not affect fish growth, energy mobilized through the microbial food chain increased calanoid copepod biomass; the favored prey species of planktivorous fish in this system.
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| 11. |
- Faithfull, Carolyn, et al.
(författare)
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Transfer of bacterial production based on labile carbon to higher trophic levels in an oligotrophic pelagic system
- 2012
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Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - Montreal : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 69:1, s. 85-93
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Tidskriftsartikel (refereegranskat)abstract
- Additions of labile organic carbon (C) enhanced bacterial production (BP) and were associated with increases in crustacean zooplankton and planktivorous fish biomasses. This was shown in a mesocosm experiment where we traced the contribution of BP to zooplankton and fish using stable isotopes and labile glucose-C as a biomarker. BP increased with glucose-C addition, and all zooplankton and fish incorporated some glucose-C. However, the effect of labile-C addition on zooplankton was taxa-dependant, as although cladocerans incorporated the most labile-C, increased BP did not affect cladoceran biomass. Instead, calanoid copepod biomass increased with glucose addition. This suggests that the ability to selectively graze on high quality food, such as bacterial grazing protists capable of trophic upgrading, had a stronger positive effect on calanoid copepods biomass than unselective grazing on bacteria and protists had on cladoceran biomass. Higher BP was associated with increased survival and population growth of young-of-the-year perch (Perca fluviatilis) when stocked at high densities, which suggested that BP had a density-dependant positive effect on fish growth.
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| 12. |
- Fiocchi, Alessandro, et al.
(författare)
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Sensitization pattern to inhalant and food allergens in symptomatic children at first evaluation
- 2015
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Ingår i: The Italian Journal of Pediatrics. - : Springer Science and Business Media LLC. - 1720-8424 .- 1824-7288. ; 41
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Tidskriftsartikel (refereegranskat)abstract
- Background: Data on specific IgE sensitization prevalence in children with allergy-like symptoms seen in the primary care setting are rare. Early diagnosis of allergic diseases is important to prevent clinical manifestations, exacerbations or expansion of allergic diseases to other organ systems. The present study aims to assess the usefulness of early serological diagnosis in children with common allergic symptoms. Methods: 532 children (<15 years of age), with at least one of ten allergy-like symptoms, from 21 primary care centers in two geographic areas of Italy and Spain were included in the study. Patients were tested with, either Phadiatop (R) Infant (0-5 years of age) or Phadiatop (R) and food mix (fx5e) (>5 years of age) to discriminate atopic from non-atopic subjects. A blood sample of atopic subjects was taken for additional 6-26 specific IgE antibody determinations from a predefined panel using the ImmunoCAP (R) System. Results: 267 children (50.2 %) were positive in the initial test and were classified as atopic. 14 % were mono-sensitized, 37 % were sensitized to 2-3 allergens and 49 % to more than 3 allergens. The average number of symptoms in the atopic group was 3.3 vs 2.8 in the non-atopic group. The prevalence of sensitization to single allergens was highest for grass and ragweed pollen and house-dust mites (19-28 %). Sensitization to tree allergens was highest for olive tree (16.5 %). Cow's milk and egg white were the most sensitizing foods (similar to 15 %). Food allergen sensitization predominated in younger children (OR = 2.8) whereas the inverse occurred with inhalant allergens (OR = 2.5 to 5.6). A significant positive correlation between patient age and the number of sensitizations was found. Conclusions: Specific IgE sensitization in children with allergy-like symptoms is common. Multiple sensitization is predominating. Number of clinical symptoms was higher in the atopic group compared to the non-atopic without a correlation with the number of positive allergens. Age seems to play a crucial role in the development of sensitization with a significant positive correlation between patient age and the number of sensitizations.
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| 13. |
- Garnier, Aurélie, et al.
(författare)
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Coastal darkening exacerbates eutrophication symptoms through bottom-up and top-down control modification
- 2023
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Ingår i: Limnology and Oceanography. - : Wiley. - 1939-5590 .- 0024-3590. ; 68:3, s. 678-691
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Tidskriftsartikel (refereegranskat)abstract
- Coastal eutrophication due to excessive anthropogenic nutrient loading is a major threat worldwide, and especially in estuaries and semi-enclosed waterbodies, like the brackish Baltic Sea. In addition, coastal waters may become darker (coastal darkening) due to increased input of colored compounds from terrestrial run-off and sediment resuspension. Still, the effects of darkening on coastal food web responses to eutrophication are unknown. In a mesocosm experiment with benthic and pelagic habitats, we manipulated nutrient loading, presence of fish and light availability to disentangle bottom-up and top-down control of eutrophication symptoms in ambient and darkened waters. Overall, we found higher pelagic Chlorophyll a concentrations (a proxy of algal biomass) with darkening and with nutrient enrichment in both clear and dark waters. Albeit fish had a strong impact on zooplankton and zoobenthos, they had no cascading effect on algae. We conclude that coastal darkening due to changes in land use and climate change can pose an additional challenge concerning the recovery of coastal waters from eutrophication.
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| 14. |
- Gårdmark, Anna, et al.
(författare)
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Individual variation and interactions explain food web responses to global warming
- 2020
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Ingår i: Philosophical transactions of the Royal Society of London. Series B, Biological sciences. - : The Royal Society. - 0080-4622. ; 375
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Tidskriftsartikel (refereegranskat)abstract
- Understanding food web responses to global warming, and their consequences for conservation and management, requires knowledge on how responses vary both among and within species. Warming can reduce both species richness and biomass production. However, warming responses observed at different levels of biological organization may seem contradictory. For example, higher temperatures commonly lead to faster individual body growth but can decrease biomass production of fishes. Here we show that the key to resolve this contradiction is intraspecific variation, because (i) community dynamics emerge from interactions among individuals, and (ii) ecological interactions, physiological processes and warming effects often vary over life history. By combining insights from temperature-dependent dynamic models of simple food webs, observations over large temperature gradients and findings from short-term mesocosm and multi-decadal whole-ecosystem warming experiments, we resolve mechanisms by which warming waters can affect food webs via individual-level responses and review their empirical support. We identify a need for warming experiments on food webs manipulating population size structures to test these mechanisms. We stress that within-species variation in both body size, temperature responses and ecological interactions are key for accurate predictions and appropriate conservation efforts for fish production and food web function under a warming climate.
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| 15. |
- Gårdmark, Anna, et al.
(författare)
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Regime shifts in exploited marine food webs : detecting mechanisms underlying alternative stable states using size-structured community dynamics theory
- 2015
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 370:1659, s. 20130262-
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Tidskriftsartikel (refereegranskat)abstract
- Many marine ecosystems have undergone 'regime shifts', i.e. abrupt reorganizations across trophic levels. Establishing whether these constitute shifts between alternative stable states is of key importance for the prospects of ecosystem recovery and for management. We show how mechanisms underlying alternative stable states caused by predator-prey interactions can be revealed in field data, using analyses guided by theory on size-structured community dynamics. This is done by combining data on individual performance (such as growth and fecundity) with information on population size and prey availability. We use Atlantic cod (Gadus morhua) and their prey in the Baltic Sea as an example to discuss and distinguish two types of mechanisms, 'cultivation-depensation' and 'overcompensation', that can cause alternative stable states preventing the recovery of overexploited piscivorous fish populations. Importantly, the type of mechanism can be inferred already from changes in the predators' body growth in different life stages. Our approach can thus be readily applied to monitored stocks of piscivorous fish species, for which this information often can be assembled. Using this tool can help resolve the causes of catastrophic collapses in marine predatory-prey systems and guide fisheries managers on how to successfully restore collapsed piscivorous fish stocks.
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| 16. |
- Hasmats, Johanna, et al.
(författare)
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Validation of whole genome amplification for analysis of the p53 tumor suppressor gene in limited amounts of tumor samples
- 2012
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 425:2, s. 379-383
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Tidskriftsartikel (refereegranskat)abstract
- Personalized cancer treatment requires molecular characterization of individual tumor biopsies. These samples are frequently only available in limited quantities hampering genomic analysis. Several whole genome amplification (WGA) protocols have been developed with reported varying representation of genomic regions post amplification. In this study we investigate region dropout using a 929 polymerase based WGA approach. DNA from 123 lung cancers specimens and corresponding normal tissue were used and evaluated by Sanger sequencing of the p53 exons 5-8. To enable comparative analysis of this scarce material, WGA samples were compared with unamplified material using a pooling strategy of the 123 samples. In addition, a more detailed analysis of exon 7 amplicons were performed followed by extensive cloning and Sanger sequencing. Interestingly, by comparing data from the pooled samples to the individually sequenced exon 7, we demonstrate that mutations are more easily recovered from WGA pools and this was also supported by simulations of different sequencing coverage. Overall this data indicate a limited random loss of genomic regions supporting the use of whole genome amplification for genomic analysis.
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| 17. |
- Huss, Magnus, et al.
(författare)
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Cohort Dynamics Give Rise to Alternative Stable Community States
- 2013
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Ingår i: American Naturalist. - : University of Chicago Press. - 0003-0147 .- 1537-5323. ; 182, s. 374-392
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Tidskriftsartikel (refereegranskat)abstract
- Many ecological systems can exhibit alternative stable states (ASS), which implies that ecological communities may diverge depending on their initial state, despite identical environmental conditions. Here we present a new mechanism that can cause ASS in competition systems. Using a physiologically structured model of competing populations, representing Baltic Sea sprat and herring and their resources, we show how cohort-driven population cycles may result in priority effects leading to ASS. Similar mechanisms could, depending on mortality level, also result in a resident strikes back phenomenon. We argue that the prerequisites for the occurrence of ASS in our model system, that is, communities with competing populations exhibiting cohort cycles and variation in size at maturation, may be common in ecological systems.
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| 18. |
- Huss, Magnus, 1979-, et al.
(författare)
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Effects of ontogenetic scaling on resource exploitation and cohort size distributions
- 2010
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Ingår i: Oikos. - : John Wiley & Sons, Inc.. - 0030-1299 .- 1600-0706. ; 119:2, s. 384-392
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Tidskriftsartikel (refereegranskat)abstract
- Variation in growth rates among individuals leading to the formation of broad size distributions is commonly observed in animal cohorts. Here we use laboratory derived size-scaling relationships to identify mechanisms driving changes in size distribution patterns within cohorts during early ontogeny. We introduced young-of-the-year perch (Perca fluviatilis) cohorts with different variation in body size distributions in pond enclosures. We kept the exploitative competitive environment constant by adjusting the number of introduced fish such that metabolic requirements were constant between different treatments. Based on modelling results we theoretically derived relative growth rates of differently sized fish when only taken exploitative competitive interactions into account. In agreement with predictions we found that initial variation in body size was negatively correlated with subsequent changes in body size variation in the pond experiment. Corresponding results were obtained in a field study covering 13 studied young-of-the-year perch cohorts in a small lake. Besides having a lower maximum growth capacity, initially large fish also suffered more from resource limitation in our experiment. The results suggest that exploitation competition is a major factor behind growth patterns in young fish cohorts, generally leading to size convergence. To explain the commonly observed pattern of size divergence in animal cohorts, including fish, we suggest that differential timing of diet shifts or mechanisms not related to exploitative interactions must be taken into account. For diet shifts to lead to size divergence we suggest that individuals with an initial size advantage need access to an exclusive prey which has a high growth potential. This, in turn, allows initially larger individuals to surf on a wave of growing prey while individuals only capable to feed on a depressed initial resource experience low growth rates.
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| 19. |
- Huss, Magnus, 1979-, et al.
(författare)
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Experimental evidence for emergent facilitation : promoting the existence of an invertebrate predator by killing its prey
- 2011
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Ingår i: Journal of Animal Ecology. - : John Wiley & Sons. - 0021-8790 .- 1365-2656. ; 80:3, s. 615-621
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Tidskriftsartikel (refereegranskat)abstract
- 1. Recent theoretical insights have shown that predator species may help each other to persist by size-selective foraging on a shared prey. By feeding on a certain prey stage, a predator may induce a compensatory response in another stage of the same prey species, thereby favouring other predators; a phenomenon referred to as emergent facilitation. 2. To test whether emergent facilitation may occur in a natural system, we performed an enclosure experiment where we mimicked fish predation by selectively removing large zooplankton and subsequently following the response of the invertebrate predator Bythotrephes longimanus. 3. Positive responses to harvest were observed in the biomass of juvenile individuals of the dominant zooplankton Holopedium gibberum and in Bythotrephes densities. Hence, by removing large prey, we increased the biomass of small prey, i.e. stage-specific biomass overcompensation was present in the juvenile stage of Holopedium. This favoured Bythotrephes, which preferentially feed on small Holopedium. 4. We argue that the stage-specific overcompensation occurred as a result of increased per capita fecundity of adult Holopedium and as a result of competitive release following harvest. If shown to be common, emergent facilitation may be a major mechanism behind observed predator extinctions and patterns of predator invasions.
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| 20. |
- Huss, Magnus, et al.
(författare)
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Experimental evidence of gradual size-dependent shifts in body size and growth of fish in response to warming
- 2019
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 25, s. 2285-2295
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Tidskriftsartikel (refereegranskat)abstract
- A challenge facing ecologists trying to predict responses to climate change is the few recent analogous conditions to use for comparison. For example, negative relationships between ectotherm body size and temperature are common both across natural thermal gradients and in small-scale experiments. However, it is unknown if short-term body size responses are representative of long-term responses. Moreover, to understand population responses to warming, we must recognize that individual responses to temperature may vary over ontogeny. To enable predictions of how climate warming may affect natural populations, we therefore ask how body size and growth may shift in response to increased temperature over life history, and whether short-and long-term growth responses differ. We addressed these questions using a unique setup with multidecadal artificial heating of an enclosed coastal bay in the Baltic Sea and an adjacent reference area (both with unexploited populations), using before-after control-impact paired time-series analyses. We assembled individual growth trajectories of similar to 13,000 unique individuals of Eurasian perch and found that body growth increased substantially after warming, but the extent depended on body size: Only among small-bodied perch did growth increase with temperature. Moreover, the strength of this response gradually increased over the 24 year warming period. Our study offers a unique example of how warming can affect fish populations over multiple generations, resulting in gradual changes in body growth, varying as organisms develop. Although increased juvenile growth rates are in line with predictions of the temperature-size rule, the fact that a larger body size at age was maintained over life history contrasts to that same rule. Because the artificially heated area is a contemporary system mimicking a warmer sea, our findings can aid predictions of fish responses to further warming, taking into account that growth responses may vary both over an individual's life history and over time.
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| 21. |
- Huss, Magnus, et al.
(författare)
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Facilitation of fisheries by natural predators depends on life history of shared prey
- 2014
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 123, s. 1071-1080
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Tidskriftsartikel (refereegranskat)abstract
- Predators commonly share prey with human exploiters, intuitively suggesting that there is an inherent human-predator conflict through competition for prey. Here we studied the effects of fishing and predation mortality on biomass distributions and yields of shared prey using a size-structured model of competing populations, describing the life histories of Baltic Sea sprat and herring. Whereas both species responded in a similar fashion to increased fishing mortality, with decreasing juvenile and adult biomasses, we found that responses to predation mortality differed between species. Sprat only display weak compensatory responses with increasing predation mortality, while over a substantial range of mortalities there was a strong increase in adult (and total) herring biomass, i.e. overcompensation. The observed biomass overcompensation results from relaxed intraspecific competition as predation mortality increased, allowing for faster individual growth rates that in turn lead to a change in population composition (juvenile: adult biomass ratio). Our results suggest that the potential for biomass overcompensation is higher for species exhibiting substantial growth after maturation. Differences in size-selectivity of predators and fishing mortality resulted in a positive effect of predation mortality on fisheries yields, which can be explained by an overcompensatory response in adult herring biomass. Thus, somewhat counter intuitive, our results suggest that fishermen, depending on prey life history, may actually benefit from allowing for a higher abundance of predators, despite competing for shared prey.
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| 22. |
- Huss, Magnus, 1979-, et al.
(författare)
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Growing through predation windows: : effects on body size development in young fish
- 2010
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 119, s. 1796-1804
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Tidskriftsartikel (refereegranskat)abstract
- Th e degree to which growth in early life stages of animals is regulated via density-dependent feedbacks through preyresources is much debated. Here we have studied the infl uence of size- and density-dependent mechanisms as well as sizeselectivepredation pressure by cannibalistic perch Perca fl uviatilis on growth patterns of young-of-the-year (YOY) perchcovering several lakes and years. We found no infl uence of initial size or temperature on early body size development ofperch. In contrast, there was a negative relationship between reproductive output and the length of YOY perch at fi ve weeksof age. However, rather than an eff ect of density-dependent growth mediated via depressed resources the relationship wasdriven by positive size-selective cannibalism removing large individuals. Hence, given a positive correlation between thedensity of victims and predation pressure by cannibals, size-dependent interactions between cannibals and their victimsmay wrongly be interpreted as patterns of density-dependent growth in the victim cohort. Overall, our results support theview that density-dependent resource-limitation in early life stages is rare. Still, patterns of density-dependent growth mayemerge, but from variation in size-selective predation pressure rather than density as such. Th is illustrates the importanceof taking overall population demography and predatory interactions into account when studying growth patterns amongrecruiting individuals.
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| 23. |
- Huss, Magnus, 1979-, et al.
(författare)
-
Influence of growth history on the accumulation of energy reserves and winter mortality on young fish
- 2008
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Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - : EBSCO Host. - 0706-652X .- 1205-7533. ; 65:10, s. 2149-2156
-
Tidskriftsartikel (refereegranskat)abstract
- In seasonal environments accumulated energy reserves are important to avoid starvation mortality during periods of low resource levels. Here we investigated patterns of energy accumulation and the importance of growth history for winter survival in young-of-the-year Eurasian perch (Perca fluviatilis). Under simulated winter conditions in aquaria’s we showed that high winter mortality most likely relate to the depletion of energy reserves in small perch. Correspondingly in a field study, using 4 lakes covering 3-6 lake years each, overwinter survival within cohorts was positively related to individual size. However, average size in autumn did not explain the variation in overwinter survival between cohorts. Instead we showed that seasonal growth history is an important factor. High growth rates late in season may increase cohort survival over winter irrespective of average size, related to a positive growth dependent increase in allocation to energy reserves when approaching winter. Mechanisms regulating within-season temporal dynamics of growth rates are therefore suggested to be important for overall cohort performance.
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| 24. |
- Huss, Magnus, 1979-, et al.
(författare)
-
Intra-cohort cannibalism and size bimodality : a balance between hatching synchrony and resource feedbacks
- 2010
-
Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 119:12, s. 2000-2011
-
Tidskriftsartikel (refereegranskat)abstract
- Cannibalistic interactions generally depend on the size relationship between cannibals and victims. In many populations, alarge enough size variation to allow for cannibalism may not only develop among age-cohorts but also within cohorts. Westudied the implications of variation in hatching period length and initial cohort size for the emergence of cannibalism andbimodal size distributions within animal cohorts using a physiologically structured population model. We found that thedevelopment of size bimodality was critically dependent on hatching period length, victim density and the presence of afeedback via shared resources. Cannibals only gained enough energy from cannibalism to accelerate in growth when victimdensity was high relative to cannibal density at the onset of cannibalism. Furthermore, we found that the opportunity forearly hatchers to initially feed on an unexploited resource increases the likelihood both for cannibalism to occur and sizebimodality to develop. Once cannibals accelerated in growth relative to victims size bimodality, reduced victim numbersand relaxed resource competition resulted. Th us, in addition to that cannibals profi ted from cannibalism through energyextraction, their potential victims also benefi ted as the resource recovered due to cannibal thinning. To ensure recruitmentsuccess, it can be critical that a few individuals can accelerate in growth and reach a size large enough to escape sizedependentpredation and winter starvation. Hence, within-cohort cannibalism may be a potentially important mechanismto explain recruitment variation especially for cannibalistic species in temperate climates with strong seasonality. However,the scope for size bimodality to develop as a result of cannibalism may be limited by low victim densities and size andfood-dependent growth rates.
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| 25. |
- Huss, Magnus, et al.
(författare)
-
Larval fish body growth responses to simultaneous browning and warming
- 2021
-
Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 11, s. 15132-15140
-
Tidskriftsartikel (refereegranskat)abstract
- Organisms are facing global climate change and other anthropogenic pressures, but most research on responses to such changes only considers effects of single drivers. Observational studies and physiological experiments suggest temperature increases will lead to faster growth of small fish. Whether this effect of warming holds in more natural food web settings with concurrent changes in other drivers, such as darkening water color ("browning") is, however, unknown. Here, we set up a pelagic mesocosm experiment with large bags in the Baltic Sea archipelago, inoculated with larval Eurasian perch (Perca fluviatilis) and zooplankton prey and varying in temperature and color, to answer the question how simultaneous warming and browning of coastal food webs impact body growth and survival of larval perch. We found that browning decreased body growth and survival of larval perch, whereas warming increased body growth but had no effect on survival. Based on daily fish body growth estimates based on otolith microstructure analysis, and size composition and abundance of available prey, we explain how these results may come about through a combination of physiological responses to warming and lower foraging efficiency in brown waters. We conclude that larval fish responses to climate change thus may depend on the relative rate and extent of both warming and browning, as they may even cancel each other out.
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| 26. |
- Huss, Magnus, 1979-
(författare)
-
Ontogenetic scaling and the development of within-cohort size structure
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is increasingly recognized that individuals of the same species differ from each other and influence and respond to their environment in unique ways. This thesis deals with size variation among individuals that not only are of the same species but also of similar age. Such variation may develop even when individuals are born in the same environment, i.e. within a cohort. I have studied the sources and consequences of variation within and among cohorts from egg through early ontogeny using young-of-the-year (YOY) perch (Perca fluviatilis) as study organism. In agreement with predictions based on model results only taking exploitative interactions among individuals into account, I found that the broader the initial size distributions were, the more did the degree of size variation among individuals decrease over time. Still, with initially small size variation among individuals, in several experiments also size divergence was observed. Furthermore, size variation among individuals increased more under high compared to at low densities. Increased size variation over time may be explained by size-dependent diet shifts allowing for initially larger individuals to make an early diet shift when the first resource becomes limiting. However, as size divergence also was observed in situations with only shared resources available, it can be concluded that diet shifts are not a prerequisite for size divergence in young animal cohorts. Hence, I also suggest that mechanisms not related to competition for limiting resources, such as genetic variation, stochasticity and behavioural traits must be taken into account, especially when initial size differences are small. The importance of considering size variation among individuals within cohorts was demonstrated in a study of winter mortality in YOY perch cohorts. A large individual size in autumn was shown to increase overwinter survival within cohorts. However, late summer growth rather than average body size reached in autumn explained variation in overwinter survival between cohorts. Higher accumulation to lipid reserves and accordingly lower mortality over winter was observed in years with high growth rates late in the season. In another study I showed that apparent patterns of density-dependent growth can emerge among larval fish, but rather than a result of density-dependent resource limitation this was due to variation in size-selective predation pressure. Individuals in the right end of the size distributions grew in to a high predation pressure from cannibalistic perch when cannibal density was high, coinciding with high larval perch densities. Finally, as substantial size variation among individuals can develop within cohorts, also intra-cohort cannibalism can occur. Using a physiologically structured population model it was shown that the development of size bimodality within cohorts as a result of intra-cohort cannibalism is critically dependent on long hatching periods, high victim densities and density-dependent feedbacks on shared resources.
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| 27. |
- Huss, Magnus, et al.
(författare)
-
Ontogenetic specialism in predators with multiple niche shifts prevents predator population recovery and establishment
- 2014
-
Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 95, s. 2409-2422
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of ontogenetic niche shifts on community structure and dynamics are underexplored, despite the occurrence of such shifts in the majority of animal species. We studied the form of niche shifts in a predator that exhibits multiple ontogenetic niche shifts, and analyzed how this life history complexity affects the size-structured predator-prey dynamics in the system. The predator represents either an ontogenetic generalist, exhibiting a partial shift to predation (in which case an alternative resource is also available) or an ontogenetic specialist, exhibiting a complete shift (in which case the predator depends entirely on predation). We showed two effects on community dynamics from accounting for a complete niche shift to predation: (1) occurrence of alternative stable community states (coexistence and a prey-only community state) and (2) occurrence of deterministic extinction following initially successful invasion (predators can invade an equilibrium with only prey, but are bound to go extinct after a few generations). Both phenomena are due to the match or mismatch in the timing of predators and suitably sized prey and the growth trajectory of the predator, which is plastic, due to the population feedback on available resources. In the case of persistence without invasion (alternative stable community states), slow growth during the pre-piscivorous life stage is necessary to stay in tune with the prey cycle; in the case of extinction following invasion, slow growth through the pre-piscivorous life stage causes the predator to reach the completely piscivorous stage when there is no prey available to feed upon. Somatic growth rates are directly coupled to food availability, which, in turn, is the result of density-dependent feedbacks in the system. Since they primarily determine these density-dependent feedbacks, the ontogenetic niche shifts in predator life history structure the community to a major extent.
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| 28. |
- Huss, Magnus, 1979-, et al.
(författare)
-
Resource heterogeneity, diet shifts and intra-cohort competition : effects on size divergence in YOY fish
- 2008
-
Ingår i: Oecologia. - Berlin / Heidelberg : Springer. - 0029-8549 .- 1432-1939. ; 158:2, s. 249-257
-
Tidskriftsartikel (refereegranskat)abstract
- Most organisms exhibit a substantial size variation among individuals due to individual differences in experienced biotic and abiotic environmental conditions and because individuals undergo growth and development during most of their life time. One important issue in this context is how size variation within cohorts may develop over time. Here we tested the hypothesis, in gape-limited animals such as fish, that size divergence among individuals within a cohort depends on the opportunity to undergo size-dependent diet shifts, by allowing initially larger individuals to make an early diet shift when the first resource becomes limiting. We used young-of-the-year perch (Perca fluviatilis) as our study organism. Competitive intensity and the opportunity to undergo a diet shift from zooplankton to macroinvertebrates affected both mean growth rates and the extent to which inter-individual variation in growth was manifested. As predicted, increased competition combined with the presence of both zooplankton and benthic macroinvertebrates increased the degree of size variation. However, size divergence was also observed among individuals when only the initial resource, zooplankton, was available. We argue that only non-exploitative interactions, such as dominance structures and social interactions could have caused this latter pattern, as exploitative competition is expected to lead to size convergence due to the superior competitive ability of smaller individuals. Our results suggest that diet shifts are not a prerequisite for size divergence in animal cohorts and that dominance and social interactions may have similar effects on size variation within cohorts. Finally, development of size variation is suggested to have strong implications for overall cohort performance.
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| 29. |
- Huss, Magnus, et al.
(författare)
-
Size- and food-dependent growth drives patterns of competitive dominance along productivity gradients
- 2012
-
Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 93, s. 847-857
-
Tidskriftsartikel (refereegranskat)abstract
- Patterns of coexistence among competing species exhibiting size- and food-dependent growth remain largely unexplored. Here we studied mechanisms behind coexistence and shifts in competitive dominance in a size-structured fish guild, representing sprat and herring stocks in the Baltic Sea, using a physiologically structured model of competing populations. The influence of degree of resource overlap and the possibility of undergoing ontogenetic diet shifts were studied as functions of zooplankton and zoobenthos productivity. By imposing different size-dependent mortalities, we could study the outcome of competition under contrasting environmental regimes representing poor and favorable growth conditions. We found that the identity of the dominant species shifted between low and high productivity. Adding a herring-exclusive benthos resource only provided a competitive advantage over sprat when size-dependent mortality was high enough to allow for rapid growth in the zooplankton niche. Hence, the importance of a bottom-up effect of varying productivity was dependent on a strong top-down effect. Although herring could depress shared resources to lower levels than could sprat and also could access an exclusive resource, the smaller size at maturation of sprat allowed it to coexist with herring and, in some cases, exclude it. Our model system, characterized by interactions among size cohorts, allowed for consumer coexistence even at full resource overlap at intermediate productivities when size-dependent mortality was low. Observed shifts in community patterns were crucially dependent on the explicit consideration of size- and food-dependent growth. Accordingly, we argue that accounting for food-dependent growth and size-dependent interactions is necessary to better predict changes in community structure and dynamics following changes in major ecosystem drivers such as resource productivity and mortality, which are fundamental for our ability to manage exploitation of living resources in, e.g., fisheries.
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| 30. |
- Huss, Magnus
(författare)
-
Species divergence under competition and shared predation
- 2023
-
Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 26, s. 111-123
-
Tidskriftsartikel (refereegranskat)abstract
- Species competing for resources also commonly share predators. While competition often drives divergence between species, the effects of shared predation are less understood. Theoretically, competing prey species could either diverge or evolve in the same direction under shared predation depending on the strength and symmetry of their interactions. We took an empirical approach to this question, comparing antipredator and trophic phenotypes between sympatric and allopatric populations of threespine stickleback and prickly sculpin fish that all live in the presence of a trout predator. We found divergence in antipredator traits between the species: in sympatry, antipredator adaptations were relatively increased in stickleback but decreased in sculpin. Shifts in feeding morphology, diet and habitat use were also divergent but driven primarily by stickleback evolution. Our results suggest that asymmetric ecological character displacement indirectly made stickleback more and sculpin less vulnerable to shared predation, driving divergence of antipredator traits between sympatric species.
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| 31. |
- Huss, Magnus, 1979-, et al.
(författare)
-
The origin and development of individual size variation in early pelagic stages of fish
- 2007
-
Ingår i: Oecologia. - Berlin / Heidelberg : Springer. - 0029-8549 .- 1432-1939. ; 153:1, s. 57-67
-
Tidskriftsartikel (refereegranskat)abstract
- Size variation among individuals born at the same time in a common environment (within cohorts) is a common phenomenon in natural populations. Still, the mechanisms behind the development of such variation and its consequences for population processes are far from clear. We experimentally investigated the development of early within-cohort size variation in larval perch (Perca fluviatilis). Specifically we tested the influence of initial variation, resulting from variation in egg strand size, and intraspecific density for the development of size variation. Variation in egg strand size translated into variation in initial larval size and time of hatching, which, in turn, had effects on growth and development. Perch from the smallest egg strands performed on average equally well independent of density, whereas larvae originating from larger egg strands performed less well under high densities. We related this difference in density dependence to size asymmetries in competitive abilities leading to higher growth rates of groups consisting of initially small individuals under high resource limitation. In contrast, within a single group of larvae, smaller individuals grew substantially slower under high densities whereas large individuals performed equally well independent of density. As a result, size variation among individuals within groups (i.e. originating from the same clutch) increased under high densities. This result may be explained by social interactions or differential timing of diet shifts and a depressed resource base for the initially smaller individuals. It is concluded that to fully appreciate the effects of density-dependent processes on individual size variation and size-dependent growth, consumer feedbacks on resources need to be considered.
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| 32. |
- Huss, Magnus, et al.
(författare)
-
Timing of the diet shift from zooplankton to macroinvertebrates and size at maturity determine whether normally piscivorous fish can persist in otherwise fishless lakes
- 2013
-
Ingår i: Freshwater Biology. - : Wiley-Blackwell. - 0046-5070 .- 1365-2427. ; 58:7, s. 1416-1424
-
Tidskriftsartikel (refereegranskat)abstract
- Using a size-structured population model, life-history information and records of piscivores in systems without prey fish, we analysed the role of the timing of shifting from small-to-large invertebrate prey types in regulating piscivore performance, especially under conditions of low availability of prey fish. Large invertebrate prey are generally absent or at low densities in pelagic habitats; consequently, pelagic piscivorous fish species with a poor ability to exploit zooplankton depend on prey fish in order to persist. In contrast, our model shows that abundant large invertebrate prey in the littoral habitat may allow littoral piscivores to persist in the absence of prey fish if they can shift diet from zooplankton to macroinvertebrates early in life. However, if the diet shift from zooplankton to macroinvertebrates is delayed, or density dependence reduces growth rate, the persistence of even littoral piscivorous fish species in the absence of other prey fish is severely constrained. Our results suggest that undergoing an early diet shift from zooplankton to macroinvertebrates may be necessary to reach sizes large enough to enable successful exploitation of the piscivorous niche. These insights can help to understand the persistence of piscivorous fish species, or their absence, in otherwise fishless lakes.
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| 33. |
- Huss-Marp, J, et al.
(författare)
-
Can Immunoglobulin E-measurement replace challenge tests in allergic rhinoconjunctivits to grass pollen?
- 2011
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Ingår i: CLINICAL AND EXPERIMENTAL ALLERGY. - 0954-7894. ; 41:8, s. 1116-1124
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: There is minimal data available concerning the dose-response relationship between allergen exposure and clinical reactivity for outdoor aeroallergens, such as timothy grass pollen. Timothy pollen-specific IgE (sIgE) determinations might assist in predicting the clinical reactivity in patients with allergic rhinoconjunctivitis (ARC). METHODS: Allergen-sIgE antibody levels of timothy grass pollen were correlated with individual threshold doses eliciting allergic reactions in skin prick test (SPT), conjunctival (CPT) and nasal (NPT) provocation tests in patients suffering from pollen-induced rhinoconjunctivitis and healthy controls. RESULTS: One hundred and four patients with ARC (median age: 27 years; range: 18-64; females: 58%) and 36 controls (25 years (22-77); females: 70%) were included in the study. Ninety-six percent of the patients showed a positive reaction in the nasal and 57% showed a positive reaction in the conjunctival provocation. With regarding to titrated SPT, 98% of the patients showed a positive skin test reaction; correlating with the level of sIgE for timothy (P < 0.001). For both provocation protocols, there was no correlation between the provocation concentration at the reaction and the level of sIgE for timothy. The ratio of sIgE/total IgE correlated with the dilution level of SPT (P < 0.002) and CPT (P < 0.01), respectively. CONCLUSION AND CLINICAL RELEVANCE: A dose-response relationship between the levels of sIgE and clinical outcome of timothy allergen exposure could not be established. Although IgE-determination remains an important key element in allergy diagnosis, provocation tests are procedures of choice if the clinical relevance of an allergen has to be confirmed.
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| 34. |
- Jacobson, Philip, et al.
(författare)
-
Growth variation of Atlantic salmon Salmo salar at sea affects their population-specific reproductive potential
- 2021
-
Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 671, s. 165-174
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the processes shaping the dynamics of anadromous fish populations is essential for their management and conservation. Yet, little is known about how variation in performance at sea affects their population dynamics. Here we show that variation in body growth at sea contributes to explaining variation in the reproductive potential for 2 Atlantic salmon Salmo salar populations, but to a varying extent. To this end, we assembled data collected during 50 yr for 2 Baltic salmon populations of hatchery origin, including annually released smolts, survival at sea estimates, size-specific growth at sea, annual length distributions of returning adult females and their reproductive potential. The regression models fitted to explain the reproductive potential of our 2 study populations improved when growth at sea was included as an explanatory variable, in addition to smolt year class abundance and estimates of their survival at sea. This link between body growth at sea and population-level reproductive potential suggests that growth at sea can be important to consider when resolving variation in recovery and dynamics among salmon populations sharing the same sea.
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| 35. |
- Jacobson, Philip, et al.
(författare)
-
Population and size-specific distribution of Atlantic salmon Salmo salar in the Baltic Sea over five decades
- 2020
-
Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 96, s. 408-417
-
Tidskriftsartikel (refereegranskat)abstract
- Population-specific assessment and management of anadromous fish at sea requires detailed information about the distribution at sea over ontogeny for each population. However, despite a long history of mixed-stock sea fisheries on Atlantic salmon, Salmo salar, migration studies showing that some salmon populationsfeed in different regions of the Baltic Sea and variation in dynamics occurs among populations feeding in the Baltic Sea, such information is often lacking. Also, current assessment of Baltic salmon assumes equal distribution at sea and therefore equal responses to changes in off-shore sea fisheries. Here, we test for differences in distribution at sea among and within ten Atlantic salmon Salmo salar populations originating from ten river-specific hatcheries along the Swedish Baltic Sea coast, using individual data from >125,000 tagged salmon, recaptured over five decades. We show strong population and size-specific differences in distribution at sea, varying between year classes and between individuals within year classes. This suggests that Atlantic salmon in the Baltic Sea experience great variation in environmental conditions and exploitation rates over ontogeny depending on origin and that current assessment assumptions about equal exploitation rates in the offshore fisheries and a shared environment at sea are not valid. Thus, our results provide additional arguments and necessary information for implementing population-specific management of salmon, also when targeting life stages at sea.
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| 36. |
- Jacobson, Philip, et al.
(författare)
-
Size-dependent prey availability affects diet and performance of predatory fish at sea: a case study of Atlantic salmon
- 2018
-
Ingår i: Ecosphere. - : Wiley. - 2150-8925. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Identifying factors determining the performance of individuals is an essential part of resolving what drives population dynamics. For species undergoing ontogenetic shifts in resource and habitat use, this entails assessing individual performance in all habitats used. Whereas survival and growth of anadromous Atlantic salmon, Salmo salar L., in its juvenile, river habitat are known to depend on size-dependent foraging and food availability, individual performance of salmon in the growth habitat out at sea is commonly explained only by abiotic factors. Still, individuals undergo this habitat shift to grow large, suggesting performance should be food-dependent also in the growth habitat. Because fish communities are highly size-structured, the link between predators and their prey may depend on their respective body sizes. Here, we study whether the performance of Baltic Sea salmon in its growth habitat is food- and size-dependent, by combining extensive diet and body size data of Baltic salmon with spatially resolved monitoring data on abundance and size distribution of their main prey, herring, Clupea harengus L., and sprat, Sprattus sprattus L. We found that both the species and size composition of prey in the diet varied with salmon body size. By accounting for this size-dependent predation and the spatially varying size distribution of prey species, we could explain the variation in salmon diet composition among salmon individuals in different Baltic Sea basins and of different length. The proportion of sprat in diet of salmon was better explained by size-specific prey availability (SSP) than total prey biomass, especially for small salmon. Further, salmon body condition increased with SSP, whereas total prey biomass could not explain variation in the condition of salmon. These findings demonstrate that food- and size-dependent processes indeed can influence the performance of anadromous fish also in large marine systems. Thus, we argue that consideration of these processes, stretching across habitats, is important for understanding performance and dynamics of predatory fish in open aquatic systems, as well as for successful management of species such as Atlantic salmon.
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| 37. |
- Kabir, Mohammad, 1974, et al.
(författare)
-
A Test Vehicle for RF/DC Evaluation and Destructive Testing Of Vertically Grown Nanostructures (VGCNS)
- 2011
-
Ingår i: Proceedings of the NT11 International Conference on the Science and Application of Nanotubes, Cambridge, UK, July 10-16, 2011.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have developed an RF test vehicle suitable for measuring DC and microwave performance of vertically grown carbon nanostructures (VGCNS) as via-interconnects. A first version of the interconnect test vehicles devices were designed, fabricated and characterized. The RF small signal (S-parameter) and large signal measurements show that carbon nanofibres can be used as interconnects in microwave circuit, even for power devices. The design of test vehicle employs a three metal layer concept, forming sequentially the ground, signal and device under test structures for characterization in a microstrip configuration. The structures as such consisted of interconnects of dimensions ranging from 50 nm to 100 µm diameter made of VGCNS. In the first version of the interconnect test vehicles, the interconnects were made of carbon nanofibers grown at 450 C. From SEM measurement we found that the resulting height was around 1.5-2 µm. Epoxy polymer SU-8 was employed by spinning on the device and a subsequent etch back process was carried out to open up the tip of the fibres to connect to consecutive interconnects with the third metallisation layer. After growing the nanofibres, it was observed, using SEM, that interconnect sizes smaller than 10 µm diameter suffered from parasitic growth and therefore the effective device dimension deviated from the initial design. We carried out small signal measurements using a vector network analyser for frequency ranging from 1 to 25 GHz, in order to characterise the transmission and reflection/absorption of the devices as function of their diameter size. The large signal evaluation was performed by measuring the gain compression of the devices. In addition destructive tests, aiming at testing the current carrying capability of the interconnect, have also been performed.The resistivity of interconnects was measured to vary varies from 0.2 µΩ·mm-1.3 mΩ·mm. Apparently, the device performance is considerably influenced by the fill factor of the interconnect with VGCNS. Small variations in fill factor (in %) provided a large variations in device resistivity. Furthermore, it was also observed that the resistance drops at higher power levels. RF conductivity of interconnects ranges from 5x10^3 S/m to 7x10^5 S/m. The average input power before interconnect destruction is larger than 25W with effective device diameter ranging from 3 µm to 100 µm interconnects. In addition, the average gain compression before interconnect destruction was found to be 0.6 dB. It was not possible to extract the conductivity value of an individual nanofiber using comparison to simulation data, since the devices might have suffered from parasitic growth as well as pinhole metal diffusion during top metal contact formation. This certainly affects the actual device dimension and properties. Nevertheless, the proof of concept of design and manufacturing a test vehicle for RF measurements of vertically grown nanostructures was achieved. We will report the findings and anomalies in the measured devices. Further improvement is expected in the coming test vehicle version.
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| 38. |
- Lindmark, Max, et al.
(författare)
-
Size-based ecological interactions drive food web responses to climate warming
- 2019
-
Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 22, s. 778-786
-
Tidskriftsartikel (refereegranskat)abstract
- Predicting climate change impacts on animal communities requires knowledge of how physiological effects are mediated by ecological interactions. Food-dependent growth and within-species size variation depend on temperature and affect community dynamics through feedbacks between individual performance and population size structure. Still, we know little about how warming affects these feedbacks. Using a dynamic stage-structured biomass model with food-, size- and temperature-dependent life history processes, we analyse how temperature affects coexistence, stability and size structure in a tri-trophic food chain, and find that warming effects on community stability depend on ecological interactions. Predator biomass densities generally decline with warming - gradually or through collapses - depending on which consumer life stage predators feed on. Collapses occur when warming induces alternative stable states via Allee effects. This suggests that predator persistence in warmer climates may be lower than previously acknowledged and that effects of warming on food web stability largely depend on species interactions.
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| 39. |
- Lindmark, Max, et al.
(författare)
-
Temperature-dependent body size effects determine population responses to climate warming
- 2018
-
Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 21, s. 181-189
-
Tidskriftsartikel (refereegranskat)abstract
- Current understanding of animal population responses to rising temperatures is based on the assumption that biological rates such as metabolism, which governs fundamental ecological processes, scale independently with body size and temperature, despite empirical evidence for interactive effects. Here, we investigate the consequences of interactive temperature- and size scaling of vital rates for the dynamics of populations experiencing warming using a stage-structured consumer-resource model. We show that interactive scaling alters population and stage-specific responses to rising temperatures, such that warming can induce shifts in population regulation and stage-structure, influence community structure and govern population responses to mortality. Analysing experimental data for 20 fish species, we found size-temperature interactions in intraspecific scaling of metabolic rate to be common. Given the evidence for size-temperature interactions and the ubiquity of size structure in animal populations, we argue that accounting for size-specific temperature effects is pivotal for understanding how warming affects animal populations and communities.
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| 40. |
- Niiranen, Susa, 1982-
(författare)
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Baltic Sea food web dynamics and response to environmental change
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Baltic Sea ecosystem is subject to a combination of external pressures such as fishery, changing climate and land-based nutrient inputs. In combination with internal food web mechanisms these external forces can lead to changes in the food web structure and function. In this licentiate thesis a new Baltic Sea Ecopath with Ecosim food web model for the open Baltic Proper (BaltProWeb) is introduced as a tool to study the past (1974-2006) food web dynamics (paper 1) and the sensitivity of this model to data uncertainties is analyzed (paper 2). BaltProWeb includes 22 functional groups from phytoplankton to top-predators, is calibrated with biomass data across trophic levels and can accommodate external forcing such as fishery and environmental change. The model can reproduce the main trends observed in the biomass development of most Baltic Proper functional groups as well as the late 1980s ecosystem reorganization, or regime shift, from the cod (Gadus morhua) dominated state into the sprat (Sprattus sprattus) dominated one. In addition to changes in the functional group biomasses, changes in ecosystem flows were observed. For example the energy flow from the benthic system into the pelagic one (via cod diet) was large during the pre-regime shift period, but decreased in importance after the sharp post-regime shift increase in the sprat biomass. The proportions of both clupeid and zooplankton production required to support the Baltic Sea fisheries were large throughout the model run suggesting that fisheries have potential to be an ecosystem structuring actor in the Baltic Proper. Successful reproduction of the past biomass dynamics required the inclusion of fishery and environmental forcing together with appropriate trophic control during the calibration process. This finding motivates to develop ecosystem models that can incorporate both external pressures as well as internal ecosystem dynamics. The BaltProWeb model turned out to be sensitive to uncertainty in both model input data (1974 biomasses) as well as environmental forcing functions used. The functional groups the parameterization of which the model was most sensitive to were, in decreasing order of importance, (i) 2-3 year old cod, (ii) adult sprat, (iii) macrozoobenthos, (iv) Pseudocalanus sp. and (v) other mesozooplankton. Changing the initial biomass values of these groups within the boundaries of input data uncertainty (measured as coefficients of variation) together with model recalibration resulted in a set of new Ecosim models with a rather large range in model fit, biomass projections and trophic control. When future (2007-2100) fishery and climate change scenarios were run using the different models, and by this way taking the uncertainties in the input data into account, the range of model outcomes was yet larger than observed during the calibration period (1974-2006). This indicates that model uncertainties cannot be ignored when modeling results are used as basis for ecosystem management. Further, the results highlight that evaluating the model only based on the model fit with data is not sufficient, but also studying the realized trophic control of different models is crucial and that sensitivity analysis can actually be one tool to study possible trophic control mechanisms with. This sensitivity study gave valuable information about both the model sensitivity and the need to communicate the uncertainties when the BaltProWeb model is used in the project ECOSUPPORT to project the future climate change effects on the Baltic Sea ecosystem.
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| 41. |
- Niu, Jingyao, et al.
(författare)
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Decades of warming alters maturation and reproductive investment in fish
- 2023
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Ingår i: Ecosphere. - : Wiley. - 2150-8925. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- How does warming affect maturation and reproductive investment in ectotherms? Younger age and smaller size at maturation, as well as altered reproduction processes, have been found in a few species subjected to elevated temperatures. These observations, however, come from studies that do not distinguish effects of warming on maturation from those on growth, are also restricted to single generation responses to warming, or have additional stressors besides warming in the study system. Here, we study warming effects on maturation and reproductive investment in wild, unexploited fish populations using a whole-ecosystem heating experiment. The experiment is conducted on Eurasian perch (Perca fluviatilis) in a heated and control area (with > 5 degrees C temperature difference) in the Baltic Sea. We compare female perch size at maturation using estimated probabilistic maturation reaction norms (PMRNs) and the gonado-somatic index over 17 years of heating, spanning approximately five to eight perch generations. Using the PMRN approach, we show that warming has substantial effects on maturation size independent of warming-induced changes in body growth. We found that young fish mature at a smaller size and invest more in developing their gonads in the heated population than in the unheated population. Our findings suggest that warming effects on reproductive investment may initially compensate for the cost of warming-induced decrease in maturation size caused by the trade-off between early maturation and size-dependent fecundity. After multiple additional generations of warming, maturation and reproduction traits in perch differed from those in the first generations following the onset of warming, which suggests that warming-induced evolution may have occurred. Our study is particularly relevant in the context of climate change because of the unusually large temperature difference between the areas and the fact that the heating occurred on an ecosystem level. We call for experimental studies resolving mechanisms of trait responses to warming across generations, complemented with genomic analyses, to aid understanding of organisms' long-term responses to climate change.
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| 42. |
- Nour, Eiman, et al.
(författare)
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Low-Frequency Self-Powered Footstep Sensor Based on ZnO Nanowires on Paper Substrate
- 2016
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Ingår i: Nanoscale Research Letters. - : Springer Science and Business Media LLC. - 1931-7573 .- 1556-276X. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we design and fabricate a wireless system with the main operating device based on zinc oxide (ZnO) nanowires. The main operating device is based on piezoelectric nanogenerator (NG) achieved using ZnO nanowires grown hydrothermally on paper substrate. The fabricated NG is capable of harvesting ambient mechanical energy from various kinds of human motion, e.g., footsteps. The harvested electric output has been used to serve as a self-powered pressure sensor. Without any storage device, the signal from a single footstep has successfully triggered a wireless sensor node circuit. This study demonstrates the feasibility of using ZnO nanowire piezoelectric NG as a low-frequency self-powered sensor, with potential applications in wireless sensor networks.
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| 43. |
- Otto, Saskia A., et al.
(författare)
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Ekosystembaserad utveckling av indikatorer för pelagiska födovävar
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Utveckling av indikatorer under EU:s ramdirektiv om en marin strategi, Havsmiljödirektivet, är en särskild utmaning när det gäller födovävar. Dessa indikatorer ska helst beskriva tillståndet i ett marint system, trots att sådana system är dynamiska och har komplexa interaktioner som ofta är icke-linjära. Havsområden som karaktäriseras av tydliga miljögradienter, som exempelvis Östersjön, medför ytterligare svårighet vid bedömningar av systemets tillstånd, eftersom det är nödvändigt att känna till hur pass relevanta indikatorerna är över hela spannet av miljöförhållanden som finns i området. Robusta tester och utvärderingar av indikatorerna är därför nödvändiga, särskilt för att undersöka hur de svarar på samtidiga påverkansvariabler och hur olika indikatorer är länkade genom artinteraktioner. I detta projekt använde vi flera olika metoder för att på ett robust sätt testa indikatorer för pelagiska födovävar i flera utsjöregioner i Östersjön: Bornholmsbassängen, Gotlandsbassängen, och Bottenhavet. Arbetet organiserades i tre delprojekt.I delprojekt 1 utvecklade vi ett modellbaserat ramverk där enskilda indikatorer testades mot enskilda påverkansvariabler, som till exempel koncentration av näringsämnen och fiskeintensitet. Detta möjliggjorde utvärdering av indikatorerna med avseende på deras sensitivitet, robusthet och specificitet. Med hjälp av ramverket kunde vi jämföra sex djurplanktonbaserade födovävsindikatorer och sju fiskbaserade födovävsindikatorer i två bassänger i Östersjön (Bornholmsbassängen och Gotlandsbassängen), medan i Bottenhavet jämfördes sex djurplanktonbaserade indikatorer (i detta område saknas längre tidsserier för fisk). De indikatorer som fick bäst resultat, inklusive de två tidigare föreslagna indikatorerna (’HELCOM core indicators’) baserade på djurplankton: Total djurplanktonförekomst (Total Zooplankton Abundance, TZA) och Medelstorlek av djurplankton (Mean Size, MS), analyserades vidare för att förstå eventuellt samspeloch påverkan mellan indikatorer.Två metoder för att testa indikatorer utvecklades för att kunna förstå och kvantifiera kopplingen mellan indikatorer orsakade av interaktioner (samspel) mellan olika arter, samt hur förhållandet mellan indikatorer och påverkansvariabler ser ut när hänsyns tas till indikatorernas koppling pga samspel mellan arter. Dessa metoder tillämpades sedan på olika typer av födovävsindikatorer på två samspelande nivåer i födoväven (delprojekt 2, storleksbaserade indikatorer samt mängd av fiskätande fisk och av bytesfiskar) och på tre samspelande nivåer (delprojekt 3, olika fisk och djurplanktonbaserade indikatorer) i Bornholmsbassängen och Gotlandsbassängen.Länkar mellan födovävsindikatorer från olika trofinivåer, som beror på de olika arternas samspel, var nödvändiga att ta hänsyn till för att kunna förklara hur dessa indikatorer varierade över tid. Detta visades i analyser av födovävsindikatorerna baserade på torsk Gadus morhua, en rovfisk, och i de indikatorer baserade på dess huvudsakliga bytesdjur skarpsill Sprattus sprattus och strömming Clupea harengus i Bornholmsbassängen, där både länkar (som motsvarar samspelet mellan rovdjur och byten) samt täthetsberoende effekter inom varje art behövde inkluderas för att förklara variationen i dessa pelagiska födovävsindikatorer från 1980-talet fram till 2012. Detta gällde för både abundans- och storleksbaserade indikatorer, men variationen över tid kunde förklaras bättre för de förstnämnda (testade 1979-2012) än de senare (testade 1984-2012). Vi lyckades inte anpassa någon statistiskt säkerställd modell för dessa två typer av indikatorer i Gotlandsbassängen, där mängden oförklarad variation förblev stor. När indikatorer testades på tre samspelande trofinivåer med en annan metod visade även dessa analyser att indikatorer på olika trofinivåer ofta påverkade varandra. Robusta modeller som förklarade variationen över tid kunde utvecklas för de djurplanktonbaserade indikatorerna (i båda bassängerna) och för indikatorn baserad på rovfisk (torsk) i Bornholmsbassängen. Utvecklingen över tid för storleksbaserade fiskindikatorerna förklarades sämre av modellerna än för de andra indikatorerna också i denna testmetod.Båda typerna av analyser i delprojekt 2 och 3 (två och tre samspelande nivåer i födoväven) visade att indikatorerna i allmänhet svarade mot ett flertal påverkansvariabler snarare än en enda, och att dessa var variabler kopplade till klimat, fiske och koncentration av näringsämnen eller primärproduktion. I studierna av två samspelande nivåer i födoväven, i detta fall de olika fiskbaserade indikatorerna, var salthalt, temperatur och syreförhållanden samt näringsämnen väsentliga för att kunna förklara utvecklingen av indikatorerna över tid. När tre samspelande nivåer i födoväven studerades – dvs. när djurplanktonbaserade indikatorer även var med i analysen – hade klimatvariabler ofta en starkare effekt på indikatorerna än fiske och primärproduktion. Detta belyser vikten av att ta hänsyn till klimatförändring när indikatorer tolkas och används till utvärdering av förvaltningsinsatser. Indikatorernas svar på externa påverkansvariabler var i många fall icke-linjära och berodde i vissa fall på nivån av en annan påverkansvariabel. Detta visar på nyttan med avancerade modellverktyg som kan fånga upp den relevanta dynamiken i system som karakteriseras av olika tillstånd (där olika orsakssamband kan gälla under olika tillstånd, s.k. ’alternativa regimer’).Projektets resultat utgör de första stegen mot en bedömning av födovävarnas nuvarande status, baserat på bassängspecifika uppsättningar av välfungerande fiskoch djurplanktonbaserade födovävsindikatorer. Våra resultat visar att (1) kopplingar mellan olika indikatorer, som uppkommer genom samspel mellan arter på olika nivåer i födoväven, bör beaktas i arbetet med att utveckla indikatorer för födovävar, (2) indikatorer för pelagiska födovävar som representerar djurplankton, planktonätande fisk och fiskätande fisk svarar alla mot flera samtidiga påverkansvariabler och (3) variationen över tid i variabler relaterade till fiske, övergödning (primärproduktion och näringsämnen) och klimatförändring förklarade indikatorernas historiska utveckling (1979/1984-2012).Det fanns ett fåtal skillnader mellan de olika metodernas resultat vad gäller de specifika sambanden mellan indikatorer och påverkansvariabler, men vi bedömer de samband som identifierats av minst två metoder som tillförlitliga. Dessa påverkansvariabler anses därför som de huvudsakliga. Det var dock inte alla indikatorer som hade statistiskt tillförlitliga samband till påverkansvariabler, varken inom en metod eller vid jämförelser mellan metoder. Därför är det ett urval av indikatorer som vi rekommenderar, givet det underliggande datamaterialet och provtagningsförfarandet.Vi rekommenderar att följande indikatorer används till riskanalyser eller utvärdering av förvaltningsalternativ för pelagiska födovävar i de studerade områdena, inom Havsmiljödirektivet:• För Bornholmsbassängen: Total djurplanktonförekomst (Total Zooplankton Abundance, TZA), förhållandet mellan hinnkräftor och hoppkräftor (Ratio Cladocerans to Copepods, RCC), skarpsill (Sprat), strömming (Herring), samt torsk (Cod).• För Gotlandsbassängen: Medelstorlek av djurplankton (Mean Size, MS), förhållandet mellan hinnkräftor och hoppkräftor (Ratio Cladocerans to Copepods, RCC), skarpsill (Sprat), strömming (Herring), samt torsk (Cod).• För Bottenhavet (där långsiktiga fiskdata saknas): Total djurplanktonförekomst (Total Zooplankton Abundance, TZA), Medelstorlek av djurplankton (Mean Size, MS) samt hoppkräftsbiomassa (Cops).
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| 44. |
- Ozerov, Mikhail, et al.
(författare)
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Whole-genome sequencing illuminates multifaceted targets of selection to humic substances in Eurasian perch
- 2022
-
Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 31, s. 2367-2383
-
Tidskriftsartikel (refereegranskat)abstract
- Extreme environments are inhospitable to the majority of species, but some organisms are able to survive in such hostile conditions due to evolutionary adaptations. For example, modern bony fishes have colonized various aquatic environments, including perpetually dark, hypoxic, hypersaline and toxic habitats. Eurasian perch (Perca fluviatilis) is among the few fish species of northern latitudes that is able to live in very acidic humic lakes. Such lakes represent almost "nocturnal" environments; they contain high levels of dissolved organic matter, which in addition to creating a challenging visual environment, also affects a large number of other habitat parameters and biotic interactions. To reveal the genomic targets of humic-associated selection, we performed whole-genome sequencing of perch originating from 16 humic and 16 clear-water lakes in northern Europe. We identified over 800,000 single nucleotide polymorphisms, of which >10,000 were identified as potential candidates under selection (associated with >3000 genes) using multiple outlier approaches. Our findings suggest that adaptation to the humic environment may involve hundreds of regions scattered across the genome. Putative signals of adaptation were detected in genes and gene families with diverse functions, including organism development and ion transportation. The observed excess of variants under selection in regulatory regions highlights the importance of adaptive evolution via regulatory elements, rather than via protein sequence modification. Our study demonstrates the power of whole-genome analysis to illuminate the multifaceted nature of humic adaptation and provides the foundation for further investigation of causal mutations underlying phenotypic traits of ecological and evolutionary importance.
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| 45. |
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| 46. |
- Tanash, Hanan A., et al.
(författare)
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Burn injury during long-term oxygen therapy in Denmark and Sweden : the potential role of smoking
- 2017
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Ingår i: The International Journal of Chronic Obstructive Pulmonary Disease. - 1176-9106 .- 1178-2005. ; 12, s. 193-197
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Long-term oxygen therapy (LTOT) increases life expectancy in patients with COPD and severe hypoxemia. Smoking is the main cause of burn injury during LTOT. Policy regarding smoking while on LTOT varies between countries. In this study, we compare the incidence of burn injury that required contact with a health care specialist, between Sweden (a country with a strict policy regarding smoking while on LTOT) and Denmark (a country with less strict smoking policy). Methods: This was a population-based, cohort study of patients initiating LTOT due to any cause in Sweden and Denmark. Data on diagnoses, external causes, and procedures were obtained from the Swedish and Danish National Patient Registers for inpatient and outpatient care. Patients were followed from January 1, 2000, until the first of the following: LTOT withdrawal, death, or study end (December 31, 2009). The primary end point was burn injury during LTOT. Results: A total of 23,741 patients received LTOT in Denmark and 7,754 patients in Sweden. Most patients started LTOT due to COPD, both in Sweden (74%) and in Denmark (62%). The rate of burn injury while on LTOT was higher in Denmark than in Sweden; 170 (95% confidence interval [CI], 126-225) vs 85 (95% CI, 44-148) per 100,000 person-years; rate ratio 2.0 (95% CI, 1.0-4.1). The risk remained higher after adjustment for gender, age, and diagnosis in multivariate Cox regression, hazard ratio 1.8 (95% CI, 1.0-3.5). Thirty-day mortality after burn injury was 8% in both countries. Conclusion: Compared to Sweden, the rate of burn injury was twice as high in Denmark where smoking is not a contraindication for prescribing LTOT.
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| 47. |
- Tanash, Hanan, et al.
(författare)
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The risk of burn injury during long-term oxygen therapy : a 17-year longitudinal national study in Sweden
- 2015
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Ingår i: The International Journal of Chronic Obstructive Pulmonary Disease. - 1176-9106 .- 1178-2005. ; 10, s. 2479-2484
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Long-term oxygen therapy (LTOT) improves the survival time in hypoxemic chronic obstructive pulmonary disease. Despite warnings about potential dangers, a considerable number of patients continue to smoke while on LTOT. The incidence of burn injuries related to LTOT is unknown. The aim of this study was to estimate the rate of burn injury requiring health care contact during LTOT. Methods: Prospective, population-based, consecutive cohort study of people starting LTOT from any cause between January 1, 1992 and December 31, 2009 in the Swedish National Register of Respiratory Failure (Swedevox). Results: In total, 12,497 patients (53% women) were included. The mean (standard deviation) age was 72 +/- 9 years. The main reasons for starting LTOT were chronic obstructive pulmonary disease (75%) and pulmonary fibrosis (15%). Only 269 (2%) were active smokers when LTOT was initiated. The median follow-up time to event was 1.5 years (interquartile range, 0.55-3.1). In total, 17 patients had a diagnosed burn injury during 27,890 person-years of LTOT. The rate of burn injury was 61 (95% confidence interval, 36-98) per 100,000 person-years. There was no statistically significant difference in the rate of burn injury between ever-smokers and never-smokers, or between men and women. Conclusion: The rate of burn injuries in patients on LTOT seems to be low in Sweden. The strict requirements in Sweden for smoking cessation before LTOT initiation may contribute to this finding.
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| 48. |
- Thunell, Viktor, et al.
(författare)
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Optimal energy allocation trade-off driven by size-dependent physiological and demographic responses to warming
- 2023
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 104
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Tidskriftsartikel (refereegranskat)abstract
- Body size-dependent physiological effects of temperature influence individual growth, reproduction, and survival, which govern animal population responses to global warming. Considerable knowledge has been established on how such effects can affect population growth and size structure, but less is known of their potential role in temperature-driven adaptation in life-history traits. In this study, we ask how warming affects the optimal allocation of energy between growth and reproduction and disentangle the underlying fitness trade-offs. To this end, we develop a novel dynamic energy budget integral projection model (DEB-IPM), linking individuals' size- and temperature-dependent consumption and maintenance via somatic growth, reproduction, and size-dependent energy allocation to emergent population responses. At the population level, we calculate the long-term population growth rate (fitness) and stable size structure emerging from demographic processes. Applying the model to an example of pike (Esox lucius), we find that optimal energy allocation to growth decreases with warming. Furthermore, we demonstrate how growth, fecundity, and survival contribute to this change in optimal allocation. Higher energy allocation to somatic growth at low temperatures increases fitness through survival of small individuals and through the reproduction of larger individuals. In contrast, at high temperatures, increased allocation to reproduction is favored because warming induces faster somatic growth of small individuals and increased fecundity but reduced growth and higher mortality of larger individuals. Reduced optimum allocation to growth leads to further reductions in body size and an increasingly truncated population size structure with warming. Our study demonstrates how, by incorporating general physiological mechanisms driving the temperature dependence of life-history traits, the DEB-IPM framework is useful for investigating the adaptation of size-structured organisms to warming.
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| 49. |
- Torres, Marian, et al.
(författare)
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Food-web indicators accounting for species interactions respond to multiple pressures
- 2017
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Ingår i: Ecological Indicators. - : Elsevier BV. - 1470-160X .- 1872-7034. ; 77, s. 67-79
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Tidskriftsartikel (refereegranskat)abstract
- Food-web indicators for marine management are required to describe the functioning and structure of marine food-webs. In Europe, the Marine Strategy Framework Directive (MSFD), intended to lead to a 'good environmental status' of the marine waters, requires indicators of the status of the marine environment that also respond to manageable anthropogenic pressures. Identifying such relationships to pressures is particularly challenging for food-web indicators, as they need to be disentangled from linkages between indicators of different functional groups caused by species interactions. Still, such linkages have not been handled in the indicator development. Here we used multivariate autoregressive time series models to identify how fish indicators in an exploited food-web relate to fishing, climate and eutrophication, while accounting for the linkages between indicators caused by species interactions. We assembled 31-year long time series of indicators of key functional groups of fish in the Central Baltic Sea pelagic food-web, which is characterized by strong trophic links between cod (Gadus morhua) and its main fish prey sprat (Sprattus sprattus) and herring (Clupea harengus). These food-web indicators were either abundance-based indicators of key piscivores (cod) and zooplanktivores (sprat and herring) or size-based indicators of the corresponding trophic groups (biomass of large predatory fish (cod >= 38 cm) and biomass of small prey fish (sprat and herring <10 cm)). Comparative analyses of models with and without linkages among indicators showed that for both types of indicators, linkages corresponding to predator-prey feedbacks and intra-specific density-dependence were essential to explain temporal variation in the indicators. Thus, no indicator-pressure relationships could be found that explained the indicators' variation unless such linkages were accounted for. When accounting for these, we found that the indicators overall respond to multiple pressures acting simultaneously rather than to single pressures, as no pressure alone could explain how the indicators developed over time. The manageable pressures fishing and eutrophication, as well as the prevailing hydrological conditions influenced by climate, were all needed to reproduce the inter-annual changes in these food-web indicators combined, although individual relationships differed between the indicators. We conclude that our innovative indicator-testing framework can therefore be used to identify responses of food-web indicators to manageable pressures while accounting for the biotic interactions in food-webs linking such indicators.
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| 50. |
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