| 1. |
- Berg, Sofia, et al.
(författare)
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Ekologisk funktionalitet av värdekärnor för barrskogar inom Västra Götalands län : Ett strategiskt underlag för planering av förändrad skogsskötsel av barrskogsområden inom Västra Götalands län i syfte att stärka skogarnas förutsättningar att stödja biologisk mångfald och skogens klimatnytta
- 2022
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Rapport (populärvet., debatt m.m.)abstract
- Skogsstyrelsen redovisar i sin utvärdering av miljömålet Levande skogar 2019 att centrala hinder för uppfyllelse av miljömålet är minskande och fragmenterade livsmiljöer och minskande och/eller små populationer av ett antal hotade arter knutna till skogsekosystemet. En väg framåt för att vända denna trend är att framtidens skogsbruk bland annat bör utvecklas utifrån ett landskapsperspektiv och där hyggesfria skogsbruksmetoder ökar i omfattning.Länsstyrelserna i Sverige har genom sitt arbete med regionala handlingsplaner för grön infrastruktur identifierat så kallade värdekärnor – områden av stor betydelse för skogsarternas överlevnad. I denna studie har Västra Götalands läns värdekärnor analyserats med avseende på deras förmåga att stödja biologisk mångfald i ett landskapsperspektiv. Arbetet har gjorts i samverkan med Länsstyrelsen för Västra götalands län.Metoden som använts är Biotope Biodiversity Capacity Indicator (BBCI). Metoden har utvecklats inom forskningsprojektet “Landscape biodiversity capacity: a tool for measuring, monitoring and managing” finansierat av Naturvårdsverkets miljöforskningsanslag (2019-2022).Resultaten visar vilka geografiskt avgränsade värdekärnor som idag har hög ekologisk funktionalitet och som utgör biologiska överlevnads- och spridningshotspots för arter knutna till barrskogar. Vidare visar resultaten att endast sju kommuner har BBCI-värden över 1, det vill säga, ett hållbart skogslandskap som kan hålla fokusarten i ett 100-årsperspektiv.För att nå de svenska miljömålen Levande skogar och Ett rikt växt- och djurliv samt skapa bättre förutsättningar för skogens biologiska mångfald att fortleva behöver nuvarande skogsmetoder med trakthyggesbruk anpassas till brukningsformer som tar större hänsyn till skogens ekosystem. Resultaten från denna studie kan ge prioriteringsunderlag för inom vilka produktionsskogar en så kallad återvildning genom förändrad brukningsmetod skulle kunna resultera i betydelsefull ökad ekologisk funktionalitet på landskapsnivå för de västgötska barrskogarna.
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| 2. |
- Jonsson, Annie, et al.
(författare)
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Landskapets förmåga att hålla biologisk mångfald : – en indikator för biologisk mångfald och ett planeringsverktyg för prioritering av markanvändning
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten beskriver ett nytt verktyg framtaget för att underlätta planering av grön infrastruktur på landskapsnivå och ger via fallstudier exempel på hur verktyget kan användas. Projektet har utförts i ett samarbete med expertis inom teoretisk ekologi, ekologi, biodiversitetsinformatik och tillämpad matematik.Forskningsprojektet har utvecklat en modell för att uppskatta ett landskaps för-måga att hålla biologisk mångfald i dess olika biotoper (Biotope Biodiversity Capacity Indicator, BBCI). Ett teoretiskt ramverk baserat på ekologisk kunskap har tagits fram som grund för modellen.Syftet med BBCI är att modellen ska kunna användas som ett planeringsverktyg för att:stärka biologisk mångfald i ett landskap,förbättra förutsättningarna för arter att använda hela landskapet ochskapa bättre förutsättningar för hänsyn till biologisk mångfald i samband med samhällsutveckling.För att testa och beskriva verktygets användbarhet har fyra fallstudier genomförts med olika fokus:Analys av fragmenteringen i ett barrskogslandskap som sköts med särskild naturhänsyn i Västernorrlands län.Analys av barrskogsvärdekärnors kapacitet för biologisk mångfald inom Västra Götalands län som synliggör vikten av kommunöverskridande samverkan.Analys av potentiella målkonflikter mellan två biotoper, ädellövskog och öppen mark med skyddsvärda träd i Valle.Analys av kapacitet för biologisk mångfald hos äldre ädellövträd i ett landskap mixat med urbana miljöer och landsbygd, Mjölby kommun.Parallellt med utvcklingen av BBCI har en tät dialog och samverkan skett med olika intressenter och slutanvändare. Den breda dialogen har medfört ett effektivt kun-skapsutbyte mellan olika parter.Rapporten avslutas med att beskriva utmaningar och verktygets utvecklings-potential både avseende pedagogik och teknik men även hur modellen kan byggas på och utvecklas med ytterligare funktioner för en breddad tillämpning.
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| 3. |
- Jonsson, Annie, et al.
(författare)
-
Utvärdering av Hornborgasjöns restaurering : måluppfyllelse och effekter på biologisk mångfald med fokus på vegetation och fågelfauna
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Hornborgasjön räknas idag som en av Sveriges rikaste fågelsjöar och är internationellt utpekad som en av Sveriges värdefullaste våtmarker. Sjön har stor betydelse som både rast- och häckplats för en mängd fågelarter. Området är också av stort intresse för friluftslivet och som ett levande kulturlandskap. Under de senaste 150 åren har Hornborgasjön genomgått stora förändringar. En serie av sjösänkningar under 1800 och 1900-talen ledde till kraftig igenväxning och följdes av ett storskaligt restaureringsprojekt i senare tid. Syftet med Hornborgasjöns restaurering var att säkerställa Hornborgasjöns framtid som fågelsjö. Restaureringen är ett av Sveriges största naturvårdsprojekt. I denna rapport har vi utvärderat hur Hornborgasjöns restaurering påverkat vegetation och fågelfauna. Syftet var att analysera om och till vilken grad de biologiska målen med restaureringen uppnåtts.För att utvärdera måluppfyllelsen har vi i första hand jämfört olika naturtypers utbredning mellan åren 1905 och 2010 samt förändringar i fågelfaunan under flera tidsperioder. Analyser av vegetationskartor visar att vass- och buskområden kraftigt reducerats och att en stor öppen vattenspegel och omgivande mader återskapats. Våtmarksfåglarnas numerär har generellt sett återhämtat sig från igenväxningsperioden och är för vissa arter till och med större än vid förra sekelskiftet. För vissa naturtyper och fågelarter, som till exempel vassområden och häckande vadare, är dagens situation dock inte i linje med målen. Det står ändå klart att det övergripande målet och många av de mer specifika delmålen har uppfyllts så att Hornborgasjön idag är en levande våtmark med stort antal häckande och rastande fågelarter.I analyser av fågeldata från senare tid finns indikationer på negativa trender som man behöver vara observant på för att för framtiden säkra en biologiskt rik Hornborgasjö. En utmaning för denna utvärdering har dock varit bristen på högkvalitativa och jämförbara data att basera analyserna på. Vi belyser därför vikten av att ha ett fungerande övervakningssystem som kontinuerligt följer upp statusen i ekosystemet.
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| 4. |
- Jonsson, Tomas, et al.
(författare)
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Food web structure affects the extinction risk of species in ecological communities
- 2006
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Ingår i: Ecological Modelling. - : Elsevier. - 0304-3800 .- 1872-7026. ; 199:1, s. 93-106
-
Tidskriftsartikel (refereegranskat)abstract
- This paper studies the effect of food web structure on the extinction risk of species. We examine 793 different six-species food web structures with different number, position and strength of trophic links and expose them to stochasticity in a model with Lotka–Volterra predator–prey dynamics. The characteristics of species (intrinsic rates of increase as well as intraspecific density dependence) are held constant, but the interactions with other species and characteristics of the food web are varied.Extinctions of producer species occurred but were rare. Species at all trophic levels went extinct in communities with strong interactions as compared to communities with no strong interactions where only the secondary consumer went extinct. Extinction of a species directly involved in a strong interaction was more frequent than extinctions of species not directly involved in strong interactions (here termed direct and indirect extinctions, respectively). In model webs where both direct and indirect extinctions occurred, roughly 20% were indirect extinctions. The probability of indirect extinctions decreased with number of links. It is concluded that not just the presence of strong interactions but also their position and direction can have profound effects on extinction risk of species.Three principal components, based on 11 different food web metrics, explained 76.6% of the variation in trophic structure among food webs that differed in the number and position, but not strength, of trophic links. The extinction risk of consumer species was closely correlated to at least two of the three principal components, indicating that extinction risk of consumer species were affected by food web structure. The existence of a relationship between food web structure and extinction risk of a species was confirmed by a regression tree analysis and a complementary log-linear analysis. These analyses showed that extinction of consumer species were affected by the position of strong interactions and a varying number of other food web metrics, different for intermediate and top species. Furthermore, the degree to which the equilibrium abundance of a species is affected by a press perturbation is an indication of the risk of extinction that this species faces when exposed to environmental stochasticity. It is concluded that extinction risk of a species is determined in a complicated way by an interaction among species characteristics, food web structure and the type of disturbance.
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| 5. |
- Jonsson, Tomas, et al.
(författare)
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Trophic interactions affect the population dynamics and risk of extinction of basal species in food webs
- 2010
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Ingår i: Ecological Complexity. - : Elsevier. - 1476-945X .- 1476-9840. ; 7:1, s. 60-68
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses effects of trophic complexity on basal species, in a Lotka–Volterra model with stochasticity. We use simple food web modules, with three trophic levels, and expose every species to random environmental stochasticity and analyze (1) the effect of the position of strong trophic interactions on temporal fluctuations in basal species’ abundances and (2) the relationship between fluctuation patterns and extinction risk. First, the numerical simulations showed that basal species do not simply track the environment, i.e. species dynamics do not simply mirror the characteristics of the applied environmental stochasticity. Second, the extinction risk of species was related to the fluctuation patterns of the species.More specifically, we show (i) that despite being forced by random stochasticity without temporal autocorrelation (i.e. white noise), there is significant temporal autocorrelation in the time series of all basal species’ abundances (i.e. the spectra of basal species are red-shifted), (ii) the degree of temporal autocorrelation in basal species time series is affected by food web structure and (iii) the degree of temporal autocorrelation tend to be correlated to the extinction risks of basal species.Our results emphasize the role of food web structure and species interactions in modifying the response of species to environmental variability. To shed some light on the mechanisms we compare the observed pattern in abundances of basal species with analytically predicted patterns and show that the change in the predicted pattern due to the addition of strong trophic interactions is correlated to the extinction risk of the basal species. We conclude that much remain to be understood about the mechanisms behind the interaction among environmental variability, species interactions, population dynamics and vulnerability before we quantitatively can predict, for example, effects of climate change on species and ecological communities. Here, however, we point out a new possible approach for identifying species that are vulnerable to environmental stochasticity by checking the degree of temporal autocorrelation in the time series of species. Increased autocorrelation in population fluctuations can be an indication of increased extinction risk.
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| 6. |
- Karlsson, Patrik, et al.
(författare)
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Food web structure and interaction strength pave the way for vulnerability to extinction
- 2007
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Ingår i: Journal of Theoretical Biology. - : Elsevier. - 0022-5193 .- 1095-8541. ; 249:1, s. 77-92
-
Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on how food web structure and interactions among species affects the vulnerability, due to environmental variability, to extinction of species at different positions in model food webs. Vulnerability is here not measured by a traditional extinction threshold but is instead inspired by the IUCN criteria for endangered species: an observed rapid decline in population abundance. Using model webs influenced by stochasticity with zero autocorrelation, we investigate the ecological determinants of species vulnerability, i.e. the trophic interactions between species and food web structure and how these interact with the risk of sudden drops in abundance of species. We find that (i) producers fulfil the criterion of vulnerable species more frequently than other species, (ii) food web structure is related to vulnerability, and (iii) the vulnerability of species is greater when involved in a strong trophic interaction than when not. We note that our result on the relationship between extinction risk and trophic position of species contradict previous suggestions and argue that the main reason for the discrepancy probably is due to the fact that we study the vulnerability to environmental stochasticity and not extinction risk due to overexploitation, habitat destruction or interactions with introduced species. Thus, we suggest that the vulnerability of species to environmental stochasticity may be differently related to trophic position than the vulnerability of species to other factors.Earlier research on species extinctions has looked for intrinsic traits of species that correlate with increased vulnerability to extinction. However, to fully understand the extinction process we must also consider that species interactions may affect vulnerability and that not all extinctions are the result of long, gradual reductions in species abundances. Under environmental stochasticity (which importance frequently is assumed to increase as a result of climate change) and direct and indirect interactions with other species some extinctions may occur rapidly and apparently unexpectedly. To identify the first declines of population abundances that may escalate and lead to extinctions as early as possible, we need to recognize which species are at greatest risk of entering such dangerous routes and under what circumstances. This new perspective may contribute to our understanding of the processes leading to extinction of populations and eventually species. This is especially urgent in the light of the current biodiversity crisis where a large fraction of the world's biodiversity is threatened.
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| 7. |
- Roos, Henrik, et al.
(författare)
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Identification of patches with high ecological importance of broadleaved forests and open lands with valuable trees in Valle : Using a biodiversity capacity landscape metric, combining area and connectivity, to examining management options
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This study is a complement to previous studies of regional action plans of green infrastructure in Valle (County Administrative Board 2016; County Administrative Board 2019). The aim was to identify the relative importance of biotope patches of broadleaved forest and open lands with valuable trees, respectively, in Valle for the maintenance and enhancement of biodiversity. A testversion of the method Biotope Biodiversity Capacity Indicator (BBCI) was applied on the two biotopes of broadleaved forest and open lands with valuable trees in Valle. BBCI was developed within the project “Landscape biodiversity capacity: a tool for measuring, monitoring and managing” financed by the Swedish Environmental Protection Agency, Miljövårdsanslaget (2019-2021).The results of the BBCI-analysis identified hotspots areas for the two studied biotopes in Valle, that is, areas with important patches for the sustainability of BBCI. For broadleaved forest, the northern part of Valle stands out as highly importantand for open lands with valuable trees the south-southwest parts of Valle stands out as the most important area. In this study, effects on BBCI from restauration of broadleaved forests to open land with valuable trees was evaluated. Calculations of BBCI shows encouraging results of an increased capacity for biodiversity of the biotope with open lands with valuable trees but not a significant decrease in biodiversity capacity of broadleaved forest, despite the area losses and fragmentation caused from the restauration. Both biotopes have BBCI values above one, showing that they are sustainable within a 100 year period. The result can be used as support to management plans of nature reserves in a landscape setting and as recommendations or advice to private land owners. Moreover, the study was produced within the work of BIOGOV, where regional action plans for nature, tourisms, culture and small enterprises were under development.
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| 8. |
- Berg, Sofia, et al.
(författare)
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Analys av grön infrastruktur för barrnaturskog inom projektområde för planerad vindpark vid Trollugnsberget
- 2023
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten presenterar och redovisar ett kunskapsunderlag om förutsättningar för biologisk mångfald knuten till barrnaturskog inom och i närområdet av projektområde för vindkraftspark Trollugnsberget i Smedjebackens kommun. Utifrån underlaget kan OX2 prioritera markanvändning och arbeta för att bibehålla och utveckla en grön infrastruktur som bidrar till att uppfylla miljökvalitetsmålen Ett rikt växt- och djurliv samt Levande skogar.Kunskapsunderlaget har tagits fram med en ny metod benämnt Biotope Biodiversity Capacity Indicator (BBCI). BBCI är en indikator som uppskattar ett biotoplandskaps förmåga att hålla biologisk mångfald. Metodutveckling har finansierats av Naturvårdsverkets miljöforskningsanslag och framtagning av det specifika underlaget och analyserna i rapporten har finansierats av OX2.BBCI bygger på ekologisk kunskap om hur landskapets struktur påverkar arters överlevnad och biologisk mångfald. Med hjälp av indikatorn kan man undersöka om i) landskapet som helhet är hållbart ur ett biologiskt mångfaldsperspektiv, ii) hur många och vilka patcher1 som inte är hållbara i sig själva och iii) hur känsligt landskapets biologiska mångfald är för negativ påverkan på specifika patcher och var en förstärkning skulle kunna göra störst nytta.BBCI har beräknats för barrnaturskog som finns inom projektområdet för vindparken samt i dess närhet. Som underlag och indata till biotoplandskapens struktur användes data från genomförd naturvärdesinventering samt från skogsbolagens nyckelbiotopsklassificering. I rapporten redovisas barrnaturskogens långsiktiga hållbarhet för biologisk mångfald och dess känslighet för tidsperspektivet 100 år. Beräkningar har gjorts utifrån två olika fokusarter2 där fokusart 1 har mindre arealkrav jämfört med fokusart 2. Resultaten visar att befintliga förekomster av barrnaturskog inte är hållbara i ett 100-årsperspektiv, varken för fokusart 1 eller 2. Åtgärder som stärker barrnaturskogens förutsättningar att hålla biologisk mångfald är därför att rekommendera.1 Patcher kallas de fragment eller avgränsade ytor som finns i landskapet och som består av den biotop som studeras. En patch är ett avgränsat fragment av biotopen som omges av andra typer av livsmiljöer än den som biotopen består av.2 BBCI bygger på modellering av fokusarter. En fokusarts möjlighet att fortleva i landskapet indikerar även att många andra arter, som är en del av det ekosystem fokusarten representerar, också kan fortleva i landskapet och därmed biologisk mångfald.
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| 9. |
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| 10. |
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| 11. |
- Ekelund Ugge, Gustaf Magnus Oskar, et al.
(författare)
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Evaluation of transcriptional biomarkers using a high-resolution regression approach : Concentration-dependence of selected transcripts in copper-exposed freshwater mussels (Anodonta anatina)
- 2022
-
Ingår i: Environmental Toxicology and Pharmacology. - : Elsevier. - 1382-6689 .- 1872-7077. ; 90
-
Tidskriftsartikel (refereegranskat)abstract
- We tested concentration-dependence of selected gene transcripts (cat, gst, hsp70, hsp90, mt and sod) for evaluation as biomarkers of chemical stress. Contrary to the common approach of factorial designs and few exposure concentrations, we used regression across a high-resolution concentration series. Specifically, freshwater mussels (Anodonta anatina) were acutely (96 h) exposed to Cu (13 nominal concentrations, measuring 0.13–1 600 µg/L), and transcripts were measured by RT-qPCR. In digestive glands, cat, hsp90 and mt decreased with water Cu (p < 0.05), but response magnitudes saturated at < 2-fold decreases. In gills, gst, hsp70, hsp90 and mt increased with water Cu (p < 0.05). While hsp70, hsp90 and mt exceeded 2-fold increases within the exposure range, high Cu concentrations were required (38–160 µg/L). Although gill responses were generally more robust compared to digestive glands, overall small response magnitudes and moderate sensitivity may set limit for potential application as general biomarkers of chemical stress.
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| 12. |
- Ekelund Ugge, Gustaf Magnus Oskar, et al.
(författare)
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Molecular biomarker responses in the freshwater mussel Anodonta anatina exposed to an industrial wastewater effluent
- 2022
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 29:2, s. 2158-2170
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Tidskriftsartikel (refereegranskat)abstract
- Using a selection of molecular biomarkers, we evaluated responses in freshwater mussels (Anodonta anatina) exposed to effluent from an industrial wastewater treatment facility. The aims of this work were to (1) assess biomarkers of general toxicity under sublethal exposure to an anthropogenic mixture of chemicals, represented by an arbitrary effluent, and (2) evaluate the potential of A. anatina as a bioindicator of pollution. Adult mussels (n = in total 32; 24 males and 8 females) were exposed (96 h) in the laboratory to a fixed dilution of effluent or to a control treatment of standardized freshwater. Metal concentrations were in general higher in the effluent, by an order of magnitude or more, compared to the control. Toxic unit estimates were used as proxies of chemical stress, and Cu, Ni, and Zn were identified as potential major contributors (Cu> Ni > Zn). Six transcriptional (cat, gst, hsp70, hsp90, mt, sod) and two biochemical (AChE, GST) biomarkers were analyzed in two tissues, gills, and digestive glands. Out of the 16 responses (eight biomarkers x two tissues), 14 effect sizes were small (within +/- 28 % of control) and differences non-significant (p > 0.05). Results did however show that (1) AChE activity increased by 40% in gills of exposed mussels compared to control, (2) hsp90 expression was 100% higher in exposed female gills compared to control, and (3) three marker signals (AChE in both tissues, and hsp70 in gills) differed between sexes, independent of treatment. Results highlight a need for further investigation of molecular biomarker variability and robustness in A. anatina.
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| 13. |
- Ekelund Ugge, Gustaf Magnus Oskar, et al.
(författare)
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Transcriptional and biochemical biomarker responses in a freshwater mussel (Anodonta anatina) under environmentally relevant Cu exposure
- 2020
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Ingår i: Environmental Science and Pollution Research. - : Springer Berlin/Heidelberg. - 0944-1344 .- 1614-7499. ; 27:9, s. 9999-10010
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Tidskriftsartikel (refereegranskat)abstract
- Molecular biomarkers, like gene transcripts or enzyme activities, are potentially powerful tools for early warning assessment of pollution. However, a thorough understanding of response and baseline variation is required to distinguish actual effects from pollution. Here, we assess the freshwater mussel Anodonta anatina as a biomarker model species for freshwater ecosystems, by testing responses of six transcriptional (cat, gst, hsp70, hsp90, mt, and sod) and two biochemical (AChE and GST) biomarkers to environmentally relevant Cu water concentrations. Mussels (n = 20), collected from a stream free from point source pollution, were exposed in the laboratory, for 96 h, to Cu treatments (< 0.2 mu g/L, 0.77 +/- 0.87 mu g/L, and 6.3 +/- 5.4 mu g/L). Gills and digestive glands were extracted and analyzed for transcriptional and biochemical responses. Biological and statistical effect sizes from Cu treatments were in general small (mean log(2) fold-change <= 0.80 and Cohen's f <= 0.69, respectively), and no significant treatment effects were observed. In contrast, four out of eight biomarkers (cat, gst, hsp70, and GST) showed a significant sex:tissue interaction, and additionally one (sod) showed significant overall effects from sex. Specifically, three markers in gills (cat, mt, GST) and one in digestive gland (AChE) displayed significant sex differences, independent of treatment. Results suggest that sex or tissue effects might obscure low-magnitude biomarker responses and potential early warnings. Thus, variation in biomarker baselines and response patterns needs to be further addressed for the future use of A. anatina as a biomarker model species.
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| 14. |
- Ekelund Ugge, Gustaf Magnus Oskar, 1990-
(författare)
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Transcriptional biomarkers of toxicity – powerful tools or random noise? : An applied perspective from studies on bivalves
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aquatic organisms are constantly at risk of being exposed to potentially harmful chemical compounds of natural or anthropogenic origin. Biological life can for instance respond to chemical stressors by changes in gene expression, and thus, certain gene transcripts can potentially function as biomarkers, i.e. early warnings, of toxicity and chemical stress. A major challenge for biomarker application is the extrapolation of transcriptional data to potential effects at the organism level or above. Importantly, successful biomarker use also requires basal understanding of how to distinguish actual responses from background noise. The aim of this thesis is, based on response magnitude and variation, to evaluate the biomarker potential in a set of putative transcriptional biomarkers of general toxicity and chemical stress.Specifically, I addressed a selection of six transcripts involved in cytoprotection and oxidative stress: catalase (cat), glutathione-S-transferase (gst), heat shock proteins 70 and 90 (hsp70, hsp90), metallothionein (mt) and superoxide dismutase (sod). Moreover, I used metal exposures to serve as a proxy for general chemical stress, and due to their ecological relevance and nature as sedentary filter-feeders, I used bivalves as study organisms.In a series of experiments, I tested transcriptional responses in the freshwater duck mussel, Anodonta anatina, exposed to copper or an industrial wastewater effluent, to address response robustness and sensitivity, and potential controlled (e.g. exposure concentration) and random (e.g. gravidness) sources of variation. In addition, I performed a systematic review and meta-analysis on transcriptional responses in metal exposed bivalves to (1) evaluate what responses to expect from arbitrary metal exposures, (2) assess the influence from metal concentration (expressed as toxic unit), exposure time and analyzed tissue, and (3) address potential impacts from publication bias in the scientific literature.Response magnitudes were generally small in relationship to the observed variation, both for A. anatina and bivalves in general. The expected response to an arbitrary metal exposure would generally be close to zero, based on both experimental observations and on the estimated impact from publication bias. Although many of the transcripts demonstrated concentration-response relationships, large background noise might in practice obscure the small responses even at relatively high exposures. As demonstrated in A. anatina under copper exposure, this can be the case already for single species under high resolution exposures to single pollutants. As demonstrated by the meta-regression, this problem can only be expected to increase further upon extrapolation between different species and exposure scenarios, due to increasing heterogeneity and random variation. Similar patterns can also be expected for time-dependent response variation, although the meta-regression revealed a general trend of slightly increasing response magnitude with increasing exposure times.In A. anatina, gravidness was identified as a source of random variability that can potentially affect the baseline of most assessed biomarkers, particularly when quantified in gills. Response magnitudes and variability in this species were generally similar for selected transcripts as for two biochemical biomarkers included for comparison (AChE, GST), suggesting that the transcripts might not capture early warnings more efficiently than other molecular endpoints that are more toxicologically relevant. Overall, high concentrations and long exposure durations presumably increase the likelihood of a detectable transcriptional response, but not to an extent that justifies universal application as biomarkers of general toxicity and chemical stress. Consequently, without a strictly defined and validated application, this approach on its own appears unlikely to be successful for future environmental risk assessment and monitoring. Ultimately, efficient use of transcriptional biomarkers might require additional implementation of complementary approaches offered by current molecular techniques.
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| 15. |
- Ekelund Ugge, Gustaf Magnus Oskar, et al.
(författare)
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Transcriptional Responses as Biomarkers of General Toxicity : A Systematic Review and Meta-Analysis on Metal-Exposed Bivalves
- 2023
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Ingår i: Environmental Toxicology and Chemistry. - : John Wiley & Sons. - 0730-7268 .- 1552-8618. ; 42:3, s. 628-641
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Forskningsöversikt (refereegranskat)abstract
- Through a systematic review and a series of meta-analyses, we evaluated the general responsiveness of putative transcriptional biomarkers of general toxicity and chemical stress. We targeted metal exposures performed on bivalves under controlled laboratory conditions, and selected six transcripts associated with general toxicity for evaluation: catalase (cat), glutathione-S-transferase (gst), heat shock proteins 70 and 90 (hsp70, hsp90), metallothionein (mt) and superoxide dismutase (sod). Transcriptional responses (n = 396) were extracted from published scientific articles (k = 22) and converted to log response ratios (lnRRs). By estimating toxic units (TUs), we normalized different metal exposures to a common scale, as a proxy of concentration. Using Bayesian hierarchical random effect models, we then tested the effects of metal exposure on lnRR, both for metal exposure in general and in meta-regressions using TU and exposure time as independent variables. Corresponding analyses were also repeated with transcript and tissue as additional moderators. Observed patterns were similar for general as for transcript- and tissue-specific responses. The expected overall response to arbitrary metal exposure was a lnRR of 0.50, corresponding to a 65 % increase relative a non-exposed control. However, when accounting for publication bias, the estimated ‘true’ response showed no such effect. Furthermore, expected response magnitude increased slightly with exposure time, but there was little support for general monotonic concentration-dependence with regards to TU. Altogether, this work reveals potential limitations that need consideration prior to applying the selected transcripts as biomarkers in environmental risk assessment. This article is protected by copyright. All rights reserved. Environ Toxicol Chem 2022;00:0–0.
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| 16. |
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| 17. |
- Frisk, Mikael, et al.
(författare)
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Route optimization as an instrument to improve animal welfare and economics in pre-slaughter logistics
- 2018
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 13:3
-
Tidskriftsartikel (refereegranskat)abstract
- Each year, more than three million animals are transported from farms to abattoirs in Sweden. Animal transport is related to economic and environmental costs and a negative impact on animal welfare. Time and the number of pick-up stops between farms and abattoirs are two key parameters for animal welfare. Both are highly dependent on efficient and qualitative transportation planning, which may be difficult if done manually. We have examined the benefits of using route optimization in cattle transportation planning. To simulate the effects of various planning time windows and transportation time regulations and number of pick-up stops along each route, we have used data that represent one year of cattle transport. Our optimization model is a development of a model used in forestry transport that solves a general pick-up and delivery vehicle routing problem. The objective is to minimize transportation costs. We have shown that the length of the planning time window has a significant impact on the animal transport time, the total driving time and the total distance driven; these parameters that will not only affect animal welfare but also affect the economy and environment in the pre-slaughter logistic chain. In addition, we have shown that changes in animal transportation regulations, such as minimizing the number of allowed pick-up stops on each route or minimizing animal transportation time, will have positive effects on animal welfare measured in transportation hours and number of pick-up stops. However, this leads to an increase in working time and driven distances, leading to higher transportation costs for the transport and negative environmental impact.
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| 18. |
- George-Chandy, Annie, 1969, et al.
(författare)
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Th17 development and autoimmune arthritis in the absence of reactive oxygen species
- 2008
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Ingår i: European Journal of Immunology. - : Wiley. - 0014-2980 .- 1521-4141. ; 38:4, s. 1118-1126
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Tidskriftsartikel (refereegranskat)abstract
- Dendritic cells (DC) express a functional NADPH oxidase and produce reactive oxygen species (ROS) upon interaction with microbes and T cells. Exposure to ROS leads to DC activation and maturation, as evidenced by phenotypic and functional changes. We have evaluated how endogenous ROS production affects the cytokine secretion pattern and T cell-activating capacity of bone marrow-derived murine DC. DC treated with ROS scavengers, as well as DC from mice that lack a functional NADPH oxidase (and thereby inherently deficient in ROS production) produced significantly increased levels of IL-1β, IL-6, TNF-α and TGF-β in response to microbial activation. DC deficient in ROS production induced high levels of IFN-γ and IL-17 in responding T cells after Ag-specific or superantigen-induced activation. Finally, we show that ROS deficiency affected the induction of a T cell-dependent inflammatory condition, collagen-induced arthritis (CIA). C57BL/6 mice that lack a functional NADPH oxidase developed a severe and erosive CD4-dependent CIA, whereas the majority of the congenic wild-type animals remained healthy. These data suggest that ROS act as immunomodulators in DC-driven T cell activation and perhaps also in T cell-dependent immunopathology.
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| 19. |
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| 20. |
- Håkansson, Nina, et al.
(författare)
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Generating structure specific networks
- 2010
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Ingår i: Advances in Complex Systems. - : World Scientific Publishing Company. - 0219-5259. ; 13:2, s. 239-250
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical exploration of network structure significance requires a range of different networks for comparison. Here, we present a new method to construct networks in a spatial setting that uses spectral methods in combination with a probability distribution function. Nearly all previous algorithms for network construction have assumed randomized distribution of links or a distribution dependent on the degree of the nodes. We relax those assumptions. Our algorithm is capable of creating spectral networks along a gradient from random to highly clustered or diverse networks. Number of nodes and link density are specified from start and the structure is tuned by three parameters (gamma, sigma, kappa). The structure is measured by fragmentation, degree assortativity, clustering and group betweenness of the networks. The parameter gamma regulates the aggregation in the spatial node pattern and sigma and kappa regulates the probability of link forming.
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| 21. |
- Håkansson, Nina, et al.
(författare)
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Improvement of animal welfare by strategic analysis and logistic optimisation of animal slaughter transportation
- 2016
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Ingår i: Animal Welfare. - : Universities Federation for Animal Welfare. - 0962-7286 .- 2054-1538. ; 25:2, s. 255-263
-
Tidskriftsartikel (refereegranskat)abstract
- The transportation of animals to slaughterhouses is a major welfare concern. The number of slaughterhouses has decreased over time in Europe due to centralisation. This is expected to increase transport time for animals and as a consequence negatively affect animal welfare. We propose an optimisation model based on a facility location model to perform strategic analysis to improve transportation logistics. The model is tested on the Swedish slaughter transport system. We show that, by strategic planning and redirection of transports while keeping the slaughterhouse capacities as of the originaldata, the potential exists to reduce transport distance by 25% for pigs and 40% for cattle. Furthermore, we demonstrated that approximately 50% of Swedish slaughterhouses can be shut down with a minimal effect on total transport distances. This implies that in terms of the overall welfare picture, the decision of which animals to send where plays a for more significant role than the number of slaughterhouses. In addition, by changing relative weights on distances in the optimisation function the amount of individualtransports with longjourney times can be decreased. We also show results from altered slaughterhouse capacity and geographical location of slaughterhouses. This is the first time an entire country has been analysed in great detail with respect to the location, capacity and number of slaughterhouses. The focus is mainly on the analysis of unique and detailed information of actual animal transports in Sweden and a demonstration of the potential impact redirection of the transports and/ or altering of slaughterhouses can have on animal welfare.
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| 22. |
- Håkansson, Nina
(författare)
-
Network analysis and optimization of animal transports
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is about animal transports and their effect on animal welfare. Transports are needed in today’s system of livestock farming. Long transports are stressful for animals and infectious diseases can spread via animal transports. With optimization methods transport times can be minimized, but there is a trade-off between short distances for the animals and short distances for the trucks. The risk of disease spread in the transport system and disease occurrence at farms can be studied with models and network analysis.The animal transport data and the quality of the data in the Swedish national database of cattle and pig transports are investigated in the thesis. The data is analyzed regarding number of transports, number of farms, seasonality, geographical properties, transport distances, network measures of individual farms and network measures of the system. The data can be used as input parameters in epidemic models.Cattle purchase reports are double reported and we found that there are incorrect and missing reports in the database. The quality is improving over the years i.e. 5% of cattle purchase reports were not correctly double reported in 2006, 3% in 2007 and 1% in 2008. In the reports of births and deaths of cattle we detected date preferences; more cattle births and deaths are reported on the 1st, 10th and 20th each month. This is because when we humans don’t remember the exact number we tend to pick nice numbers (like 1, 10 and 20). This implies that the correct date is not always reported.Network analysis and network measures are suggested as tools to estimate risk for disease spread in transport systems and risk of disease introduction to individual holdings. Network generation algorithms can be used together with epidemic models to test the ability of network measures to predict disease risks. I have developed, and improved, a network generation algorithm that generates a large variety of structures.In my thesis I also suggest a method, the good choice heuristic, for generating non-optimal routes. Today coordination of animal transports is neither optimal nor random. In epidemic simulations we need to model routes as close to the actual driven routes as possible and the good choice heuristic can model that. The heuristic is tuned by two parameters and creates coordination of routes from completely random to almost as good as the Clarke and Wright heuristic. I also used the method to make the rough estimate that transport distances for cattle can be reduced by 2-24% with route-coordination optimization of transports-to-slaughter.Different optimization methods can be used to minimize the transport times for animal-transports in Sweden. For transports-to-slaughter the strategic planning of “which animals to send where” is the first step to optimize. I investigated data from 2008 and found that with strategic planning, given the slaughterhouse capacity, transport distances can be decreased by about 25% for pigs and 40% for cattle. The slaughterhouse capacity and placement are limiting the possibility to minimize transport times for the animals. The transport distances could be decreased by 60% if all animals were sent to the closest slaughterhouse 2008. Small-scale and mobile slaughterhouses have small effect on total transport work (total transport distance for all the animals) but are important for the transport distances of the animals that travel the longest.
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| 23. |
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| 24. |
- Jonsson, Annie, et al.
(författare)
-
Analys av infrastruktur för biologisk mångfald i Biosfärområde Vänerskärgården med Kinnekulle : ett planeringsunderlag för bevarande av biologisk mångfald och prioritering utifrån ett landskapsperspektiv
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten presenterar och redovisar ett kunskapsunderlag som tagits fram för arbete med blå och grön infrastruktur i Mariestad, Götene och Lidköping kommun. Utifrån underlaget kan kommunerna prioritera markanvändning så att man bibehåller och utvecklar en grön infrastruktur som bidrar till att uppfylla miljökvalitetsmålet Ett rikt växt-och djurliv1. Andra miljökvalitetsmål som också berörs är Myllrande våtmarker, Levande skogar, Ett rikt odlingslandskap och God bebyggd miljö.Kunskapsunderlaget har tagits fram med en ny metod som utvecklats parallellt under projektets gång. Metoden som använts är Biotope Biodiversity Capacity Indicator (BBCI). En indikator som uppskattar ett biotoplandskaps förmåga att hålla biologisk mångfald. Metodutveckling har finansierats av Naturvårdsverkets miljöforskningsanslag och framtagning av det specifika underlaget och analyserna i rapporten har finansierats av ett LONA projekt.BBCI bygger på ekologisk kunskap om hur landskapets struktur påverkar arters överlevnadoch biologisk mångfald. Med hjälp av indikatorn kan man undersöka om i) landskapet som helhet är hållbart ur ett biologisk mångfaldsperspektiv, ii) hur många och vilka patcher som inte är hållbara i sig själva och iii) hur känsligt landskapets biologiskamångfald är för påverkan på specifika patcher.Sammantaget har BBCI beräknats för fem biotoplandskap, som valts i dialog med de tre kommunerna. De analyserade biotoperna är gräsmark, äldre barrskog, ädellövskog, våtmarker samt fågelskär. Som underlag och indata till biotoplandskapens struktur användes marktäckedata från fler olika databaser. I rapporten redovisas biotoplandskapens långsiktiga hållbarhet för biologisk mångfald och känslighet för tidsperspektivet 100 år. BBCI analyser presenteras dels i ett regionalt perspektiv och dels i ett kommunalt perspektiv.1 Miljökvalitetsmålen beskriver det tillstånd i den svenska miljön som ska nås. Det finns 16 miljökvalitetsmål som alla berör viktiga miljöområden. Arbetet med att nå miljökvalitetsmålen och generationsmålet utgör grunden för den nationella miljöpolitiken.
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| 25. |
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| 26. |
- Jonsson, Annie, et al.
(författare)
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Are certain life histories particularly prone to local extinction?
- 2001
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Ingår i: Journal of Theoretical Biology. - : Elsevier BV. - 0022-5193 .- 1095-8541. ; 209:4, s. 455-463
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Tidskriftsartikel (refereegranskat)abstract
- Using stochastic simulations and elasticity analysis, we show that there are inherent differences in the risk of extinction between life histories with different demographies. Which life history is the most vulnerable depends on which vital rate varies. When juvenile survival varies semelparous organisms with delayed reproduction are the most vulnerable ones, while a varying developmental rate puts a greater threat to semelparous organisms with rapid development. Iteroparous organisms are the most vulnerable ones when adult survival varies. Generally, we do not expect to observe organisms in nature having variation in vital rates that produce a high risk of extinction. Given the results here we therefore predict that iteroparous organisms should show low variation in adult survival. Moreover, we predict that semelparous organisms should show low variation in juvenile survival and low variation in developmental rate. The effect of temporal correlation on extinction risk is most pronounced in organisms with semelparous life histories. © 2001 Academic Press.
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| 27. |
- Jonsson, Annie
(författare)
-
Life histories and population dynamics
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the last decades there has been a growing interest and attention to random variation in population densities and their causes. It has been shown that even in constant environments (deterministic population growth) the dynamics of populations can display random like behaviour depending on parameter values. Thus, chaotic dynamics, defined as bounded fluctuations in the state variables with sensitive dependence on initial conditions, has been suggested as a source of variability in population densities. However, convincing evidence for chaotic dynamics in natural populations is limited. This may be due to difficulties in detecting chaos in the few time series available or that most populations may actually exhibit chaotic fluctuations. In paper I we present a possible explanation for the lack of chaos. We show that natural selection often lead to stable population dynamics, at least in organisms with plastic growth.Apart from the possibility of internally driven fluctuations, most natural populations are also exposed to an external fluctuating environment. Disregarding more or less deterministic variation like diurnal, lunar and seasonal cycles still leave a large amount of environmental variability that can be considered stochastic. The response of a population to such variation can be expected to depend on the kind of life history that the organism exhibits. Life histories are defined by the pattern in the vital rates (i. e., birth, growth, and survival rates). Responses of these rates to environmental variation determine the structure and dynamics of the population. The incorporation of stochasticity in models of population growth result in a lowered long-run growth rate of the populations. An effect of stochastic variation in vital rates can thus be to drive population numbers into a long-term decline and eventually to extinction. A fundamental issue is, therefore, how environmental variation affects the risk of extinction and evolution in organisms with different types of life histories. We investigate this in paper II and III.In addition to the fact that natural populations fluctuate in density, most long-term studies of population dynamics show an incrasing variance in populations densities with time. Noise that leads to an increasing variance with time is termed red noise. In contrast to white noisered noise causes a temporal con-elation in the vital rates it affects (so called autocon-elation). Which type of environmental noise that is used in population modelling may be important for the resulting dynamics. In paper IV we investigate the effects of different types of noise for approximations of long-run growth rate for organisms with different life histories.
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| 28. |
- Jonsson, Annie
(författare)
-
Robustness of life histories to environmental variability in complex versus simple life cycles
- 2021
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Ingår i: Theoretical Ecology. - : Springer. - 1874-1738 .- 1874-1746. ; 14:2, s. 335-344
-
Tidskriftsartikel (refereegranskat)abstract
- Most animal species have a complex life cycle (CLC) with metamorphosis. It is thus of interest to examine possible benefits of such life histories. The prevailing view is that CLC represents an adaptation for genetic decoupling of juvenile and adult traits, thereby allowing life stages to respond independently to different selective forces. Here I propose an additional potential advantage of CLCs that is, decreased variance in population growth rate due to habitat separation of life stages. Habitat separation of pre- and post-metamorphic stages means that the stages will experience different regimes of environmental variability. This is in contrast to species with simple life cycles (SLC) whose life stages often occupy one and the same habitat. The correlation in the fluctuations of the vital rates of life stages is therefore likely to be weaker in complex than in simple life cycles. By a theoretical framework using an analytical approach, I have (1) derived the relative advantage, in terms of long-run growth rate, of CLC over SLC phenotypes for a broad spectrum of life histories, and (2) explored which life histories that benefit most by a CLC, that is avoid correlation in vital rates between life stages. The direction and magnitude of gain depended on life history type and fluctuating vital rate. One implication of our study is that species with CLCs should, on average, be more robust to increased environmental variability caused by global warming than species with SLCs.
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| 29. |
- Jonsson, Annie, et al.
(författare)
-
Spatial distribution and age structure of the freshwater unionid mussels Anodonta anatina and Unio tumidus : Implications for environmental monitoring
- 2013
-
Ingår i: Hydrobiologia. - : Springer Netherlands. - 0018-8158 .- 1573-5117. ; 711:1, s. 61-70
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Tidskriftsartikel (refereegranskat)abstract
- Surveys of unionid populations have been incorporated into the Swedish national environmental monitoring program. Nevertheless there is still lack of knowledge of important aspects of the biology of many unionid species. There may also be differences between species. This work compares the spatial distribution of two unionid species, Anodonta anatina and Unio tumidus, at four sites in Sweden. Samples were taken at transects along the shoreline at different water depths on the surface bed and in the sediments. Individual mussel ages were determined. Our results indicated that younger mussel individuals do not show differences in horizontal spatial distribution compared to older mussel individuals. However, they showed a preference to be burrowed in the sediment compared to older individuals that were predominantly found at the sediment surface. We also found a large difference in burrowing frequency between species with a higher frequency of burrowed adult individuals of A. anatina than U. tumidus. This result may be due to the timing of our field survey that coincided with the period of glochidia release for U. tumidus. We can conclude that a monitoring program for freshwater mussel populations needs to be carefully planned in time. © 2013 Springer Science+Business Media Dordrecht.
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| 30. |
- Jonsson, Annie
(författare)
-
Vetenskaplig utvärdering av åtgärdseffekter mot almsjukan inom projektet LifeELMIAS : Rapport till Naturvårdsverket 2017-10-31
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- EU-projektet ”LifeELMIAS - Saving wooded Natura 2000 habitats from invasive alien fungi species on the Island of Gotland, Sweden” startade i augusti 2013 och avslutas under 2018. Projektet har haft sitt fokus på att bekämpa och i bästa fall utrota almsjukan på Gotland, samt långsiktigt skydda och bevara den biologiska mångfalden som är speciellt knuten till alm och även ask. Projektet drivs av Skogsstyrelsen med flera samarbetspartners bland annat Naturvårdsverket. Från 2013 har bekämpningsåtgärderna finansierats i projektet LifeElmias och det kostar i medeltal 5 miljoner kronor per år. För att kunna ta ställning till hur almsjukan ska hanteras på Gotland efter projektavslut har Naturvårdsverket beställt följande utvärdering. I uppdraget har det ingått att sammanställa vad som genomförts i LifeElmias och vilka slutsatser man kan göra, samt en diskussion om framtida möjligheter. Så snart almsjukan upptäcktes på Gotland 2005 sattes bekämpningsåtgärder in som har pågått fram till idag. Till och med 2009 spred sig sjukdomen mycket snabbt på ön. Därefter har den stoppats upp och dess spridningstakt har inte ökat signifikant sedan dess. Det finns tyvärr inget som tyder på att det skulle vara möjligt att utrota sjukdomen på Gotland. Ett uppehåll i bekämpningen kommer att innebära att almsjukan återigen går in i en starkt växande fas. Då skulle upp till 90% av almbeståndet kunna slås ut på bara några år. Fram till idag har endast 3% av beståndet på 1 miljon almar insjuknat. Almarterna dör inte ut helt om man slutar med bekämpningen men förekomsterna kommer till största delen bestå av unga träd och buskartade bestånd. Vilken total effekt det har på den biologiska mångfalden generellt går inte att förutsäga. Artsammansättningen kommer dock att förändras och populationsstorlekar påverkas i både negativ och positiv riktning. Den hittills mest effektiva metoden att bekämpa almsjukan har varit att upptäcka sjuka träd och destruera dem. Nya möjligheter med fjärranalys för att inventera finns inom räckhåll och med hjälp av ekologisk geografisk modellering skulle man kunna finna strategier för att effektivisera kontrollen eller upprätta skyddszoner för specifikt bevarande av almbestånden inom Natura 2000-områdena. Både fjärranalys och ekologisk modellering kräver dock ett utvecklingsarbete med anpassningar för de specifika situationerna med almsjuka, Gotlands geografi, klimat med flera faktorer. Men dessa metoder skulle långsiktigt kunna effektivisera arbetet och minska kostnaderna för ett fortsatt kontrollprogram.
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| 31. |
- Jonsson, Annie, et al.
(författare)
-
Ökad biologisk mångfald och renare vatten med livskraftiga stormusselbestånd i Göta älvs vattensystem : Dagens situation och åtgärder för att minska vattenkraftens negativa påverkan
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Göta älv är Sveriges största vattendrag. Älven används av många olika intressen. Människan utnyttjande av älven påverkar dock vattenekosystemen negativt. Sötvattenslevande stormusslor har drabbats hårt av människans exploatering av vattendrag och mark kring vattendrag. De är betydelsefulla organismer som tillhandahåller flera ekosystemtjänster.Projektets första mål har varit att samla in kunskap om alla de stora sötvattensmusselarternas förekomster i Göta älvs vattensystem (biflöden) från Vänern till havet. Det finns stora kunskapsluckor över musslornas förekomster i Sverige, särskilt de mer vanligt förekommande arterna. Projektets andra mål har varit att samla in miljödata och analysera vilka eventuella miljöproblem som påverkar musselförekomsterna i de olika delarna av vattensystemet. Utifrån resultaten har vi diskuterat olika åtgärder och prioriteringar i generella drag och även kort för respektive biflödessystem.Resultatet visar att musselförekomsterna är få och svaga. Musslor har påträffats i knappt en tredjedel av de undersökta 201 lokalerna. Musslor har bara påträffats i 10 av de 25 undersökta biflödessystemen. Positivt är dock att fynd har gjorts av alla de fem arterna allmän dammussla, större dammussla, flat dammussla, spetsig målarmussla och flodpärlmussla. Föryngring har också förekommit någonstans i systemet av dessa arter. Alltså har vi möjlighet att handla!Projektet har finasierats av Naturskyddsföreningen och Göta älvs vattenvårdsförbund.
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| 32. |
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| 33. |
- Lennartsson, Jenny, et al.
(författare)
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Is a Sampled Network a Good Enough Descriptor? Missing Links and Appropriate Choice of Representation
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Missing links due to sampling difficulties can be a limitation in network analysis. Measurements and analysis of networks with insufficient data may make the actual properties indistinct and thus include too much uncertainty to lead to accurate inferences. In addition, in dynamical networks with low link degrees and high stochasticity one sample of the network structure during a finite time window may not be sufficient for general conclusions. Our interest here is to examine the possible consequences of analysis of networks with insufficient data. We studied how mean link degree in sampled networks affects predictions of the spread of disease. Networks with weighted links were used to run scenarios that assumed distance-dependent probabilities of disease transmission when applying general simulation methodology. These scenarios were compared with scenarios including randomly drawn probabilities of disease transmission. For both types of scenarios, we also tested two link-forming methods, one based on distance-dependence and the other on a random approach. Our findings imply that sampled networks must be improved by using statistical measures before attempting to estimate or predict the spread of disease. We conclude that, under the assumption of weighted links, predictions about the extent of an epidemic can be drawn only at mean degrees that are much higher than found in empirical studies. In reality, neither sampling procedures nor disease transmissions are completely dependent on distance. Our results show how this aspect enforces an even higher level of mean degree to be present in order to achieve reasonable predictions.
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| 34. |
- Lennartsson, Jenny, et al.
(författare)
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Network measures efficiency as predictors for disease transmission in spatial farm networks
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Networks can be categorised using different measures of connectivity and topology of the network. We have examined if such network measures can be used as predictors of disease transmission in networks. In this study, virtual networks with a wide range of different structures are generated using the SpecNet algorithm. Measures are calculated for both the network as a whole and for individual nodes. The virtual networks generated a large variation in number of infected farms. In general, a large variation was still present for networks with equal value of a measure which implies that single network measures may not be sufficient as predictor for spread of disease. Yet, mean degree and the average clustering coefficient were the global network measures that could best explain the variation in the number of infected farms of a network. At the local level the degree and the clustering coefficient of the initially infected farm explain most of the variation in the number of infected farms. Hence, our results also points out that one should also consider the characteristics of the initially infected farm when predicting the spread of a disease.
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| 35. |
- Lennartsson, Jenny
(författare)
-
Networks and epidemics - impact of network structure on disease transmission
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The spread of infectious diseases, between animals as well as between humans, is a topic often in focus. Outbreaks of diseases like for example foot-and-mouth disease, avian influenza, and swine influenza have in the last decades led to an increasing interest in modelling of infectious diseases since such models can be used to elucidate disease transmission and to evaluate the impact of different control strategies. Different kind of modelling techniques can be used, e.g. individual based disease modelling, Bayesian analysis, Markov Chain Monte Carlo simulations, and network analysis. The topic in this thesis is network analysis, since this is a useful method when studying spread of infectious diseases. The usefulness lies in the fact that a network describes potential transmission routes, and to have knowledge about the structure of them is valuable in predicting the spread of diseases. This thesis contains both a method for generating a wide range of different theoretical networks, and also examination and discussion about the usefulness of network analysis as a tool for analysing transmission of infectious animal diseases between farms in a spatial context. In addition to the theoretical networks, Swedish animal transport networks are used as empirical examples.To be able to answer questions about the effect of the proportion of contacts in networks, the effect of missing links and about the usefulness of network measures, there was a need to manage to generate networks with a wide range of different structures. Therefore, it was necessary to develop a network generating algorithm. Papers I and II describes that network generating algorithm, SpecNet, which creates spatial networks. The aim was to develop an algorithm that managed to generate a wide range of network structures. The performance of the algorithm was evaluated by some network measures. In the first study, Paper I, the algorithm succeeded to generate a wide range of most of the investigated network measures. Paper II is an improvement of the algorithm to produce networks with low negative assortativity by adding two classes of nodes instead of one. Except to generate theoretical networks from scratch, it is also relevant that a network generating algorithm has the potential to regenerate a network with given specific structures. Therefore, we tested to regenerate two Swedish animal transport networks according to their structures. SpecNet managed to mimic the two empirical networks well in comparison with a non-spatial network generating algorithm that was not equally successful in regenerating the requested structures.Sampled empirical networks are rarely complete, since contacts are often missing during sampling, e.g. due to difficulties to sample or due to too short time window during sampling. In Paper III, the focus is on the effect on disease transmission, due to number of contacts in the network, as well as on the reliability of making predictions from networks with a small proportion of missing links. In addition, attention is also given to the spatial distribution of animal holdings in the landscape and on what effect this distribution has on the resulting disease transmission between the holdings. Our results indicate that, assuming weighted contacts, it is maybe risky to make predictions about disease transmission from one single network replicate with as low proportion of contacts as in most empirical animal transport networks.In case of a disease outbreak, it would be valuable to use network measures as predictors for the progress and the extent of the disease transmission. Then a reliable network is required, and also that the used network measures has the potential to make reasonable predictions about the epidemic. In Paper IV we investigate if network measures are useful as predictors for eventual disease transmissions. Moreover, we also analyse if there is some measure that correlates better with disease transmission than others. Disease transmission simulations are performed in networks with different structures to mimic diverse spatial conditions, thereafter are the simulation results compared to the values of the network structures.
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| 36. |
- Lennartsson, Jenny, et al.
(författare)
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SpecNet : A Spatial Network Algorithm that Generates a Wide Range of Specific Structures
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 7:8
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Tidskriftsartikel (refereegranskat)abstract
- Network measures are used to predict the behavior of different systems. To be able to investigate how various structures behave and interact we need a wide range of theoretical networks to explore. Both spatial and non-spatial methods exist for generating networks but they are limited in the ability of producing wide range of network structures. We extend an earlier version of a spatial spectral network algorithm to generate a large variety of networks across almost all the theoretical spectra of the following network measures: average clustering coefficient, degree assortativity, fragmentation index, and mean degree. We compare this extended spatial spectral network-generating algorithm with a non-spatial algorithm regarding their ability to create networks with different structures and network measures. The spatial spectral networkgenerating algorithm can generate networks over a much broader scale than the non-spatial and other known network algorithms. To exemplify the ability to regenerate real networks, we regenerate networks with structures similar to two real Swedish swine transport networks. Results show that the spatial algorithm is an appropriate model with correlation coefficients at 0.99. This novel algorithm can even create negative assortativity and managed to achieve assortativity values that spans over almost the entire theoretical range.
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| 37. |
- Lindström, Tom, et al.
(författare)
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Estimation of distance related probability of animal movements between holdings and implications for disease spread modeling
- 2009
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Ingår i: Preventive Veterinary Medicine. - : Elsevier. - 0167-5877 .- 1873-1716. ; 91:2-4, s. 85-94
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Tidskriftsartikel (refereegranskat)abstract
- Between holding contacts are more common over short distances and this may have implications for the dynamics of disease spread through these contacts. A reliable estimation of how contacts depend on distance is therefore important when modeling livestock diseases. In this study, we have developed a method for analyzing distant dependent contacts and applied it to animal movement data from Sweden. The data were analyzed with two competing models. The first model assumes that contacts arise from a purely distance dependent process. The second is a mixture model and assumes that, in addition, some contacts arise independent of distance. Parameters were estimated with a Bayesian Markov Chain Monte Carlo (MCMC) approach and the model probabilities were compared. We also investigated possible between model differences in predicted contact structures, using a collection of network measures. We found that the mixture model was a much better model for the data analyzed. Also, the network measures showed that the models differed considerably in predictions of contact structures, which is expected to be important for disease spread dynamics. We conclude that a model with contacts being both dependent on, and independent of, distance was preferred for modeling the example animal movement contact data.
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| 38. |
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| 39. |
- Nordquist, Annie, et al.
(författare)
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A physical model study of swirl phenomena in a top blown bath
- 2006
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Ingår i: Steel Research International. - : Wiley. - 1611-3683. ; 77, s. 234-241
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Tidskriftsartikel (refereegranskat)abstract
- The present study is focused on swirl motion in a top blown water model, where a deep water swirl motion is observed. During the experiments, the top lance, with cylindrical nozzles, was placed above the water surface and thereby produced an external force on the bath. The effect on how different parameters, such as nozzle diameter and the distance between the bath surface and nozzle exit, i.e. the lance height, affect the swirl motion were studied. More specifically, the amplitude and period of the swirl as well as the starting and damping time of the swirl were determined. The amplitude was found to increase with an increased nozzle diameter and gas flow, while the period had a constant value of about 0.5 s for all nozzle diameters, gas flows and lance heights. The starting time for the swirl motion was found to decrease with an increased gas flow, while the damping time was found to be independent of gas flow rate, nozzle diameter, lance height and ratio of depth to diameter.
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| 40. |
- Nordquist, Annie, et al.
(författare)
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The effect of nozzle diameter, lance height and flow rate on penetration depth in a top-blown water model
- 2006
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Ingår i: Steel Research International. - : Wiley. - 1611-3683. ; 77, s. 82-90
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Tidskriftsartikel (refereegranskat)abstract
- This work aimed at investigating the penetration depth in a water model during lance blowing. A study of accessible literature was carried out to summarise previous work that had studied penetration depth. Based on the literature study an experimental plan was devised consisting of experiments focused on studying the effect of nozzle diameter, lance height and flow rate on the penetration depth. However, the primary focus was on studying the effect of small nozzle diameters on the penetration depth, which has not previously been reported in the literature. It was found that the results of the experiments in general agreed well with previous work, namely: the penetration depth increases with decreasing nozzle diameter, decreasing lance height and increasing gas flow rate. All equations known previously were used to calculate the penetration depth based on current experimental data. Thereafter, it was deduced which of the empirical relationships best fitted the experimental data. The jet momentum number was also determined from the experimental data and it was found that the penetration depth increased with an increased jet momentum number. However, for smaller nozzle diameters there was a considerable deviation. Therefore, a new correlation was suggested, heuristically derived from a macroscopic energy conservation consideration, and it was shown to result in better agreement between experiments and predictions for small nozzle diameters.
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| 41. |
- Nöremark, Maria, et al.
(författare)
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Network analysis of cattle and pig movements in Sweden : Measures relevant for disease control and risk based surveillance
- 2011
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Ingår i: Preventive Veterinary Medicine. - : Elsevier. - 0167-5877 .- 1873-1716. ; 99:2-4, s. 78-90
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Tidskriftsartikel (refereegranskat)abstract
- Registration ofcattle and pigmovements is mandatory in Sweden and all registered movements between farms in the years 2006–2008 were investigated using network analysis. The networks were analysed as monthly and yearly networks, separately per species and with the two species together. Measures that have been previously discussed in relation to outbreaks and disease control were calculated; moreover a measure of the ingoing infection chain was constructed.The ingoing infection chain captures in going contacts through other holdings, taking the temporal aspect and sequence of the movements into account. The distribution of the contacts among the holdings was skewed.Many farms had few or no contacts, while others had many, a pattern which has also been described from other countries. The cattle network and the combined network showed a recurring seasonal pattern, while this was not seen in the pig network.The in-degree was not equivalent to the ingoing infection chain; there were holdings with limited direct contacts, but a large number of indirect contacts.The ingoing infection chain could be a useful measure when setting up strategies for disease control and for risk based surveillance as it identifies holdings with many contacts through live animal movements and thus at potentially higher risk for introduction of contagious diseases.
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| 42. |
- Sellman, Stefan, et al.
(författare)
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Reducing the amount of slaughter transports in modern Swedish cattle production systems
- 2012
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Ingår i: Tackling the Future Challenges of Organic Animal Husbandry. - Braunschweig : Johann Heinrich von Thünen-Institut. - 9783865760944 ; 362, s. 262-265
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Konferensbidrag (refereegranskat)abstract
- Two methods that can help to reduce the distances involved in transportation of cattle to slaughter are presented, route optimization and spatial redistribution of slaughter capacities. In a comparison ot three route optimization techniques we show that RuttOpt is the most effective and that the number of stops on routes can be reduced compared to what is the case today. We also find that transport distances can be reduced by 40 % compared to the real transports of 2008 if animals are sent to the closest available facilities. We believe that the metods highlighted here can help improve the sustainability and animal health in both organic and conventional farming.
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| 43. |
- Stocks, Tanja, 1977-
(författare)
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Metabolic factors and cancer risk : prospective studies on prostate cancer, colorectal cancer, and cancer overall
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: A large number of prospective studies have shown that overweight and diabetes are related to an increased risk of many cancers, including colorectal cancer. In contrast, diabetes has been related to a decreased risk of prostate cancer, and overweight has been related to an increased risk of fatal, but not of incident, prostate cancer. Data from studies on metabolic factors related to overweight and diabetes, and the association with cancer risk, are limited. Aim: The aim of this thesis was to study metabolic factors in relation to risk of prostate cancer (paper I and III), colorectal cancer (paper II and V), and cancer overall (paper VI). Methods: Study designs were i) case-control studies, nested within the Northern Sweden Health and Disease Cohort (paper I and II), and ii) cohort studies of the Swedish Construction Workers cohort (paper III), and the Metabolic syndrome and Cancer project (Me-Can) comprising seven European cohorts (paper V and VI). Paper IV was a descriptive paper of Me-Can. Results, prostate cancer: In paper I, increasing levels of several factors related to insulin resistance (insulin, insulin resistance index, leptin, HbA1c, and glucose) were associated with a decreased risk of overall incident prostate cancer, and the associations were stronger for non-aggressive tumours. In paper III, increasing levels of blood pressure was associated with a significant decreased risk of overall incident prostate cancer and of non-aggressive tumours. Body mass index (BMI) was significantly positively related to fatal prostate cancer. Results, colorectal cancer: In paper II, obesity, hypertension, and hyperglycaemia, were associated with an increased risk of colorectal cancer, and presence of two or three of these factors was associated with a higher risk than the presence of one single factor. In paper V, BMI was associated with a significant linear positive association with risk of colorectal cancer in men and women, and significant positive associations were also found in men for blood pressure and triglycerides. A high metabolic syndrome score, based on levels of BMI, blood pressure, glucose, cholesterol, and triglycerides, was associated with a significant increased risk of colorectal cancer in men and women. The association was stronger than for any of the factors in single, but there was no evidence of a positive interaction between these metabolic factors. Results, cancer overall: Blood glucose was significantly positively associated with risk of incident and fatal cancer overall, and at several specific sites. The associations were stronger in women than in men, and for fatal than for incident cancer. Conclusions: Results from these studies indicate that elevated blood glucose is related to an increased risk of cancer overall and at several specific sites, and further, that overweight and metabolic aberrations increase the risk of colorectal cancer in an additive way. The association with prostate cancer seems to be more complex; insulin resistance and high blood pressure were in our studies related to a decreased risk of overall incident prostate cancer and of non-aggressive tumours, whereas overweight increased the risk of fatal prostate cancer.
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| 44. |
- Torra, Vicenç, et al.
(författare)
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Synthetic generation of spatial graphs
- 2018
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Ingår i: International Journal of Intelligent Systems. - : John Wiley & Sons. - 0884-8173 .- 1098-111X. ; 33:12, s. 2364-2378
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Tidskriftsartikel (refereegranskat)abstract
- Graphs can be used to model many different types of interaction networks, for example, online social networks or animal transport networks. Several algorithms have thus been introduced to build graphs according to some predefined conditions. In this paper, we present an algorithm that generates spatial graphs with a given degree sequence. In spatial graphs, nodes are located in a space equiped with a metric. Our goal is to define a graph in such a way that the nodes and edges are positioned according to an underlying metric. More particularly, we have constructed a greedy algorithm that generates nodes proportional to an underlying probability distribution from the spatial structure, and then generates edges inversely proportional to the Euclidean distance between nodes. The algorithm first generates a graph that can be a multigraph, and then corrects multiedges. Our motivation is in data privacy for social networks, where a key problem is the ability to build synthetic graphs. These graphs need to satisfy a set of required properties (e.g., the degrees of the nodes) but also be realistic, and thus, nodes (individuals) should be located according to a spatial structure and connections should be added taking into account nearness.
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| 45. |
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