| 1. |
- Berglund, Åsa M. M., 1978-, et al.
(author)
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Effects on the food-web structure and bioaccumulation patterns of organic contaminants in a climate-altered Bothnian Sea mesocosms
- 2023
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In: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 10
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Journal article (peer-reviewed)abstract
- Climate change is expected to alter global temperature and precipitation patterns resulting in complex environmental impacts. The proposed higher precipitation in northern Scandinavia would increase runoff from land, hence increase the inflow of terrestrial dissolved organic matter (tDOM) in coastal regions. This could promote heterotrophic bacterial production and shift the food web structure, by favoring the microbial food web. The altered climate is also expected to affect transport and availability of organic micropollutants (MPs), with downstream effects on exposure and accumulation in biota. This study aimed to assess climate-induced changes in a Bothnian Sea food web structure as well as bioaccumulation patterns of MPs. We performed a mesocosms-study, focusing on aquatic food webs with fish as top predator. Alongside increased temperature, mesocosm treatments included tDOM and MP addition. The tDOM addition affected nutrient availability and boosted both phytoplankton and heterotrophic bacteria in our fairly shallow mesocosms. The increased tDOM further benefitted flagellates, ciliates and mesozooplankton, while the temperature increase and MP addition had minor effect on those organism groups. Temperature, on the other hand, had a negative impact on fish growth and survival, whereas tDOM and MP addition only had minor impact on fish. Moreover, there were indications that bioaccumulation of MPs in fish either increased with tDOM addition or decreased at higher temperatures. If there was an impact on bioaccumulation, moderately lipophilic MPs (log Kow 3.6 - 4.6) were generally affected by tDOM addition and more lipophilic MPs (log Kow 3.8 to 6.4) were generally affected by increased temperature. This study suggest that both increased temperatures and addition of tDOM likely will affect bioaccumulation patterns of MPs in shallow coastal regions, albeit with counteracting effects.
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| 2. |
- Capo, Eric, et al.
(author)
-
Droplet digital PCR applied to environmental DNA, a promising method to estimate fish population abundance from humic-rich aquatic ecosystems
- 2021
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In: Environmental DNA. - : John Wiley & Sons. - 2637-4943. ; 3:2, s. 343-352
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Journal article (peer-reviewed)abstract
- Measures of environmental DNA (eDNA) concentrations in water samples have the potential to be both a cost-efficient and a nondestructive method to estimate fish population abundance. However, the inherent temporal and spatial variability in abiotic and biotic conditions in aquatic systems have been suggested to be a major obstacle to determine relationships between fish eDNA concentrations and fish population abundance. Moreover, once water samples are collected, methodological biases are common, which introduces additional sources of variation to potential relationships between eDNA concentrations and fish population abundance. Here, we evaluate the performance of applying the droplet digital PCR (ddPCR) method to estimate fish population abundance in experimental enclosures. Using large-scale enclosure ecosystems that contain populations of nine-spined stickleback (Pungitius pungitius), we compared the concentrations of fish eDNA (COI mitochondrial region, 134 bp) obtained with the ddPCR method with high precision estimates of fish population abundance (i.e., number of individuals) and biomass. To evaluate the effects of contrasted concentrations of humic substances (potential PCR inhibitors) on the performance of ddPCR assays, we manipulated natural dissolved organic carbon (DOC) concentrations (range 4–11 mg/L) in the enclosures. Additionally, water temperature (+2°C) was manipulated in half of the enclosures. Results showed positive relationships between eDNA concentration and fish abundance and biomass estimates although unexplained variation remained. Still and importantly, fish eDNA estimates from high DOC enclosures were not lowered by potential inhibitory effects with our procedure. Finally, water temperature (although only 2°C difference) was neither detected as a significant factor influencing fish eDNA estimates. Altogether, our work highlights that ddPCR-based eDNA is a promising method for future quantification of fish population abundance in natural systems.
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| 3. |
- Capo, Eric, et al.
(author)
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Effects of filtration methods and water volume on the quantification of brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) eDNA concentrations via droplet digital PCR
- 2020
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In: Environmental DNA. - : John Wiley & Sons. - 2637-4943. ; 2:2, s. 152-160
-
Journal article (peer-reviewed)abstract
- The quantification of the abundance of aquatic organisms via the use of environmental DNA (eDNA) molecules present in water is potentially a useful tool for efficient and noninvasive population monitoring. However, questions remain about the reliability of molecular methods. Among the factors that can hamper the reliability of the eDNA quantification, we investigated the influence of five filtration methods (filter pore size, filter type) and filtered water volume (1 and 2 L) on the total eDNA and the fish eDNA concentrations of two species, brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) from tanks with known number of individuals and biomass. We applied a droplet digital PCR (ddPCR) approach to DNA extracted from water samples collected from two cultivation tanks (each of them containing one of the targeted species). Results showed that the quantification of fish eDNA concentrations of both species varies with filtration methods. More specifically, the 0.45-µm Sterivex enclosed filters were identified to recover the highest eDNA concentrations. Difficulties to filter 2 L water samples were present for small pore size filters (≤0.45 µm) and likely caused by filter clogging. To overcome issues related to filter clogging, common in studies aiming to quantify fish eDNA molecules from water samples, we recommend a procedure involving filtration of multiple 1 L water samples with 0.45-µm enclosed filters, to recover both high quality and high concentrations of eDNA from targeted species, and subsequent processing of independent DNA extracts with the ddPCR method.
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| 4. |
- Hamdan, Mohammed, et al.
(author)
-
An experimental test of climate change effects in northern lakes : Increasing allochthonous organic matter and warming alters autumn primary production
- 2021
-
In: Freshwater Biology. - : John Wiley & Sons. - 0046-5070 .- 1365-2427. ; 66:5, s. 815-825
-
Journal article (peer-reviewed)abstract
- Climate changes are predicted to influence gross primary production (GPP) of lakes directly through warming and indirectly through increased loads of allochthonous coloured dissolved organic matter (cDOM) from surrounding landscapes. However, few studies have investigated this combined effect.Here we tested the effects of warming (elevated 3celcius) and cDOM input (three levels of humic river water addition) on GPP in autumn (2 months including open water and ice-covered periods) in experimental pond ecosystems.The cDOM input decreased whole-ecosystem GPP at natural temperature conditions mainly as a result of lower benthic GPP not fully counteracted by an increase in pelagic GPP, while warming increased whole-ecosystem GPP due to a positive response of mainly pelagic GPP at all levels of cDOM input.Warming delayed autumn ice cover formation by 2 weeks but did not affect light availability in the water column compared to ambient ice-covered treatments. Gross primary production during this period was still affected by warming and cDOM.The results stress the importance of accounting for multiple climate drivers and habitats when predicting lake GPP responses to climate change. We conclude that climate change may shift whole-ecosystem GPP through different responses of habitat-specific GPP to increasing cDOM inputs and warming.
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| 5. |
- Hamdan, Mohammed, 1978-, et al.
(author)
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Carbon dioxide limitation of benthic primary production in a boreal lake
- 2022
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In: Freshwater Biology. - : John Wiley & Sons. - 0046-5070 .- 1365-2427. ; 67:10, s. 1752-1760
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Journal article (peer-reviewed)abstract
- Gross primary production (GPP) by benthic microalgae growing on soft sediments is an important contributor to lake productivity in many lakes world-wide. As benthic microalgae have access to nutrients in the sediment they have been regarded as primarily controlled by light, while the role of CO2 as a limiting factor for benthic GPP in lake ecosystems is largely unknown.In this study, we experimentally tested for CO2 limitation of benthic GPP by collecting littoral surface sediments, with associated benthic microalgae, from a typical boreal lake. Intact sediment cores were incubated at different depths (light conditions) after addition of dissolved inorganic (bicarbonate) or organic (DOC; glucose) carbon as direct and indirect sources of CO2, respectively.Benthic microalgal GPP was stimulated by both dissolved inorganic carbon and DOC additions at high, but not at low, light levels.This study shows that benthic microalgal GPP can be CO2-limited when light is not limiting and suggests that both direct (e.g., via groundwater inflow) and indirect (via mineralisation of DOC) CO2 supply can stimulate benthic GPP.
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| 6. |
- Hamdan, Mohammed, 1978-
(author)
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Effects of temperature and terrestrial carbon on primary production in lake ecosystems
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Climate warming is predicted to affect northern lake food webs in two ways: (1)directly via changes in water temperature and ice conditions, and (2) indirectlyvia changes in catchment characteristics and processes that influence input ofallochthonous coloured dissolved organic matter (cDOM) and nutrients. Input ofcDOM increases carbon dioxide (CO2) availability, causes brownification andreduced light conditions, and may increase nutrient availability especially forpelagic primary producers. Increased water temperature and light penetrationand longer ice-free periods affect metabolic rates. These changes are expected toinfluence gross primary production (GPP) and growth of higher trophic levels.However, majority of studies focus on pelagic processes and net effects at wholelake scale is not well understood. Consequently, the lack of knowledge of whatfactors control benthic GPP makes predictions of net effects of climate change onwhole-ecosystem GPP spurious. The aim of this thesis was to experimentally testeffects of warming and increased input of allochthonous cDOM on habitatspecific and whole-ecosystem GPP in lakes. First, by manipulating the CO2concentrations in large scale pond ecosystems, we showed that increased CO2stimulated whole-ecosystem GPP. In a separate incubation study with naturallake sediments in a boreal lake, we tested the role of CO2 as a limiting factor forbenthic GPP under different light levels. The results showed that CO2 supplystimulated benthic GPP at high but not at low light availability, suggesting thatbenthic GPP can be CO2-limited. In the same experimental pond ecosystems, thecombined effect of increased allochthonous cDOM and warming (+3.5°C) on GPPwas studied. The results showed that cDOM input decreases whole-ecosystemGPP, mainly as a result of decreased benthic GPP due to light limitation not fullycounteracted by an increase in pelagic GPP under ambient conditions. Warmingon the other caused a hump shaped increase in whole-ecosystem GPP withincreasing cDOM input mainly due to a positive response in pelagic GPP due torelaxed nutrient limitation. Finally, by manipulating the fish consumer biomassin the same experimental pond ecosystems we showed that whole-ecosystem GPPcan be controlled by top-down effects under warm (+ 3.0°C) but not ambienttemperature conditions. The decline in whole-ecosystem GPP was mainlyattributed to a warming-stimulated consumer-driven trophic cascade in thepelagic habitat and top-down control by zooplankton on phytoplankton growth,while no corresponding cascade was evident in the benthic habitat.Taken together, the results suggest that climate change impacts, as increasinginputs of cDOM, warming and changes in food webs, have different effects onhabitat specific GPP and alone or in combination have impacts on whole-lakeGPP. This thesis offers important insights to better understand the factors thatcontrol lake GPP and to predict future lake ecosystem responses to environmentalchange.
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| 7. |
- Hansen, Joakim, 1978-, et al.
(author)
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Våtmarker som fiskevårdsåtgärd vid kusten : utvärdering av restaurerade våtmarkers effekt på fiskreproduktion och ekosystemet längs Östersjökusten
- 2020
-
Reports (other academic/artistic)abstract
- Många av Östersjöns kustfiskar är av sötvattenursprung och fortplantar sig i grunda vikar och kustnära våtmarker. Historiska utdikningar, kustexploatering och övergödning har lett till förluster av fiskens lek- och uppväxtområden, vilket tillsammans med fiske bidragit till minskande bestånd av exempelvis gädda och abborre. För att motverka nedgången har flera förvaltningsåtgärder initierats.Ungefär 100 våtmarker har restaurerats längs svenska ostkusten för att gynna reproduktionen av gädda och abborre. I samma syfte har fiskvandringshinder i kustmynnande vattendrag tagits bort på cirka 40 platser.Det fåtal uppföljningar som genomförts visar att sådana åtgärder har en god potential att bidra till stärkta kustbestånd av gädda och abborre. Mängden gäddyngel i kustvattnen utanför våtmarkerna tenderar att öka kraftigt efter åtgärderna, medan ingen tydlig förändring kan ses för mängden abborryngel. Det är dock stor variation i utfallet. En studie indikerar även en tydlig lokal ökning av gäddbestånden i kustvattnen utanför våtmarkerna. Sammanställningen visar även att borttagning av vandringshinder i kustmynnande vattendrag förbundna med olika sjösystem kan vara en effektivare metod än att restaurera våtmarker för attgynna abborre, vilket bör undersökas vidare.Det finns få studier som specifikt undersökt om åtgärderna kan ge så stark effekt på rovfiskbestånden att det indirekt påverkar resten av födoväven och ekosystemet. Det finns en potential för sådan påverkan. Men ökningen av rovfisk till följd av de åtgärdade våtmarkerna har i dagsläget inte varit tillräckligt kraftig för att leda till tydliga ekosystemeffekter, så som mindre mängd bytesfisk och påväxtalger.Även om våtmarker kan ge en lokal ökning av mängden fisk måste fler och kompletterande åtgärder till för att stärka kustens rovfiskbestånd. Åtgärderna bör utformas som en del av en tydligt samordnad och långsiktig förvaltning av kust och hav. Förutom en starkare reglering av kustfisket behövs exempelvis bättre skydd mot exploatering av fiskens lek- och uppväxtområden. Även lokal reduktion av mängden gråsäl och storskarv kan vara en möjlig åtgärd i områden där dessa rovdjur medför hög dödlighet på gädda och abborre.Utformningen av fiskeriförförvaltningen i öppet hav måste ha en mer rigid tillämpning av ekosystemansatsen och beakta konsekvenser för kustens ekosystem. Exempelvis tyder mycket på att förändringar i utsjöns fiskbestånd är en viktig bidragande orsak till att storspigg har ökat kraftigt de senaste decennierna. Storspiggen migrerar mellan utsjö och kust. Eftersom den äter gädd- och abborryngel minskar möjligheten att med lokala åtgärder stärka rovfiskbestånden vid kusten.Sammanställningen visar på en bristfällig koordinering och uppföljningav det senaste decenniets fiskevårdsåtgärder. För att skapa en bättre kunskapsbas för framtida förvaltningsbeslut finns därför ett behov av fler och samordnade mångåriga uppföljningar av åtgärder på såväl yngelproduktionoch lokala fiskbestånd som på kustekosystemet.
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| 8. |
- Koizumi, Shuntaro, 1993-
(author)
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Climate change impacts on aquatic consumer communities
- 2023
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Doctoral thesis (other academic/artistic)abstract
- Climate change represents a serious threat to aquatic ecosystems, with an increase in lake temperatures already observed that is expected to continue in the near future. Aside from the direct effects of warming, climate change is also partially responsible for the browning of lakes. Browning is an ongoing phenomenon related to the increased export of terrestrial dissolved organic matter into lakes. With ongoing climate changes, lakes are becoming warmer and browner. This has major impacts on the food web dynamics of these systems. Many studies have previously examined the effects of warming and browning on consumer responses, mainly through spatial surveys. However, a mechanistic understanding of how consumers in the food web will respond to simultaneously occurring warming and browning remains poorly understood. Using two large-scale ecosystem experiments, I studied the effects of warming and browning on consumer growth, size-structure, and population responses, and the potential mechanisms that dictate the emergent responses. In general, warming led to reduced consumer biomass and size structure, whilst browning led to an increase. Specifically, warming reduced intermediate consumer biomass and fish top consumer abundance, biomass and size structure, while browning either led to little to no changes in intermediate consumers, but increased fish top consumer abundance, biomass, and production. However, these responses were determined by food-web structure, interactions, and context-dependent mechanisms. This thesis advances our understanding of the mechanisms that drive changes in consumer responses to warming and browning and provides a better understanding of how ongoing climate may affect the structure and functioning of freshwater ecosystems.
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| 9. |
- Koizumi, Shuntaro, 1993-, et al.
(author)
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Experimental warming and browning influence autumnal pelagic and benthic invertebrate biomass and community structure
- 2023
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In: Freshwater Biology. - : John Wiley & Sons. - 0046-5070 .- 1365-2427. ; 68:7, s. 1224-1237
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Journal article (peer-reviewed)abstract
- Globally, lakes are warming and browning with ongoing climate change. These changes significantly impact a lake's biogeochemical properties and all organisms, including invertebrate consumers. The effects of these changes are essential to understand, especially during critical periods after and before the growing season, that is, autumn and spring, which can determine the composition of the invertebrate consumer community.In this study, we used a large-scale experimental pond system to test the combined effect of warming (+3°C) and increased input of terrestrial and coloured dissolved organic carbon (gradient of 1.6–8.8 mg/L in the ambient and 1.6–9.3 mg/L in the warm)—which causes browning—on zooplankton and benthic macroinvertebrate biomass and composition during the autumn and the following spring.Total zooplankton biomass decreased with warming and increased with browning, while total zoobenthos did not respond to either treatment. Warming and browning throughout the autumn had no overall interactive effects on zooplankton or zoobenthos. Autumnal warming decreased total pelagic consumer biomass, caused by a decrease in both Rotifera and Copepoda. In contrast, there was no effect on overall benthic consumer biomass, with only Asellus sp. biomass showing a negative response to warming. An autumnal increase in dissolved organic carbon led to increased total pelagic consumer biomass, which was related to increases in Daphnia sp. biomass but did not affect zoobenthos biomass. While we expected zooplankton and zoobenthos biomass to follow responses in primary and bacterial production to treatments, we did not find any relationship between consumer groups and these estimates of resource production.Our results suggest that consumer responses to warming and browning during autumn may lead to less overarching general changes in consumer biomass, and responses are mostly taxon-specific.This study gives novel insights into the effects of warming and browning on consumer biomass during autumn and spring and increases the understanding of the effects of climate change on invertebrate community biomass in the different habitats.
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| 10. |
- Norman, Sven, et al.
(author)
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Effects of habitat-specific primary production on fish size, biomass, and production in northern oligotrophic lakes
- 2022
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In: Ecosystems. - : Springer. - 1432-9840 .- 1435-0629. ; 25:7, s. 1555-1570
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Journal article (peer-reviewed)abstract
- Ecological theory predicts that the relative distribution of primary production across habitats influence fish size structure and biomass production. In this study, we assessed individual, population, and community-level consequences for brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) of variation in estimated habitat specific (benthic and pelagic) and total whole lake (GPPwhole) gross primary production in 27 northern oligotrophic lakes. We found that higher contribution of benthic primary production to GPPwhole was associated with higher community biomass and larger maximum and mean sizes of fish. At the population level, species-specific responses differed. Increased benthic primary production (GPPBenthic) correlated to higher population biomass of brown trout regardless of being alone or in sympatry, while Arctic char responded positively to pelagic primary production (GPPPelagic) in sympatric populations. In sympatric lakes, the maximum size of both species was positively related to both GPPBenthic and the benthic contribution to GPPWhole. In allopatric lakes, brown trout mean and maximum size and Arctic char mean size were positively related to the benthic proportion of GPPWhole. Our results highlight the importance of light-controlled benthic primary production for fish biomass production in oligotrophic northern lakes. Our results further suggest that consequences of ontogenetic asymmetry and niche shifts may cause the distribution of primary production across habitats to be more important than the total ecosystem primary production for fish size, population biomass, and production. Awareness of the relationships between light availability and asymmetric resource production favoring large fish and fish production may allow for cost-efficient and more informed management actions in northern oligotrophic lakes.
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| 11. |
- Norman, Sven, 1984-
(author)
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Lake bathymetry as driver of salmonid population size structure and biomass
- 2023
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Doctoral thesis (other academic/artistic)abstract
- Most fish species undergo ontogenetic niche shifts from feeding on pelagic zooplankton, to larger benthic invertebrates and in some cases also to fish. These ontogenetic niche shifts have strong impact on the interactions within and between species, with effects on individual growth, population abundance and food web dynamics. The productivity of northern lakes is mainly controlled by light-limited primary production in benthic habitats, highlighting the importance of lake bathymetry for the abundance of benthic algae feeding macroinvertebrates, which is an important resource for fish. Theory predicts that variation in fish size structure and biomass can arise due to size-dependent differences in competitive abilities between juvenile and adults in each of their niches and by variation in niche- and habitat-specific resource production i.e. pelagic zooplankton and benthic macroinvertebrates.In this thesis, using gradient studies in mountain lakes, I studied how habitat-specific production and lake bathymetry variation affect growth, size structure and biomass in Arctic char and brown trout populations. Results showed that lake bathymetry determine the benthic contribution to whole lake primary production and the degree of ontogenetic niche shift from zooplankton to macroinvertebrates. In correspondence with theory, production of Arctic char and brown trout were related to stage- and habitat-specific gross primary production (GPP) as an increased benthic contribution to whole lake GPP in general increased individual size, population production and biomasses. Lake bathymetry also influenced the niche shift to piscivory in brown trout as reliance on piscivory were higher in relatively deep lakes more dominated by Arctic char. Finally, in a model approach, responses to different size selective harvest regulations showed that the size structure of Arctic char were more sensitive to fishing in shallow than in deep lakes. Size regulations protecting both smaller and the largest adults were shown to best preserve size structure, especially in shallower lakes. Collectively, these results contribute to the understanding of how variation in productivity and availability of stage- and habitat-specific resources and the presence of ontogenetic niche shifts affect the growth, size structure and biomass of fish. Specifically, the results highlighted the importance of shallow benthic habitats for individual size and biomass of salmonids in mountain lakes and suggests that management strategies based on relationships between lake bathymetry and population size structure and biomass could be a simple approach for sustainable management of lake salmonid population.
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| 12. |
- Rosenbaum, William, et al.
(author)
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Hybrid capture-based next-generation sequencing of new and old world Orthohantavirus strains and wild-type Puumala isolates from humans and bank voles
- 2024
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In: Journal of Clinical Virology. - : Elsevier. - 1386-6532 .- 1873-5967. ; 172
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Journal article (peer-reviewed)abstract
- Orthohantaviruses, transmitted primarily by rodents, cause hemorrhagic fever with renal syndrome (HFRS) in Eurasia and hantavirus pulmonary syndrome in the Americas. These viruses, with documented human-to-human transmission, exhibit a wide case-fatality rate, 0.5–40 %, depending on the virus species, and no vaccine or effective treatment for severe Orthohantavirus infections exists. In Europe, the Puumala virus (PUUV), carried by the bank vole Myodes glareolus, causes a milder form of HFRS. Despite the reliance on serology and PCR for diagnosis, the three genomic segments of Swedish wild-type PUUV have yet to be completely sequenced.We have developed a targeted hybrid-capture method aimed at comprehensive genomic sequencing of wild-type PUUV isolates and the identification of other Orthohantaviruses. Our custom-designed panel includes >11,200 probes covering the entire Orthohantavirus genus. Using this panel, we sequenced complete viral genomes from bank vole lung tissue, human plasma samples, and cell-cultured reference strains. Analysis revealed that Swedish PUUV isolates belong to the Northern Scandinavian lineage, with nucleotide diversity ranging from 2.8 % to 3.7 % among them. Notably, no significant genotypic differences were observed between the viral sequences from reservoirs and human cases except in the nonstructural protein.Despite the high endemicity of PUUV in Northern Sweden, these are the first complete Swedish wild-type PUUV genomes and substantially increase our understanding of PUUV evolution and epidemiology. The panel's sensitivity enables genomic sequencing of human samples with viral RNA levels reflecting the natural progression of infection and underscores our panel's diagnostic value, and could help to uncover novel Orthohantavirus transmission routes.
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| 13. |
- Seekell, David A., et al.
(author)
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Patterns and Variation of Littoral Habitat Size Among Lakes
- 2021
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In: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 48:20
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Journal article (peer-reviewed)abstract
- The littoral zone varies in size among lakes from ∼3% to 100% of lake surface area. In this paper, we derive a simple theoretical scaling relationship that explains this variation, and test this theory using bathymetric data across the size spectra of freshwater lakes (surface area = 0.01–82,103 km2, maximum depth = 2–1,741 m). Littoral area primarily reflects the ratio of the maximum depth of photosynthesis to maximum lake depth. However, lakes that are similar in these characteristics can have different relative littoral areas because of variation in basin shape. Hypsometric (area-elevation) models that describe these patterns for individual lakes can be generalized among lakes to accurately predict the relative size of littoral habitat when there is incomplete bathymetric information. Collectively, our results provide simple rules for understanding patterns of littoral habitat size at the regional and global scales.
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| 14. |
- Seekell, David A., et al.
(author)
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Problems With the Shoreline Development Index—A Widely Used Metric of Lake Shape
- 2022
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In: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 49:10
-
Journal article (peer-reviewed)abstract
- The shoreline development index—The ratio of a lake’s shore length to the circumference of a circle with the lake’s area—Is a core metric of lake morphometry used in Earth and planetary sciences. In this paper, we demonstrate that the shoreline development index is scale-dependent and cannot be used to compare lakes with different areas. We show that large lakes will have higher shoreline development index measurements than smaller lakes of the same characteristic shape, even when mapped at the same scale. Specifically, the shoreline development index increases by about 14% for each doubling of lake area. These results call into question previously reported patterns of lake shape. We provide several suggestions to improve the application of this index, including a bias-corrected formulation for comparing lakes with different surface areas.
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| 15. |
- Seekell, David A., et al.
(author)
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The Fractal Scaling Relationship for River Inlets to Lakes
- 2021
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In: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 48:9
-
Journal article (peer-reviewed)abstract
- Scaling relationships provide simple rules for understanding complex hydrographic patterns. Globally, river inlet abundance varies among lakes by about three orders of magnitude, but few scaling relationships describe this aspect of lake-river connectivity. In this study, we describe a simple theoretical scaling relationship between lake surface area and river inlet abundance, and test this theory using data from Scandinavia. On average, the number of inlets increases by 67% for each doubling of lake area. However, lakes of vastly different areas can have the same number of inlets with relatively small variations of drainage density, lake shape, or junction angle - characteristics that can often be linked to specific geological processes. Our approach bridges the gap between the detailed understanding of geomorphic processes and large-scale statistical relationships, and engenders predictions about additional patterns including the relationship between lake area and water residence time.
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| 16. |
- Seekell, David A., et al.
(author)
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The Scaling Relationship for the Length of Tributaries to Lakes
- 2022
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In: Geophysical Research Letters. - : John Wiley & Sons. - 0094-8276 .- 1944-8007. ; 49:7
-
Journal article (peer-reviewed)abstract
- Globally, the length of tributaries to lakes varies from 0 to more than 15,000 km, but scaling relationships describing this aspect of lake-river connectivity are lacking. In this study, we describe a simple theoretical scaling relationship for tributary length based on the principle of line intercepts of topographic features, and test this theory using data from Scandinavia. Tributary length increases by 73% for each doubling of lake area. This pattern reflects the relationship between catchment and lake area, and is modified by inlet frequency, junction angle, and lake shape—factors related to specific geologic and hydrologic processes. The theory is precise (r2 = 0.74), with low bias (mean error is 14% of mean tributary length) when the characteristic junction angle (∼76°) is estimated statistically. Our study bridges the gap between geomorphic and large-scale statistical relationships to provide simple rules for understanding complex patterns of lake-river connectivity.
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