11 results on '"Vojar J"'
Search Results
2. Individual consistency in exploration and shyness but not activity in smooth newts (Lissotriton vulgaris): the effect of habituation?
- Author
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Chajma, P., primary, Kopecký, O., additional, and Vojar, J., additional
- Published
- 2020
- Full Text
- View/download PDF
3. Chytridiomycosis risk among Central European amphibians based on surveillance data
- Author
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Baláž, V, primary, Vojar, J, additional, Civiš, P, additional, Šandera, M, additional, and Rozínek, R, additional
- Published
- 2014
- Full Text
- View/download PDF
4. Can trail characteristics influence visitor numbers in natural protected areas? A quantitative approach to trail choice assessment
- Author
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Svobodova Kamila, Monteiro Luis, Vojar Jiri, and Gdulova Katerina
- Subjects
tourism ,route attributes ,trail research ,nature conservation ,krkonoše mountains national park ,Environmental sciences ,GE1-350 - Abstract
Planning for recreational activities in protected areas involves an understanding of multiple and complex factors. Trails constitute the main recreation facility in protected areas. They are an important and common infrastructure that concentrates visitor movement. Their sustainable planning and management requires an understanding of how the visitors made their selection. The aim of this study was to identify the effect of trail attributes on visitor numbers in the Krkonoše Mountains National Park in the Czech Republic. The methods used in this study present an analytical approach involving geographic information system analysis, field monitoring and data analyses using generalised linear models. The results showed the preferential tendencies among visitors to certain trail attributes. Marginal significance and a rather strong variability in preferences (over 10%) were identified for five trail characteristics: the amount of local attractions; diversity of land cover types; dominant land cover along a trail; soil erosion; and the type of trail surface. In our study, we illustrate an analytical framework for the assessment of trail characteristics that can help guide trail analyses and management efforts. On the other hand, our findings raise new research questions and point to the requirements for further research in order to better understand how environmental attributes influence visitor choice and to use this knowledge for trail planning and management.
- Published
- 2019
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5. Nano zerovalent Fe did not reduce metal(loid) leaching and ecotoxicity further than conventional Fe grit in contrasting smelter impacted soils: A 1-year field study.
- Author
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Lewandowská Š, Vaňková Z, Beesley L, Cajthaml T, Wickramasinghe N, Vojar J, Vítková M, Tsang DCW, Ndungu K, and Komárek M
- Subjects
- Metals, Heavy analysis, Metal Nanoparticles chemistry, Metallurgy, Environmental Restoration and Remediation methods, Soil Pollutants analysis, Iron chemistry, Soil chemistry
- Abstract
The majority of the studies on nanoscale zero-valent iron (nZVI) are conducted at a laboratory-scale, while field-scale evidence is scarce. The objective of this study was to compare the metal(loid) immobilization efficiency of selected Fe-based materials under field conditions for a period of one year. Two contrasting metal(loid) (As, Cd, Pb, Zn) enriched soils from a smelter-contaminated area were amended with sulfidized nZVI (S-nZVI) solely or combined with thermally stabilized sewage sludge and compared to amendment with microscale iron grit. In the soil with higher pH (7.5) and organic matter content (TOC = 12.7 %), the application of amendments resulted in a moderate increase in pH and reduced As, Cd, Pb, and Zn leaching after 1-year, with S-nZVI and sludge combined being the most efficient, followed by iron grit and S-nZVI alone. However, the amendments had adverse impacts on microbial biomass quantity, S-nZVI being the least damaging. In the soil with a lower pH (6.0) and organic matter content (TOC = 2.3 %), the results were mixed; 0.01 M CaCl
2 extraction data showed only S-nZVI with sludge as remaining effective in reducing extractable concentrations of metals; on the other hand, Cd and Zn concentrations were increased in the extracted soil pore water solutions, in contrast to the two conventional amendments. Despite that, S-nZVI with sludge enhanced the quantity of microbial biomass in this soil. Additional earthworm avoidance data indicated that they generally avoided soil treated with all Fe-based materials, but the presence of sludge impacted their preferences somewhat. In summary, no significant differences between S-nZVI and iron grit were observed for metal(loid) immobilization, though sludge significantly improved the performance of S-nZVI in terms of soil health indicators. Therefore, this study indicates that S-nZVI amendment of soils alone should be avoided, though further field evidence from a broader range of soils is now required., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2024
- Full Text
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6. Specialization directs habitat selection responses to a top predator in semiaquatic but not aquatic taxa.
- Author
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Šigutová H, Harabiš F, Šigut M, Vojar J, Choleva L, and Dolný A
- Subjects
- Animals, Bufonidae, Coleoptera, Fishes, Fresh Water, Herbivory physiology, Odonata, Predatory Behavior physiology, Animal Distribution physiology, Food Chain
- Abstract
Habitat selectivity has become an increasingly acknowledged mechanism shaping the structure of freshwater communities; however, most studies have focused on the effect of predators and competitors, neglecting habitat complexity and specialization. In this study, we examined the habitat selection of semiaquatic (amphibians: Bufonidae; odonates: Libellulidae) and aquatic organisms (true bugs: Notonectidae; diving beetles: Dytiscidae). From each family, we selected one habitat generalist species able to coexist with fish (Bufo bufo, Sympetrum sanguineum, Notonecta glauca, Dytiscus marginalis) and one species specialized in fishless habitats (Bufotes viridis, Sympetrum danae, Notonecta obliqua, Acilius sulcatus). In a mesocosm experiment, we quantified habitat selection decisions in response to the non-consumptive presence of fish (Carassius auratus) and vegetation structure mimicking different successional stages of aquatic habitats (no macrophytes; submerged and floating macrophytes; submerged, floating, and littoral-emergent macrophytes). No congruence between habitat specialists and generalists was observed, but a similar response to fish and vegetation structure defined both semiaquatic and aquatic organisms. While semiaquatic generalists did not distinguish between fish and fishless pools, specialists avoided fish-occupied pools and had a preferred vegetation structure. In aquatic taxa, predator presence affected habitat selection only in combination with vegetation structure, and all species preferred fishless pools with floating and submerged macrophytes. Fish presence triggered avoidance only in the generalist bug N. glauca. Our results highlight the significance of habitat selectivity for structuring freshwater ecosystems and illustrate how habitat selection responses to a top predator are dictated by specialization and life history., (© 2021. The Author(s).)
- Published
- 2021
- Full Text
- View/download PDF
7. Dual Detection of the Chytrid Fungi Batrachochytrium spp. with an Enhanced Environmental DNA Approach.
- Author
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Lastra González D, Baláž V, Vojar J, and Chajma P
- Abstract
Environmental DNA (eDNA) is becoming an indispensable tool in biodiversity monitoring, including the monitoring of invasive species and pathogens. Aquatic chytrid fungi Batrachochytrium dendrobatidis ( Bd ) and B. salamandrivorans ( Bsal ) are major threats to amphibians. However, the use of eDNA for detecting these pathogens has not yet become widespread, due to technological and economic obstacles. Using the enhanced eDNA approach (a simple and cheap sampling protocol) and the universally accepted qPCR assay, we confirmed the presence of Bsal and Bd in previously identified sites in Spain, including four sites that were new for Bsal . The new approach was successfully tested in laboratory conditions using manufactured gene fragments (gBlocks) of the targeted DNA sequence. A comparison of storage methods showed that samples kept in ethanol had the best DNA yield. Our results showed that the number of DNA copies in the Internal Transcribed Spacer region was 120 copies per Bsal cell. Eradication of emerging diseases requires quick and cost-effective solutions. We therefore performed cost-efficiency analyses of standard animal swabbing, a previous eDNA approach, and our own approach. The procedure presented here was evaluated as the most cost-efficient. Our findings will help to disseminate information about efforts to prevent the spread of chytrid fungi.
- Published
- 2021
- Full Text
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8. Recent Findings of Potentially Lethal Salamander Fungus Batrachochytrium salamandrivorans.
- Author
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Lastra González D, Baláž V, Solský M, Thumsová B, Kolenda K, Najbar A, Najbar B, Kautman M, Chajma P, Balogová M, and Vojar J
- Subjects
- Animal Diseases diagnosis, Animals, Polymerase Chain Reaction, Animal Diseases microbiology, Chytridiomycota classification, Chytridiomycota genetics, Chytridiomycota isolation & purification, Mycoses veterinary, Urodela microbiology
- Abstract
The distribution of the chytrid fungus Batrachochytrium salamandrivorans continues to expand in Europe. During 2014-2018, we collected 1,135 samples from salamanders and newts in 6 countries in Europe. We identified 5 cases of B. salamandrivorans in a wild population in Spain but none in central Europe or the Balkan Peninsula.
- Published
- 2019
- Full Text
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9. Chytridiomycosis risk among Central European amphibians based on surveillance data.
- Author
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Balá V, Vojar J, Civi P, Andera M, and Rozínek R
- Subjects
- Animals, Czech Republic, Mycoses epidemiology, Time, Amphibians microbiology, Chytridiomycota isolation & purification, Mycoses veterinary
- Abstract
The Czech Republic hosts a surprisingly rich biodiversity of amphibians representing the majority of amphibian species present in all of Central and Eastern Europe. Surveillance data of Batrachochytrium dendrobatidis (Bd) collected during 2008 to 2012 were analysed for basic patterns of prevalence and infection intensity among species, age groups and localities. In addition, an investigation was made into possible data bias due to varying PCR inhibition. Infection prevalence in the genus Pelophylax was significantly higher than in other sampled taxa, while Bombina and Bufo were infected with intermediate prevalence. Individual mortalities putatively caused by chytridiomycosis were detected in Bombina and Bufo, but not in Pelophylax. Differences among localities were seen to modulate the pathogen's infection rate and influence overall individual infection intensities. PCR inhibition occurred significantly more often in samples from the genus Pelophylax than in other tested taxa (Bufo bufo, B. viridis, Bombina bombina, Pelobates fuscus and Rana dalmatina). Although we found no completely inhibited samples within the genus Bombina, the infection loads were lower in the sample set processed without bovine serum albumin, suggesting some level of PCR inhibition. The combination of high Bd prevalence with no apparent deleterious effect and the high dispersal abilities of water frogs predispose them to act as vectors for chytridiomycosis. It is possible that the role of Pelophylax frogs in the spread of Bd is overlooked due to a large proportion of unrecognized false negatives, but this issue needs further confirmation.
- Published
- 2014
- Full Text
- View/download PDF
10. Consensus in landscape preference judgments: the effects of landscape visual aesthetic quality and respondents' characteristics.
- Author
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Kalivoda O, Vojar J, Skřivanová Z, and Zahradník D
- Subjects
- Adolescent, Adult, Consensus, Czech Republic, Female, Humans, Judgment, Male, Middle Aged, Perception, Young Adult, Conservation of Natural Resources, Esthetics
- Abstract
Landscape's visual aesthetic quality (VAQ) has been widely regarded as a valuable resource worthy of protection. Although great effort has been devoted to determining the factors driving aesthetic preferences, public consensus in judgments has been neglected in the vast majority of such studies. Therefore, the aim of our study was to analyze three main possible sources of judgment variance: landscape VAQ, landscape type, and variability among respondents. Based upon an extensive perception-based investigation including more than 400 hikers as respondents, we found that variance in respondents' judgments differed significantly among assessed landscape scenes. We discovered a significant difference in judgment variances within each investigated respondent characteristic (gender, age, education level, occupational classification, and respondent's type of residence). Judgment variance was at the same time affected by landscape VAQ itself - the higher the VAQ, the better the consensus. While differences caused by characteristics indicate subjectivity of aesthetic values, the knowledge that people better find consensus for positively perceived landscapes provides a cogent argument for legal protection of valuable landscape scenes., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2014
- Full Text
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11. Assessing risk and guidance on monitoring of Batrachochytrium dendrobatidis in Europe through identification of taxonomic selectivity of infection.
- Author
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Baláž V, Vörös J, Civiš P, Vojar J, Hettyey A, Sós E, Dankovics R, Jehle R, Christiansen DG, Clare F, Fisher MC, Garner TW, and Bielby J
- Subjects
- Animals, Chytridiomycota physiology, Europe, Mycoses microbiology, Polymerase Chain Reaction veterinary, Prevalence, Risk Assessment, Amphibians microbiology, Chytridiomycota isolation & purification, Conservation of Natural Resources, Mycoses epidemiology
- Abstract
Amphibians are globally threatened, but not all species are affected equally by different threatening processes. This is true for the threat posed by the chytridiomycete fungus (Batrachochytrium dendrobatidis). We compiled a European data set for B. dendrobatidis to analyze the trends of infection in European amphibians. The risk of infection was not randomly distributed geographically or taxonomically across Europe. Within countries with different prevalence, infection was nonrandom in certain amphibian taxa. Brown frogs of the genus Rana were unlikely to be infected, whereas frogs in the families Alytidae and Bombinatoridae were significantly more likely to be infected than predicted by chance. Frogs in the 2 families susceptible to B. dendrobatidis should form the core of attempts to develop spatial surveillance studies of chytridiomycosis in Europe. Ideally, surveys for B. dendrobatidis should be augmented by sampling the widespread genus Pelophylax because this taxon exhibits geographically inconsistent overinfection with B. dendrobatidis and surveillance of it may facilitate recognition of factors causing spatial variability of infection intensity. Several European amphibian taxa were not represented in our data set; however, surveillance of unsampled species should also occur when warranted., (© 2013 Society for Conservation Biology.)
- Published
- 2014
- Full Text
- View/download PDF
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