scholarly journals Modelling the amphibian chytrid fungus spread by connectivity analysis: towards a national monitoring network in Italy

2021 ◽  
Author(s):  
Andrea Costa ◽  
Lorenzo Dondero ◽  
Giorgia Allaria ◽  
Bryan Nelson Morales Sanchez ◽  
Giacomo Rosa ◽  
...  
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
National Level ◽  
Monitoring Network ◽  
Electric Circuit ◽  
Population Declines ◽  
Climate Data ◽  
Landscape Permeability ◽  
National Monitoring ◽  
Climatic Scenarios ◽  
Amphibian Chytrid Fungus

AbstractThe emerging amphibian disease, Batrachochytrium dendrobatidis (Bd), is driving population declines worldwide and even species extinctions in Australia, South and Central America. In order to mitigate effects of Bd on amphibian populations, high-exposed areas should be identified at the local scale and effective conservation measures should be planned at the national level. This assessment is actually lacking in the Mediterranean basin, and in particular in Italy, one of the most relevant amphibian diversity hotspots in the entire region. In this study, we reviewed the available information on Bd in Italy, and conducted a 5-year molecular screening on 1274 individual skin swabs belonging to 18 species. Overall, we found presence of Bd in 13 species and in a total of 56 known occurrence locations for peninsular Italy and Sardinia. We used these occurrence locations and climate data to model habitat suitability of Bd for current and future climatic scenarios. We then employed electric circuit theory to model landscape permeability to the diffusion of Bd, using a resistance map. With this procedure, we were able to model, for the first time, the diffusion pathways of Bd at the landscape scale, characterising the main future pathways towards areas with a high probability of Bd occurrence. Thus, we identified six national protected areas that will become pivotal for a nationally-based strategic plan in order to monitor, mitigate and possibly contrast Bd diffusion in Italy.

scholarly journals Establishement of a national monitoring program based on environmental DNA for amphibians and the chytrid fungus Batrachochytrium dendrobatidis     

2021 ◽  
Vol 4 ◽  
Author(s):  
Omneya Osman ◽  
Johan Andersson ◽  
Tomas Larsson ◽  
Mats Töpel ◽  
Alexander Eiler
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
National Level ◽  
Monitoring Program ◽  
12S Rrna ◽  
Rrna Gene ◽  
Chytrid Fungus ◽  
Rana Arvalis ◽  
Amphibian Species ◽  
National Monitoring ◽  
Wide Range

National monitoring programs provide the basis for evaluating the integrity of ecosystems, their responses to disturbances, and the success of actions taken to conserve or recover biodiversity. In this study, we successfully established a national program for the invasive chytrid fungus Batrachochytrium dendrobatidis (Bd) based on dual TaqMan assays. Amphibian diversity based on metabarcoding of the mitochondrial 12S rRNA gene was also performed. Assays were optimized for sensitive detection of target species from a wide range of amphibian ponds with variable potential of inhibitions for eDNA based detection. An amphibian mock community of 5 species was used to validate the metabarcoding approach while internal standards were used in the case of the dual TaqMan assays. First sampling of over 170 ponds in Norway resulted in Bd detection in 12 environmental samples and one swab sample taken over multiple years indicating the establishment of Bd in Norway. Five amphibian species Bufo bufo, Lissotriton vulgaris, Triturus cristatus, Rana arvalis and Rana temporaria as predicted from data in long-term citizen science reporting systems were widely detected in the collected eDNA samples. Our large scale-monitoring program indicates a low risk of a Bd outbreak and amphibian decline caused by chytridiomycosis but continued monitoring is recommended in the future. These findings indicate that eDNA is an effective method to detect invasive species, and to monitor endangered amphibian species. Still, several shortcomings (such as PCR inhibitors and sample volume) were identified that need to be addressed to improve eDNA-based monitoring at the national level.

scholarly journals Ancestral chytrid pathogen remains hypervirulent following its long coevolution with amphibian hosts

2019 ◽  
Vol 286 (1904) ◽  
pp. 20190833 ◽  
Author(s):  
Minjie Fu ◽  
Bruce Waldman
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Population Declines ◽  
Amphibian Species ◽  
South Korean ◽  
Global Pandemic ◽  
Litoria Caerulea ◽  
Experimental Treatments ◽  
Amphibian Chytrid Fungus ◽  
Genomic Recombination ◽  
Blank Solution

Many amphibian species around the world, except in Asia, suffer morbidity and mortality when infected by the emerging infectious pathogen Batrachochytrium dendrobatidis (Bd). A lineage of the amphibian chytrid fungus isolated from South Korean amphibians (BdAsia-1) is evolutionarily basal to recombinant global pandemic lineages (BdGPL) associated with worldwide amphibian population declines. In Asia, the Bd pathogen and its amphibian hosts have coevolved over 100 years or more. Thus, resilience of Asian amphibian populations to infection might result from attenuated virulence of endemic Bd lineages, evolved immunity to the pathogen or both. We compared susceptibilities of an Australasian amphibian, Litoria caerulea , known to lack resistance to BdGPL, with those of three Korean species, Bufo gargarizans , Bombina orientalis and Hyla japonica , after inoculation with BdAsia-1, BdGPL or a blank solution. Subjects became infected in all experimental treatments but Korean species rapidly cleared themselves of infection, regardless of Bd lineage. They survived with no apparent secondary effects. By contrast, L. caerulea , after infection by either BdAsia-1 or BdGPL, suffered deteriorating body condition and carried progressively higher Bd loads over time. Subsequently, most subjects died. Comparing their effects on L. caerulea , BdAsia-1 induced more rapid disease progression than BdGPL. The results suggest that genomic recombination with other lineages was not necessary for the ancestral Bd lineage to evolve hypervirulence over its long period of coevolution with amphibian hosts. The pathogen's virulence may have driven strong selection for immune responses in endemic Asian amphibian host species.

scholarly journals Single infection with Batrachochytrium dendrobatidis or Ranavirus does not increase probability of co-infection in a montane community of amphibians

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jaime Bosch ◽  
Camino Monsalve-Carcaño ◽  
Stephen J. Price ◽  
Jon Bielby
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Disease Outbreaks ◽  
Single Infection ◽  
Chytrid Fungus ◽  
Population Declines ◽  
Emerging Pathogens ◽  
Amphibian Species ◽  
Management Interventions ◽  
Amphibian Chytrid Fungus ◽  
Common Situation

AbstractUnderstanding the occurrence and consequence of co-infections can be useful in designing disease management interventions. Amphibians are the most highly threatened vertebrates, and emerging pathogens are a serious threat to their conservation. The amphibian chytrid fungus and the viruses of the Ranavirus genus are already widely distributed, causing disease outbreaks and population declines worldwide. However, we lack information about the occurrence and consequences of coinfection with these pathogens across age-classes of amphibian hosts. Here, we analyze the occurrence of infection of the amphibian chytrid fungus and ranaviruses during one season in two susceptible amphibian species at two different locations at which outbreaks have occurred. We found that the co-occurrence of both pathogens in a particular host is not common except in highly susceptible life-stages, and that single infections are the most common situation. Moreover, we found that the occurrence of one pathogen in a particular host did not predict the occurrence of the other. We attribute these results to the niches in which both pathogens proliferate in amphibian hosts.

Low infection prevalence of the amphibian chytrid fungus Batrachochytrium dendrobatidis (Chytridiomycetes: Rhizophydiales) in Cuba

2017 ◽  
Vol 38 (2) ◽  
pp. 243-249 ◽  
Author(s):  
Joana Sabino-Pinto ◽  
Molly C. Bletz ◽  
Manuel Iturriaga ◽  
Miguel Vences ◽  
Ariel Rodríguez
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Infection Prevalence ◽  
Chytrid Fungus ◽  
Population Declines ◽  
Amphibian Chytrid Fungus

The chytrid fungus Batrachochytrium dendrobatidis (Bd) is responsible for population declines and extinctions of amphibians worldwide. The distribution and prevalence of Bd in Cuba has remained unknown to date, with only a single report on its presence. We collected 182 samples from wild anuran populations across 21 species and 16 localities and tested for the presence of Bd using qPCRs. Only six Bd positive samples from four species were detected in three very close localities in Central Cuba. Bd prevalence was of 10-20% in the positive localities, and the island-wide prevalence was only 3.2%. These results indicate that Bd occurrence in Cuba might be concentrated in or even restricted to the central Guamuhaya Massif and call for increased conservation and monitoring efforts in these mountains along with additional sampling in areas and species not covered in this study.

scholarly journals Enhanced call effort in Japanese tree frogs infected by amphibian chytrid fungus

2016 ◽  
Vol 12 (3) ◽  
pp. 20160018 ◽  
Author(s):  
Deuknam An ◽  
Bruce Waldman
Keyword(s):  
Disease Transmission ◽  
Life Histories ◽  
Batrachochytrium Dendrobatidis ◽  
Sublethal Effects ◽  
Population Declines ◽  
Tree Frogs ◽  
Amphibian Chytrid Fungus ◽  
Host Behaviour ◽  
Immune Defences

Some amphibians have evolved resistance to the devastating disease chytridiomycosis, associated with global population declines, but immune defences can be costly. We recorded advertisement calls of male Japanese tree frogs ( Hyla japonica ) in the field. We then assessed whether individuals were infected by Batrachochytrium dendrobatidis (Bd), the causal agent of the disease. This allowed us to analyse call properties of males as a function of their infection status. Infected males called more rapidly and produced longer calls than uninfected males. This enhanced call effort may reflect pathogen manipulation of host behaviour to foster disease transmission. Alternatively, increased calling may have resulted from selection on infected males to reproduce earlier because of their shortened expected lifespan. Our results raise the possibility that sublethal effects of Bd alter amphibian life histories, which contributes to long-term population declines.

scholarly journals Is overwintering mortality driving enigmatic declines? Evaluating the impacts of trematodes and the amphibian chytrid fungus on an anuran from hatching through overwintering

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0262561
Author(s):  
Olivia Wetsch ◽  
Miranda Strasburg ◽  
Jessica McQuigg ◽  
Michelle D. Boone
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Species Conservation ◽  
Emerging Infectious Diseases ◽  
The Novel ◽  
Chytrid Fungus ◽  
Growth And Survival ◽  
Critical Life Events ◽  
Overwintering Mortality ◽  
Amphibian Chytrid Fungus

Emerging infectious diseases are increasing globally and are an additional challenge to species dealing with native parasites and pathogens. Therefore, understanding the combined effects of infectious agents on hosts is important for species’ conservation and population management. Amphibians are hosts to many parasites and pathogens, including endemic trematode flatworms (e.g., Echinostoma spp.) and the novel pathogenic amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]). Our study examined how exposure to trematodes during larval development influenced the consequences of Bd pathogen exposure through critical life events. We found that prior exposure to trematode parasites negatively impacted metamorphosis but did not influence the effect of Bd infection on terrestrial growth and survival. Bd infection alone, however, resulted in significant mortality during overwintering—an annual occurrence for most temperate amphibians. The results of our study indicated overwintering mortality from Bd could provide an explanation for enigmatic declines and highlights the importance of examining the long-term consequences of novel parasite exposure.

Non-detection of mycoviruses in amphibian chytrid fungus (Batrachochytrium dendrobatidis) from Australia

2021 ◽  
Author(s):  
Rebecca J. Webb ◽  
Alexandra A. Roberts ◽  
Stephen Wylie ◽  
Tiffany Kosch ◽  
Luís Felipe Toledo ◽  
...  
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Chytrid Fungus ◽  
Amphibian Chytrid Fungus

Source Process-Related Delays in Earthquake Early Warning for Example Cases in Greece

2021 ◽  
Author(s):  
Nikolaos Vavlas ◽  
Anastasia A. Kiratzi ◽  
Zafeiria Roumelioti
Keyword(s):  
Early Warning ◽  
Monitoring Network ◽  
Earthquake Early Warning ◽  
Source Process ◽  
Spatial Density ◽  
Intermediate Depth ◽  
National Monitoring ◽  
Gulf Of Corinth ◽  
Crete Island ◽  
Finite Fault

ABSTRACT We explore a hypothetical zero-latency earthquake early warning (EEW) system in Greece, aiming to provide alerts before warning thresholds of the intensity of ground motion are exceeded. Within the seismotectonic context of Greece, both shallow- and intermediate-depth earthquakes (along the Hellenic subduction zone) are plausible and, thus, examined. Using regionally applicable attenuation relations, we combine and adjust the methodologies of Minson et al. (2018) and Hoshiba (2020) to examine what are the minimum magnitudes required to invoke the warning thresholds at the user site. With simple modeling, we examine how fast an alert can be issued and what is the available warning time when taking into account delays due to finite-fault rupture propagation, alongside other delays. These computations are merged with delays introduced due to the present-day configuration of the Greek national monitoring network (varying spatial density of permanent monitoring stations). This approach serves as a tool to assess the feasibility of an EEW system at specific sites and to redesign the national permanent monitoring network to serve such a system more effectively (we provide results for four sites.). Warning times for on-land crustal earthquakes are found to be shorter, whereas for intermediate-depth earthquakes in Greece an EEW system is feasible (provides warning times of several tens of seconds at large cities, e.g., on Crete Island) even with the current configuration of the national monitoring network, which is quite sparse in the southern part of the country. The current network configuration also provides sufficient early warning (e.g., of the order of 10 s for a warning threshold of 0.05g) at the center of Athens from earthquakes of the eastern Gulf of Corinth—a zone posing elevated hazard in the broader area of the Greek capital. Several additional assumptions and factors affecting the operability of an EEW system in Greece (i.e., source process complexity and uncertainty in attenuation laws) are also discussed.

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