scholarly journals Evaluating eDNA-based monitoring of fire salamander larvae under field conditions

2021 ◽  
Vol 4 ◽  
Author(s):  
Bianca Spitzl ◽  
Daniela Sint ◽  
Florian Glaser ◽  
Gerda Ludwig ◽  
Michael Traugott
Keyword(s):  
Water Samples ◽  
Field Conditions ◽  
Population Declines ◽  
Amphibian Species ◽  
Batrachochytrium Salamandrivorans ◽  
Small Streams ◽  
Key Species ◽  
Fire Salamander ◽  
Regional Population ◽  
Salamander Larvae

Amphibians globally belong to the most threatened animal groups and monitoring their populations is of critical importance for their conservation. The fire salamander (Salamandra salamandra) is one of the European amphibian species which has been experiencing drastic regional population declines due to the spread of the invasive chytrid fungus Batrachochytrium salamandrivorans, making it a key species for monitoring efforts. Here, we evaluated how the sampling and analysis of eDNA can aid the monitoring of larval salamander populations in small streams under field conditions. Nine small streams with known adult and larval fire salamander populations were investigated in Tirol (Austria). Per steam a stretch of 30 m downstream from its source was divided into 10 m sections where salamander larvae were counted. Water samples were taken at the end of each section and filtered on site. The DNA extracted from these filters was tested by a new PCR assay developed for the detection of mitochondrial DNA of S. salamandra. This assay combines endpoint PCR with capillary electrophoresis, allowing to relatively quantify the amount of fire salamander eDNA present in the water samples. In two of the nine streams no eDNA of S. Salamandra could be detected. The outcomes of an analysis of how larval densities, discharge and volume of filtered water affected the detection of salamander eDNA will be presented. Finally, we will conclude on the practical implications of the current findings for eDNA-based monitoring of fire salamander populations.

scholarly journals Long distance (>20 km) downstream detection of endangered stream frogs suggests an important role for eDNA in surveying for remnant amphibian populations

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12013
Author(s):  
Cecilia Villacorta-Rath ◽  
Conrad J. Hoskin ◽  
Jan M. Strugnell ◽  
Damien Burrows
Keyword(s):  
Water Samples ◽  
Survey Methods ◽  
Environmental Dna ◽  
Small Population ◽  
Population Declines ◽  
Long Distance ◽  
Amphibian Species ◽  
Filtration Method ◽  
North East ◽  
Water Volumes

Background Globally, amphibian species have suffered drastic population declines over the past 40 years. Hundreds of species are now listed as Critically Endangered, with many of these considered “possibly extinct”. Most of these species are stream-dwelling frogs inhabiting remote, montane areas, where remnant populations are hard to find using traditional surveys. Environmental DNA (eDNA) could revolutionize surveys for ‘missing’ and endangered amphibian populations by screening water samples from downstream sections to assess presence in the upstream catchments. However, the utility of this survey technique is dependent on quantifying downstream detection probability and distances. Methods Here we tested downstream detection distances in two endangered stream frogs (Litoria lorica and L. nannotis) that co-occur in a remote stream catchment in north-east Australia, and for which we know precise downstream distributional limits from traditional surveys. Importantly, the two last populations of L. lorica persist in this catchment: one small (~1,000 frogs) and one very small (~100 frogs). We conducted eDNA screening at a series of sites kilometers downstream from the populations using precipitation from two fixed water volumes (15 and 100 mL) and via water filtering (mean 1,480 L). Results We detected L. nannotis and the small L. lorica population (~1,000 frogs) at most sampling sites, including 22.8 km downstream. The filtration method was highly effective for far-downstream detection, as was precipitation from 100 mL water samples, which also resulted in consistent detections at the far-downstream sites (including to 22.8 km). In contrast, we had limited downstream detection success for the very small L. lorica population (~100 frogs). Discussion The ecological aspects of our study system, coupled with thorough traditional surveys, enabled us to measure downstream eDNA detection distances with accuracy. We demonstrate that eDNA from a small population of approximately 1,000 frogs can be detected as far as 22.8 km downstream from the population. Water filtration is considered best for eDNA detection of rare aquatic species—indeed it was effective in this study—but we also achieved far-downstream detections when precipitating eDNA from 100 mL water samples. Collecting small water volumes for subsequent precipitation in the lab is more practical than filtration when surveying remote areas. Our downstream detection distances (>20 km) suggest eDNA is a valuable tool for detecting rare stream amphibians. We provide recommendations on optimal survey methods.

scholarly journals DNA-based biomonitoring in the tropics: Detection and control of Batrachochytrium dendrobatidis in Ecuadorian ecosystem

2021 ◽  
Vol 4 ◽  
Author(s):  
Lenin Riascos-Flores ◽  
Andrea Carrera ◽  
Leopoldo Naranjo ◽  
Jomira Yanez ◽  
Peter Goethals ◽  
...  
Keyword(s):  
Invasive Species ◽  
Water Samples ◽  
Large Scale ◽  
Batrachochytrium Dendrobatidis ◽  
Action Plan ◽  
Detection Methods ◽  
Population Declines ◽  
Amphibian Species ◽  
Tissue Samples ◽  
And Control

Batrachochytrium dendrobatidis (Bd) is a fungus that parasites vertebrates, and is associated with population declines worldwide in endemic amphibian species. As such, it is one of several invasive species which pose a serious threat to a variety of vertebrate hosts, in casu: amphibians. Detection of such invasive species is generally based on DNA-based methods where, for instance, swabs or tissue samples of candidate hosts are analysed for their presence. Any management strategy of these invasive species would greatly benefit from sensitive and rapid detection methods which can be applied at a large scale. The analysis of eDNA from the habitat of candidate host organisms may hold significant potential for this purpose. In this study, we compare the ability of eDNA from habitat samples with that of swab and/or tissue samples of candidate hosts to detect the presence of Bd in Ecuador. We collected individuals from the amphibians: Pristimantis (Anura: Craugastoridae), Rhinella (Anura: Bufonidae), Gastroteca (Anura: Hemiphractidae), from the endangered toad species of the genus Atelopus (Anura: Bufonidae) as well as water samples from different water bodies in Andean and coastal Ecuadorian areas. Samples were processed using a portable field molecular laboratory. Commercial primers for the internal transcribed spacer (ITS), in combination with a new set of primers designed from Bd sequences from tropical countries, were used. Positive PCR results from both types of samples were obtained within eight hours after sampling. Prevalence of BD was detected in eDNA, swab and tissue samples in four of the six ecosystems monitored -14 out of 26 water samples and 27 out of 43 amphibian of in total 12 species- including three endangered toad species (Atelopus balios, A. nanay, and the rediscovered A. bomolochos). Our results highlight the potential of eDNA-based monitoring to assess the presence and prevalence of Bd in Ecuadorian aquatic ecosystems, in accordance with the National Action Plan for the Conservation of Ecuadorian Amphibians. Furthermore, our field lab approach leads to reliable and fast results for the monitoring of invasive species in a tropical context of a pandemic.

Intercohort size structure dynamics of fire salamander larvae in ephemeral habitats: a mesocosm experiment

Oecologia ◽  
2015 ◽  
Vol 179 (2) ◽  
pp. 425-433 ◽  
Author(s):  
Asaf Sadeh ◽  
Antonina Polevikov ◽  
Marc Mangel ◽  
Leon Blaustein
Keyword(s):  
Size Structure ◽  
Mesocosm Experiment ◽  
Structure Dynamics ◽  
Fire Salamander ◽  
Salamander Larvae ◽  
Ephemeral Habitats

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.

Genetic markers reveal high PIT tag retention rates in giant salamanders (Cryptobranchus alleganiensis)

2012 ◽  
Vol 33 (2) ◽  
pp. 313-317 ◽  
Author(s):  
Shem D. Unger ◽  
Nicholas G. Burgmeier ◽  
Rod N. Williams
Keyword(s):  
Cost Effective ◽  
Retention Rates ◽  
Population Declines ◽  
Pit Tag ◽  
Amphibian Species ◽  
Pit Tags ◽  
Tag Retention ◽  
Cryptobranchus Alleganiensis ◽  
Genetic Tagging ◽  
Secondary Methods

Estimation of population size using mark-recapture (MRR) methods are based on the fundamental assumption that individuals retain their marks throughout the course of study. Passive Integrated Transponder (PIT) tags are useful as a cost effective, reliable marking method in many amphibian and reptile species. Few studies however, use secondary methods to evaluate tag retention rates. Failure to do so can lead to biased population estimates, erroneous conclusions, and thus poor management decisions. Surprisingly, estimates of PIT tag retention are currently lacking for the majority of amphibian species, many of which are experiencing population declines. Herein, we use genetic tagging to assess the retention of PIT tags of the eastern hellbender (Cryptobranchus alleganiensis alleganiensis). We captured and tagged 78 individuals across 35 sites. Recapture rate was 24% and genetic tagging revealed 100% tag retention across all recaptured individuals.

scholarly journals Mitigating Batrachochytrium salamandrivorans in Europe

2019 ◽  
Vol 40 (3) ◽  
pp. 265-290 ◽  
Author(s):  
Valarie Thomas ◽  
Yu Wang ◽  
Pascale Van Rooij ◽  
Elin Verbrugghe ◽  
Vojtech Baláž ◽  
...  
Keyword(s):  
Ex Situ Conservation ◽  
Preventive Measures ◽  
Public Awareness ◽  
Ex Situ ◽  
Chytrid Fungus ◽  
Population Declines ◽  
Batrachochytrium Salamandrivorans ◽  
Mitigation Methods

Abstract The infectious chytrid fungus Batrachochytrium salamandrivorans (Bsal) has been responsible for severe population declines of salamander populations in Europe. Serious population declines and loss of urodelan diversity may occur if appropriate action is not taken to mitigate against the further spread and impact of Bsal. We provide an overview of several potential mitigation methods, and describe their possible advantages and limitations. We conclude that long-term, context-dependent, multi-faceted approaches are needed to successfully mitigate adverse effects of Bsal, and that these approaches should be initiated pre-arrival of the pathogen. The establishment of ex situ assurance colonies, or management units, for species threatened with extinction, should be considered as soon as possible. While ex situ conservation and preventive measures aimed at improving biosecurity by limiting amphibian trade may be implemented quickly, major challenges that lie ahead are in designing in situ disease containment and mitigation post-arrival and in increasing public awareness.

Developmental costs of yellow colouration in fire salamanders and experiments to test the efficiency of yellow as a warning colouration

2020 ◽  
Vol 41 (3) ◽  
pp. 373-385 ◽  
Author(s):  
Barbara A. Caspers ◽  
E. Tobias Krause ◽  
Isabelle Hermanski ◽  
Christopher Wiesbrock ◽  
Friedrich-Wilhelm Kastrup ◽  
...  
Keyword(s):  
Predation Risk ◽  
Carabid Beetles ◽  
Colour Pattern ◽  
Natural Habitats ◽  
Yellow Colour ◽  
Risk Of Predation ◽  
Fire Salamander ◽  
Food Conditions ◽  
In Fire ◽  
Salamander Larvae

Abstract Warning colouration reduces predation risk by signalling or mimicking the unpleasantness of prey and therefore increases survival. We tested in two experiments the evolutionary costs and benefits of the yellow colour pattern in fire salamanders (Salamandra salamandra), which display a yellow/black colour pattern usually associated with toxic alkaloids. Our first experiment aimed to test whether the development of colouration is condition dependent and thus related to developmental costs, i.e. influenced by resource availability during the developmental process. Therefore, we reared fire salamander larvae under different nutritional conditions and compared the relative amount of yellow they developed after metamorphosis. Fire salamander larvae reared under limited food conditions had a lower proportion of yellow following metamorphosis than control larvae reared under superior food conditions. In a second experiment we tested whether the proportion of yellow has an impact on the risk of being attacked using artificial models. We tested, in salamander-free and salamander-occupied natural habitats, whether artificial clay models with different proportions of yellow and black receive different attack rates from potential predators (birds, mammals, insects). In clay models the proportion of yellow and the site had a significant effect on predation risk. Models with larger amounts of yellow had fewer bite marks from predators such as carabid beetles and birds, but only in sympatry with salamanders. In conclusion, the early expression of conspicuous colouration seems to be condition dependent and therefore potentially costly. Furthermore, the yellow colouration of fire salamanders act as a signal that potentially reduces their risk of being attacked by predators. Thus, the yellow colouration of fire salamanders seems to represent an adaptive trait that reduces the risk of predation, which can be expressed in higher quantity by individuals of a certain condition.

scholarly journals Recovery and resiliency of skin microbial communities on the southern leopard frog (Lithobates sphenocephalus) following two biotic disturbances

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Denita M. Weeks ◽  
Matthew J. Parris ◽  
Shawn P. Brown
Keyword(s):  
Microbial Communities ◽  
Fungal Pathogen ◽  
Bacterial Species ◽  
Leopard Frog ◽  
Multiple Time ◽  
Population Declines ◽  
Community Interactions ◽  
Amphibian Species ◽  
Functional Relationships ◽  
Species Specific

Abstract Background Microorganisms have intimate functional relationships with invertebrate and vertebrate taxa, with the potential to drastically impact health outcomes. Perturbations that affect microbial communities residing on animals can lead to dysbiosis, a change in the functional relationship, often associated with disease. Batrachochytrium dendrobatidis (Bd), a fungal pathogen of amphibians, has been responsible for catastrophic amphibian population declines around the globe. Amphibians harbor a diverse cutaneous microbiome, including some members which are known to be antagonistic to Bd (anti-Bd). Anti-Bd microorganisms facilitate the ability of some frog populations to persist in the presence of Bd, where other populations that lack anti-Bd microorganisms have declined. Research suggests disease-antagonistic properties of the microbiome may be a function of microbial community interactions, rather than individual bacterial species. Conservation efforts have identified amphibian-associated bacteria that exhibit anti-fungal properties for use as ‘probiotics’ on susceptible amphibian populations. Probiotic application, usually with a single bacterial species, may benefit from a greater understanding of amphibian species-specific microbiome responses to disturbances (e.g. dysbiosis vs. recovery). We assessed microbiome responses to two microbial disturbance events over multiple time points. Results Exposing Lithobates sphenocephalus (southern leopard frog) adults to the biopesticidal bacteria Bacillus thuringiensis, followed by exposure to the fungal pathogen Bd, did not have long term impacts on the microbiome. After initial shifts, microbial communities recovered and returned to a state that resembled pre-disturbance. Conclusions Our results indicate microbial communities on L. sphenocephalus are robust and resistant to permanent shifts from some disturbances. This resiliency of microbial communities may explain why L. sphenocephalus is not experiencing the population declines from Bd that impacts many other species. Conservation efforts may benefit from studies outlining amphibian species-specific microbiome responses to disturbances (e.g. dysbiosis vs. recovery). If microbial communities on a threatened amphibian species are unlikely to recover following a disturbance, additional measures may be implemented to ameliorate the impacts of physical and chemical stressors on host-associated microbial communities.

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