Presence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in threatened corroboree frog populations in the Australian Alps

Hunter, David; Speare, Rick; Marantelli, Gerry; Méndez, Diana; Pietsch, Rod; Osborne, Will

doi:10.3354/dao02118

Cited by 48 publications

(52 citation statements)

References 31 publications

(53 reference statements)

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“…Real-time sampling and monitoring indicates that sub-alpine P. pengilleyi populations (at altitudes of approximately 1400 to 1750 m above sea level) have exhibited an epidemiological pattern of progressive decline to extinction (Osborne et al 1999, Hunter et al 2010. In contrast, montane populations (at lower altitudes, 800 to 1400 m) have exhibited an epidemiological pattern of initial decline, followed by stabilisation at lower densities with endemic chytridiomycosis in the surviving populations (Osborne et al 1999, Hunter et al 2010). The long-term persistence of montane populations despite the ongoing presence of chytrid fungus is consistent with patterns of chytridiomycosis outbreaks observed for other Australian (McDonald et al 2005), European (Walker et al 2010) and Central American (Lips et al 2008) amphibian species.…”

Section: Study Speciesmentioning

confidence: 99%

“…Since the late 1980s there has been considerable concern surrounding the decline of P. pengilleyi (Osborne 1989, Hunter et al 2010. Retrospective analysis has implicated chytrid fungus in initial declines during the 1980s (Hunter et al 2010).…”

Section: Study Speciesmentioning

confidence: 99%

Section: Study Speciesmentioning

confidence: 99%

“…Retrospective analysis has implicated chytrid fungus in initial declines during the 1980s (Hunter et al 2010). Real-time sampling and monitoring indicates that sub-alpine P. pengilleyi populations (at altitudes of approximately 1400 to 1750 m above sea level) have exhibited an epidemiological pattern of progressive decline to extinction (Osborne et al 1999, Hunter et al 2010. In contrast, montane populations (at lower altitudes, 800 to 1400 m) have exhibited an epidemiological pattern of initial decline, followed by stabilisation at lower densities with endemic chytridiomycosis in the surviving populations (Osborne et al 1999, Hunter et al 2010).…”

Section: Study Speciesmentioning

confidence: 99%

“…During this drought, precipitation deficiencies were 45% more severe than during the previous driest period (Timbal et al 2010), and a recent multi-proxy precipitation reconstruction concluded that there was a 97% probability that it was the worst drought since European settlement in 1788 (Gergis et al 2012). We hypothesised that P. pengilleyi would be severely affected by these conditions because populations already have been reduced by chytridiomycosis (Hunter et al 2010) and the species has a highly restricted geographic range, low fecundity and is dependent on seasonal pools (Osborne 1989). Globally, restricted geographic range, low fecundity and the presence of multiple threatening processes are characteristics often associated with declining amphibian species (Cooper et al 2008, Murray et al 2011.…”

Section: Introductionmentioning

confidence: 99%

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Decline of an endangered amphibian during an extreme climatic event

et al. 2012

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Abstract. Climate change is a poorly understood, emerging threat to many amphibian species. One of the ways climate change is likely to affect amphibians is through increased recruitment failure associated with more frequent climatic extremes. To understand the risk posed by this threat, we combined 13 years of annual monitoring and multi-scaled habitat modelling at the site (n ¼ 60), pool (n ¼ 105) and nest (n ¼ 170) levels to investigate the decline of the endangered northern corroboree frog (Pseudophryne pengilleyi ), during the most severe drought on record in southern Australia. We documented the local extinction of 42% of P. pengilleyi breeding sites during the climatic extreme. Using logistic regression we investigated habitat variables associated with extinction sites. We found that locally extinct sites now resemble historically absent sites, with fewer pools, less water, and drying-related tree invasion. Extended periods of limited water availability at extinction sites is likely to have restricted breeding, contributing to localised extinctions. Habitat variables recorded at the pool and nest level did not significantly influence P. pengilleyi presence/absence, indicating that site level wetness had an overriding effect. We anticipate that increasing climate variability is likely to disproportionately threaten seasonal pool-breeding amphibian species, exacerbating the global amphibian biodiversity crisis. However, our work with P. pengilleyi suggests there are a range of simple habitat manipulations that could help to ameliorate the impacts.

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Section: Study Speciesmentioning

confidence: 99%

Section: Study Speciesmentioning

confidence: 99%

Section: Study Speciesmentioning

confidence: 99%

Section: Study Speciesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Decline of an endangered amphibian during an extreme climatic event

et al. 2012

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Improving breed‐and‐release programmes in the face of a threatening pathogen, Batrachochytrium dendrobatidis

Klop‐Toker

Valdez

Stockwell

et al. 2021

Aquatic Conservation

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As the proportion of threatened species increases, so too does the need for effective conservation strategies. In response, captive breed‐and‐release and habitat mitigation programmes are two conservation actions that are increasing in use and effectiveness. Success of these programmes is frequently hampered by the continued presence of threatening processes. In the case of amphibian reintroductions, a key threatening process that is difficult to eliminate is the deadly fungal pathogen, Batrachochytrium dendrobatidis (Bd). This pathogen is the proximate cause of decline for the threatened green and golden bell frog, Litoria aurea, and has contributed to the failure of previous breed‐and‐release programmes of this amphibian. To investigate whether is it possible to establish a captive‐bred population of L. aurea that could persist in the presence of Bd, a breed‐and‐release programme was conducted in a created habitat that included increased salinity to inhibit fungal growth rates, exclusion of potential reservoir hosts and source animals bred from parents ‘experienced’ with the strain of Bd present in the release environment. The population persisted in the created habitat for more than 4 years (the timescale of monitoring) but suffered higher infection levels compared with nearby extant populations of L. aurea. These infections significantly reduced apparent survival. Infection dynamics were linked to temperature, host density in the previous season, and size and age of the host, and these factors differed from those in extant populations and are likely to have contributed to the high levels of Bd infection at the created site. This article discusses how it may be possible to manipulate these factors to improve the success of future breed‐and‐release programmes, and recommends the construction of warm water bodies and a strategy of prioritizing the release of fewer, large propagules of high body condition and mixed‐age class, over large numbers of younger, smaller animals.

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Identification of Bufadienolides from the Boreal Toad, Anaxyrus boreas, Active Against a Fungal Pathogen

et al. 2017

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Amphibian granular glands provide a wide range of compounds on the skin that defend against pathogens and predators. We identified three bufadienolides-the steroid-like compounds arenobufagin, gamabufotalin, and telocinobufagin-from the boreal toad, Anaxyrus boreas, through liquid chromatography mass spectrometry (LC/MS). Compounds were detected both after inducing skin gland secretions and in constitutive mucosal rinses from toads. We described the antimicrobial properties of each bufadienolide against Batrachochytrium dendrobatidis (Bd), an amphibian fungal pathogen linked with boreal toad population declines. All three bufadienolides were found to inhibit Bd growth at similar levels. The maximum Bd inhibition produced by arenobufagin, gamabufotalin, and telocinobufagin were approximately 50%, in contrast to the complete Bd inhibition shown by antimicrobial skin peptides produced by some amphibian species. In addition, skin mucus samples significantly reduced Bd viability, and bufadienolides were detected in 15 of 62 samples. Bufadienolides also appeared to enhance growth of the anti-Bd bacterium Janthinobacterium lividum, and thus may be involved in regulation of the skin microbiome. Here, we localized skin bacteria within the mucus layer and granular glands of toads with fluorescent in situ hybridization. Overall, our results suggest that bufadienolides can function in antifungal defense on amphibian skin and their production is a potentially convergent trait similar to antimicrobial peptide defenses found on the skin of other species. Further studies investigating bufadienolide expression across toad populations, their regulation, and interactions with other components of the skin mucosome will contribute to understanding the complexities of amphibian immune defense.

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Presence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in threatened corroboree frog populations in the Australian Alps

Cited by 48 publications

References 31 publications

Decline of an endangered amphibian during an extreme climatic event

Decline of an endangered amphibian during an extreme climatic event

Improving breed‐and‐release programmes in the face of a threatening pathogen, Batrachochytrium dendrobatidis

Identification of Bufadienolides from the Boreal Toad, Anaxyrus boreas, Active Against a Fungal Pathogen

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