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Altobelli JT, Dickinson KJM, Godfrey SS, Bishop PJ. Methods in amphibian biotelemetry: Two decades in review. AUSTRAL ECOL 2022. [DOI: 10.1111/aec.13227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joseph T. Altobelli
- Department of Zoology University of Otago 340 Great King Street, PO Box 56 Dunedin 9054 New Zealand
| | | | - Stephanie S. Godfrey
- Department of Zoology University of Otago 340 Great King Street, PO Box 56 Dunedin 9054 New Zealand
| | - Phillip J. Bishop
- Department of Zoology University of Otago 340 Great King Street, PO Box 56 Dunedin 9054 New Zealand
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Garnham JI, Bower DS, Stockwell MP, Pickett EJ, Pollard CJ, Clulow J, Mahony MJ. Seasonal variation in the prevalence of a fungal pathogen and unexpected clearance from infection in a susceptible frog species. DISEASES OF AQUATIC ORGANISMS 2022; 148:1-11. [PMID: 35142293 DOI: 10.3354/dao03628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) causes the disease chytridiomycosis, which is a primary driver for amphibian population declines and extinctions worldwide. For highly susceptible species, such as the green and golden bell frog Litoria aurea, large numbers of Bd-related mortalities are thought to occur during the colder season (winter), when low temperatures favour the growth of the pathogen. However, extant L. aurea populations are persisting with Bd. We measured Bd prevalence and infection levels of wild L. aurea using capture-mark-recapture and radio-tracking methods. Using this information, we sought to determine host and environmental correlates of Bd prevalence and infection load. Mean ± SE infection load was higher in frogs sampled in autumn (431.5 ± 310.4 genomic equivalents; GE) and winter (1147.5 ± 735.8 GE), compared to spring (21.8 ± 19.3 GE) and summer (0.9 ± 0.8 GE). Furthermore, prevalence of Bd infection in L. aurea was highest in winter (43.6%; 95% CI 33.1-54.7%) and lowest in summer (11.2%; 95% CI 6.8-17.9%). Both prevalence and infection load decreased with increasing temperature. Seven frogs cleared their fungal infection during the coolest months when Bd prevalence was highest; however, these clearances were not permanent, as 5 frogs became infected again. Understanding the factors that allow amphibians to clear their Bd infections when temperatures are optimal for Bd growth presents the potential for manipulating such factors and provides an important step in future research.
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Affiliation(s)
- James I Garnham
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales 2308, Australia
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Bosch J, Carrascal LM, Manica A, Garner TWJ. Significant reductions of host abundance weakly impact infection intensity of Batrachochytrium dendrobatidis. PLoS One 2020; 15:e0242913. [PMID: 33253322 PMCID: PMC7703926 DOI: 10.1371/journal.pone.0242913] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 11/10/2020] [Indexed: 11/19/2022] Open
Abstract
Infectious diseases are considered major threats to biodiversity, however strategies to mitigate their impacts in the natural world are scarce and largely unsuccessful. Chytridiomycosis is responsible for the decline of hundreds of amphibian species worldwide, but an effective disease management strategy that could be applied across natural habitats is still lacking. In general amphibian larvae can be easily captured, offering opportunities to ascertain the impact of altering the abundance of hosts, considered to be a key parameter affecting the severity of the disease. Here, we report the results of two experiments to investigate how altering host abundance affects infection intensity in amphibian populations of a montane area of Central Spain suffering from lethal amphibian chytridiomycosis. Our laboratory-based experiment supported the conclusion that varying density had a significant effect on infection intensity when salamander larvae were housed at low densities. Our field experiment showed that reducing the abundance of salamander larvae in the field also had a significant, but weak, impact on infection the following year, but only when removals were extreme. While this suggests adjusting host abundance as a mitigation strategy to reduce infection intensity could be useful, our evidence suggests only heavy culling efforts will succeed, which may run contrary to objectives for conservation.
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Affiliation(s)
- Jaime Bosch
- Research Unit of Biodiversity (CSIC, UO, PA), Gonzalo Gutiérrez Quirós s/n, Oviedo University - Campus Mieres, Edificio de Investigación, Mieres, Spain
- Centro de Investigación, Seguimiento y Evaluación, Rascafría, Spain
- Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain
| | | | - Andrea Manica
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
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Stutz WE, Calhoun DM, Johnson PTJ. Resistance and tolerance: A hierarchical framework to compare individual versus family-level host contributions in an experimental amphibian-trematode system. Exp Parasitol 2019; 199:80-91. [PMID: 30862495 DOI: 10.1016/j.exppara.2019.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 01/22/2019] [Accepted: 03/06/2019] [Indexed: 11/18/2022]
Abstract
Hosts have two general strategies for mitigating the fitness costs of parasite exposure and infection: resistance and tolerance. The resistance-tolerance framework has been well developed in plant systems, but only recently has it been applied to animal-parasite interactions. However, difficulties associated with estimating fitness, controlling parasite exposure, and quantifying parasite burden have limited application of this framework to animal systems. Here, we used an experimental approach to quantify the relative influence of variation among host individuals and genetic families in determining resistance and tolerance within an amphibian-trematode system. Importantly, we used multiple, alternative metrics to assess each strategy, and employed a Bayesian analytical framework to compare among responses while incorporating uncertainty. Relative to unexposed hosts, exposure to the pathogenic trematode (Ribeiroia ondatrae) reduced the survival and growth of California newts (Taricha torosa) (survival: 93% vs. 74%; growth: 0.29 vs. -0.5 vs mm day -1). Similarly, parasite infection success (the inverse of resistance) ranged from 8% to 100%. Yet despite this broad variation in host resistance and tolerance among individual newts, we found no evidence for transmissable, among-family variation in any of the resistance or tolerance metrics. This suggests that opportunities for evolution of these traits is limited, likely requiring significant increases in mutation, gene flow, or environmental heterogeneity. Our study provides a quantitative framework for evaluating the importance of alternative metrics of resistance and tolerance across multiple time points in the study of host-parasite interactions in animal systems.
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Affiliation(s)
- William E Stutz
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Dana M Calhoun
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309, USA.
| | - Pieter T J Johnson
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309, USA
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5
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Campbell L, Bower DS, Clulow S, Stockwell M, Clulow J, Mahony M. Interaction between temperature and sublethal infection with the amphibian chytrid fungus impacts a susceptible frog species. Sci Rep 2019; 9:83. [PMID: 30643160 PMCID: PMC6331562 DOI: 10.1038/s41598-018-35874-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/07/2018] [Indexed: 11/09/2022] Open
Abstract
The amphibian chytrid fungus Batrachochytrium dendrobatidis is an emerging infectious pathogen present on every continent except Antarctica. It causes the disease chytridiomycosis in a subset of species but does not always result in disease or death for every host. Ambient temperature influences both amphibian metabolism and chytrid pathogenicity, however the interactive effects on host physiology is not well understood. We investigated the sublethal effect of B. dendrobatidis infection on a susceptible host, Litoria aurea to test (1) whether the infection load, metabolic activity, body fat and gonad size differed in L. aurea at either 24 °C or 12 °C ambient temperatures and (2) whether previous Bd infection caused long-term changes to body fat and gonad size. Litoria aurea in 12 °C treatments had higher infection loads of B. dendrobatidis and lower survivorship. Metabolic rate was higher and fat mass was lower in infected individuals and in animals in 24 °C treatments. Male L. aurea previously infected with B. dendrobatidis had smaller testes 5 months-post clearance of infection, an effect likely to translate to fitness costs in wild populations. These experiments demonstrate a physiological cost to sublethal B. dendrobatidis infection, which suggests a reduction in host fitness mediated by temperature in the host's environment regardless of whether infection leads to mortality.
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Affiliation(s)
- Lachlan Campbell
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia.
| | - Deborah S Bower
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia.,James Cook University, Townsville, 4811, Qld, Australia
| | - Simon Clulow
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia.,Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Michelle Stockwell
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia
| | - John Clulow
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia
| | - Michael Mahony
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia
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Mosher BA, Huyvaert KP, Chestnut T, Kerby JL, Madison JD, Bailey LL. Design- and model-based recommendations for detecting and quantifying an amphibian pathogen in environmental samples. Ecol Evol 2017; 7:10952-10962. [PMID: 29299272 PMCID: PMC5743658 DOI: 10.1002/ece3.3616] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 10/12/2017] [Accepted: 10/16/2017] [Indexed: 12/25/2022] Open
Abstract
Accurate pathogen detection is essential for developing management strategies to address emerging infectious diseases, an increasingly prominent threat to wildlife. Sampling for free‐living pathogens outside of their hosts has benefits for inference and study efficiency, but is still uncommon. We used a laboratory experiment to evaluate the influences of pathogen concentration, water type, and qPCR inhibitors on the detection and quantification of Batrachochytrium dendrobatidis (Bd) using water filtration. We compared results pre‐ and post‐inhibitor removal, and assessed inferential differences when single versus multiple samples were collected across space or time. We found that qPCR inhibition influenced both Bd detection and quantification in natural water samples, resulting in biased inferences about Bd occurrence and abundance. Biases in occurrence could be mitigated by collecting multiple samples in space or time, but biases in Bd quantification were persistent. Differences in Bd concentration resulted in variation in detection probability, indicating that occupancy modeling could be used to explore factors influencing heterogeneity in Bd abundance among samples, sites, or over time. Our work will influence the design of studies involving amphibian disease dynamics and studies utilizing environmental DNA (eDNA) to understand species distributions.
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Affiliation(s)
- Brittany A Mosher
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins CO USA
| | - Kathryn P Huyvaert
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins CO USA
| | - Tara Chestnut
- US Geological Survey Oregon Water Science Center Portland OR USA
| | - Jacob L Kerby
- Department of Biology University of South Dakota Vermillion SD USA
| | - Joseph D Madison
- Department of Biology University of South Dakota Vermillion SD USA
| | - Larissa L Bailey
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins CO USA
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Infection increases vulnerability to climate change via effects on host thermal tolerance. Sci Rep 2017; 7:9349. [PMID: 28839273 PMCID: PMC5571046 DOI: 10.1038/s41598-017-09950-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 08/01/2017] [Indexed: 11/10/2022] Open
Abstract
Unprecedented global climate change and increasing rates of infectious disease emergence are occurring simultaneously. Infection with emerging pathogens may alter the thermal thresholds of hosts. However, the effects of fungal infection on host thermal limits have not been examined. Moreover, the influence of infections on the heat tolerance of hosts has rarely been investigated within the context of realistic thermal acclimation regimes and potential anthropogenic climate change. We tested for effects of fungal infection on host thermal tolerance in a model system: frogs infected with the chytrid Batrachochytrium dendrobatidis. Infection reduced the critical thermal maxima (CTmax) of hosts by up to ~4 °C. Acclimation to realistic daily heat pulses enhanced thermal tolerance among infected individuals, but the magnitude of the parasitism effect usually exceeded the magnitude of the acclimation effect. In ectotherms, behaviors that elevate body temperature may decrease parasite performance or increase immune function, thereby reducing infection risk or the intensity of existing infections. However, increased heat sensitivity from infections may discourage these protective behaviors, even at temperatures below critical maxima, tipping the balance in favor of the parasite. We conclude that infectious disease could lead to increased uncertainty in estimates of species’ vulnerability to climate change.
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Greenspan SE, Bower DS, Webb RJ, Roznik EA, Stevenson LA, Berger L, Marantelli G, Pike DA, Schwarzkopf L, Alford RA. Realistic heat pulses protect frogs from disease under simulated rainforest frog thermal regimes. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12944] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Sasha E. Greenspan
- College of Science and Engineering James Cook University Townsville Qld Australia
| | - Deborah S. Bower
- College of Science and Engineering James Cook University Townsville Qld Australia
| | - Rebecca J. Webb
- One Health Research Group College of Public Health Medical and Veterinary Sciences James Cook University Douglas Qld Australia
| | | | - Lisa A. Stevenson
- College of Science and Engineering James Cook University Townsville Qld Australia
| | - Lee Berger
- One Health Research Group College of Public Health Medical and Veterinary Sciences James Cook University Douglas Qld Australia
| | | | | | - Lin Schwarzkopf
- College of Science and Engineering James Cook University Townsville Qld Australia
| | - Ross A. Alford
- College of Science and Engineering James Cook University Townsville Qld Australia
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Klop-Toker KL, Valdez JW, Stockwell MP, Edgar ME, Fardell L, Clulow S, Clulow J, Mahony MJ. Assessing host response to disease treatment: how chytrid-susceptible frogs react to increased water salinity. WILDLIFE RESEARCH 2017. [DOI: 10.1071/wr16145] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Context
The severity and prevalence of the amphibian fungal pathogen, Batrachochytrium dendrobatidis (Bd) is correlated with several environmental variables, including salinity, temperature, and moisture content, which influence the pathogen’s growth and survival. Habitats that contain these environmental variables at levels outside of those optimal for Bd growth and survival may facilitate the survival of susceptible host species. Therefore, manipulation of environmental salinity is a potential management strategy to help conserve Bd-susceptible species. However, host behaviour also influences disease dynamics, and the success of habitat manipulation programs depends on how hosts use this altered habitat.
Aims
To assess if the Bd-susceptible green and golden bell frog, Litoria aurea, will select waterbodies with a salinity increased to S=3; if this selection is affected by infection; and if a frog’s time in a waterbody of this salinity affects infection load or blood physiology.
Methods
We conducted a filmed choice experiment and a 3-year field study where infected and uninfected frogs could choose between fresh or saline waterbodies.
Key results
In both the laboratory experiment and field study, Bd-infected L. aurea spent a significantly greater amount of time in or closer to a waterbody than uninfected frogs. Experimentally infected frogs tended to prefer the saline water over fresh, but their choice of water usage did not differ statistically from uninfected frogs. In the field, frogs began to avoid ponds when salinities rose above S=5.
Conclusions
Because both wild and captive, and infected and uninfected L. aurea readily selected waterbodies with a salinity of S=3, this salinity could potentially be used as a passive method for reducing the severity of Bd when managing this species. However, further testing is needed to understand the efficacy of this treatment, and care must be taken to prevent salinities rising above S=5, because this level seems to produce an avoidance response and therefore may not be suitable in every location.
Implications
Manipulation of aquatic habitats may be a worthwhile focus for Bd management in habitats where water level fluctuations are minimal.
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