Beyond the swab: ecosystem sampling to understand the persistence of an amphibian pathogen

Understanding the ecosystem-level persistence of pathogens is essential for predicting and measuring host–pathogen dynamics. However, this process is often masked, in part due to a reliance on host-based pathogen detection methods. The amphibian pathogens Batrachochytrium dendrobatidis (Bd) and B. s...

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Bibliographic Details
Published in:Oecologia 2018-09, Vol.188 (1), p.319-330
Main Authors: Mosher, Brittany A., Huyvaert, Kathryn P., Bailey, Larissa L.
Format: Article
Language:English
Subjects:
Aquatic reptiles
Biodiversity
Biomedical and Life Sciences
Classification
Conservation
CONSERVATION ECOLOGY – ORIGINAL RESEARCH
Criteria
Detection
Dynamics
Ecology
Ecosystems
Environmental monitoring
Hydrology/Water Resources
Life Sciences
Modelling
Pathogens
Plant Sciences
Probability theory
Water filtration
Water purification
Wildlife conservation
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Summary:Understanding the ecosystem-level persistence of pathogens is essential for predicting and measuring host–pathogen dynamics. However, this process is often masked, in part due to a reliance on host-based pathogen detection methods. The amphibian pathogens Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) are pathogens of global conservation concern. Despite having free-living life stages, little is known about the distribution and persistence of these pathogens outside of their amphibian hosts. We combine historic amphibian monitoring data with contemporary host-and environment-based pathogen detection data to obtain estimates of Bd occurrence independent of amphibian host distributions. We also evaluate differences in filter-and swab-based detection probability and assess inferential differences arising from using different decision criteria used to classify samples as positive or negative. Water filtration-based detection probabilities were lower than those from swabs but were > 10 %, and swab-based detection probabilities varied seasonally, declining in the early fall. The decision criterion used to classify samples as positive or negative was important; using a more liberal criterion yielded higher estimates of Bd occurrence than when a conservative criterion was used. Different covariates were important when using the liberal or conservative criterion in modeling Bd detection. We found evidence of long-term Bd persistence for several years after an amphibian host species of conservation concern, the boreal toad (Anaxyrus boreas boreas), was last detected. Our work provides evidence of long-term Bd persistence in the ecosystem, and underscores the importance of environmental samples for understanding and mitigating disease-related threats to amphibian biodiversity.
ISSN:0029-8549
1432-1939
DOI:10.1007/s00442-018-4167-6