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Abstract To combat the loss of species due to emerging infectious diseases, scientists must incorporate ecological parameters, such as temperature and humidity, to understand how the environment affects host–pathogen interactions. The fungal disease chytridiomycosis is a compelling case study to investigate the role of both temperature and humidity on infectious disease, as both the fungal pathogen (Batrachochytrium dendrobatidis, Bd) and the host (amphibians) are heavily influenced by these abiotic factors. We performed two experiments to investigate the importance of relative humidity and temperature on frog immunity (production of antimicrobial skin secretions) and disease development in captive golden frogs (Atelopus zeteki) of Panama. We found that the quantity of skin secretions significantly decreased over time in frogs moved from low to medium and high relative humidity treatments. FollowingBdexposure, frogs in high temperature (26–27 °C) and high relative humidity (80–90%) had lower pathogen loads and survived significantly longer than frogs kept in all other treatment conditions, including high temperature and low relative humidity. These results suggest that high relative humidity may be an important, although less understood, mediator ofBdinfection and the survival of golden frogs. Because the environment can drastically alter disease dynamics, understanding how temperature and humidity influence chytridiomycosis outcomes in golden frogs may be essential for the success of the reintroduction of captive frogs.
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Release trial of captive-bred variable harlequin frogs Atelopus varius shows that frogs disperse rapidly, are difficult to recapture and do not readily regain skin toxicity
Abstract Variable harlequin frogsAtelopus variushave declined significantly throughout their range as a result of infection with the fungal pathogenBatrachochytrium dendrobatidis(Bd). The Panama Amphibian Rescue and Conservation Project maintains an ex situ population of this Critically Endangered species. We conducted a release trial with surplus captive-bredA. variusindividuals to improve our ability to monitor frog populations post-release, observe dispersal patterns after freeing them into the wild and learn about threats to released frogs, as well as to determine whether natural skin toxin defences of frogs could be restored inside mesocosms in the wild and to compare Bd dynamics in natural amphibian communities at the release site vs a non-release site. The 458 released frogs dispersed rapidly and were difficult to re-encounter unless they carried a radio transmitter. No frog was seen after 36 days following release. Thirty frogs were fitted with radio transmitters and only half were trackable by day 10. Tetrodotoxin was not detected in the skins of the frogs inside mesocosms for up to 79 days. Bd loads in other species present at sites were high prior to release and decreased over time in a pattern probably driven by weather. No differences were observed in Bd prevalence between the release and non-release sites. This trial showed that refinements of our methods and approaches are required to study captiveAtelopusfrogs released into wild conditions. We recommend continuing release trials of captive-bred frogs with post-release monitoring methods, using an adaptive management framework to advance the field of amphibian reintroduction ecology.
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- Award ID(s):
- 2120084
- PAR ID:
- 10512697
- Publisher / Repository:
- Oryx
- Date Published:
- Journal Name:
- Oryx
- Volume:
- 58
- Issue:
- 3
- ISSN:
- 0030-6053
- Page Range / eLocation ID:
- 323 to 335
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1017/S0030605323001254
