Amphibian chytrid prevalence on boreal toads in SE Alaska and NW British Columbia: tests of habitat, life stages, and temporal trends

Authors: Blake R Hossack; M J Adams; R K Honeycutt; J Belt; S Pyare
Contribution Number: 723

https://doi.org/10.3354/dao03430

Abstract/Summary

Tracking and understanding variation in pathogens such as Batrachochytrium dendrobatidis
(Bd), the agent of amphibian chytridiomycosis, which has caused population declines
globally, is a priority for many land managers. However, relatively little sampling of amphibian
communities has occurred at high latitudes. We used skin swabs collected during 2005?2017 from
boreal toads Anaxyrus boreas (n = 248), in southeast Alaska (USA; primarily in and near Klondike
Gold Rush National Historical Park [KLGO]) and northwest British Columbia (Canada) to determine
how Bd prevalence varied across life stages, habitat characteristics, local species richness,
and time. Across all years, Bd prevalence peaked in June and was >3 times greater for adult toads
(37.5%) vs. juveniles and metamorphs (11.2%). Bd prevalence for toads in the KLGO area, where
other amphibian species are rare or absent, was highest from river habitats (55.0%), followed by
human-modified upland wetlands (32.3%) and natural upland wetlands (12.7%)—the same rankorder
these habitats are used for toad breeding. None of the 12 Columbia spotted frogs Rana
luteiventris or 2 wood frogs R. sylvatica from the study area tested Bd-positive, although all were
from an area of low host density where Bd has not been detected. Prevalence of Bd on toads in the
KLGO area decreased during 2005?2015. This trend from a largely single-species system may be
encouraging or concerning, depending on how Bd is affecting vital rates, and emphasizes the
need to understand effects of pathogens before translating disease prevalence into management
actions.

Publication details
Published Date: 2020
Outlet/Publisher: Diseases of Aquatic Organisms 137:159-165
Media Format:

ARMI Organizational Units:
Rocky Mountains, Northern - Biology
Topics:
Disease; Monitoring and Population Ecology; Species and their Ecology; Stressors
Place Names:
Alaska
Keywords:
amphibians; ARMI; Bd; chytrid fungus; Chytridiomycosis; conservation; density effects; disease; habitat; monitoring; pathogen; population; stream; stressors; trends; wetlands; wilderness
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