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Source: InCites
Abstract
Amphibia Batrachochytrium dendrobatidis Disease Metamorphic climax Mortality Population dynamics Wildlife and habitat management Terrestrial biodiversity
Amphibian populations are undergoing extensive declines globally. The fungal disease chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd), is a primary contributor to these declines. The amphibian metamorphic stages (Gosner stages 42–46) are particularly vulnerable to a range of stressors, including Bd. Despite this, studies that explicitly examine host response to chytridiomycosis throughout the metamorphic stages are lacking. We aimed to determine how Bd exposure during the larval stages impacts metamorphic development and infection progression in the endangered Fleay's barred frog (Mixophyes fleayi). We exposed M. fleayi to Bd during pro-metamorphosis (Gosner stages 35–38) and monitored infection dynamics throughout metamorphosis. We took weekly morphological measurements (weight, total body length, snout-vent-length and Gosner stage) and quantified Bd load using qPCR. While we observed minimal impact of Bd infection on animal growth and development, Bd load varied throughout ontogeny, with an infection load plateau during the tadpole stages (Gosner stages 35–41) and temporary infection clearance at Gosner stage 42. Bd load increased exponentially between Gosner stages 42 and 45, with most exposed animals becoming moribund at Gosner stage 45, prior to the completion of metamorphosis. There was variability in infection outcome of exposed individuals, with a subgroup of animals (n = 5/29) apparently clearing their infection while the majority (n = 21/29) became moribund with high infection burdens. This study demonstrates the role that metamorphic restructuring plays in shaping Bd infection dynamics and raises the concern that substantial Bd-associated mortality could be overlooked in the field due to the often cryptic nature of these latter metamorphic stages. We recommend future studies that directly examine the host immune response to Bd infection throughout metamorphosis, incorporating histological and molecular methods to elucidate the mechanisms responsible for the observed trends.
Details
Title
Chytridiomycosis causes high amphibian mortality prior to the completion of metamorphosis
Creators
Josephine E. Humphries - Griffith University
Chantal M. Lanctôt - Griffith University
Hamish I McCallum - Griffith University
David A Newell - Southern Cross University
Laura F Grogan - Griffith University
Publication Details
Environmental research, Vol.247, 118249
Publisher
Elsevier
Grant note
JH was supported by the New South Wales Department of Planning Industry and Environment via the Saving Our Species program and the Griffith University Postgraduate research scholarship. LG was supported by Australian Research Council (ARC) grants DP180101415 and DE200100490 funded by the Australian Government. CL was supported by an ARC Discovery Early Career Researcher Award (DE180101286). HM and DN were supported by ARC grant DP180101415.