Natural disturbance reduces disease risk in endangered rainforest frog populations

TL;DR

A tropical cyclone that damaged rainforest canopies reduced the risk of a deadly fungal infection in endangered frogs by altering their microclimate.

Contribution

The study shows natural canopy disturbance reduces infection risk in frogs by creating warmer, drier microclimates.

Findings

Cyclone-damaged areas had 11–28% lower frog infection risk compared to undisturbed areas.

Reduced canopy cover increased microhabitat temperatures and evaporative water loss.

Altered microclimates can reduce disease outbreaks in threatened amphibian populations.

Abstract

Natural disturbances can drive disease dynamics in animal populations by altering the microclimates experienced by hosts and their pathogens. Many pathogens are highly sensitive to temperature and moisture, and therefore small changes in habitat structure can alter the microclimate in ways that increase or decrease infection prevalence and intensity in host populations. Here we show that a reduction of rainforest canopy cover caused by a severe tropical cyclone decreased the risk of endangered rainforest frogs (Litoria rheocola) becoming infected by a fungal pathogen (Batrachochytrium dendrobatidis). Reductions in canopy cover increased the temperatures and rates of evaporative water loss in frog microhabitats, which reduced B. dendrobatidis infection risk in frogs by an average of 11–28% in cyclone-damaged areas, relative to unaffected areas. Natural disturbances to the rainforest canopy can therefore provide an immediate benefit to frogs by altering the microclimate in ways that reduce infection risk. This could increase host survival and reduce the probability of epidemic disease outbreaks. For amphibian populations under immediate threat from this pathogen, targeted manipulation of canopy cover could increase the availability of warmer, drier microclimates and therefore tip the balance from host extinction to coexistence.

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