Fighting an uphill battle: the recovery of frogs in Australia's Wet Tropics

Abstract

In the 1980s and early 1990s, an outbreak of the fungal disease chytridiomycosis caused multiple species of frog to decline or disappear throughout the Wet Tropics of northern Queensland, Australia (Richards et al. 1993, McDonald and Alford 1999). This disease is caused by the pathogen Batrachochytrium dendrobatidis (Bd; Berger et al. 1998), which does not grow well at warm temperatures (Piotrowski et al. 2004). As a result, the declines often followed elevational gradients, with the most severe declines occurring at cool, high-elevation sites. For example, populations of the waterfall frog (Litoria nannotis), common mist frog (Litoria rheocola), and Australian lace-lid frog (Litoria [Nyctimystes] dayi) disappeared above 300-400 m, but these species did not decline noticeably in the lowlands (Richards et al. 1993; Laurance et al. 1996; McDonald and Alford 1999). The green-eyed tree frog (Litoria serrata; formerly L. genimaculata) also declined sharply above 300-400 m, but it did not completely disappear from those sites (Richards and Alford 2005). Although these declines and disappearances are well documented, much less attention has been given to the fact that many of the upland populations have recovered to varying degrees, even though Bd persists at a relatively high prevalence.