Prevalence of Chytrid in populations of frogs in eastern New South Wales

Michael Mahony

Department of Biological Sciences, University of Newcastle, Callaghan , NSW 2308, Australia

Email: bimjm@cc.newcastle.edu.au

Field surveys to determine the prevalence of Chytrid infection in wild populations of stream, pond and terrestrial frogs were conducted in eastern New South Wales in the summer of 1998 and 1999. Toe clips were taken from up to thirty individuals of each selected species per survey area. No evidence of Chytrid infection was detected in permanent pond breeding species (Family Myobatrachidae; Crinia signifera, Limnodyanstes peroni, Lim. tasmaniensis, Lim. dumerilli; Family Hylidae; Litoria fallax, L. latopalmata). Infection and deaths were observed in a population of Litoria aurea that occurred in a matrix of semi-permanent and permanent ponds, and in the ephemeral pond breeder L. chloris. Conversely, no infection was detected in 30 specimens of other species collected from the same source (L. fallax, Lim. tasmaniensis). Various levels of prevalence were detected in stream species (Myobatrachids; Adelotus brevis, Mixophyes fasciolatus, M. fleayi, M. iteratus; Hylids; L. citropa, Litoria lesueuri, L. barringtonensis, L. phyllochroa). The highest level was found in a population of Adelotus brevis (4 of 10 individuals) from low altitude (> 100 m a.s.l.) and the lowest in several populations of L. lesueuri and L. phyllochroa (1 or 2 individuals in 30). Absence of infection was found in one population of M. fleayi, two populations of M. iteratus and in several populations of L. barringtonensis, L. phyllochroa and L. lesueuri. No evidence of the fungus was found in 18 specimens of the terrestrial Assa darlingtoni from one site.

The fungus appears to be widespread in a range of habitats in eastern NSW, at low and high altitudes and was most prevalent in stream frog communities. Most specimens were apparently healthy when collected.