Application of the Survey Protocol for Chytridiomycosis to Queensland, Australia

Vol. 92: 117–129, 2010 DISEASES OF AQUATIC ORGANISMS Published online November 25, 2010 doi: 10.3354/dao02272 Dis Aquat Org Contribution to DAO Special 4 ‘Chytridiomycosis: an emerging disease’ Application of the survey protocol for chytridiomycosis to Queensland, Australia Lee F. Skerratt1,*, Keith R. McDonald2, Harry B. Hines3, Lee Berger1, Diana Mendez1, Andrea D. Phillott1, Scott D. Cashins1, Kris A. Murray4, Richard Speare1 1Amphibian Disease Ecology Group, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, Queensland 4811, Australia 2Amphibian Disease Ecology Group, Queensland Parks and Wildlife Service, PO Box 975, Atherton, Queensland 4883, Australia 3Queensland Parks and Wildlife Service, PO Box 64, Bellbowrie, Queensland 4070, Australia 4The Ecology Centre, School of Biological Sciences, University of Queensland, St Lucia, Queensland 4072, Australia ABSTRACT: Spread of the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), which causes chytridiomycosis, has resulted in the extinction of frogs, but the distribution of Bd is incom- pletely known. We trialled the survey protocol for Bd by attempting to systematically map its distribution in Queensland, Australia. Bd was easily detected in known infected areas, such as the Wet Tropics and South East Queensland. It was not detected in bioregions adjacent to, but inland from or to the north of, infected regions: Einasleigh Uplands and Cape York adjacent to the infected Wet Tropics; and Brigalow Belt South adjacent to the infected South East Queensland bioregion. These regions where Bd was not detected have bordered infected regions for between 15 yr (in northern Queensland) and 30 yr (in southern Queensland), and so they define the geographical limits of Bd with regard to the long-term environmental conditions in Queensland. The Gulf Plains, a bioregion distant from infected bioregions, was also negative. Bd was confined to rainforest and bordering habitats, such as wet eucalypt forests. Infections were largely confined to permanent water-associated species, consistent with this being an important cause of this group having the greatest declines. Our data supports biogeographic climatic models that show much of inland and northern Australia to be too hot and dry to support Bd. As there is limited opportunity for Bd to spread further in Queens- land, the priority for management is reducing the impact of Bd in affected populations and assisting frogs to disperse into their former distributions. Given that the survey protocol has been applied suc- cessfully in Australia it may be useful for mapping the distribution of Bd in other parts of the world. KEY WORDS: Chytridiomycosis · Amphibian · Threatening process · Spread · Management · Disease Resale or republication not permitted without written consent of the publisher INTRODUCTION Department of the Environment and Heritage 2006a). However, due to a lack of systematic surveillance, it is The disease chytridiomycosis, caused by the fungus not known whether chytridiomycosis is continuing to Batrachochytrium dendrobatidis (Bd), probably in- spread or whether it has reached the limits of its dis- vaded Australia in the 1970s, resulting in declines and tribution in Australia. This information is important extinctions of susceptible frog species (Berger et al. for conservation of amphibians and vital for wildlife 1999a, Skerratt et al. 2007). Infection with the amphib- managers. ian chytrid fungus resulting in chytridiomycosis is a Although a national survey to map the distribution of key threatening process for Australian frogs and there chytridiomycosis was recommended in the Australian is a Threat Abatement Plan (Australian Government Threat Abatement Plan for infection of frogs with the *Email: [email protected] © Inter-Research 2010 · www.int-res.com 118 Dis Aquat Org 92: 117–129, 2010 amphibian chytrid fungus (Australian Government gracilenta, most Uperoleia spp, Cyclorana spp.) and Department of the Environment and Heritage 2006a), (3) terrestrial group — frogs that are not associated as yet such a survey has not been completed. The cur- with water bodies, such as those with intracapsular or rent data on the distribution of Bd in Australia is direct development (e.g. Assa darlingtoni and the incomplete and has been derived from opportunistic microhylids such as Cophixalus ornatus) (Tyler 1994, collection of sick or dead frogs (Berger et al. 2004) or Cogger 2000). Some frog species typically breed in surveys of healthy frogs from targeted locations, both permanent and ephemeral water bodies (e.g. including examination of archived specimens (Retal- Litoria rubella, Litoria caerulea, Litoria bicolor and lick et al. 2004, McDonald et al. 2005, Speare et al. Litoria inermis). If sampling these species, then the 2005, Obendorf 2005, Obendorf & Dalton 2006, Kriger type of water body that they are associated with & Hero 2007a, Speare & Berger 2007, Kriger et al. should be recorded. 2007). Chytridiomycosis has a very broad amphibian To begin mapping Australia in a systematic way and host range and is known to occur in eastern Australia to trial the protocol, we tested threatened populations from Victoria north to Cooktown, occurring mainly on in South East Queensland and Wet Tropics bioregions; or between the Great Dividing Range and the coast, in populations of unknown infection status in the biore- Tasmania, around Adelaide in South Australia, and in gions Einasleigh Uplands, Cape York and Brigalow southwest Western Australia (Aplin & Kirkpatrick Belt South, which are adjacent to infected bioregions; 2000, Berger et al. 2004, Speare et al. 2005, Obendorf ecological groups and species not previously sampled & Dalton 2006, Murray et al. 2010). Climatic models in infected bioregions South East Queensland and Wet describing the known distribution show that it is Tropics; and the Gulf Plans bioregion, which is distant unlikely to occur in hot or dry areas such as the North- from infected bioregions. ern Territory, northwest Western Australia and inland In the present study, the term anthropogenic spread arid areas of Queensland (Retallick 2003). This is sup- is used to mean spread of Bd through human-associ- ported by laboratory studies showing that heat (≥27°C) ated activities, deliberate or accidental. To date there and desiccation are detrimental to the fungus (Berger is no evidence in Queensland that Bd has been trans- 2001, Johnson et al. 2003, Berger et al. 2004, 2009). A mitted by anthropogenic means, apart from the origi- histological survey of 580 frogs from the Ord region in nal introduction into South East Queensland, possibly northwest Western Australia was negative, excluding via an infected imported amphibian into the port of a minimum apparent prevalence of 1% at a likelihood Brisbane in the 1970s, as the first museum record of Bd of 0.95 (Australian Government Department of the in Australia occurred there in 1979 (Australian Gov- Environment and Heritage 2006b). ernment Department of the Environment and Heritage Skerratt et al. (2008) proposed a standard survey 2006b). Hygiene protocols recommended in guidelines protocol for Australia designed to maximize the likeli- and enforced through Queensland Parks and Wildlife hood and cost efficiency of detecting Bd in frog popu- scientific permits aim to reduce the likelihood of lations and to enable systematic surveillance and anthropogenic spread (Phillott et al. 2010, this Special). monitoring. The protocol contained 13 guidelines with Evaluating the survey protocol for Bd in Skerratt et an additional 5 sub-guidelines (a–e in Step 1) (see al. (2008) is important internationally as it is the only below in ‘Materials and methods’). Areas were di- published protocol and can be adapted to other coun- vided into bioregions using the interim biogeographic tries which are also dealing with this spreading regionalisation as defined by geology, climate and pathogen. Data collected opportunistically prior to vegetation for our sampling scale, and to prioritise implementation of the protocol is included for compar- sampling based on likelihood of a region having Bd ison. The feasibility of the protocol is described in (see Fig. 1 for Queensland example, Environment ‘Materials and methods’. Australia 2000, Australian Government Department of the Environment and Water Resources 2007). Species were allocated to groups by the water body they MATERIALS AND METHODS inhabit in order to prioritise sampling based on risk of infection and to extrapolate findings to non-sampled We followed the survey protocol (Skerratt et al. 2008) species. The 3 ecological groups were (1) permanent to test its feasibility for Queensland. Each frog was water group — aquatic frogs and those that breed in captured by hand, with a pair of single-use disposable permanent (lentic or lotic) water bodies (e.g. Litoria plastic bags or gloves covering the hands, in order to wilcoxii, Litoria rheocola, Litoria peronii, Litoria fallax, avoid transferring pathogens between individuals, Limnodynastes peronii, Rheobatrachus spp.), (2) from 2005 onwards. We followed the hygiene protocol ephemeral water group — frogs that breed in tempo- described by Speare et al. (2004). We swabbed the pos- rary lentic water bodies (e.g. Litoria caerulea, Litoria terior ventral surfaces of the lower abdomen, thighs, Skerratt et al.: Mapping chytridiomycosis 119 and all hands and feet of individual frogs twice. Real Valley, border the Wet Tropics infected bioregion.

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