Oral Presentation 64th International Conference of the Wildlife Disease Association 2015

Disease ecology during the breeding season in the endangered Litoria verreauxii alpina and management implications (#31)

Laura A Brannelly 1 , David A Hunter 2 , Daniel Lenger 3 , Ben C Scheele 4 , Laura F Grogan 5 , Rebecca Webb 1 , Lee F Skerratt 1 , Lee Berger 1
  1. One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook Univeristy, Townsville, Queensland, Australia
  2. New South Wales Office of Environment and Heritage, Queanbeyan, New South Wales, Australia
  3. Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana, United States
  4. Fenner School of Environment and Society, Australia National University, Canberra, Australia Capital Territory, Australia
  5. Griffith University, Brisbane, Queensland, Australia

Amphibians are currently experiencing the greatest biodiversity decline of all vertebrate taxa, and one of the major drivers of this loss is the fungal disease chytridiomycosis.  Some amphibian species, like the endangered Litoria verreauxii alpina, have drastically declined in parts of their range since the introduction of chytridiomycosis, yet persist in a small number of seemingly stable remnant populations.  We studied chytridiomycosis dynamics during the breeding season to improve our understanding of how remnant populations persist with endemic infection, and to inform disease management .  We monitored two populations during their ten-week breeding season through capture-mark-recapture analysis.  We found that infection prevalence and intensity increased throughout the breeding season in both sites, but infection prevalence and intensity was higher at the site that had higher population density, suggesting that Bd transmission is density dependant. There was low recovery from infection in L. v. alpina, which was lower when the animals were heavily infected with Bd

            With high infection intensity at the end of the breeding season and low recovery from infection, population survival of this species is dependant on high recruitment.  We further explored how disease may affect reproductive output by investigating spermatogenesis in a laboratory based infection experiment.  We found that spermatogenesis increases when animals are infected with Bd.  Infected animals had more overall activity, and a larger proportion of spermatozoa bundles in the seminiferous tubules.  If infected animals are increasing reproductive efforts and producing more offspring before succumbing to disease, it is possible that population level selection for disease resistance or tolerance is minimized.  In the absence of population level disease resistance or tolerance, conservation and management efforts for endangered species should focus on habitat management to support recruitment.