Oral Presentation Australian Society for Limnology Congress 2013

Impacts of large-scale bushfire on the freshwater crayfish of the Grampians National Park (#132)

Kerrylyn Johnston 1
  1. Murdoch University, Murdoch, WA, Australia

Bushfire is a relatively common natural occurrence in Australia which can affect hundreds of square kilometres of land per fire event. The Grampians National Park (GNP) in south-west Victoria has been affected by large-scale bushfires in recent years. It is a diversity hot-spot for freshwater crayfish, including the threatened and range restricted species Euastacus bispinosus and Gramastacus insolitus. Bushfire may be a largely unrecognised threat to crayfish survival through habitat alteration and degradation. The Mt Lubra bushfires occurred in 2006 and burnt around one half of the GNP area. The current study compared pre-fire and post-fire freshwater crayfish abundance data (five species) and various water quality and physical environmental habitat parameters to assess the post-fire status of crayfish populations. Fire altered crayfish abundances at sites throughout the GNP but affected different habitat types and the different crayfish species that inhabit each in distinct ways. For example, preliminary analysis shows that for stream crayfish, the most significant fire effects were reduction of stream depth, water quality and habitat heterogeneity. This was largely caused by sedimentation resulting from the loss of riparian vegetation that usually stabilises stream banks and prevents silt/sediment entering streams. Increased crayfish predation from visual predators such as birds also reduced abundances. In contrast, the timing of these bushfires appear to have had minimal negative impacts on crayfish species inhabiting seasonal floodplain wetlands, because they occurred when substrates were still wet and covered in green aquatic vegetation, which acted as a buffer against the worst effects of the bushfire.