Optimising frog breeding responses to flooding in managed wetlands (ii) frog distributions through the Murray Floodplain: Report to Murray Wetlands Working Group

Frog communities were surveyed along the Murray River corridor from the Hume Dam to the New South Wales/South Australia border between August 2008 and January 2010. The aim of the study is to investigate species occupancy patterns with respect to variation in wetland biophysical conditions and hydrology. A total of ten frog species were recorded, two of these, Litoria raniformis and Crinia Sloanei are listed under the Environment Protection and Biodiversity Conservation Act 1999.
Wetland habitats were grouped into three broad hydrological classes,; permanent, long hydroperiod (5-9 months) and temporary waterbodies (2-3 months). Frog communities differed significantly between the three hydrological classes - long hydroperiod waters contained the highest species richness and were more likely to support listed species than either permanent or temporary wetlands. Occupancy patterns were modeled in relation to the measured biophysical habitat parameters (water quality, vegetation and hydrology) for seven species using logistic regression. Individual species differed in their sensitivity to the measured habitat parameters and overall measures of physical habitat such as vegetation complexity and hydrology were better predictors of occupancy than water quality. The interaction between wetland hydrology and aquatic vegetation diversity was also important for many species. Importantly maintaining a higher diversity of aquatic vegetation increased the probability of occupancy within permanent waterbodies, but was less important within long hydroperiod and temporary wetlands.
Despite the prolonged dry period, wetlands of the Murray River Floodplain still have the potential to support a high diversity of frog species, however much of this diversity is confined to seasonally flooded wetlands with a long hydroperiod, which typically received environmental flooding