Battling habitat loss: suitability of anthropogenic waterbodies for amphibians associated with naturally acidic, oligotrophic environments

Habitat destruction is a key threatening process for amphibians. Modified or anthropogenic waterbodies can be used to compensate for habitat loss, with several amphibian species utilising created or modified waterbodies. We measured usage of anthropogenic/modified waterbodies by adult and tadpole frog species, including threatened species, in coastal wallum habitat in eastern Australia. Nine road trenches/ditches, 8 artificial 'lakes', 6 golf course waterbodies and 13 natural waterbodies were surveyed for frog adults and tadpoles during the summer/spring period 2011-2012. Additionally, we examined the relationship between frog assemblages and environmental factors (water chemistry, aquatic predators, vegetation types), focusing on Litoria olongburensis and Litoria fallax. Frog species richness differed between waterbody types, with two of three threatened frog species present in both natural and anthropogenic/modified waterbodies. The frog assemblage was influenced by pH, turbidity, salinity and percentage cover of certain vegetation types. Measured abundance of L. olongburensis adults and tadpoles were highest in natural waterbodies with high sedge density and low pH. The measured abundance of adult L. fallax was highest within artificial lakes. We conclude that differences in water chemistry and vegetation density can affect the amphibian assemblage within these environments. Therefore, effective conservation of all frog species would be enhanced by conserving a variety of waterbody types. However, natural waterbodies are more likely to be used by threatened species and the conservation of these waterbodies provides the best conservation outcomes. Where habitat offsets may be required, environmental managers should critically assess the quality of constructed habitat for specialist frog species including those associated with acidic, oligotrophic environments.