Lovers in strange places: amphibian calling and amplexus detected in tidal mangrove creeks after rainfall

Temporary freshwater lenses can form in saline environments after rainfall, providing essential resources for species including drinking water and dispersal routes. However, there is limited indication that these lenses can also be used for breeding. Herein, we provide evidence of the green and golden bell frog, Litoria aurea, performing breeding activities, including calling and amplexus, in tidal mangrove creeks on Kooragang Island, NSW, Australia. Our findings suggest that these creeks intermittently phase into a low salinity state after the influx of fresh water from rainfall, forming temporary freshwater lenses that can be exploited before the creeks revert to a saline state. These lenses had salinities (1.4 ppt and 4.5 ppt) within the tolerance limit of L. aurea tadpoles, although we are unsure whether oviposition took place and offspring survival to metamorphosis was achieved. It is possible that anthropogenic disturbances to hydrology on Kooragang Island have benefited L. aurea by restricting tidal influences in mangrove creeks, prolonging the duration of freshwater lenses. Temporary freshwater lenses that form in saltwater environments after heavy rainfall provide unique ecological opportunities for species. We present evidence of an Australian amphibian engaging in breeding activities, including calling and amplexus, in tidal mangrove creeks that have been flushed by rainwater. Freshwater lenses may be advantageous for amphibian offspring by reducing exposure to predators found in more permanent freshwater ponds, but at the expense of an increased risk of mortality due to salt exposure from tidal influences. Photograph by John Gould.