Factors influencing predation on eggs and tadpoles of the endangered Green and Golden Bell FrogLitoria aureaby the introduced Plague MinnowGambusia holbrooki

Abstract

The Green and Golden Bell Frog Litoria aurea has declined dramatically in New South Wales. One hypothesis suggests that this decline is largely due to predation by the Plague Minnow Gambusia holbrooki, which was introduced into Australia as part of efforts to control mosquitoes. Other frog species, such as Striped Marsh Frog Limnodynasres peronii and Peron's Tree Frog Litoria peranii have not apparently suffered from this predation to the same degree.Laboratory experiments were undertaken in order to evaluate the extent t o which predation on eggs, fry and tadpoles of L aurea by Gambusia is influenced by the presence of rocks (as potential shelter), the presence of other frog species (as alternative food) and a number of variables that reflect the ratio of the number of prey available to the amount of food that would be required to satiate the fish. These experiments showed that the proportion of available L aurea eggs or tadpoles eaten increased with both decreases in the number of prey available and inc...