Removal of an exotic fish influences amphibian breeding site selection

Abstract

For pond‐breeding species, the distribution of larvae is a reflection of habitat suitability and adult breeding site selection. Some species preferentially breed in ephemeral ponds, which can provide benefits for larvae. An alternative strategy used by adults to increase offspring survival is to detect aquatic predators and avoid them when selecting breeding sites. We investigated whether either of these types of breeding site selection are contributing to the negative correlation between the distributions of tadpoles of the threatened green and golden bell frog (Litoria aurea) and the introduced eastern gambusia (Gambusia holbrooki) in Sydney, Australia. From 2003 to 2012 we drained ponds to temporarily remove gambusia and examined the effect of removal on the numbers of male, female, and juvenile frogs, and tadpoles. We found that males preferentially selected fish‐free ponds as breeding sites. In addition, the removal of gambusia increased tadpole abundance to over 140 times that of an undrained pond. Pond draining did not influence female or juvenile abundances. The ability to detect and avoid gambusia may be mitigating the effect of predation to a certain extent. We conclude that pond draining to remove exotic fish is an effective strategy that can be used to greatly increase the reproductive success of this and potentially other threatened amphibian species in the presence of exotic predators. © 2017 The Wildlife Society.

Multi‐species occupancy modeling provides novel insights into amphibian metacommunity structure and wetland restoration

“…However, as discussed previously, emergent vegetation should not be allowed to completely cover wetlands, and the best management regime may be to create a mosaic of both sparsely and densely vegetated habitats (Fardell et al 2018). This outcome could also be achieved by pond draining to both eradicate Gambusia and thin macrophytes (Pollard et al 2017). One experimental study suggested that aquatic vegetation may provide insufficient refuge for aquatic invertebrates and amphibian larvae from Gambusia predation, and that direct removal of this fish is the best method to improve the conservation potential of restored wetlands (Shulse et al 2013).…”

A simple design feature to increase hydro‐period in constructed ephemeral wetlands to avoid tadpole desiccation‐induced mortality

“…The main threat to Green and Golden Bell Frog would be from the Plague Minnow ( Gambusia holbrooki ), which is a hardy species and can survive in puddles (Pollard et al . 2017). The only current feasible method for eliminating the Plague Minnow is by draining and drying wetlands and thus killing the fish or by natural drying (O'Meara & Darcovich 2015).…”

Preliminary evidence for a two‐for‐one deal: Wetland restoration for a threatened frog may benefit a threatened bat

“…These adaptive management actions include removal of aquatic vegetation and draining of wetlands that have been colonised by the invasive Plague Minnow (Gambusia holbrooki, hereafter referred to as Gambusia) (O'Meara & Darcovich 2015;Pollard, et al 2017). Both these management actions have been undertaken in attempts to increase the breeding output of the Bell Frog, as some evidence suggests this species requires warm water temperatures and wetlands free from invasive fish to breed in (Pollard, et al 2017). High density and coverage of aquatic vegetation have been shown to reduce the water temperature and abundance of the Bell Frog (Lenga 2017), and hence has resulted in the prescription of emergent vegetation removal in managed populations.…”