Life stage specific variation in the occupancy of ponds by<i><scp>L</scp>itoria aurea</i>, a threatened amphibian

Bower, Deborah S.; Stockwell, Michelle P.; Pollard, Carla J.; Pickett, Evan J.; Garnham, James I.; Clulow, John; Mahony, Michael

doi:10.1111/j.1442-9993.2012.02452.x

Cited by 17 publications

(14 citation statements)

References 30 publications

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“…Only in cases where ponds could not be completely dried because of adverse weather was there no conservation benefit for the funds spent on this management action. Although pond draining did not influence the distribution of juvenile frogs, this is likely to be due to the rapid dispersal of bell frogs away from their home ponds soon after metamorphosis, which has been observed at our study site (Bower et al ) and for other bell frog populations (van de Mortel and Goldingay , Goldingay and Lewis ).…”

Section: Discussionsupporting

confidence: 45%

Removal of an exotic fish influences amphibian breeding site selection

et al. 2017

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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.

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Section: Discussionsupporting

confidence: 45%

Removal of an exotic fish influences amphibian breeding site selection

et al. 2017

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“…Other frog species were recorded when they were seen and a relative abundance index was determined following the methods of Bower et al . ().…”

Section: Methodsmentioning

confidence: 97%

Six-year demographic study reveals threat of stochastic extinction for remnant populations of a threatened amphibian

et al. 2013

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Sustained demographic studies are essential for early detection of species decline in time for effective management response. A paucity of such background data hindered the potential for successful conservation during the global amphibian decline and remains problematic today. The current study analysed 6 years of mark-recapture data to determine the vital demographic rates in three habitat precincts of the threatened frog, Litoria aurea (Hylidae) and to understand the underlying causes of variability in population size. Variability in population size of L. aurea was similar to many pond-breeding species; however this level of fluctuation is rare among threatened amphibians. Highly variable populations are at greater risk of local extinction and the low level of connectivity between L. aurea populations means they are at a greater risk of further decline due to stochastic extinction events and incapacity to recolonize distant habitat. We recommend that management of this species should encourage recolonization through creation of habitat corridors and reintroduction of L. aurea to areas where stochastic extinction events are suspected.

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“…Over time, some of those persisting populations are going extinct, while few, if any remaining ones can be regarded as secure (Mahony et al., ; White & Pyke, ). Coexistence of pathogen and host in remnant populations arguably leads to ongoing demographic instability in those populations (Bower et al., ), and understanding this is complicated by a temporal (seasonal) component to disease expression and impact (Stockwell et al., ), as well as spatial heterogeneity of environmental variables such as salinity that may affect survival and demographic parameters (Stockwell, Clulow, et al., ). Considering that this species has been subject to numerous translocation and reintroduction attempts (Germano et al., ; James, Stockwell, Clulow, Clulow, & Mahony, ; McFadden et al., ), many of which have failed due to the ongoing presence of Bd in the wild (Stockwell et al., ), it is an ideal species to explore the concept of environmental manipulation to mitigate the threat of disease.…”

Section: Introductionmentioning

confidence: 99%

Elevated salinity blocks pathogen transmission and improves host survival from the global amphibian chytrid pandemic: Implications for translocations

Clulow

Gould

James

et al. 2017

Journal of Applied Ecology

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Emerging infectious diseases are one of the greatest threats to global biodiversity. Chytridiomycosis in amphibians is perhaps the most extreme example of this phenomenon known to science. Translocations are increasingly used to fight disease‐induced extinctions. However, many programmes fail because disease is still present or subsequently establishes in the translocation environment. There is a need for studies in real‐world scenarios to test whether environmental manipulation could improve survival in populations by generating unfavourable environmental conditions for pathogens. Reintroductions of amphibians impacted by chytridiomycosis into environments where the disease persists provide a scenario where this paradigm can be tested. We tested the hypothesis that manipulating environmental salinity in outdoor mesocosms under near‐identical environmental conditions, present in a nearby translocation programme for an endangered amphibian, would improve survival and determine the mechanisms involved. One hundred and sixty infected and 288 uninfected, captive‐bred, juvenile frogs were released into 16 outdoor mesocosms in which salinity was controlled (high‐ or low‐salinity treatment). The experiment was run for 25 weeks from the mid‐austral winter to the mid‐austral summer of 2013 in a temperate coastal environment, Australia. Increasing salinity from c. 0.5 ppt to 3.5–4.5 ppt reduced pathogen transmission between infected and uninfected animals, resulting in significantly reduced mortality in elevated salt mesocosms (0.13, high‐salt vs. 0.23, low‐salt survival at 23 weeks). Increasing water temperature associated with season (from mean 13 to 25°C) eventually cleared all surviving animals of the pathogen. Synthesis and applications. We identified a mechanism by which environmental salinity can protect amphibian hosts from chytridomycosis by reducing disease transmission rates. We conclude that manipulating environmental salinity in landscapes where chytrid‐affected amphibians are currently translocated could improve the probability of population persistence for hundreds of species. More broadly, we provide support for the paradigm that environmental manipulation can be used to mitigate the impact of emerging infectious diseases.

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Life stage specific variation in the occupancy of ponds byLitoria aurea, a threatened amphibian

Cited by 17 publications

References 30 publications

Removal of an exotic fish influences amphibian breeding site selection

Removal of an exotic fish influences amphibian breeding site selection

Six-year demographic study reveals threat of stochastic extinction for remnant populations of a threatened amphibian

Elevated salinity blocks pathogen transmission and improves host survival from the global amphibian chytrid pandemic: Implications for translocations

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