https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:48961 Wed 19 Apr 2023 12:34:46 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:19056 Wed 11 Apr 2018 15:45:47 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:33311 Litoria aurea were placed in water collected from ponds that were used by this species for breeding and ponds where breeding was not detected at Sydney Olympic Park, Australia. After 19 days, the tadpoles were placed in enclosures in the same breeding and non‐breeding ponds, and monitored until they metamorphosed. There was no difference in tadpole survival, time to metamorphosis or body condition between the two treatments, indicating that poor water quality was not a cause of low pond occupancy by tadpoles at the site and resources should be directed towards investigating other potential causes. We suggest that this method of an ex situ followed by an in situ exposure study is an effective approach to eliminating or confirming poor water quality as a cause of population declines and reduced occupancy, for species that are aquatic for at least part of their life cycle. Other applications include establishing that artificially created habitat provides suitable water chemistry, or identifying a potential location for a reintroduction project.]]> Wed 10 Oct 2018 12:10:24 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:23928 Litoria aurea, which exhibits high temporal variability in population size due to its fast life-history traits. Projections of population size from the viability model were highly variable, and removing parametric uncertainty only slightly improved overall model certainty, thus demonstrating the limits of population viability analysis for predicting abundance in fast life-history species. Sensitivity analysis identified recruitment of adults, female survival, male survival and rate of maturity as having the most impact on population viability. This population viability model provides a starting point to incorporate future research findings and better elucidate the causes of local extinction in this species. This study also reinforces the importance of egg-juvenile survival for amphibian populations, but also exemplifies the variability of amphibian viability analyses for identifying important parameters. As a case study for amphibian conservation, this analysis shows the utility of population viability analyses for fast life-history species, even with incomplete knowledge of all life-history stages.]]> Tue 31 Jul 2018 16:35:16 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:50737 Thu 03 Aug 2023 16:36:36 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:31415 Litoria aurea) to compare differences in microhabitat-use patterns in both a remnant and a constructed habitat. A detectability study was also conducted to determine detection probabilities among microhabitats. Key results: Aquatic vegetation was used more than expected in both the remnant and constructed habitats, and rock piles were utilised less than expected in the constructed habitat, despite their recommendation in most habitat templates. We found that detection probabilities altered the outcomes of abundance estimates for nearly all the measured microhabitat variables. Conclusions: Future management for this species should focus on providing high proportions of aquatic vegetation. Furthermore, although rock piles have been utilised greatly in past L. aurea habitat creation, placing large rocks on a managed site is expensive and time consuming. Future management initiatives may need to focus on providing smaller proportion of rocks, which would be a more appropriate use of resources. Implications: With conservation management projects increasing over the next few decades, understanding habitat use before implementing strategies should be a priority as it will provide important insights and inform decision-making for optimum habitat creation and restoration. Furthermore, accounting for detectability in microhabitat use studies is essential to avoid wrong conclusions that may negatively affect the success of ecological management strategies.]]> Sat 24 Mar 2018 08:43:55 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20082 Sat 24 Mar 2018 08:00:08 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20083 Sat 24 Mar 2018 08:00:05 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:19302 Sat 24 Mar 2018 07:56:07 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:29688 Batrachochytrium dendrobatidis limits population recovery and conservation actions for threatened amphibians. As such, the effect of reservoirs on disease risk within host community assemblages needs to be considered, but rarely is. Aims: In this study we aimed to determine if amphibian species co-occurring with the green and golden bell frog Litoria aurea, a declining species susceptible to B. dendrobatidis, act as alternate hosts. Methods: We quantified B. dendrobatidis infection levels, sub-lethal effects on body condition and terminal signs of disease in amphibian communities on Kooragang Island and Sydney Olympic Park in New South Wales, Australia, where two of the largest remaining L. aurea populations persist. Key results: We found L. aurea carried infections at a similar prevalence (6–38%) to alternate species. Infection loads ranged widely (0.01–11 107.3 zoospore equivalents) and L. aurea differed from only one alternate host species (higher median load in Litoria fallax) at one site. There were no terminal or sub-lethal signs of disease in any species co-occurring with L. aurea. Conclusion: Our results suggest that co-occurring species are acting as alternate hosts to L. aurea and whether their presence dilutes or amplifies B. dendrobatidis in the community is a priority for future research. Implications: For L. aurea and many other susceptible species, confirming the existence of reservoir hosts and understanding their role in community disease dynamics will be important for optimising the outcomes of threat mitigation and habitat creation initiatives for their long-term conservation.]]> Sat 24 Mar 2018 07:38:49 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26808 Sat 24 Mar 2018 07:36:28 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:30290 Batrachochytrium dendrobatidis (Bd) infection has led to the decline of many amphibian species. Despite increasing knowledge on how Bd varies in its effects among species, little is known on the interaction between susceptibility and development within host species. We compared the ontogenetic susceptibility of post-metamorphic green and golden bell frogs Litoria aurea to chytridiomycosis by simultaneously measuring three host-pathogen responses as indicators of the development of the fungus—infection load, survival rate, and host immunocompetence—following Bd exposure in three life stages (recently metamorphosed juveniles, subadults, adults) over 95 days. Frogs exposed to Bd as recently metamorphosed juveniles acquired higher infection loads and experienced lower immune function and lower survivorship than subadults and adults, indicating an ontogenetic decline in chytridiomycosis susceptibility. By corresponding with an intrinsic developmental maturation in immunocompetence seen in uninfected frogs, we suggest these developmental changes in host susceptibility in L. aurea may be immune mediated. Consequently, the physiological relationship between ontogeny and immunity may affect host population structure and demography through variation in life stage survival, and understanding this can shape management targets for effective amphibian conservation.]]> Sat 24 Mar 2018 07:33:34 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:28845 litoria aurea, l. castanea, and l. raniformis. there is considerable debate about the role of threatening processes in the decline and uncertainty in how best to develop conservation mitigation strategies for these species. to develop a clear picture of the research priorities necessary to enhance the conservation outcomes for the three species we conducted a literature review to focus on the critical gaps in ecological understanding that prevents consensus, and to set research priorities to address these gaps. Unresolved questions were identified and prioritized, and a set of priority research directions and management actions considered to be integral for the persistence of the species were formulated.]]> Sat 24 Mar 2018 07:33:21 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:29797 Batrachochytrium dendrobatidis, a pathogen that can cause the fatal disease chytridiomycosis. We measured the infection load and observed signs of disease in Litoria aurea. Receiver operating characteristic curves were used to quantify the dissimilarity between the infection loads of L. aurea that showed signs associated with chytridiomycosis and those that did not. Litoria aurea had a 78% probability of developing chytridiomycosis past a threshold of 68 zoospore equivalents (ZE) per swab and chytridiomycosis occurred within a variable range of 0.5–490 ZE. Studies should incorporate a species-specific threshold as a predictor of chytridiomycosis, rather than a binary diagnosis. Measures of susceptibility to chytridiomycosis must account not only for the ability of B. dendrobatidis to increase its abundance on the skin of amphibians but also to determine how each species tolerates these infection loads.]]> Sat 24 Mar 2018 07:30:36 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26628 Batrachochytrium dendrobatidis has been a major contributing factor to the global decline of amphibians. Knowledge of the distribution of B. dendrobatidis can contribute to understanding patterns of species decline and prioritizing action. Therefore, we surveyed four spatially distinct populations of a B. dendrobatidis susceptible species, the green and golden bell frog (Litoria aurea), for evidence of infection in the population. Three mainland populations were infected at a prevalence of 3.5-28.3 %, with median infection loads of 0.28-627.18 genomic equivalents (GE). Conversely, we did not detect infection in an island population 3 km from the mainland; the isolation and infrequent visitation of the island suggests that the pathogen has not arrived. Management actions for B. dendrobatidis and conservation of susceptible frog species are heavily dependent on the presence and absence of the pathogen in the population. Prevention of the accidental introduction of B. dendrobatidis and safe guarding genetic diversity of L. aurea is necessary to preserve unique diversity of the island population, whereas containment and control of the pathogen can be directed towards mainland populations. Knowledge of disease dynamics also provides a context to understand the ecology of remaining populations as variation in the physiology or habitat of the mainland populations have facilitated persistence of these populations alongside B. dendrobatidis. Other islands should be a priority target in disease surveillance, to discover refuges that can assist conservation.]]> Sat 24 Mar 2018 07:26:48 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:30517 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.]]> Sat 24 Mar 2018 07:25:07 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:23886 Litoria aurea) using radio tracking methods during winter when detection is low and knowledge is limited. We followed 26 individuals between May and July, 2011 to determine whether they selected specific overwintering microhabitats and related this to levels of individual exposure to predators, distance from the edge of the water and temperature of microhabitats. We found that overwintering bell frogs inhabited reeds and rock gabions more frequently than expected and that females used a reduced subset of microhabitats compared to males. Additionally, microhabitats used were more likely to conceal an individual from view, and the majority of overwintering sites were located within 5m of the edge of the water which may be important for reducing the risk of predation and desiccation. Rock gabions had significantly warmer (1.2°C-1.8°C) mean temperatures than the other microhabitats used. The information presented here can be used in habitat creation and reintroduction programmes to provide habitat which is suitable during both the breeding and non-breeding season for the conservation of other populations.]]> Sat 24 Mar 2018 07:13:40 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32085 Batrachochytrium dendrobatidis (Bd) is correlated with several environmental variables, including salinity, temperature, and moisture content, which influence the pathogen’s growth and survival. Habitats that contain these environmental variables at levels outside of those optimal for Bd growth and survival may facilitate the survival of susceptible host species. Therefore, manipulation of environmental salinity is a potential management strategy to help conserve Bd-susceptible species. However, host behaviour also influences disease dynamics, and the success of habitat manipulation programs depends on how hosts use this altered habitat. Aims: To assess if the Bd-susceptible green and golden bell frog, Litoria aurea, will select waterbodies with a salinity increased to S = 3; if this selection is affected by infection; and if a frog’s time in a waterbody of this salinity affects infection load or blood physiology. Methods: We conducted a filmed choice experiment and a 3-year field study where infected and uninfected frogs could choose between fresh or saline waterbodies. Key results: In both the laboratory experiment and field study, Bd-infected L. aurea spent a significantly greater amount of time in or closer to a waterbody than uninfected frogs. Experimentally infected frogs tended to prefer the saline water over fresh, but their choice of water usage did not differ statistically from uninfected frogs. In the field, frogs began to avoid ponds when salinities rose above S = 5. Conclusions: Because both wild and captive, and infected and uninfected L. aurea readily selected waterbodies with a salinity of S = 3, this salinity could potentially be used as a passive method for reducing the severity of Bd when managing this species. However, further testing is needed to understand the efficacy of this treatment, and care must be taken to prevent salinities rising above S = 5, because this level seems to produce an avoidance response and therefore may not be suitable in every location. Implications: Manipulation of aquatic habitats may be a worthwhile focus for Bd management in habitats where water level fluctuations are minimal.]]> Fri 27 Apr 2018 14:12:51 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:48628 Fri 24 Mar 2023 09:46:36 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49405 Fri 12 May 2023 14:48:07 AEST ]]>