Reading tea leaves worldwide: Decoupled drivers of initial litter decomposition mass-loss rate and stabilization

The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models.

The Program for Biodiversity Research in Brazil: The role of regional networks for biodiversity knowledge, dissemination, and conservation

The Program for Biodiversity Research (PPBio) is an innovative program designed to integrate all biodiversity research stakeholders. Operating since 2004, it has installed long-term ecological research sites throughout Brazil and its logic has been applied in some other southern-hemisphere countries. The program supports all aspects of research necessary to understand biodiversity and the processes that affect it. There are presently 161 sampling sites (see some of them at Supplementary Appendix), most of which use a standardized methodology that allows comparisons across biomes and through time. To date, there are about 1200 publications associated with PPBio that cover topics ranging from natural history to genetics and species distributions. Most of the field data and metadata are available through PPBio web sites or DataONE. Metadata is available for researchers that intend to explore the different faces of Brazilian biodiversity spatio-temporal variation, as well as for managers intending to improve conservation strategies. The Program also fostered, directly and indirectly, local technical capacity building, and supported the training of hundreds of undergraduate and graduate students. The main challenge is maintaining the long-term funding necessary to understand biodiversity patterns and processes under pressure from global environmental changes.

Rate-Pressure Product Responses to Static Contractions Performed at Various Altitudes

Simmonds, Michael J., Surendran Sabapathy, and Jean-Marc Hero. Rate-pressure product responses to static contractions performed at various altitudes. High Alt Med Biol. 22: 166-173, 2021. Background: Adventure tourism has led to an unprecedented number of individuals being exposed to altitude, including those with subclinical cardiometabolic disorders. The disproportionate hemodynamic challenge associated with small-muscle static activities is potentially dangerous at altitude as these may compound the risk for cardiac events. We thus examined the cardiovascular response to, and during recovery from, static exercise performed at altitude. Methods: Eighteen individuals completed this study at three altitudes (sea level; ∼1,500 m; ∼3,000 m) in central Nepal. At each altitude, individuals performed two handgrip contractions for 2 minutes at the same intensity (30% maximal voluntary contraction [MVC]), with two distinct recovery periods: during control recovery was completed quietly at rest, while during ischemic challenge recovery was conducted with a cuff occluding the upper limb. Results: Oxygen saturation decreased during ascent to 1,500 m (-2%) and 3,000 m (-8%), compared with sea level. Handgrip MVC was not affected by altitude, although heart rate at rest (∼70 beat/min), during static exercise (range ∼90-95 beat/min), and during recovery in both conditions (each ∼70 beat/min) was significantly increased by ∼15% at 3,000 m, but not 1,500 m. The magnitude of the muscle metaboreflex during recovery from static exercise was unaffected by altitude; however, the rate-pressure product was significantly elevated by ∼10% during and following static exercise at 3,000 m. Conclusions: A significant increase in the rate-pressure product during static exercise was observed at altitude, which persisted during recovery. Individuals at risk for cardiac events should use awareness of static contractions while at altitude, especially considering that stress induced by static exercise is additive to that of dynamic activities such as hiking.

Research priorities for natural ecosystems in a changing global climate

Climate change poses significant emerging risks to biodiversity, ecosystem function and associated socioecological systems. Adaptation responses must be initiated in parallel with mitigation efforts, but resources are limited. As climate risks are not distributed equally across taxa, ecosystems and processes, strategic prioritization of research that addresses stakeholder-relevant knowledge gaps will accelerate effective uptake into adaptation policy and management action. After a decade of climate change adaptation research within the Australian National Climate Change Adaptation Research Facility, we synthesize the National Adaptation Research Plans for marine, terrestrial and freshwater ecosystems. We identify the key, globally relevant priorities for ongoing research relevant to informing adaptation policy and environmental management aimed at maximizing the resilience of natural ecosystems to climate change. Informed by both global literature and an extensive stakeholder consultation across all ecosystems, sectors and regions in Australia, involving thousands of participants, we suggest 18 priority research topics based on their significance, urgency, technical and economic feasibility, existing knowledge gaps and potential for cobenefits across multiple sectors. These research priorities provide a unified guide for policymakers, funding organizations and researchers to strategically direct resources, maximize stakeholder uptake of resulting knowledge and minimize the impacts of climate change on natural ecosystems. Given the pace of climate change, it is imperative that we inform and accelerate adaptation progress in all regions around the world.

Gut microbiota and their putative metabolic functions in fragmented Bengal tiger population of Nepal

Bengal tigers (Panthera tigris tigris) serve a pivotal role as an apex predator in forest ecosystems. To increase our knowledge on factors impacting the viability and health of this endangered species, we studied the gut microbiota in 32 individual Bengal tigers from three geographically separated areas (Chitwan National Park (CNP), Bardia National Park (BNP) and Suklaphanta Wildlife Reserve (SWR)) in Nepal, using noninvasive genetic sampling methods. Gut microbiota influence the immune system, impact various physiological functions, and modulates metabolic reactions, that ultimately impact the host health, behavior and development. Across the tiger populations in Nepal, we found significant differences in the composition of microbial communities based on their geographic locations. Specifically, we detected significant differences between CNP and the other two protected areas (CNP vs BNP: pseudo t = 1.944, P = 0.006; CNP vs SWR: pseudo t = 1.9942, P = 0.0071), but no differences between BNP and SWR. This mirrors what has been found for tiger gene flow in the same populations, suggesting gut microbiota composition and host gene flow may be linked. Furthermore, predictive metagenome functional content analysis (PICRUSt) revealed a higher functional enrichment and diversity for significant gut microbiota in the Chitwan tiger population and the lowest enrichment and diversity in Suklaphanta. The CNP tiger population contained higher proportions of microbiota that are associated with predicted functions relevant for metabolism of amino acid, lipid, xenobiotics biodegradation, terpenoides and polyketides than the SWR population. We conclude the tiger population structure, gut microbiota profile and associated functional metabolic categories are correlated, with geographically most separated CNP and SWR tiger population having the most distinct and different host genotype and microbiota profiles. Our work dramatically expands the understanding of tiger microbiota in wild populations and provides a valuable case study on how to investigate genetic diversity at different hierarchical levels, including hosts as well as their microbial communities.

Species, sex and geo-location identification of seized tiger (Panthera tigris tigris) parts in Nepal-A molecular forensic approach

Tiger (Panthera tigris) populations are in danger across their entire range due to habitat loss, poaching and the demand for tiger parts. The Bengal tiger (Panthera tigris tigris) is an endangered apex predator with a population size estimated to be less than 200 in Nepal. In spite of strict wildlife protection laws, illegal trade of tiger parts is increasing; and Nepal has become one of the major sources and transit routes for poached wildlife parts. Identification of wildlife parts is often challenging for law enforcement officials due to inadequate training and lack of available tools. Here, we describe a molecular forensic approach to gain insight into illegally trafficked tiger parts seized across Nepal. We created Nepal's first comprehensive reference genetic database of wild tigers through the Nepal Tiger Genome Project (2011-2013). This database has nuclear DNA microsatellite genotype and sex profiles, including geo-spatial information, of over 60% (n = 120) of the wild tigers of Nepal. We analyzed 15 putative cases of confiscated poached tiger parts and all were confirmed to be of tiger. Ten samples were identified as male and five were female. We determined probable geo-source location for 9 of the 14 samples with 6-8 nuclear DNA microsatellite loci using inferences from four different statistical assignment methods. Six samples were assigned to Bardia National Park and one of these was an exact match to a female tiger previously profiled in our fecal DNA reference database. Two tiger samples were assigned to Shuklaphanta Wildlife Reserve and one to Chitwan National Park. We are unable to definitively assign five tiger samples which could be offspring dispersers or might have come from tiger population outside of Nepal. Our study revealed that the western region, particularly Bardia National Park, is a poaching hotspot for illegal tiger trade in Nepal. We present feasibility of using molecular forensic based evidence to incriminate criminals in a court of law in the fight against wildlife crime.

Calling phenology of a diverse amphibian assemblage in response to meteorological conditions

The strong association between amphibian activity, breeding and recruitment with local environmental conditions raises concerns regarding how changes in climate may affect the persistence of species populations into the future. Additionally, in a highly diverse assemblage of anurans, competition for breeding sites affects the time and duration of activity, as species compete for limited resources such as water. Meteorological conditions are strong drivers of amphibian activity, so we assessed whether temperature, rainfall, atmospheric pressure and humidity were associated with the calling phenology of an assemblage of anurans in South East Queensland, Australia. We performed calling surveys and collected digital recordings at 45 ponds in an area known for high anuran diversity. We performed detection analyses to investigate the influence of 10 meteorological variables in detection of calling activity in 19 amphibian species. Our results suggest four breeding strategies in the assemblage: explosive summer breeders, prolonged breeders, opportunistic breeders and a winter breeder. Classifying these species into associations provides a framework for understanding how species respond to environmental conditions. Explosive breeders (i.e. species demonstrating short and highly synchronised breeding periods) were particularly responsive to temperature. Our findings help elucidate the breeding phenology of frogs and provide valuable information on their mating systems in native Australian forests. This study highlights the difficulties of surveying even common anurans. We highlight the importance of predictability and stability in climate and the vulnerability of species for which reproduction appears to require highly specific environmental cues.

Assessment of genetic diversity, population structure, and gene flow of tigers (Panthera tigris tigris) across Nepal's Terai Arc Landscape

With fewer than 200 tigers (Panthera tigris tigris) left in Nepal, that are generally confined to five protected areas across the Terai Arc Landscape, genetic studies are needed to provide crucial information on diversity and connectivity for devising an effective country-wide tiger conservation strategy. As part of the Nepal Tiger Genome Project, we studied landscape change, genetic variation, population structure, and gene flow of tigers across the Terai Arc Landscape by conducting Nepal’s first comprehensive and systematic scat-based, non-invasive genetic survey. Of the 770 scat samples collected opportunistically from five protected areas and six presumed corridors, 412 were tiger (57%). Out of ten microsatellite loci, we retain eight markers that were used in identifying 78 individual tigers. We used this dataset to examine population structure, genetic variation, contemporary gene flow, and potential population bottlenecks of tigers in Nepal. We detected three genetic clusters consistent with three demographic sub-populations and found moderate levels of genetic variation (H_e = 0.61, A_R = 3.51) and genetic differentiation (F_ST = 0.14) across the landscape. We detected 3–7 migrants, confirming the potential for dispersal-mediated gene flow across the landscape. We found evidence of a bottleneck signature likely caused by large-scale land-use change documented in the last two centuries in the Terai forest. Securing tiger habitat including functional forest corridors is essential to enhance gene flow across the landscape and ensure long-term tiger survival. This requires cooperation among multiple stakeholders and careful conservation planning to prevent detrimental effects of anthropogenic activities on tigers.

Fine-scale changes in spatial habitat use by a low-density koala population in an isolated periurban forest remnant

Koala (Phascolarctos cinereus) populations in south-east Queensland are in decline. Although various studies have looked at broad-scale tree preference and habitat quality, there has been little attempt to quantify fine-scale activity shifts from one year to the next or examination of activity at the mesoscale. This study quantified koala activity levels in a 909-ha forest patch at Karawatha Forest Park, in south Brisbane. The Spot Assessment Technique was used to quantify activity and tree selection on 33 long-term monitoring plots in 2009 and 2010. In total, 843 trees were searched and koala pellets were found underneath 34 and 47 trees in 2009 and 2010, respectively. A higher proportion of pellets was found underneath Eucalyptus tindaliae and E. fibrosa and there was weak selection for larger trees. A low occurrence of revisits and a minor shift in activity distribution from 2009 to 2010 indicate that the koala population exists at a low density. Rapid declines in koala populations are occurring in primary habitats. Hence, stable low-density koala populations are important for maintaining genetic diversity and connectivity in fragmented urban landscapes.

Spatial modelling of bilby (Macrotis lagotis) and rabbit (Oryctolagus cuniculus) pellets within a predator-proof enclosure

A traditional design-reliant estimate of abundance is calculated by multiplying a density estimate obtained from transects to reflect the size of the study area. This type of estimate tells nothing about the nature of a species’ distribution between the samples. In contrast, model-based inference can better estimate abundance by interpolating transect estimates over the study area with the aid of covariates. This study used density surface modelling (DSM) to predict spatial distribution of greater bilby (Macrotis lagotis) and rabbit (Oryctolagus cuniculus) pellets within a predator-proof enclosure at Currawinya National Park, south-west Queensland. Pellets and latrines were counted using distance sampling and plot sampling on 30 PPBio plots during 2012 and 2014. Pellets and latrines were not strongly associated with habitat features, reflecting the generalist nature of both species. Bilby pellets were found on 23 plots in 2012 and 5 plots in 2014. Rabbit pellets were present on 29 plots in 2012 and 16 plots during 2014. These substantial declines in pellet abundances coincided with invasion of the feral cat (Felis catus) into the enclosure. While DSM modelling can allow managers to make informed decisions about applying survey effort or management practices, it is not suited to all species or situations.

Temporal Variation of the Skin Bacterial Community and Batrachochytrium dendrobatidis Infection in the Terrestrial Cryptic Frog Philoria loveridgei

In animals and plants, symbiotic bacteria can play an important role in disease resistance of host and are the focus of much current research. Globally, amphibian population declines and extinctions have occurred due to chytridiomycosis, a skin disease caused by the pathogen Batrachochytrium dendrobatidis (Bd). Currently amphibian skin bacteria are increasingly recognized as important symbiont communities with a relevant role in the defense against pathogens, as some bacteria can inhibit the growth of B. dendrobatidis. This study aims to document the B. dendrobatidis infection status of wild populations of a terrestrial cryptic frog (Philoria loveridgei), and to determine whether infection status is correlated with changes in the skin microbial communities. Skin samples of P. loveridgei were collected along an altitudinal range within the species distribution in subtropical rainforests in southeast Australia. Sampling was conducted in two years during two breeding seasons with the first classified as a “La Niña” year. We used Taqman real-time PCR to determine B. dendrobatidis infection status and 16S amplicon sequencing techniques to describe the skin community structure. We found B. dendrobatidis-positive frogs only in the second sampling year with low infection intensities, and no correlation between B. dendrobatidis infection status and altitude, frog sex or size. Skin bacterial diversity was significantly higher in P. loveridgei frogs sampled in the 1st year than in the 2nd year. In addition, 7.4% of the total OTUs were significantly more abundant in the 1st year compared to the 2nd year. We identified 67 bacterial OTUs with a significant positive correlation between infection intensity and an OTU’s relative abundance. Forty-five percent of these OTUs belonged to the family Enterobacteriaceae. Overall, temporal variation was strongly associated with changes in B. dendrobatidis infection status and bacterial community structure of wild populations of P. loveridgei.

Visualizing Phonotactic Behavior of Female Frogs in Darkness

Many animals use sounds produced by conspecifics for mate identification. Female insects and anuran amphibians, for instance, use acoustic cues to localize, orient toward and approach conspecific males prior to mating. Here we present a novel technique that utilizes multiple, distributed sound-indication devices and a miniature LED backpack to visualize and record the nocturnal phonotactic approach of females of the Australian orange-eyed tree frog (Litoria chloris) both in a laboratory arena and in the animal’s natural habitat. Continuous high-definition digital recording of the LED coordinates provides automatic tracking of the female’s position, and the illumination patterns of the sound-indication devices allow us to discriminate multiple sound sources including loudspeakers broadcasting calls as well as calls emitted by individual male frogs. This innovative methodology is widely applicable for the study of phonotaxis and spatial structures of acoustically communicating nocturnal animals.

The Australian SuperSite Network: A continental, long-term terrestrial ecosystem observatory

Ecosystem monitoring networks aim to collect data on physical, chemical and biological systems and their interactions that shape the biosphere. Here we introduce the Australian SuperSite Network that, along with complementary facilities of Australia's Terrestrial Ecosystem Research Network (TERN), delivers field infrastructure and diverse, ecosystem-related datasets for use by researchers, educators and policy makers. The SuperSite Network uses infrastructure replicated across research sites in different biomes, to allow comparisons across ecosystems and improve scalability of findings to regional, continental and global scales. This conforms with the approaches of other ecosystem monitoring networks such as Critical Zone Observatories, the U.S. National Ecological Observatory Network; Analysis and Experimentation on Ecosystems, Europe; Chinese Ecosystem Research Network; International Long Term Ecological Research network and the United States Long Term Ecological Research Network. The Australian SuperSite Network currently involves 10 SuperSites across a diverse range of biomes, including tropical rainforest, grassland and savanna; wet and dry sclerophyll forest and woodland; and semi-arid grassland, woodland and savanna. The focus of the SuperSite Network is on using vegetation, faunal and biophysical monitoring to develop a process-based understanding of ecosystem function and change in Australian biomes; and to link this with data streams provided by the series of flux towers across the network. The Australian SuperSite Network is also intended to support a range of auxiliary researchers who contribute to the growing body of knowledge within and across the SuperSite Network, public outreach and education to promote environmental awareness and the role of ecosystem monitoring in the management of Australian environments.

Does physiological response to disease incur cost to reproductive ecology in a sexually dichromatic amphibian species?

It is well known that the disease chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) has contributed to amphibian declines worldwide. The impact of Bd varies, with some species being more susceptible to infection than others. Recent evidence has shown that Bd can have sub-lethal effects, whereby increases in stress hormones have been associated with infection. Could this increased stress response, which is a physiological adaptation that provides an increased resilience against Bd infection, potentially be a trade-off with important life-history traits such as reproduction? We studied this question in adult male frogs of a non-declining species (Litoria wilcoxii). Frogs were sampled for (1) seasonal hormone (testosterone and corticosterone), color and disease profiles, (2) the relationship between disease infection status and hormone levels or dorsal color, (3) subclinical effects of Bd by investigating disease load and hormone level, and (4) reproductive and stress hormone relationships independent of disease. Testosterone levels and color score varied seasonally (throughout the spring/summer months) while corticosterone levels remained stable. Frogs with high Bd prevalence had significantly higher corticosterone levels and lower testosterone levels compared to uninfected frogs, and no differences in color were observed. There was a significant positive correlation between disease load and corticosterone levels, and a significant negative relationship between disease load and testosterone. Our field data provides novel evidence that increased physiological stress response associated with Bd infection in wild frogs, could suppress reproduction by down-regulating gonadal hormones in amphibians, however the impacts on reproductive output is yet to be established.

Maximizing the reliability of non-invasive endocrine sampling in the tiger (Panthera tigris): environmental decay and intra-sample variation in faecal glucocorticoid metabolites

Evaluation of physiological stress in the tiger (Panthera tigris) using faecal cortisol metabolite (FCM) enzyme immunoassays (EIAs) provides a powerful conservation physiology tool for the species. However, it is important to validate non-invasive endocrine sampling techniques in field conditions to ensure that the method provides a reliable parameter of physiological stress in the species. This is because endocrine measurements are highly species specific and FCM concentrations can be influenced by environmental factors. Here, we studied the impact of the decay rate of FCMs and intra-sample variation of FCMs using a previously validated EIA. To determine the decay rate of FCMs, we measured FCMs in freshly deposited tiger faeces (n = 8 tigers and 48 scats) that were randomly exposed to the natural environment (dry conditions with no rainfall) for up to 192 h. To determine intra-sample variation in FCMs, we used 10 scats from 10 tigers, divided each sample into four sections and each section into four sub-sections and measured FCMs in each section and sub-section. The results of this decay-rate experiment showed that FCMs in tiger faeces began to decay after 48 h exposure to the environmental conditions available. Thus, FCMs within freshly deposited tiger faeces are influenced by available environmental conditions. Changes in weather conditions (e.g. increased rainfall and humidity) could influence the stability of FCMs. The results of the intra-sample variation study showed that inter-variation among scats accounted for 52% of the variations in FCMs, while intra-sample variation between sections (32%) was greater than the sub-sample variation (16%). Intra-sample variation can be reduced by homogenizing the entire lyophilized faecal sample prior to the EIA. In conclusion, careful evaluation of decay rate and complete homogenization of faeces prior to EIA analysis will increase the reliability of FCMs as a non-invasive index of physiological stress in the tiger.

Estimating the abundance of the bilby (Macrotis lagotis): a vulnerable, uncommon, nocturnal marsupial

The bilby (Macrotis lagotis) is listed as Vulnerable in Australia, is strictly nocturnal and shy, and it has proven difficult to estimate its population abundance. The aim of this study was to determine methodology that would reliably estimate the abundance of the bilby within an enclosure at Currawinya National Park, south-west Queensland. We estimated the abundance of bilbies on long-term monitoring plots by counting pellets comparing two methods: counting standing odorous pellets using distance sampling and counting newly deposited pellets (FAR). Pellet deposition rate and decay rate were also estimated to enable population estimation using distance sampling. The density of odorous (<14 days old) standing pellets and old pellets was highest in October 2011 and dropped dramatically when plots were revisited in March 2012 and July 2012. Counting standing pellets using distance sampling provided a rigorous estimate of abundance of bilbies at Currawinya. Bilby density and pellet deposition rates were too low for the FAR method to accurately or precisely estimate bilby density. A population crash within the enclosure following an invasion of feral cats was mirrored by a dramatic decrease in pellet density. Incorporating detectability into abundance estimation should be carefully considered for conservation purposes.

Determinants of tree assemblage composition at the mesoscale within a subtropical eucalypt forest

A variety of environmental processes, including topography, edaphic and disturbance factors can influence vegetation composition. The relative influence of these patterns has been known to vary with scale, however, few studies have focused on environmental drivers of composition at the mesoscale. This study examined the relative importance of topography, catchment flow and soil in influencing tree assemblages in Karawatha Forest Park; a South-East Queensland subtropical eucalypt forest embedded in an urban matrix that is part of the Terrestrial Ecosystem Research Network South-East Queensland Peri-urban SuperSite. Thirty-three LTER plots were surveyed at the mesoscale (909 ha), where all woody stems ≥1.3 m high rooted within plots were sampled. Vegetation was divided into three cohorts: small (≥1-10 cm DBH), intermediate (≥10-30 cm DBH), and large (≥30 cm DBH). Plot slope, aspect, elevation, catchment area and location and soil chemistry and structure were also measured. Ordinations and smooth surface modelling were used to determine drivers of vegetation assemblage in each cohort. Vegetation composition was highly variable among plots at the mesoscale (plots systematically placed at 500 m intervals). Elevation was strongly related to woody vegetation composition across all cohorts (R2: 0.69-0.75). Other topographic variables that explained a substantial amount of variation in composition were catchment area (R2: 0.43-0.45) and slope (R2: 0.23-0.61). Soil chemistry (R2: 0.09-0.75) was also associated with woody vegetation composition. While species composition differed substantially between cohorts, the environmental variables explaining composition did not. These results demonstrate the overriding importance of elevation and other topographic features in discriminating tree assemblage patterns irrespective of tree size. The importance of soil characteristics to tree assemblages was also influenced by topography, where ridge top sites were typically drier and had lower soil nutrient levels than riparian areas.

The neuro-hormonal control of rapid dynamic skin colour change in an amphibian during amplexus

Sexual signalling using dynamic skin colouration is a key feature in some vertebrates; however, it is rarely studied in amphibians. Consequently, little is known about the hormonal basis of this interesting biological phenomenon for many species. Male stony creek frogs (Litoria wilcoxii) are known to change dorsal colouration from brown to lemon yellow within minutes. This striking change is faster then what has been seen most amphibians, and could therefore be under neuronal regulation, a factor that is rarely observed in amphibians. In this study, we observed colour changes in wild frogs during amplexus to determine the natural timing of colour change. We also investigated the hypothesis that colour change is mediated by either reproductive or neuro- hormones. This was achieved by injecting frogs with epinephrine, testosterone, saline solution (control 1) or sesame oil (control 2). A non-invasive approach was also used wherein hormones and controls were administered topically. Male frogs turned a vivid yellow within 5 minutes of initiation of amplexus and remained so for 3-5 hours before rapidly fading back to brown. Epinephrine-treated frogs showed a significant colour change from brown to yellow within 5 minutes, however, testosterone-treated frogs did not change colour. Our results provide evidence of the role neuronal regulation plays in colour change systems.

Evaluating physiological stress in Sumatran tigers (Panthera tigris ssp. sumatrae) managed in Australian zoos

Glucocorticoid quantification using non-invasive methods provides a powerful tool for assessing the health and welfare of wildlife in zoo-based programmes. In this study, we provide baseline data on faecal-based glucocorticoid (cortisol) monitoring of Sumatran tigers (Panthera tigris ssp. sumatrae) managed at the Melbourne Zoo in Victoria, Australia. We sampled five tigers daily for 60 days. Faecal cortisol metabolites (FCMs) in tiger faecal extracts were quantified using enzyme immunoassays that were successfully validated using parallelism and accuracy recovery checks. Two female tigers had significantly higher mean FCM levels than the two males and another female, suggesting that females may have higher FCM levels. A significant elevation was noted in the FCM levels for one female 2 days after she was darted and anaesthetized; however, the FCM levels returned to baseline levels within 3 days after the event. Comparative analysis of FCM levels of tigers sampled at Melbourne Zoo with tigers sampled earlier at two other Australian Zoos (Dreamworld Themepark and Australia Zoo) showed that FCM levels varied between zoos. Differences in the enclosure characteristics, timing of sampling, size and composition of groupings and training procedures could all contribute to this variation. Overall, we recommend the use of non-invasive sampling for the assessment of adrenocortical activity of felids managed in zoos in Australia and internationally in order to improve the welfare of these charismatic big cats.

Over-wintering tadpoles of Mixophyes fasciolatus act as reservoir host for Batrachochytrium dendrobatidis

Batrachochytrium dendrobatidis (Bd), a cutaneous amphibian fungus that causes the lethal disease chytridiomycosis, has been implicated as a cause of many amphibian declines. Bd can tolerate low temperatures with an optimum thermal range from 17-24°C. It has been shown that Bd infection may result in species extinction, avoiding the transmission threshold presented by density dependent transmission theory. Prevalence of Bd during autumn and winter has been shown to be as low as 0% in some species. It is currently unclear how Bd persists in field conditions and what processes result in carry-over between seasons. It has been hypothesised that overwintering tadpoles may host Bd between breeding seasons. The Great Barred Frog (Mixophyes fasciolatus) is a common, stable and widespread species in Queensland, Australia, and is known to carry Bd. Investigation into Bd infection of different life stages of M. fasciolatus during seasonally low prevalence may potentially reveal persistence and carry-over methods between seasons. Metamorphs, juveniles, and adults were swabbed for Bd infection over three months (between March and May, 2011) at 5 sites of varying altitude (66 m-790 m). A total of 93 swabs were analysed using Polymerase Chain Reaction (PCR) real-time analysis. PCR analysis showed 6 positive (1 excluded), 4 equivocal and 83 negative results for infection with Bd. Equivocal results were assumed to be negative using the precautionary principle. The 5 positive results consisted of 4 emerging (Gosner stage 43-45) metamorphs and 1 adult M. fasciolatus. Fisher's exact test on prevalence showed that the prevalence was significantly different between life stages. All positive results were sampled at high altitudes (790 m); however prevalence was not significantly different between altitudes. Infection of emerging metamorphs suggests that individuals were infected as tadpoles. We hypothesise that M. fasciolatus tadpoles carry Bd through seasons. Thus, Mixophyes fasciolatus may act as disease reservoirs at multiple life stages.

Acute thermal stressor increases glucocorticoid response but minimizes testosterone and locomotor performance in the cane toad (Rhinella marina)

Climatic warming is a global problem and acute thermal stressor in particular could be considered as a major stressor for wildlife. Cane toads (Rhinella marina) have expanded their range into warmer regions of Australia and they provide a suitable model species to study the sub-lethal impacts of thermal stressor on the endocrine physiology of amphibians. Presently, there is no information to show that exposure to an acute thermal stressor could initiate a physiological stress (glucocorticoid) response and secondly, the possible effects on reproductive hormones and performance. Answering these questions is important for understanding the impacts of extreme temperature on amphibians. In this study, we experimented on cane toads from Queensland, Australia by acclimating them to mildly warm temperature (25°C) and then exposing to acute temperature treatments of 30°, 35° or 40°C (hypothetical acute thermal stressors). We measured acute changes in the stress hormone corticosterone and the reproductive hormone testosterone using standard capture and handling protocol and quantified the metabolites of both hormones non-invasively using urinary enzyme-immunoassays. Furthermore, we measured performance trait (i.e. righting response score) in the control acclimated and the three treatment groups. Corticosterone stress responses increased in all toads during exposure to an acute thermal stressor. Furthermore, exposure to a thermal stressor also decreased testosterone levels in all toads. The duration of the righting response (seconds) was longer for toads that were exposed to 40°C than to 30°, 35° or 25°C. The increased corticosterone stress response with increased intensity of the acute thermal stressor suggests that the toads perceived this treatment as a stressor. Furthermore, the results also highlight a potential trade-off with performance and reproductive hormones. Ultimately, exposure acute thermal stressors due to climatic variability could impact amphibians at multiple eco-physiological levels through impacts on endocrine physiology, performance and potentially fitness traits (e.g. reproductive output).

The founding charter of the Genomic Observatories Network

The co-authors of this paper hereby state their intention to work together to launch the Genomic Observatories Network (GOs Network) for which this document will serve as its Founding Charter. We define a Genomic Observatory as an ecosystem and/or site subject to long-term scientific research, including (but not limited to) the sustained study of genomic biodiversity from single-celled microbes to multicellular organisms.An international group of 64 scientists first published the call for a global network of Genomic Observatories in January 2012. The vision for such a network was expanded in a subsequent paper and developed over a series of meetings in Bremen (Germany), Shenzhen (China), Moorea (French Polynesia), Oxford (UK), Pacific Grove (California, USA), Washington (DC, USA), and London (UK). While this community-building process continues, here we express our mutual intent to establish the GOs Network formally, and to describe our shared vision for its future. The views expressed here are ours alone as individual scientists, and do not necessarily represent those of the institutions with which we are affiliated.

Faecal cortisol metabolites in Bengal (Panthera tigris tigris) and Sumatran tigers (Panthera tigris sumatrae)

The tiger (Panthera tigris) faces a great risk of extinction as its wild numbers have plummeted due to poaching and habitat destruction so ex-situ conservation programs are becoming ever more necessary. Reliable non-invasive biomarkers of the stress hormone (cortisol) are necessary for assessing the health and welfare of tigers in captivity. To our knowledge, non-invasive stress endocrinology methods have not been tested as widely in tigers. The first aim of this study was to describe and validate a faecal cortisol metabolite enzyme-immmunoassay (FCM EIA) for two tiger sub-species, the Bengal tiger (Panthera tigris tigris) and the Sumatran tiger (Panthera tigris sumatrae). Individual tigers (n=22) were studied in two large Zoos in Queensland, Australia (Dreamworld Theme Park and Australia Zoo). Fresh faecal samples (<12 h old) were collected each morning from both Zoos over a study period of 21 days. Biological validation was conducted separately by collecting feces 5 days before and 5 days after blood was taken from four male and five female tigers. Results showed that mean FCM levels increased by 138% and 285% in the male and female tigers within 1 day after bloods were taken, returning to baseline in 5 days. Laboratory validations of the FCM EIA were done using an extraction efficiency test and parallelism. Results showed >89% recovery of the cortisol standard that was added to tiger faecal extract. We also obtained parallel displacement of the serially diluted cortisol standard against serially diluted tiger faecal extract. Our second aim was to determine whether the FCM levels were significantly different between tiger sub-species and sex. Results showed no significant difference in mean FCM levels between the Bengal and Sumatran tiger sub-species. Mean levels of FCMs were significantly higher in females than in male tigers. Those male and female tigers with reported health issues during the study period expressed higher FCM levels than the reportedly healthy tigers. Interestingly, those tigers that took part in some activity (such as walks, photos, presentations and guest feeds) expressed moderately higher FCM levels at Dreamworld and lower FCM levels at Australia Zoo in comparison to those tigers that did not take part in such activities. These results indicate potential habituation in some tigers for routine activity through specialized training and pre-conditioning. In conclusion, the FCM EIA described in this study provides a reliable non-invasive method for evaluating the stress status of tigers in Zoos.

Changes in serum and urinary corticosterone and testosterone during short-term capture and handling in the cane toad (Rhinella marina)

Non-invasive endocrine monitoring with minimally invasive biological samples, such as urine, is being used widely for conservation biology research on amphibians. Currently, it is unknown how closely urinary measurements correspond with the traditional serum hormone measurements. We compared urinary and serum concentrations of corticosterone (CORT) and testosterone (T) in adult male cane toads (Rhinella marina) using a standard capture and handling (short-term stressor) protocol. Free-living male cane toads were captured and sampled for baseline urine (0h) with a second urine sample taken at 0.5h and hourly between 1 and 8h. A single blood sample was collected from each toad after the final urine sampling and capture handling. The mean serum CORT concentration increased between 0 and 0.5h, reaching the highest level between 6 and 8h. The mean urinary CORT concentration increased with a lag-time of 1h and continued to increase up to 8h. The mean level of serum T decreased between 0 and 7h and increased between 7 and 8h. Mean urinary T concentration decreased with a lag-time of 0.5h. Urinary T levels did not change between 4 and 8h. Mean serum T levels reached 50% of the original 0h value at 1h while mean serum CORT levels reached 200% of the original 0h value within 0.5h. Mean urinary T levels reached 50% of the original 0h value within 3h while mean urinary CORT levels reached 200% of the original 0h value within 3h. The inter-individual variation in baseline serum and urinary CORT and T levels were highly comparable, suggesting that baseline urine sample provides a reliable indicator of the physiological status of the animal. Overall, the results have demonstrated that urine sampling and standard capture handling protocol provide reliable measures of baseline corticosterone and testosterone, as well as short-term stress hormone responses in amphibians.

Non-invasive monitoring of glucocorticoid physiology within highland and lowland populations of native Australian Great Barred Frog (Mixophyes fasciolatus)

This study used non-invasive endocrinology to examine baseline corticosterone at different altitudes in a free-living Australian amphibian: the Great Barred Frog (Mixophyes fasciolatus). An enzyme immunoassay (EIA) was performed on urine samples and validated biologically using an adrenocorticotropic hormone (ACTH) challenge. Frogs were injected with ACTH on day 0 and recaptures occurred 1-10days post injection. Urine samples and body condition measurements were collected from lowland (60m) and highland (660m and 790m) sub-populations of M. fasciolatus in South East Queensland (SEQ), close to their post-breeding period during autumn 2011. We simultaneously sampled these sub-populations for Batrachochytrium dendrobatidis (Bd), a pathogenic fungus responsible for mass mortalities of amphibians worldwide. The ACTH challenge successfully validated the urinary corticosterone EIA in M. fasciolatus, with a peak urinary corticosterone response to ACTH injection on day 2 and a return to baseline levels by day 6. Polymerase chain reaction (PCR) analysis of 50 individuals returned only 1 positive result for Bd. Simple linear regression showed a strong positive relationship between baseline urinary corticosterone concentrations and altitude and no relationship with body condition. We hypothesize that higher baseline corticosterone concentrations within highland sub-populations of male M. fasciolatus could be associated with increased environmental challenge at high altitudes and geographic range limits. Whether this pattern is an indication of chronic stress in highland populations or life-time fitness and survival, warrants future investigation.

Sight of a predator induces a corticosterone stress response and generates fear in an amphibian

Amphibians, like other animals, generate corticosterone or cortisol glucocorticoid responses to stimuli perceived to be threatening. It is generally assumed that the corticosterone response of animals to capture and handling reflects the corticosterone response to stimuli such as the sight of a predator that are thought to be natural stressors. Fijian ground frogs (Platymantisvitiana) are preyed upon by the introduced cane toads (Rhinellamarina), and we used ground frogs to test the hypothesis that the sight of a predator will induce a corticosterone stress response in an amphibian. Urinary corticosterone metabolite concentrations increased in male ground frogs exposed to the sight of a toad for 1, 3 or 6 h, whereas corticosterone did not change in frogs exposed to another male ground frog, a ball, or when no stimulus was present in the test compartment. The frogs exposed to a toad initially moved towards the stimulus then moved away, whereas frogs exposed to another frog moved towards the test frog and remained closer to the frog than at the start of the test. Tonic immobility (TI) was measured as an index of fearfulness immediately after the test exposure of the frogs to a stimulus. The duration of TI was longer in frogs exposed to a toad than to another frog or to a ball. The results provide novel evidence that the sight of a predator can induce a corticosterone response and lead to increased fearfulness in amphibians. In addition, they show that endemic frogs can recognise an introduced predator as a threat.

Non-invasive evaluation of physiological stress in an iconic Australian marsupial: the Koala (Phascolarctos cinereus)

Koalas (Phascolarctos cinereus) are the only extant representatives of Australia's unique marsupial family Phascolarctidae and were listed as nationally Vulnerable in 2012. Causes of mortality are diverse, although the disease chlamydiosis, dog attacks, collisions with cars, and loss of habitat represent the principal reasons for the continued species decline. Koala breeding facilities in Queensland and New South Wales, Australia have been established for conservation and tourism. Non-invasive monitoring of physiological stress is important for determining the sub-lethal effects of environmental stressors on the well-being, reproduction and survival of Koalas in Zoos and also in the wild. In this study, we developed a faecal cortisol metabolite (FCM) enzyme-immunoassay (EIA) for monitoring physiological stress in Koalas from two established Zoos in Australia and also within a free-living sub-population from Queensland. Biological validation of the FCM EIA was done using an adrenocorticotropic hormone (ACTH) challenge. We discovered excretory lag-times of FCM of 24 h in females (n=2) and 48 h in male (n=2) Koalas in response to the ACTH challenge. FCM levels showed an episodic and delayed peak response lasting up to 9 days post ACTH challenge. This finding should be taken into consideration when designing future experiments to study the impacts of short-term (acute) and chronic stressors on the Koalas. Laboratory validations were done using parallelism and recovery checks (extraction efficiency) of the cortisol standard against pooled Koala faecal extracts. Greater than 99% recovery of the cortisol standard was obtained as well as a parallel displacement curve against Koala faecal extracts. FCM levels of the captive Koalas (n=10 males and 13 females) significantly differed by sex, reproductive condition (lactating versus non-lactating Koalas) and the handling groups. Handled male Koalas had 200% higher FCM levels than their non-handled counterparts, while females were not affected by handling as long they were not undergoing lactation. There was no significant difference in FCM levels between the captive and wild Koalas (n=9 males and 7 females). Overall, these results provide foundation knowledge on non-invasive FCM analysis in this iconic Australian marsupial. Non-invasive stress endocrinology opens up opportunities for evaluating the sub-lethal physiological effects of management activities (including caging, translocation) on the nutritional status, reproductive behaviors and disease status of captive and managed in situ Koala populations.

Effects of natural weathering conditions on faecal cortisol metabolite measurements in the greater bilby (Macrotis lagotis)

Natural weathering conditions can influence faecal cortisol metabolite (FCM) measurements in wildlife if fresh faeces cannot be collected immediately following defaecation. In this study, we evaluated this issue in a threatened Australian marsupial, the greater bilby (Macrotis lagotis). Fresh (<12 h since defaecation) faecal samples (n = 19 pellets per bilby) were collected one morning from seven adult bilbies kept in captivity. One control faecal sample (Day 1) from each bilby was immediately frozen. The remaining faecal pellets were randomly positioned outdoors. Subsequently, we froze one faecal pellet every 24 h for 19 days. FCM levels in bilby faeces were quantified using an enzyme-immunoassay. Mean FCM levels showed variation (daily mean coefficients of variation [CV %]) of 56.83–171.65% over 19 days. Overall, FCM levels were affected by exposure time; however, multiple comparisons showed that no significant change in FCM occurred after environmental exposure (no significant difference in mean FCM between control (Day 1) with any of the exposure days (Days 2–19). Individuals and sex also affected FCM levels. We found no correlation between mean daily CVs with daily minimum–maximum temperatures or rainfall. Our results indicate that FCM in bilby faeces is fairly stable to long-term environmental exposure (19 days). In future, freshly excreted bilby faeces (where the sample maintains a distinct odour for 9–13 days) should be used to study FCM levels in wild bilbies.

Inverse urinary corticosterone and testosterone metabolite responses to different durations of restraint in the cane toad (Rhinella marina)

Non-invasive measurement of urinary corticosterone and testosterone metabolites in amphibians provides opportunities for endocrine studies of responses to physiological and psychological stressors. Typically, corticosterone metabolite concentrations increase in frog urine within 1-2h of a mild capture and handling stress protocol. However, no study has investigated the effect of duration of manual restraint on the changes in corticosterone and reproductive hormones in amphibians. We quantified urinary corticosterone and testosterone metabolite responses for 8h following various durations of manual restraint (control, 5, 15 or 30min) in adult male cane toads (Rhinella marina) under controlled laboratory conditions. All toads had a corticosterone stress response over 8h to our standard capture and handling stressor. The mean corticosterone stress response was significantly higher after 15 or 30min restraint in comparison to the control (no restraint) or to 5min restraint. Manual restraint for 5, 15 or 30min caused a significant reduction in urinary testosterone concentrations over 8h. We also provide a novel method of quantifying plasticity in corticosterone stress responses in amphibians with respect to restraint duration using the concept of a "reaction norm". The reaction norm, which was calculated as slope of the regression line of integrated corticosterone response against restraint duration, was 9.69 (pg corticosterone/μg creatinineh)/min for male toads. In summary, corticosterone and testosterone responses to restraint are affected by restraint duration in male toads. Glucocorticoid reaction norms can be applied to study the change in physiological stress hormonal response with respect to restraint duration in other amphibian species.

Are baseline and short-term corticosterone stress responses in free-living amphibians repeatable?

Amphibians respond to environmental stressors by secreting corticosterone, a stress hormone which promotes physiological and behavioral responses. Capture handling can be used to stimulate physiological stress response in amphibians. The use of single blood sampling and presentation of mean data often limits the quantification of within and between individual variation in baseline and short-term corticosterone stress responses in amphibians. It is important for studies of amphibian physiological ecology to determine whether baseline and short-term corticosterone stress responses are consistent or not. We quantified repeatability (r), a statistical measure of consistency, in baseline and short-term corticosterone stress responses to a standard capture and handling stress protocol in free-living adult male cane toads (Rhinella marina). Corticosterone metabolite concentrations were measured entirely non-invasively in male toad urine samples via an enzyme-immunoassay. During the first sampling occasion, urine samples were collected manually from individual male toads (n=20) immediately upon field capture. Toads were handled for 5min then transferred to plastic bags (constituting a mild stressor), and urine samples were collected hourly over 8h in the field. The toads were resampled for baseline (0h) urine corticosterone with hourly urine sampling over 8h (for quantification of the stress induced corticosterone) at 14 day intervals on three consecutive occasions. Within and between sample variations in urinary corticosterone metabolite concentrations were also quantified. All toads expressed a corticosterone stress response over 8h to our standard capture and handling stress protocol. Variations both within and between toads was higher for corrected integrated corticosterone concentrations than corticosterone concentrations at baseline, 3 or 6h. Baseline urinary corticosterone metabolite concentration of the male toads was highly repeatable (r=0.877) together with high statistical repeatabilities for 3h (r=0.695), 6h (r=0.428) and 8h (r=0.775) corticosterone metabolite concentrations, and for the total and corrected integrated corticosterone responses (r=0.807; r=0.743 respectively). This study highlights that baseline and short-term corticosterone stress responses are repeatable in free-living amphibians. Future studies should utilize this non-invasive tool to explore repeatability among seasons and across years, and determine its functional significance in relation to behavioral ecology and reproduction in amphibians generally.

Effects of temperature on urinary corticosterone metabolite responses to short-term capture and handling stress in the cane toad (Rhinella marina)

Extreme temperature can cause metabolic, immune and behavioural changes in amphibians. Short-term stress hormonal response via increased secretion of corticosterone enables amphibians to make necessary physiological and behavioural adjustments for coping with stressors. The effect of temperature on short-term corticosterone responses has not been studied in amphibians. In this study, this relationship was evaluated in adult male cane toads (Rhinella marina). We acclimated male toads (n=24 toads per group) at low, medium and high temperature (15, 25 or 35°C) under controlled laboratory conditions for a 14 day period. After thermal acclimation, short-term corticosterone responses were evaluated in the toads subjected to a standard capture and handling stress protocol over a 24h period. Corticosterone metabolites in toad urine were measured via enzyme-immunoassay. During acclimation, mean baseline urinary corticosterone level increased after transfer of the toads from wild into captivity and returned to baseline on day 14 of acclimation for each of the three temperatures. At the end of the 14 days of thermal acclimation period, baseline corticosterone level were highest for toad group at 35°C and lowest at 15°C. All toads generated urinary corticosterone responses to the standard capture and handling stressor for each temperature. Both individual and mean short-term corticosterone responses of the toads were highest at 35°C and lowest at 15°C. Furthermore, Q(10) values (the factor by which the reaction rate increases when the temperature is raised by 10°) were calculated for mean corrected integrated corticosterone responses as follows; (15-35°C) Q(10)=1.51, (15-25°C) Q(10)=1.60; (25-35°C) Q(10)=1.43. Both total and corrected integrated corticosterone responses were highest for toads at 35°C followed by 25°C and lowest for the 15°C toad group. Overall, the results have demonstrated the thermodynamic response of corticosterone secretion to short-term capture and handling stress in an amphibian species.

Urinary corticosterone metabolite responses to capture and handling in two closely related species of free-living Fijian frogs

Studies of baseline (unstressed) and short-term corticosterone stress responses in free-living amphibians can provide crucial information on the physiological responses of different populations to environmental change. In this study, we compared baseline and urinary corticosterone metabolite responses of free-living adult males and females of two closely related Fijian frogs of the Platymantis genus (Family: Ceratobatrachidae). Fijian ground frogs (Platymantis vitiana) live on the ground while Fijian tree frogs (Platymantis vitiensis) are arboreal. We captured free-living frogs and applied our moderate stress protocol (5 min handling during urine sampling at hourly intervals), with urinary corticosterone metabolite concentrations measured by enzyme-immunoassay. Mean urinary corticosterone metabolite concentrations in male and female Fijian ground frogs increased from 0 to 2 h and continued to increase to peak concentrations 5-6 h after capture. Mean baseline corticosterone concentration was significantly different between sexes (higher in males than females) only for Fijian ground frogs. There was no significant difference between sexes in the integrated corticosterone responses for both species. Mean baseline and urinary corticosterone metabolite responses of Fijian tree frogs were lower than those of Fijian ground frogs. Corticosterone levels increased for 4-5 h in both species and began to decrease again 7 h after initial capture. Corticosterone responses were consistently higher for Fijian ground frogs than Fijian tree frogs. Individuals in both species showed markedly variable corticosterone responses over the 8h duration of the stressor, with some individuals showing low stress responses and others showing high stress responses. The magnitude of the corrected integrated response of the ground frogs was almost twice that of the tree frogs. These differences in baseline and short-term corticosterone stress responses between these two species could be a consequence of ecological differences including micro-habitat, predator interactions and/or competitive interactions with the introduced cane toad (Rhinella marina). Comparisons of corticosterone responses between populations and species provide a valuable tool for measuring the physiological responses of the amphibians to environmental change.

Individual variation and repeatability in urinary corticosterone metabolite responses to capture in the cane toad (Rhinella marina)

Urinary corticosterone metabolite enzyme-immunoassay (EIA) can be used for the non-invasive assessment of baseline levels and corticosterone responses in amphibians. In this study, urinary corticosterone responses of wild male cane toads (Rhinella marina) to confinement and repeated handling were measured to quantify individual variation in corticosterone responses for the first time in an amphibian species. Urine samples were collected at 0 h in the wild, hourly from 2 to 8 h after transfer into captivity, and again at 12 and 24 h in captivity. Toads were then held in captivity and subjected to the same sampling protocol on three occasions at 14 days intervals to quantify variation in corticosterone metabolite responses within and between toads. Baseline and individual corticosterone metabolite responses in male cane toads were generally consistent, with high statistical repeatabilities for 0 h (r=0.630), 6 h (r=0.793), 12 h (r=0.652) and 24 h (r=0.721) corticosterone metabolite concentrations, and for the total and corrected integrated corticosterone responses (r=0.567, p=0.033; r=0.728, p=0.014 respectively). Urinary corticosterone responses appear to be a stable, repeatable trait within individuals. Corticosterone responses in amphibians can be more readily measured when urine rather than plasma samples are collected, and the protocol established in the current study can now be applied to the study of variation in corticosterone responses in other amphibians.

Perch substrate use by the threatened wallum sedge frog (Litoria olongburensis) in wetland habitats of mainland eastern Australia

Understanding habitat requirements for a threatened species is important for recovery planning and management of threatening processes. This study examines utilisation of wetland habitat by the threatened wallum sedge frog (Litoria olongburensis), which breeds in acidic waters of coastal sandy lowlands in subtropical eastern Australia. Habitat utilisation was determined by comparing perch substrate observations with perch substrate availability in wetlands occupied by the species throughout its mainland distribution range. A high proportion (75.3%) of adult wallum sedge frogs perched on upright sedges, comprising Baumea, Schoenus and Chorizandra species, which was much higher than expected on the basis of availability (P < 0.001). Baloskion pallens, a thin sedge-like herbaceous plant, was utilised by 12.1% of the frogs, which was lower than expected on the basis of availability (P = 0.020). Other herbaceous species and shrubs were also utilised significantly less than expected. The identification of preferred perch species is critical for impact assessment and mitigation activities, including design, construction, restoration and maintenance of wetlands suitable for the survival and reproduction of the wallum sedge frog.

Assessing the information content of calls of Litoria chloris: quality signalling versus individual recognition

In many species, male animals produce costly signals to attract females. Intersexual indicator theories propose that these signals are indicative of male quality, whereas individual recognition models are based on the idea that male signals are used primarily to allow for individual discrimination. These two types of models make differing predictions about the nature of male signals. In particular, these models’ predictions differ in the information about a male’s quality that will be included in his signal, the frequency distributions of male signals in a population, and the ways in which the different traits that make up a signal will covary. Calls from the Australian frog Litoria chloris were tested for consistency with the predictions of intersexual indicator models and individual recognition models. The calls were found to contain minimal information on male quality, and the covariance between different signal traits was consistent with the individual recognition models. However, the frequency distributions of male signal traits agreed with intersexual indicator models. In addition, this study found evidence that the information content of calls may instead mediate intrasexual interactions, although more research is required to determine if this is the case.

Urinary corticosterone responses to capture and toe-clipping in the cane toad (Rhinella marina) indicate that toe-clipping is a stressor for amphibians

Toe-clipping, the removal of one or more toes, is a common method used to individually mark free-living animals. Whilst this method is widely used in studies of amphibians, the appropriateness of the method, and its potential detrimental effects have been the subject of debate. Here, we provide for the first time, evidence that toe-clipping is a stressor in a wild amphibian. We measured urinary corticosterone responses of male cane toads (Rhinella marina) to capture and handling only, and to toe-clipping under field conditions. Urinary testosterone concentrations and white blood cell proportions were also measured. Urinary corticosterone metabolite concentrations increased 6h after capture and handling only and remained high for 24h; corticosterone returned to baseline levels after 48 h and remained low at 72 h post capture and handling. Corticosterone concentrations in toads subjected to toe-clipping increased at 6h to significantly higher concentrations than after capture and handling only, then decreased more slowly than after capture and handling, and were still elevated (approximately double basal level) 72 h after toe-clipping. Testosterone did not change significantly after capture and handling only, whereas after toe-clipping testosterone decreased at 6h and remained low at 72 h. There were weak short-term effects of toe-clipping compared with capture and handling only on white blood cell proportions. We have clearly shown that toe-clipping is a distinctly stronger stressor than capture and handling alone. This indicates that there is an ethical cost of toe-clipping, and this should be considered when planning studies of amphibians.

Urinary corticosterone metabolite responses to capture and captivity in the cane toad (Rhinella marina)

Urinary corticosterone metabolite responses to capture have recently been shown for the first time in amphibians, and in the present study urinary corticosterone metabolite responses to capture and to confinement in captivity were measured in adult cane toads (Rhinella marina) in Queensland, Australia. An adrenocorticotropic hormone (ACTH) challenge was used to provide a biological validation for urinary corticosterone metabolite concentrations measured by radioimmunoassay (RIA). Urinary corticosterone metabolite increased 1-2 days after ACTH but not saline injection and then returned to initial values, indicating that the RIA could detect changes in corticosterone secretion in toads. Urinary corticosterone metabolite responses to short-term capture and restraint in plastic bags were first apparent 2h after capture of wild toads. Toads held communally in captivity for 5 days had elevated urinary corticosterone metabolite concentrations. Mean corticosterone concentrations declined significantly after a further 7 days in individual housing chambers. There was no sex difference in urinary corticosterone metabolite responses of toads to ACTH challenge, short-term capture or captivity. The relative amount of variation in the mean corticosterone responses was quantified by calculating coefficients of variation (CV) for each mean corticosterone response. Mean corticosterone at 0 min was more variable for captive toads than wild toads. Furthermore, initial corticosterone concentrations (0 min) were more variable than concentrations during the ACTH challenge, short-term capture and captivity. There was little change in the amount of variation of mean corticosterone levels between male and female toads with increasing time in captivity (12-29 days). This study has shown individual corticosterone responses of amphibians for the first-time, and has provided a novel method for quantifying the relative amount of variation in amphibian corticosterone responses.

Is chytridiomycosis an emerging infectious disease in Asia?

The disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has caused dramatic amphibian population declines and extinctions in Australia, Central and North America, and Europe. Bd is associated with >200 species extinctions of amphibians, but not all species that become infected are susceptible to the disease. Specifically, Bd has rapidly emerged in some areas of the world, such as in Australia, USA, and throughout Central and South America, causing population and species collapse. The mechanism behind the rapid global emergence of the disease is poorly understood, in part due to an incomplete picture of the global distribution of Bd. At present, there is a considerable amount of geographic bias in survey effort for Bd, with Asia being the most neglected continent. To date, Bd surveys have been published for few Asian countries, and infected amphibians have been reported only from Indonesia, South Korea, China and Japan. Thus far, there have been no substantiated reports of enigmatic or suspected disease-caused population declines of the kind that has been attributed to Bd in other areas. In order to gain a more detailed picture of the distribution of Bd in Asia, we undertook a widespread, opportunistic survey of over 3,000 amphibians for Bd throughout Asia and adjoining Papua New Guinea. Survey sites spanned 15 countries, approximately 36° latitude, 111° longitude, and over 2000 m in elevation. Bd prevalence was very low throughout our survey area (2.35% overall) and infected animals were not clumped as would be expected in epizootic events. This suggests that Bd is either newly emerging in Asia, endemic at low prevalence, or that some other ecological factor is preventing Bd from fully invading Asian amphibians. The current observed pattern in Asia differs from that in many other parts of the world.