ORCID Profile
0000-0002-8195-6519
Current Organisation
Territory Natural Resource Management
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Oxford University Press (OUP)
Date: 2021
Abstract: Drier and hotter conditions caused by climate change threaten species that exist close to their physiological limits, as well as those with limited ability to move. Habitat specialists may also be particularly vulnerable if they have specific abiotic requirements. Here we assess whether thermal and hydric constraints can explain the highly restricted and declining distributions of the critically endangered terrestrial-breeding frog, Geocrinia alba. We also evaluate the species’ vulnerability to climate change based on the similarity of current microclimatic conditions to their physiological limits. We found that G. alba had low thresholds of thermal and desiccation tolerance relative to other anuran species. The estimated thermal optimum (Topt) and critical thermal maxima (CTmax) were 23.3°C and 29.6°C, respectively, and adult frogs had an absorption threshold (AT, the lowest water potential at which water can be absorbed from a substrate) of −50 kPa, the lowest recorded for an hibian. Comparing environmental conditions and water loss in the field using agar models showed that riparian habitats where frogs occur provide a unique microclimate in the landscape, offering significantly lower desiccation risk during extreme summer conditions compared to immediately adjacent riparian and terrestrial habitats. Monitoring of microclimate conditions within occupied frog habitats over 2 years showed that in extreme dry and hot years the AT was exceeded at six of eight sites, and Topt was exceeded at two of eight sites. Given their specific physiological limits, the apparent rarity of suitable microclimates and a regional drying–warming trend, we suggest that G. alba occupies a potentially disappearing niche and may be indicative of other habitat specialists that rely on ephemeral drainages. More broadly, this study highlights that desiccation thresholds may tightly constrain hibian distributions and need to be considered along with thermal tolerance thresholds when predicting the impacts of climate change.
Publisher: Wiley
Date: 23-10-2022
DOI: 10.1111/AEC.13122
Abstract: Amphibian breeding is often linked to environmental cues. Given accelerating global climate change and habitat alteration, it is important to understand how environmental changes may affect male calling activity, the necessary precursor to mating. Here, we investigate the calling phenology and activity of Geocrinia alba , a critically endangered terrestrial‐breeding frog with a highly restricted distribution in southwestern Australia – a region undergoing significant warming and drying. We investigated whether calling periods differed across eight sites during a single breeding season, and the environmental conditions associated with calling activity at the start, peak and end of the calling period. We found consistent and prolonged calling activity over several months of the austral spring, but the length of the calling period varied two‐fold across sites, ranging from 3 to 6 months. Initiation of calling by G . alba was relatively similar across sites and was associated with warmer temperatures and higher soil water potential. However, the end of the calling period varied from October to January and was significantly associated with decreasing soil water potential. Calling only occurred when soils were close to saturation point, between −8 to −11 kPa, and therefore, breeding opportunities were likely also constrained by the length of time that soils were close to saturation. Changes in the regional climate, such as declining winter rainfall, could result in shorter breeding periods and consequently reduced breeding opportunities. More broadly, our study highlights the sensitivity of hibians, particularly terrestrial‐breeding species, to changes in soil water potential and temperature, and the importance of maintaining suitable hydrological conditions during the breeding period.
Publisher: Wiley
Date: 05-2022
DOI: 10.1111/EMR.12554
Abstract: The intentional movement of species outside their indigenous range – assisted colonisation – is an emerging tool in conservation. Here, we outline the process developed to identify and assess candidate sites for assisted colonisation of the critically endangered Northern Corroboree Frog ( Pseudophryne pengilleyi ), a range‐restricted species highly threatened by chytrid fungus. We first investigated the mechanisms associated with the persistence of Northern Corroboree Frog populations with chytrid fungus and then used a combination of desktop and field surveys to identify and assess sites based on habitat suitability, capacity to allow coexistence with chytrid fungus and hydrological properties. Candidate sites were further assessed by comparing environmental and climatic conditions to historical and persisting sites. Together, these methods allowed us to identify a site that appears to be highly suitable for the species. The process outlined here provides a template for assessing assisted colonisation sites for species where ongoing threats rule out recipient sites within their indigenous range.
Publisher: Springer Science and Business Media LLC
Date: 09-10-2018
Publisher: CSIRO Publishing
Date: 20-08-2021
DOI: 10.1071/PC21019
Abstract: More than a third of the world’s hibian species are listed as Threatened or Extinct, with a recent assessment identifying 45 Australian frogs (18.4% of the currently recognised species) as ‘Threatened’ based on IUCN criteria. We applied structured expert elicitation to 26 frogs assessed as Critically Endangered and Endangered to estimate their probability of extinction by 2040. We also investigated whether participant experience (measured as a self-assigned categorical score, i.e. ‘expert’ or ‘non-expert’) influenced the estimates. Collation and analysis of participant opinion indicated that eight species are at high risk ( % chance) of becoming extinct by 2040, with the disease chytridiomycosis identified as the primary threat. A further five species are at moderate–high risk (30–50% chance), primarily due to climate change. Fourteen of the 26 frog species are endemic to Queensland, with many species restricted to small geographic ranges that are susceptible to stochastic events (e.g. a severe heatwave or a large bushfire). Experts were more likely to rate extinction probability higher for poorly known species (those with experts), while non-experts were more likely to rate extinction probability higher for better-known species. However, scores converged following discussion, indicating that there was greater consensus in the estimates of extinction probability. Increased resourcing and management intervention are urgently needed to avert future extinctions of Australia’s frogs. Key priorities include developing and supporting captive management and establishing or extending in-situ population refuges to alleviate the impacts of disease and climate change.
Publisher: Elsevier BV
Date: 04-2012
DOI: 10.1016/J.WATRES.2011.12.016
Abstract: Climate change scenarios predict that rivers, lakes, and reservoirs will experience increased temperatures, more intense and longer periods of thermal stratification, modified hydrology, and altered nutrient loading. These environmental drivers will have substantial effects on freshwater phytoplankton species composition and biomass, potentially favouring cyanobacteria over other phytoplankton. In this Review, we examine how several cyanobacterial eco-physiological traits, specifically, the ability to grow in warmer temperatures buoyancy high affinity for, and ability to store, phosphorus nitrogen-fixation akinete production and efficient light harvesting, vary amongst cyanobacteria genera and may enable them to dominate in future climate scenarios. We predict that spatial variation in climate change will interact with physiological variation in cyanobacteria to create differences in the dominant cyanobacterial taxa among regions. Finally, we suggest that physiological traits specific to different cyanobacterial taxa may favour certain taxa over others in different regions, but overall, cyanobacteria as a group are likely to increase in most regions in the future.
Publisher: Springer Science and Business Media LLC
Date: 27-10-2021
DOI: 10.1007/S10531-020-02064-9
Abstract: Defining species habitat requirements is essential for effective conservation management through revealing agents of population decline and identifying critical habitat for conservation actions, such as translocations. Here we studied the habitat-associations of two threatened terrestrial-breeding frog species from southwestern Australia, Geocrinia alba and Geocrinia vitellina , to investigate if fine-scale habitat variables explain why populations occur in discrete patches, why G. alba is declining, and why translocation attempts have had mixed outcomes. We compared habitat variables at sites where the species are present, to variables at immediately adjacent sites where frogs are absent, and at sites where G. alba is locally extinct. Dry season soil moisture was the most important predictor of frog abundance for both species, and explained why G. alba had become extinct from some areas. Sites where G. alba were present were also positively associated with moss cover, and negatively with bare ground and soil conductivity. Modelling frog abundance based exclusively on dry season soil moisture predicted recent translocation successes with high accuracy. Hence, considering dry season soil moisture when selecting future translocation sites should increase the probability of population establishment. We propose that a regional drying trend is the most likely cause for G. alba declines and that both species are at risk of further habitat and range contraction due to further projected regional declines in rainfall and groundwater levels. More broadly, our study highlights that conservation areas in drying climates may not provide adequate protection and may require interventions to preserve critical habitat.
Publisher: Springer Science and Business Media LLC
Date: 11-11-2020
Location: Australia
Location: Australia
No related grants have been discovered for Emily Hoffmann.