Past and future potential range changes in one of the last large vertebrates of the Australian continent, the emu Dromaius novaehollandiae

In Australia, significant shifts in species distribution have occurred with the loss of megafauna, changes in indigenous Australian fire regime and land-use changes with European settlement. The emu, one of the last megafaunal species in Australia, has likely undergone substantial distribution changes, particularly near the east coast of Australia where urbanisation is extensive and some populations have declined. We modelled emu distribution across the continental mainland and across the Great Dividing Range region (GDR) of eastern Australia, under historical, present and future climates. We predicted shifts in emu distribution using ensemble modelling, hindcasting and forecasting distribution from current emu occurrence data. Emus have expanded their range northward into central Australia over the 6000 years modelled here. Areas west of the GDR have become more suitable since the mid-Holocene, which was unsuitable then due to high precipitation seasonality. However, the east coast of Australia has become climatically sub-optimal and will remain so for at least 50 years. The north east of NSW encompasses the range of the only listed endangered population, which now occurs at the margins of optimal climatic conditions for emus. Being at the fringe of suitable climatic conditions may put this population at higher risk of further decline from non-climatic anthropogenic disturbances e.g. depredation by introduced foxes and pigs. The limited scientific knowledge about wild emu ecology and biology currently available limits our ability to quantify these risks

Developmental asynchrony might not reduce fitness in early life in painted turtles

Synchronous hatching and emergence of turtles from nests may be adaptive in predator avoidance during dispersal. However, little is known about the phenotypic consequences of such synchrony or the generality of predator avoidance in driving the evolution of this trait. Colbert et al. (2010) found that less advanced embryos hatched early in the presence of more advanced sibs, sustaining a persistent reduction in neuromuscular function. In this study, we experimentally assessed the influence of such accelerated embryonic development on hatching success, winter survival, and survival during terrestrial dispersal from the nest. Although we predicted that shortened incubation periods would reduce survival, early-hatching individuals suffered no detectable fitness costs at any stage considered in this study. Incubation temperature did not affect hatching success, and offspring sex did not affect survival across treatment groups. Incubation regime influenced offspring body size and was negatively correlated with dispersal time, however, there was no effect on survival during winter or terrestrial dispersal. Lack of a detectable fitness cost in these key early-life stages associated with hatching synchrony is consistent with a single, predator avoidance origin for this trait and retention in C. picta and other derived turtles via phylogenetic inertia

Changes in participant behaviour and attitudes are associated with knowledge and skills gained by using a turtle conservation citizen science app

1. Citizen science has become a popular way to collect biodiversity data and engage the wider public in scientific research. It has the potential to improve the knowledge and skills of participants, and positively change their behaviour and attitude towards the environment. Citizen science outcomes are particularly valuable for wildlife conservation, as they could help alleviate human impacts on the environment. 2. We used an online questionnaire to investigate the consequences of participating in an Australian turtle mapping app, TurtleSAT, on skills and knowledge gain, and test for any association between these gains and behavioural or attitudinal changes reported by the participants. 3. One hundred and forty-eight citizen scientists completed our questionnaire, mostly from the states of New South Wales and Victoria. TurtleSAT was the third most common source of correct answers about turtle ecology and conservation, after a talk about turtles and personal observations/research. Citizen scientists who participated more often were more knowledgeable about turtles than infrequent users. Self-reported gains in knowledge and skills were positively linked to attitudinal and behavioural changes, such as being more aware of turtles on roads. However, behaviour and attitude changes were not related to participation rate. Respondents also reported that after learning about the current decline in turtle populations, they adopted several turtle-friendly practices, such as habitat restoration or moving turtles out of harm's way, underlining the importance of increasing people's awareness on species declines. 4. The reported changes in attitudes and behaviours are likely to positively impact the conservation of Australian freshwater turtles. Engagement with citizen science projects like TurtleSAT may result in participants being more interested in the natural world, by learning more about it and being more exposed to it, and therefore contributing more actively to its protection

Scavenging by threatened turtles regulates freshwater ecosystem health during fish kills

Humans are increasing the frequency of fish kills by degrading freshwater ecosystems. Simultaneously, scavengers like freshwater turtles are declining globally, including in the Australian Murray–Darling Basin. Reduced scavenging may cause water quality problems impacting both ecosystems and humans. We used field and mesocosm experiments to test whether scavenging by turtles regulates water quality during simulated fish kills. In the field, we found that turtles were important scavengers of fish carrion. In mesocosms, turtles rapidly consumed carrion, and water quality in mesocosms with turtles returned to pre-fish kill levels faster than in turtle-free controls. Our experiments have important ecological implications, as they suggest that turtles are critical scavengers that regulate water quality in freshwater ecosystems. Recovery of turtle populations may be necessary to avoid the worsening of ecosystem health, particularly after fish kills, which would have devastating consequences for many freshwater species

Training young water professionals in leadership and transdisciplinary competencies for sustainable water management in India

Young water professionals (YWPs) have a critical role in ensuring how water resources will be managed to contribute towards the 2030 Agenda for Sustainable Development. To address the challenges of climate change, population growth, and urbanization, YWPs require leadership skills, transdisciplinary competencies, technical knowledge, and practical experience. This article presents the India YWP training program, led by Western Sydney University and the Australia India Water Centre (AIWC), aimed at developing a cohort of skilled YWPs and nurturing the next generation of water leaders in support of India’s water reform agenda and the National Water Mission. The program engaged 20 YWPs, consisting of an equal gender representation, selected by the Ministry of Jal Shakti from various water management agencies and departments across India. The 11-month training program was designed to be transformative and interactive, and it used an online platform comprising online lectures, mentoring, and project-based learning facilitated by the AIWC team. The training methodology focused on engaged learning, incorporating online workshops, Situation Understanding and Improvement Projects (SUIPs), online group discussions, and mentoring. The SUIPs provided a platform for YWPs to work in pairs, receiving guidance from AIWC members, enabling them to develop practical skills and knowledge in realworld contexts. The program effectively enhanced participants’ capacities in project planning, design, implementation, and management, while fostering critical thinking and problem-solving skills by adopting transdisciplinary approaches. Furthermore, participants demonstrated improved leadership, project management, time management, and communication skills. The training helped YWPs to equip them with a holistic perspective and stakeholder-focused mindset to address diverse water challenges from a holistic and long-term standpoint

Embryonic heart rate and hatching behavior of a solitary nesting turtle

Assessing environmental cues to coordinate birth or hatching has implications for both immediate and future survival. Predators may ultimately drive early or synchronous birth or hatching, because group formation allows neonate swamping of predators and reduces the impact of prey switching when large groups of neonates emerge from a nest. Turtles often emerge from the nest as a group, but temperature differences between the top and bottom of a nest are significant, making synchronous hatching difficult. The mechanisms of synchronous hatching in turtles are not consistent; with eggs hatching prematurely in one species, and another species displaying accelerated embryonic development, whereby embryos respond to the developmental rates of their siblings to hatch at similar developmental stages. If predation ultimately drives two disparate mechanisms of synchronous hatching, the physiological mechanisms behind synchronous, or early hatching, may be less developed in solitary nesting species, or species with smaller clutch sizes. I tested the hatching behavior of the Australian turtle, Chelodina longicollis, which has small clutch sizes and nests in isolation up to 1km from water. I established developmental asynchrony within a clutch and used time to pipping to determine whether early or delayed hatching occurred. I also assessed heart rates throughout incubation to monitor changes in development. Synchronous or early hatching did not occur in C. longicollis and embryos did not adjust their rates of development in response to more or less advanced sibs within a clutch. Thus, environmental cues that are related to sibling developmental rates and hatching and which influence hatching times in other species do not affect embryonic development in C. longicollis. These results support the group formation theory for synchronous or early hatching in species that nest at communal areas, or species with large clutch sizes

How much long-term data are required to effectively manage a wide-spread freshwater turtle?

Freshwater turtle populations are globally threatened by many factors. Complicating matters, their longevity requires long-term monitoring on the scale of decades to assess changes in population size, yet few long-term studies exist. Documenting population estimates and trends is essential for identifying and conserving imperilled populations, however, the impacts of many current threats may render populations endangered well before declines become apparent. By that stage, population recovery may not be possible, thus assessing population level impacts of potential threats may provide a direct measure of risks of population extinction. Australian turtles face major threats of mortality from invasive species, vehicles, disease and declining water quality. Even Australia's most abundant and widespread species has declined by up to 91% in some populations. Here I use population models to assess the impacts of threats to multiple life history stages of an Australia turtle. This study clearly demonstrates that Chelodina longicollis, Australia's most widespread turtle (1) is resilient to high levels of nest predation for sustained periods, (2) requires only periodic levels of reduced nest predation and pulse recruitment to maintain population viability and (3) low levels of adult mortality can drive populations to extinction. Turtle populations require pulse recruitment (i.e. nest predation rates declining to <35% every ten years) and monitoring of nest predation rates for 5–6 years to determine whether nest predation level profiles are extreme. However, if terrestrial mortality of adult turtles occurs, then the risk of extinction is high regardless of nest predation levels. Monitoring protocols to assess nest predation and adult mortality rates are not widely developed for freshwater turtles and here I develop a management plan that employs Citizen Science and standardised on-ground protocols to assess levels of threats at the population level. Standardised protocols and involvement of the public and community groups creates a network for broad-scale assessment and management of a species. Although threats can be identified and easily quantified and long-term data has demonstrated the extent of the decline of freshwater turtle populations in southern Australia, solutions to minimise risks of extinction need to be developed and fast-tracked before turtles throughout Australia become critically endangered

Influence of habitat and predation on population dynamics of the freshwater turtle Myuchelys georgesi

Demographic models identify whether animals are vulnerable to local extirpation, but including all ecological parameters across life history stages may be impeded by practical difficulties. When processes acting on certain life stages cannot be measured, extrapolations are often made. A previous study documented that the range of the turtle Myuchelys georgesi is restricted to the Bellinger River, New South Wales, Australia, and its population is stable. We assessed whether M. georgesi selects certain habitats by comparing their distribution among different water holes. We assessed the threat of catfish predation by examining the stomach contents of catfish specimens. We then evaluated whether threats to M. georgesi were likely to have been underestimated by extending our previous demographic model. We did this by revising the previous estimates of adult, juvenile, and hatchling survivorship under hypothetical variations in water hole use and in the presence or absence of catfish predators. We found that M. georgesi preferentially uses moderate to deep water holes. We also found that although catfish 250-400 mm consume hatchling or juvenile turtles, those > 400 mm do to a greater extent. By making observations of catfish in the Bellinger River and incorporating their presence into our model, we found catfish presence to influence juvenile, but not adult, water hole use. Our reassessment of ? suggests that it may have been previously underestimated and that the threat to M. georgesi may be greater than we thought as the population is sensitive to variations in water hole depth and exposure of juveniles to predators. Events that alter key habitats and expose turtles to fish predators across the river should, accordingly, be evaluated further so they can be accounted for when managing the river

Demographic consequences of adaptive growth and the ramifications for conservation of long-lived organisms

Understanding how organisms respond to human impacts is increasingly challenging biologists. Shortlived organisms can adapt rapidly to changes in environmental hazards, but only recently have long-lived organisms been shown to adapt to human impacts. Changes in any life-history trait, such as individual growth rates, may affect demographic model predictions and reliability of elasticity analyses that are often used to help manage and conserve long-lived organisms. The aim of this study was to test model predictions of the effect of increased recruitment and density-dependent processes to manage populations of long-lived turtles in two continents. We explored how human-induced changes in juvenile density affect population growth estimates and the strength of selection on stage-based life-history traits. Model projections undervalued the potential effect of an increase in nest survival. Sensitivity calculations indicated greatest selection intensities for juvenile growth or maturation, whereas elasticity analyses indicated that changes in adult survival have the largest proportional effect on population fitness. Long-term use of the locality of our North American population as a recreational site may have increased adult mortality of turtles and reduced the number of nest predators, inducing rapid individual growth and early maturation. The traditional static view of turtle life history and demography thus is inappropriate even over relatively short periods of time. Anthropogenically-induced changes in demographic processes can potentially induce adaptive changes to life-history processes, which can seriously impact the reliability of long-term projections from common demographic models. Management practices must account for this dynamism accordingly

A novel hypothesis for the adaptive maintenance of environmental sex determination in a turtle

Temperature-dependent sex determination (TSD) is widespread in reptiles, yet its adaptive significance and mechanisms for its maintenance remain obscure and controversial. Comparative analyses identify an ancient origin of TSD in turtles, crocodiles and tuatara, suggesting that this trait should be advantageous in order to persist. Based on this assumption, researchers primarily, and with minimal success, have employed a model to examine sex-specific variation in hatchling phenotypes and fitness generated by different incubation conditions. The unwavering focus on different incubation conditions may be misplaced at least in the many turtle species in which hatchlings overwinter in the natal nest. If overwintering temperatures differentially affect fitness of male and female hatchlings, TSD might be maintained adaptively by enabling embryos to develop as the sex best suited to those overwintering conditions. We test this novel hypothesis using the painted turtle (Chrysemys picta), a species with TSD in which eggs hatch in late summer and hatchlings remain within nests until the following spring. We used a split-clutch design to expose field-incubated hatchlings to warm and cool overwintering (autumn-winter-spring) regimes in the laboratory and measured metabolic rates, energy use, body size and mortality of male and female hatchlings. While overall mortality rates were low, males exposed to warmer overwintering regimes had significantly higher metabolic rates and used more residual yolk than females, whereas the reverse occurred in the cool temperature regime. Hatchlings from mixed-sex nests exhibited similar sex-specific trends and, crucially, they were less energy efficient and grew less than same-sex hatchlings that originated from single-sex clutches. Such sex- and incubation-specific physiological adaptation to winter temperatures may enhance fitness and even extend the northern range of many species that overwinter terrestrially