James U. Van Dyke’s research while affiliated with La Trobe University and other places

Endocrine-disrupting contaminants (EDCs) are frequently monitored in environments because of their biological impacts on wildlife and humans. We conducted a systematic review using Web of Science to identify global research trends for EDC environmental sampling. Specifically, we aim to better understand geographic variation in (1) the compartment that EDCs were sampled in the environment; (2) the types of EDC sampled; and (3) the taxa that are sampled. A total of 9140 papers were found, of which 2554 were included in our review. The number of studies sampling EDCs varied between continents, with majority of research occurring in Europe, Asia, and North America. Although economy and access to technology will contribute to the number of articles published, we found the current output of research showed distinct disparities in sampling methods. Across all continents, water was the most frequently sampled compartment to determine EDC concentrations (sampled in 50–75% of studies). Wildlife was sampled far less often in studies across all continents, comprising 30% of studies at most. Pharmaceuticals were the most commonly studied chemical group, and fish were the most commonly sampled taxonomic group. Although far fewer studies sampled for EDCs in wildlife compared with abiotic compartments, these studies provide valuable information on the potential consequences of environmental EDC exposure and link environmental surveillance of EDCs with lab-measured organism-level effects. Studies that sampled only the water matrix for EDCs may be doing so as a proxy despite the large knowledge gaps on how environmental EDCs affect wildlife at varying concentrations. Supplementary Information The online version contains supplementary material available at 10.1007/s11356-025-36211-y.

Food availability determines the amount of energy animals can acquire and allocate to reproduction and other necessary functions. Female animals that are food limited thus experience reduced energy available for reproduction. When this occurs, females may reduce frequency of reproductive events or the number or size of offspring per reproductive bout. We assessed how maternal diet affects reproductive output in adult female Murray River short-necked turtles, Emydura macquarii, from four wetlands in Victoria. We previously found that turtle diets differ in the composition of plants and animals between our study wetlands. In this study, we tested whether differences in turtle diet composition (i.e. plants and animals) at these wetlands were associated with differences in clutch mass, individual egg mass, bulk egg composition and hatching success. We found total clutch mass increased with maternal body size at each site. At sites where filamentous green algae were scarce and E. macquarii were carnivorous, females produced smaller clutches relative to body size compared to females from sites where algae were abundant, and turtles were more herbivorous. Individual egg mass, bulk egg composition and hatching success did not differ across wetlands. Isotopic analysis revealed significant positive relationships between the carbon and nitrogen isotopes (δ13C, δ15N) of the eggs and those of the mothers, indicating that mothers allocated ratios of carbon and nitrogen isotopes to their eggs similar to those present in their tissues. Our study suggests that at sites where females are more carnivorous due to a relative absence of algae, females produce smaller clutches, but other aspects of their reproduction are not significantly impacted. The reduction in clutch size associated with differences in the availability of dietary plants and animals may have long-term consequences for E. macquarii and other freshwater turtle species that are experiencing population declines.

Australian freshwater turtle populations have declined substantially, with consequent losses to aquatic ecosystem functions. A leading hypothesis is that turtles have declined through lost recruitment caused by high nest predation by invasive foxes. The ‘fox hypothesis’ is supported by experiments showing that nest predation rates exceed 95% in many regions. Furthermore, population surveys have repeatedly found absences of juvenile turtles, and headstarting experiments have successfully replaced those juveniles in some species. We are currently leading a nationwide citizen science program, ‘1 Million Turtles’ (1millionturtles.com), to engage local communities to protect turtles from threats like nest predation using a suite of novel approaches. Our key innovation is to leverage community passion and interest for turtles to create positive conservation impacts via a nationwide support network. We provide a data collection tool and framework (TurtleSAT) and self-guided training in conservation methods. We assist with guidance for gaining licencing and permission, and applying for grants. We are evaluating our approach through both the impacts on turtle populations as well as through surveys of our engaged citizen scientists. Ultimately, we aim to create a science-supported, national grassroots conservation model where community champions can lead their own evidence-based approaches to help wildlife.

In brief Seahorses exhibit male pregnancy and are thus valuable comparative models for the study of the physiology and evolution of pregnancy. This study shows that protein is transported from fathers to developing embryos during gestation, and provides new knowledge about paternal contributions to embryonic development. Abstract Syngnathid embryos (seahorses, pipefishes and seadragons) develop on or in the male in a specialised brooding structure (brood pouch). Seahorse brood pouches supply nutrients, including lipids, to developing embryos (patrotrophy). We tested the hypothesis that proteins, vital for gene regulation and tissue growth during embryogenesis, are also transported from father to embryos, using the Australian pot-bellied seahorse, Hippocampus abdominalis. We used dry masses and total nitrogen content to estimate the total protein content of newly fertilised egg and neonate H. abdominalis . Neonates contained significantly greater protein mass than newly fertilised eggs. This result indicates that paternal protein transport to developing embryos occurs during H. abdominalis pregnancy. This study is the first to show paternal protein transport during pregnancy in seahorses, and furthers our understanding of paternal influence on embryonic development in male pregnant vertebrates.

Endocrine disrupting contaminants (EDCs) are frequently monitored in environments because of their biological impacts on wildlife and humans. We conducted a systematic review using Web of Science to identify global research trends in abiotic and biotic EDC environmental sampling. Specifically, we aim to better understand geographic variation in 1) the compartment that EDCs were sampled in the environment; 2) the types of EDC sampled; and 3) the taxa that are sampled. A total of 9,140 papers were found in our search, of which 2,554 were included in our review. The number of studies sampling environmental EDCs varied between continents, with the majority of research occurring in Europe, Asia, and North America. Across all continents, water was the most frequently sampled compartment to determine environmental EDC concentrations, and was sampled in 50–75% of studies across continents. Wildlife were sampled far less often in studies across all continents, and comprised of 30% of studies at most. Pharmaceuticals were the most-commonly studied chemical group, and fish were the most-commonly sampled taxonomic group. Although far fewer studies sampled for EDC’s in wildlife compared with abiotic compartments (i.e. water). These studies provide valuable information on the potential consequences of environmental EDC exposure and link environmental surveillance of EDCs with lab-measured organism-level effects. Studies that sampled only the water matrix for EDCs may be doing so as a proxy despite the large knowledge gaps on how environmental EDCs affect wildlife at varying concentrations.

Freshwater turtles are important consumers in Australian freshwater ecosystems. They serve as scavengers, nutrient regulators, and as food sources and Totems for Traditional Owners throughout Australia. Despite their importance, most Australian freshwater turtle species are declining. The impact of winter wetland drying on turtle populations remains unknown, and winter exposure of hibernating turtles may be an important additional source of mortality. We aimed to examine turtle responses to seasonal and episodic wetland drying in wetlands using acoustic telemetry and active trapping. Wetlands were chosen that spanned a range of hydrological connectivity to the adjacent Edward/Kolety‐Wakool River. We found that tagged Emydura macquarii typically exit wetlands disconnected from the adjacent permanent river prior to winter, and overwinter in the river. Female E. macquarii rapidly re‐entered ‘home’ wetlands (wetlands in which they were initially tagged) the following spring, whereas males tended to leave the study area, returning occasionally. Although we were not able to evaluate a winter drying event, one of the wetlands experienced partial summer drying. All three local turtle species ( E. macquarii , Chelodina expansa , C. longicollis ) exited the wetland long before winter drying would have become a potential threat. Our results suggest that turtles in this system may be protected from winter wetland drying because they move to the adjacent permanent river prior to winter. Spending the winter in the river channel reduces the risks of being trapped in a drying wetland as temperatures drop in winter.

The Australian freshwater turtle fauna is dominated by species in the family Chelidae. The extant fauna comprises a series of distinct lineages, each of considerable antiquity, relicts of a more extensive and perhaps diverse fauna that existed when wetter climes prevailed. Several phylogenetically distinctive species are restricted to single, often small, drainage basins, which presents challenges for their conservation. Specific threats include water resource development, which alters the magnitude, frequency, and timing of flows and converts lentic to lotic habitat via dams and weirs, fragmentation of habitat, sedimentation, nutrification, and a reduction in the frequency and extent of floodplain flooding. Drainage of wetlands and altered land use are of particular concern for some species that are now very restricted in range and critically endangered. The introduced European red fox is a devastatingly efficient predator of turtle nests and can have a major impact on recruitment. In the north, species such as the northern snake‐necked turtle are heavily depredated by feral pigs. Other invasive animals and aquatic weeds dramatically alter freshwater habitats, with consequential impacts on freshwater turtles. Novel pathogens such as viruses have brought at least one species to the brink of extinction. Species that routinely migrate across land are impacted by structural simplification of habitat, reduction in availability of terrestrial refugia, fencing (including conservation fencing), and in some areas, by high levels of road mortality. We report on the listing process and challenges for listing freshwater turtles under the Australian Environment Protection and Biodiversity Conservation Act, summarize the state of knowledge relevant to listing decisions, identify the key threatening processes impacting turtles, and identify key knowledge gaps that impede the setting of priorities. We also focus on how to best incorporate First Nations Knowledge into decisions on listing and discuss opportunities to engage Indigenous communities in on‐ground work to achieve conservation outcomes.

Australia's freshwater turtles have high endemicity and many are threatened by extinction. Following a symposium held at the 2022 conference of the Australian Society of Herpetologists, we summarized the current status of research and conservation for Australian freshwater turtles and identified opportunities for future research. Eight species (32%) of Australia's 25 native freshwater turtles are listed as threatened by Australia's Federal Government. Symposium discussions on the primary gaps in research identified the lack of baseline data to inform population modelling as a key deficiency. Knowledge of the most effective conservation actions, the effectiveness of attempts to aid population recovery, and whether these actions are required at all, remains lacking for many species. A heavy bias exists between some well‐studied species compared with others for which little or no information is published. Community science, engagement with First Nations people, advances in technology, and recognition of the importance of turtles are contributing to better knowledge.

Invasive mammalian predators are efficient at driving native animal declines. The red fox ( Vulpes vulpes ) kills millions of endemic reptiles in Australia each year. In areas of south‐eastern Australia, the eastern long‐necked turtle ( Chelodina longicollis ) and Murray River turtle ( Emydura macquarii ) have declined by more than 50%. High rates of nest predation by foxes limit the recruitment of young turtles in these populations, but previous methods of fox control have been ineffective at protecting turtle nests. Here, we tested the effectiveness of plastic mesh for protecting artificial turtle nests from predation by foxes, in the mid‐Murray catchment, Victoria. We also tested whether protecting a large number of artificial nests in a given area encourages foxes to give up foraging following predictions from giving‐up density theory. We made a series of plots, each containing 32 artificial turtle nests. In each plot, we covered a percentage (0%, 25%, 50%, 81% or 100%) of the nests with either 1 or 2 sheets of plastic mesh. We used remote cameras to photograph and identify any predator that attacked nests in the plots. The cameras also allowed us to estimate the amount of time a fox was visible on each plot, as a metric of how much effort foxes expended on protected nests. Nest survival rate was not increased by either 1 or 2 sheets of mesh, and increasing the number of protected nests on a plot did not reveal a giving‐up density (GUD) value for fox foraging behaviour. Our study demonstrates that plastic mesh is not effective for protecting artificial turtle nests from foxes in this region.

The source of embryonic nutrition for development varies across teleost fishes. A parentotrophy index (ratio of neonate: ovulated egg dry mass) is often used to determine provisioning strategy, but the methodologies used vary across studies. The variation in source and preservation of tissue, staging of embryos, and estimation approach impedes our ability to discern between methodological and biological differences in parentotrophy indices inter- and intra-specifically. The threshold value used to distinguish between lecithotrophy and parentotrophy (0.6–1) differs considerably across studies. The lack of a standardised approach in definition and application of parentotrophy indices has contributed to inconsistent classifications of provisioning strategy. Consistency in both methodology used to obtain a parentotrophy index, and in the classification of provisioning strategy using a threshold value are essential to reliably distinguish between provisioning strategies in teleosts. We discuss alternative methods for determining parentotrophy and suggest consistent standards for obtaining and interpreting parentotrophy indices.