Sixty percent of rivers in the Murray Darling Basin (MDB) are regulated by dams and weirs, exposing aquatic ectotherms to a variety of water quality challenges that impact their ecology, physiology and behaviour. Cold-water pollution (CWP) occurs when water from the deep, cold, bottom layer of large dams is directly released into the river. This cold-water release decreases downstream water temperature by as much as 15ºC and ‘pollutes’ river temperatures up to 200 km downstream. Peak release of CWP occurs during active turtle season (September to April), specifically when hatchlings are emerging from nests yet the effect of cold-water pollution on freshwater turtle development and behaviour remains unknown. Our research aimed to investigate the growth rates, basking activity and fitness of Emydura macquarii hatchlings exposed to increments of CWP, which represents thermal pollution across the MDB. Forty eggs were collected from gravid Emydura macquarii and upon hatching, were systematically allocated to one of four water treatments; 15ºC, 17ºC, 19ºC and 25ºC (reference temperature). Over a 126-study day period, fortnightly measurements revealed negligible growth in mass or size in the cold-water treatments, with minimal variation between treatments. Hatchlings in the cold treatments had a median mass of 4.85g (95% CI [4.56, 5.32]) which was significantly smaller than hatchlings from the reference temperature that grew over 100% larger with a median mass of 11.2g. Reduced growth of hatchlings in cold-water temperatures compromises body condition of hatchlings which is likely to reduce recruitment rates of populations in cold-water polluted reaches. Water managers should consider the timing of cold-water releases and installation of infrastructure such as bubblers and curtains in large dams to mitigate the effects on freshwater turtles.

This project sought to determine the importance of central Australian waterholes for the persistence of terrestrial wildlife in a warming world. In arid regions, long lasting waterbodies, often groundwater-fed, contribute to maintaining biodiversity and supporting ecological processes that extend far beyond their limited areal extent. Given the extreme seasonal and inter-annual climatic variability of the Australian arid zone, it was evident that decadal, or longer, records were needed to understand how species visiting waterholes persist and interact. When this project started, in 2014, motion sensitive cameras appeared to be the most suitable tool for long term faunal data collection at remote sites. Accordingly, Reconyx Hyperfire cameras were deployed at four small waterholes chosen to represent a range of water regimes from permanently wet (groundwater-fed) to usually dry (rainfall-fed). The sites were located within headwater streams in Watarrka National Park, within the MacDonnell Ranges Bioregion, NT. Now, as this project enters the eleventh year of continuous recording, it is evident that these cameras provide an enormous amount of information about the occurrence, condition and behaviour of many terrestrial vertebrate species, and some aerial invertebrate species. The role of these waterholes as ecological refuges during seasonally hot and dry times is now better understood. The impacts of both an intensive drought, and recent major floods, on animal assemblages, aquatic plants and waterhole condition, have also been documented. Where to next? The on-ground management of the project is now undertaken by NT Parks and Wildlife rangers to utilise the information on multiple aspects of the Park’s biodiversity, including the occurrence of an EPBC-listed species, the warru (black-footed rock wallaby) and feral species (cats and foxes). Planning is also underway to make the million plus accumulated images freely available to interested researchers in 2026, and to pilot test a 24/7 waterhole wildlife live-stream.

The use of stable isotopes to understand and conserve our natural world is routine and are used in enumerable studies on animals, plants and even people. Yet, stable isotopes are influenced by biological processes that can cause offsets between isotopic values in the organism and in the environment (i.e. fractionation). This means, that for some applications, like tracking animal movement, stable isotope values can be difficult to use. A striking advantage of radiogenic isotopes is that there are no isotopic offsets within biological systems and are thus prized for tracking the movement of terrestrial and freshwater species, as well as the origins of natural products. Yet, their use in marine systems is rare. Here we investigate a radiogenic isotope system that is little known to biology but has characteristics that makes it useful for marine biological applications, specifically, neodymium isotope ratios. Neodymium isotopes ratios are influenced by continental geology, as such, we analysed 143Nd/144Nd or ƐNd in 112 gastropod shells (abalone) collected from 11 geologically diverse sites in southern Australia. We found strong spatial differences in isotope ratios, which ranged from -18 ƐNd in the west of Australia to -4 ƐNd in the east. Such differences can be broadly linked to exposed continental rock age – a trend that was also apparent when comparing our data to published ƐNd data from northeast Asia. This study represents the largest analysis of Nd isotope ratios in modern biological material and provides insight into spatial trends and its robustness as a radiogenic marker. Our findings highlight the exciting potential of Nd isotopes as a tool for biologists to understand marine animal movement, and the origins of marine products.

While anthropogenic climate change poses widespread threats to aquatic ecosystems, research has disproportionately focused on warming and acidification, leaving salinity shifts, particularly hypersalinity, largely overlooked. Yet climate change actively drives hypersalinity through increased evaporation and reduced freshwater inflows, affecting aquatic fauna in ways that are poorly understood. To better understand the impacts of hypersalinity on aquatic fauna, we compiled data from 528 studies on 213 species, focusing on decapod crustaceans. Our synthesis shows that globally, only ~7% of aquatic climate change research investigates salinity changes; of these, just 14% focus on decapod crustaceans, and a mere 1% specifically examine hypersaline conditions (> 40 ppt). Despite limited attention, research in this area is gradually increasing, with studies primarily examining changes in haemolymph osmolality, muscle hydration, and metabolism. Key findings indicate that hypersalinity reduces decapod survival and growth, whilst also impairing reproduction. These declines in fitness are likely linked to energetic trade-offs due to the increased energetic demands of osmoregulation. Decapods exhibit varied physiological responses, with species-specific adjustments to haemolymph osmolality and muscle hydration. Metabolic adjustments include reduced food intake and diverse mobilisation of energy substrates (carbohydrates, lipids, proteins), sometimes shifting to anaerobic pathways. Enzyme activities, such as Na+K+-ATPase, and metabolic, antioxidant, immune, and digestive enzymes, also show species-dependent changes reflecting varied osmoregulatory and energy reallocation strategies. Transcriptomics further reveals comprehensive gene expression changes across these pathways. Knowledge gaps persist, particularly regarding long-term, sub-lethal impacts such as changes in food consumption and energy substrate utilisation. This synthesis underscores the urgent need for interdisciplinary research that integrates physiology and ecology to fully understand and predict the consequences of hypersalinity on decapod crustaceans in a rapidly changing climate.

The Rowley Shoals are globally renowned for the high levels of marine biodiversity they harbour. Located on the northern coast of Australia, these atolls have periodically been targeted for illegal fishing of sea cucumbers (trepang), which has significantly escalated in the Indo-Pacific in recent years. In this study, we highlight the significant decline in sea cucumber abundance observed at established monitoring sites from 2018 and 2023 for the three shoals: Clerke and Imperieuse (State marine parks) and Mermaid (Commonwealth nature reserve). We further describe the levels of illegal fishing (seized tonnes of catch) reported for the region over recent years, which likely contributed to the observed widespread decline. Species listed in the IUCN Red List of threatened species, including Holothuria whitmaei and Actinopyga miliaris, have severely declined across the Rowley Shoals, raising concerns about the long-term recovery potential of these populations. These findings inform management and reinforce the need to enforce protection of these biodiversity hotspots.