Anthony A. Chariton

The current liability for decommissioning offshore oil and gas infrastructure in Australia is estimated to exceed US$ 31 billion over the next 50 years. This is founded on the base-case regulatory position of complete removal of all infrastructure, with over half the liability occurring in the next 10 years. Naturally occurring radioactive materials (NORM) are ubiquitous in oil and gas reservoirs worldwide and may form contamination products including scales and sludges in production infrastructure. Globally, assessment of the ecological impact of in-situ decommissioning typically fails to consider the long-term effects of exposure to potential contaminants contained within pipelines. There remain broad gaps in our understanding of NORM contaminants in the marine environment and how to effectively assess and measure the risk of NORM to marine organisms. This article discusses the application of a tiered assessment process to determine potential radioecological impacts of pipeline scale related to decommissioning practices using real-world NORM scale: (1) advanced nuclear and imaging techniques to characterise NORM-contaminated scale; (2) conducting radiological biota dose modelling using MicroShield and ERICA for different decommissioning scenarios; and (3) performing a series of marine infauna-exposure tests to understand the bioaccumulation and organ biodistribution of scale-associated constituents. This research provides a methodological approach that contributes valuable insights to inform infrastructure decommissioning planning. Several research gaps remain in our understanding of the fate of NORM contaminants in subsea oil and gas systems relative to decommissioning risk assessments including investigating radiobiological effects in marine organisms at elevated NORM levels and the establishment of a NORM inventory to better understand its characteristics and formation from different types of infrastructure.

Naturally occurring radioactive material (NORM) may be present in offshore petroleum infrastructure, raising concerns about potential ecological impacts to marine organisms if contaminated infrastructure is left on the seabed. This study used laboratory-based sediment microcosm exposures and whole-animal imaging from X-ray fluorescence microscopy (XFM) to investigate the bioaccumulation potential of NORM-contaminated barium sulfate (baryte) scale by benthic sediment infauna (amphipod, bivalve). Organisms were exposed to NORM-contaminated sediments for 7 d followed by either 1) depuration in clean seawater for two days or 2) depuration in uncontaminated marine sediments for 7 d followed by two days in clean seawater. Half of the organisms were assigned to the longer depuration period. NORM concentrations of radium, thorium, lead and polonium were significantly higher in scale-spiked sediments. Elevated whole-body concentrations of barium, copper and zinc concentrations, along with 210Po and 226Ra were observed in scale-exposed organisms. After the clean sediment depuration phase, baryte and 210Po were bioaccumulated by both organisms (i.e. translocated to other internal organs), while 226Ra was not. Experiment-specific parameters used in a post-exposure biota radiological dose assessment suggested negligible impacts on the tested species within international thresholds for radiological exposure. Our study provides insights into the complex interactions between NORM contaminants and benthic marine organisms, emphasising the need for further research on the biokinetics and biological effects of NORM.

Southern right whale ( Eubalaena australis ; SRW) populations are recovering from the impacts of commercial whaling, however, recovery has been spatially variable, with strong associations between reproduction and prey availability. The diet of SRWs has not been widely examined, and with SRW foraging shifting away from high‐latitude foraging grounds dominated by krill, it is essential to understand their diet at different locations. The gut microbiome is closely linked to diet, and characterising gut bacterial composition can help evaluate long‐term changes in prey and ecosystem dynamics. We used DNA metabarcoding to characterise the diet and faecal microbiome of SRWs from three calving/socialising grounds and a low‐latitude foraging ground. SRW feeding was more opportunistic than previously documented. Decapoda emerged as a key component of the SRW diet, being consistently detected at higher frequency and relative read abundance than euphausiids and copepods in whales from both calving/socialising and foraging grounds. The expected prey of Calanoida were also prominent in whales from the foraging ground, as were Stomatopoda, Cumacea and Semaeostomeae. A significant correlation between diet composition and faecal bacterial composition was observed, with euphausiids being the strongest predictor of bacterial variation. Our findings provide a new understanding of the breadth and diversity of the diet of SRWs. We also provide a baseline for monitoring diet–gut microbiome interactions. Collectively, these results offer a glimpse into the trophic dynamics of a Southern Ocean predator being impacted by climate‐driven changes in zooplankton distribution, with implications for long‐term population recovery.

Mammalian gut microbiomes are essential for supporting digestion, nutrient absorption and overall host health. While diet and phylogeny are the two main in

Since the 1970s, striking amphibian declines in population abundances and presumed extinctions have been recorded globally. The chytrid fungus Batrachochytrium dendrobatidis (Bd) is one of the key drivers of these declines. To investigate the potential role of Bd in the decline of Brazil's amphibians, we first used eDNA metabarcoding to survey for DNA traces of 10 threatened amphibian species from the Southern Brazilian Atlantic forest (SBAF). Using the eDNA samples of this survey, along with eDNA samples from previous surveys of 32 threatened amphibian species from the Northern Brazilian Atlantic forest (NBAF), we examined the relationships between the presence or absence of targeted amphibians with the presence or absence of Bd lineages. We detected DNA traces of two of the 10 targeted species in the survey of SBAF, including one species that was missing for over 40 years (Cycloramphus cedrensis). We also detected DNA traces of two Bd lineages (Bd‐GPL and Bd‐Brazil) at nine of the 12 sampling sites where community‐level amphibian declines were first reported in the late 1970s. Our results support a post‐panzootic scenario, where some threatened amphibian species are coping to persist in the presence of enzootic Bd. Our research also provides novel insights into simultaneous eDNA surveys targeting both hosts and pathogens, offering important methodological contributions to tropical ecology and conservation.

Australia's vast network of inland wetlands attracts thousands of waterbirds to congregate and breed during ‘boom’ periods of rainfall and productivity. Monitoring waterbird biodiversity predominantly relies on annual aerial and ground‐based surveys, which may miss rare or elusive species of conservation importance. Environmental DNA (eDNA) metabarcoding is being increasingly used as a tool for rapid biodiversity assessments across a wide range of ecosystems. Before eDNA can be routinely applied to new ecosystems, assays need to be optimised to address several challenges, including primer bias, reference database limitations, and data curation strategies. Here, we used an eDNA assay to detect avian species at four inland wetlands in south‐eastern Australia. We assessed the impact of filtering strategies on waterbird detection probabilities and compared results against historical observational survey records. Our eDNA assay identified up to 40% of waterbirds historically recorded at the sites. Waterbirds detected with eDNA included the elusive and endangered Australasian bittern, migratory species such as gull‐billed tern and whiskered tern, and an introduced feral goose not previously recorded. Community composition varied with filtering and detection approaches, highlighting the importance of assessing the impact of data curation on species detection with respect to historical species records. This study demonstrates the potential for eDNA to be incorporated into waterbird monitoring programmes. Future research should prioritise improving reference databases and optimising field sampling protocols for these ecosystems.

Fungi represent a significant portion of Earth's biological diversity and are essential for ecosystem functions like organic matter decomposition and nutrient cycling. While fungi associated with plant roots have been extensively studied, our understanding of fungi in the forest canopies remains limited. To investigate the landscape-scale variation in the canopy mycobiome of temperate beech and spruce forest stands in the Bavarian Forest National Park (Germany), we examined the influence of geophysical conditions and host traits. We found that elevation significantly influenced fungal diversity and composition, with distinct effects observed in both beech and spruce stands. Moreover, canopy water content, a key indicator of tree vitality, was also strongly associated with changes in the canopy fungi community, suggesting a potential link between forest water stress and the forest canopy mycobiome. Our differential abundance analysis further identified a total of 41 fungal families as potential bioindicators: 17 families in beech stands and 9 in spruce stands were significantly associated with elevation, while 9 families in beech stands and 6 in spruce stands were linked to variations in leaf water content. These findings enhance our understanding of the spatial patterns of forest canopy microbial biodiversity and species distributions.

Faecal metabarcoding is widely used for mammalian diet analysis. However, most extraction protocols are designed to target high molecular weight genomic DNA, making short sequences of digested DNA challenging to extract. Here, we evaluate prey DNA metrics in baleen whale scat from a phosphate buffer DNA extraction method along with two commercial extraction kits (the QIAamp Fast DNA Stool Mini Kit and the PowerSoil kit) with the following variations: 1) different durations of incubation in a phosphate buffer (1 hour and 24 hours), 2) processing of both pellet and supernatant from phosphate buffer incubation, and 3) two different concentrations of DNA binding buffer to examine prey DNA. We found that the choice of extraction protocol influenced richness, diversity and composition of eukaryotes (18S rDNA) and crustaceans (Crust16S mtDNA) detected in SRW faecal samples. The PowerSoil protocol performed well for both markers, delivering the highest target richness for 18S rDNA and highest diversity for Crust16S mtDNA, while the pellet of the phosphate buffer yielded the highest richness for Crust16S mtDNA. The phosphate buffer supernatant protocols produced the lowest results for richness and diversity. Taxonomic composition in the supernatant alone was influenced by the duration of incubation and the concentration of binding buffer and was also distinct from the corresponding pellet. Our results reinforce the importance of having clear targets prior to selecting a method for faecal metabarcoding, as the specific aims (e.g. identifying richness versus diversity) will inform the choice of extraction protocol.