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2025 Publications (links to each paper available at read more)

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Image: An Australian sea lion on the beach at the Seal Bay Conservation Park on Kangaroo Island, South Australia. Source – Peterdownunder – Creative Commons Attribution-Share Alike 3.0

The influence of Australian sea lion foraging on benthic assemblages in temperate marine ecosystems

Corrales-Guerrero, J, S Goldsworthy; B Kelaher; M Coleman; D Miller; SD Connell; W Figueira; BM Gillanders. 2025. ICES Journal of Marine Science 92, fsaf164

Robust and thriving populations of marine predators are widely recognized as being essential to enhancing trophic complexity, structure, and biodiversity. While some pinniped populations have shown signs of recovery, many others, including Australian sea lions (Neophoca cinerea), remain at low levels or continue to decline. There is a limited understanding of the relationship between feeding habitat preferences, food web dynamics, and benthic community structure. We examined how foraging density of the endangered Australian sea lion relates to fish and invertebrate assemblage structure. We also assessed how several biophysical conditions influence these patterns across multiple South Australian coastal sites. Our methods revealed positive associations between sea lion foraging density and the abundance of their benthic prey. Depth was the primary factor explaining the variability in foraging density, followed by primary productivity (Chl a). Habitat use appears driven by prey patch characteristics, including depth, productivity, and substrate, suggesting specialized foraging strategies. Our results suggest that sea lion densities are associated with areas of elevated prey availability and local species richness, though it remains unclear whether predators influence community structure or simply select more biodiverse habitats. Long-term monitoring of sea lions and their prey in and around coexisting habitats will help to disentangle trophic interactions linked with sea lion population recovery. Further research is needed to better understand the critical habitats and trophic ecology of sea lions, and their impact on community structure in different habitats. Understanding sea lion foraging ecology and its role in structuring benthic ecosystems can enhance conservation planning by integrating predator–prey dynamics into marine management frameworks.

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Pharmaceuticals, pesticides and PFAS: Quantifying endocrine disrupting compounds in plastics and fish tissues using solvent extraction and LC-MS/MS

Dolling, S, P Reis-Santos, M Williams, BM Gillanders. 2025. Journal of Separation Science 48: e70084.

The rise of plastic pollution in marine environments has been heavily documented, with particular focus on the physical impacts the plastics can have on biota. But, plastics also sorb a range of hydrophobic chemical pollutants, acting as vectors for the transportation of these compounds throughout marine environments. Therefore, an analytical method that can target both marine biota and plastic matrices will be key to advance our understanding of the link between chemicals in the environment, plastic pollution, and effects on biota. Here, an efficient method for the detection and quantification of a broad suite of compounds in marine samples was developed. Five extraction methods were trialed for the analysis of 21 pesticides, PFAS, and pharmaceuticals in biota and plastics. This included three ultrasonic extraction methods and two QuEChERS methods. Ultrasonic extraction in acetonitrile with a microcentrifuge step then concentration by Bond Elut Carbon SPE resulted in best recovery across most compounds. Of the 21 compounds trialed, 16 were efficiently quantified. Method limits of quantification and detection were between 0.02 and 4.81 ppb (mLODs) and between 0.06 and 14.60 ppb (mLOQs). This method is widely applicable to a range of marine environments and supports routine evaluations of environmental safety and monitoring protocols.

Image: From cover of the Journal of Separation Science 2/2025.

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Growth plasticity linked to partial migration in Atlantic halibut

Gauthier, C, P Reis-Santos, BM Gillanders, JAD Fisher, D Robert, P Sirois. 2025. ICES Journal of Marine Sciences 82: fsaf132.

Partial migration is a common strategy in marine fishes, enhancing resilience through diversified movement patterns that buffer the effects of environmental changes. A key ecological outcome of migration behaviour is growth variability, which provides insights into the adaptive value of different migratory strategies. Using otolith back-calculation, we investigated how growth patterns of Atlantic halibut (Hippoglossus hippoglossus) in the Gulf St. Lawrence (Canada) varied among resident and migratory individuals whose migration histories were determined previously via otolith chemistry. Von Bertalanffy growth models fitted with nonlinear mixed-effects models revealed that migrants exhibited faster growth rates and greater theoretical maximum lengths compared to residents of both sexes, with significant differences in length-at-age emerging from the age of six. However, both contingents showed good condition, with no differences in relative condition. Overall, growth differences likely reflect the benefits of warmer temperatures and increased prey abundance or quality in shallow summer habitats for migrants, contrasted with potential increased competition in denser halibut populations in deeper channels. Overall, this observed difference in growth suggests that increased habitat quality in shallow areas can overcompensate for energy costs associated with an annual migration, which can exceed 1000 km. The complex growth dynamics between migratory and resident contingents highlight the challenges of managing species with partial migration, where specific components may disproportionately contribute to stock biomass, particularly in the context of changing environmental conditions.

Image: Graphical abstract from paper.

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Image: Graphical abstract from paper.

Examining misconceptions about plastic-particle exposure from ingestion of seafood and risk to human health

Henry, TB., DG Bucknall, AI Catarino, BM Gillanders, M Haave, NE Kaminski, C Volker, N Wootton. 2025. Environmental Science & Technology Letters 12, 1453-1461..

Plastic particles (PPs; ≤5 mm diameter) are ubiquitous environmental contaminants, and concerns exist about their potential to impact human health negatively. Public perceptions about seafood contamination by PPs have been shaped by media communications rather than scientific evidence, and these perceptions can inform behavior and public policy inappropriately. Our objective is to challenge perceptions with evidence and to discuss the extent to which concerns of PP contamination of seafoods are justified. Evidence indicates that levels of PPs in seafoods are consistent with those of other foods and beverages and that human exposure to PPs is higher via indoor air and dust than by ingestion of foods and beverages. While uncertainties remain, there is currently minimal evidence of dietary toxicity of PPs and no consumption advisories for PPs. The levels of substances (e.g., toxic contaminants) associated with PPs that may be released upon PP ingestion are often orders of magnitude below levels of toxicological concern. Overattention on PP contamination of seafoods (>70% compared to all other foods combined) in scientific media communications is unjustified and must be rebalanced to avoid misconceptions and loss of beneficial health effects of seafood consumption.

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Image: Figure from paper.

Stories of Country: Representing Indigenous cultural values in environmental economic accounting

Hill, C, M Nursey-Bray, D Mundraby, D Mundraby, N Wootton. 2026. Marine Policy, 185, 10 pages.

Environmental economic accounting frameworks are increasingly vital for valuing ecosystems like blue carbon coastal wetlands and informing their restoration and management. However, existing frameworks often struggle to represent the holistic and interconnected cultural values held by Indigenous peoples. The reductionist approach of categorisation can obscure critical links and underestimate restoration benefits. This paper presents a method for identifying, mapping, and analysing Indigenous cultural values and their interconnections, demonstrated through a co-designed case study on Mandingalbay Yidinji Country in Far North Queensland, focusing on a twenty-year coastal wetland restoration project. Data were collected from interviews, workshops, site visits, and desktop sources, coded into pre-agreed cultural value domains, triangulated across sources, and validated with community leaders. Our findings, once synthesised, were then presented in the form of stories and relayed as a culturally appropriate way to communicate these findings. Our analysis revealed that cultural values were highly interconnected, with stories linking aspects of identity, stewardship, and wellbeing. To better capture these values, we suggest including “Wellbeing services” and “Stewardship services” as additional categories to the System of Environmental Economic Accounting (SEEA) framework. We also demonstrate how assessing the increase in connectivity between cultural values offers a metric for representing the relational impact of restoration. The documentation and analysis of cultural data and then dissemination of results via stories, enriches environmental accounts, and better accommodate diverse Indigenous worldviews, providing richer insights for policy and management of vital coastal ecosystems globally.

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Image by jacopo cavalca from Pixabay

Hydropower effluent as a marine pollutant: impacts of river regulation on estuarine and coastal ecology

Lennox, RJ., J Grimsrud, SH Eldoy, BM Gillanders, U Pulg, K Thiemer, WM Twardek, AJA Sergio, O Varpe, G Velle, KW Vollset. 2025. River Research and Applications 41: 1789-1802..

The confluence of rivers with the ocean creates biological hotspots where temperature, salinity, and nutrients mix to provide excellent conditions for rearing, growth, and refuge to a multitude of organisms. Worldwide, estuaries are highly productive and biodiverse. However, estuaries are also highly degraded by development and pollution due to human settlement and exploitation of waterways. As global energy systems transition to renewable energy sources, rivers are increasingly stressed by regulation to produce power. Effluent water flowing from rivers is channeled through the river and eventually reaches the ocean, meaning that power production can dramatically alter the dynamics of freshwater input at estuaries, including marked changes in the annual cycle of discharge. Despite much research focusing on understanding and mitigating the impacts of hydropower production on river ecosystems, less research has been conducted to understand how alterations to the flow regime affect marine ecosystems where the water is discharged. We address the status of knowledge at the interface of freshwater and marine ecosystems and highlight research priorities to better understand how sensitive estuarine and coastal habitats are affected by thermal, osmotic, and physical changes caused by hydropower production in rivers.

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Image: Graphical abstract from paper.

Transnational shark trade: personal baggage and postal seizures in Australia and New Zealand

Lingard, J, P Reis-Santos, P Cassey, BM Gillanders. 2025. Pacific Conservation Biology 31: PC25006.

Context – Sharks (Chondrichthyes) are declining globally with over one third of species threatened with extinction, largely due to anthropogenic threats including overfishing driven by the international trade of products such as fin and meat.

 

Aims – We used border seizure data from Australia and Aotearoa/New Zealand (from passenger flights and unaccompanied mail) to investigate where shark products originated from and whether there were country-specific differences in the products traded through time.

 

Methods – Seizure data were collated from biosecurity and government agencies to investigate the contribution of Australia and Aotearoa/New Zealand to global shark trade.

 

Key results – In Australia, shark products were more likely to originate from Asia and the total number of seized products decreased over time. In Aotearoa/New Zealand, Australia was the top originating country. Both countries showed clear reductions in seizures in 2020–2021 when border closures were enforced due to COVID-19. Trophy items, such as preserved specimens, were more likely to originate from the USA while fin products originated from Hong Kong and China. Less than 1% of seizures from both countries contained species-specific information, with 14 of the 18 species seized listed on CITES Appendix II.

 

Conclusions – International trade of shark products for personal use in Australia and Aotearoa/New Zealand was evident, with Australia a potential source and gateway for these products, raising concerns around the trade of endangered species.

 

Implications – Improving recorded species information is essential to enhance monitoring and support regulations on the trade of sharks and endangered species.

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Image from the paper

A non-linear statistical framework to investigate changes in life history patterns within and among fish populations

Ng, CZW, P Reis-Santos, JG Gonzalez, BM Gillanders, MF Saleh, JJL Ong. 2025. Reviews in Fish Biology and Fisheries 35: 2065-2080.

Understanding movement patterns is crucial for predicting species responses to environmental change. However, in aquatic environments, the lack of long-term movement data constrains our ability to interpret how species adapt to changing conditions. Fish otoliths provide insights into individual life-history strategies via time-resolved chemical signatures but disentangling interactions between physiological and environmental processes remain challenging. Current analytical approaches often categorise life-history profiles into qualitative groups, based on sampling regions or years, overlooking intra-annual variation and simplifying data to group-level means. This study introduces a non-linear statistical framework using Generalised Additive Mixed Models (GAMMs) to explore how otolith element concentrations (Mg:Ca, Sr:Ca, Ba:Ca) vary with demographic variables (Age, Region) and temporal effects in a tropical snapper and illustrates its application on Lutjanus malabaricus across the Indo-Pacific region. Our findings revealed significant, non-linear changes in otolith Sr:Ca, reflecting shared and region-specific age patterns, suggesting that despite geographic separation, phylogenetic processes affecting Sr regulation remained consistent between regions. In contrast, distinct region-specific age differences in Ba:Ca and Mg:Ca highlight the influence of environmental and/or physiological processes on otolith chemistry. Incorporating random effects refined our analysis by accounting for temporal dependencies and individual-specific age patterns. Overall, this non-linear framework provides a powerful approach to unravelling the complex life-history and movement strategies in fish populations, providing critical insights into their adaptive responses to changing environments. Beyond otoliths, this framework can be applied to analyse continuous, time-resolved chemical data from accretionary structures across aquatic taxa, capitalising on the diverse ecological information archived across the natural world.

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Image: Graphical abstract from the paper.

Investigation of shell banding in an arcid cockle alongside trace-element concentrations to evaluate potential suitability for age estimation

Reis-Santos, P, RA Van Eck, C Gauthier, JB Widdrington, RC Chick, BM Gillanders, MD Taylor. 2025. Fisheries Research 291, 107522.

Arcid clams or cockles (Arcidae) are widespread sediment-associated bivalves that support commercial, recreational and cultural fisheries. Despite their importance, ageing in these species has received little attention, constraining stock assessment to length-based models and data limited approaches. In this context, sclerochronology (growth increments) and sclerochemistry (chemical proxies) offer valuable tools for population analysis and environmental reconstructions. Here, we investigated shell banding in Sydney Cockle (Anadara trapezia) alongside shell chemistry to assess the potential suitability for ageing. Specifically, we examined whether variation in Mg:Ca and Sr:Ca was associated with shell bands, as a means of validating seasonal growth increments. Banding patterns correlated closely with seasonal variation in shell chemistry, and application of innovative peak detection algorithms (spline quantile regression, and split moving window analysis) to chemical data improved the objectivity of increment identification, particularly for Mg:Ca and in larger, older shells. Overall, the results indicated that dark shell bands in Sydney Cockle are most likely annuli, and are likely to be appropriate for determining age composition and growth in the species. By enhancing objectivity and consistency, particularly for Mg:Ca, our integrated approach supports more robust age and growth assessments. The protocol developed for ageing and chemical analysis is relevant for ageing other arcid cockle species, but further validation work will improve confidence in ageing data using this approach.

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Image: Whale Shark (Rhincodon typus) in the Maldives.

This image was originally posted to iNaturalist by jeanpaulboerekamps at https://www.inaturalist.org/photos/420227933. It was reviewed on 1 March 2025 by INaturalistReviewBot and found to be published under the terms of the Cc-zero license.

Insights into the population demographics and residency patterns of photo-identified whale sharks Rhincodon typus in the Bird’s Head seascape, Indonesia

Setyawan, E., AW Hasan, Y Malaiholo, AB Sianipar, R Mambrasar, M Meekan, BM Gillanders, B D’Antonio, MH Putra, MV Erdmann. 2025. Frontiers in Marine Science 12, 1607027.

The whale shark (Rhincodon typus) is an iconic species in the Bird’s Head Seascape (BHS) in eastern Indonesia, yet little is known about its population and residency patterns across the region. This study documents the population demographics of this globally Endangered species from four key regions within the BHS: Cenderawasih Bay (CB), Kaimana (KA), Raja Ampat, and Fakfak. Using 13 years of photographic identification (photo-ID) data sourced from researchers and citizen scientists, we aim to provide a better understanding of population dynamics, residency patterns, and threats to the species. From September 2010 to October 2023, a total of 1,118 sightings of 268 different individuals were recorded, almost exclusively around lift-net fishing platforms (bagans). The population was strongly male-biased (8.8:1.0), with estimated total lengths ranging from 2 to 8 m, and most individuals in the 4–5 m size class, indicating a dominance of juvenile males. Over half (52.6%) of the individuals were re-sighted at least once, with one re-sighting span lasting 10.63 years. Most sightings (97.8%) were concentrated in CB (551 sightings, 159 individuals) and KA (542 sightings, 95 individuals). Only two individuals were seen in multiple regions, suggesting limited movement and potential habitat segregation. Lagged Identification Rates showed substantially higher residency in CB (77.1 days ± 34.4 SE) than in KA (37.8 days ± 9.7 SE). Scarring was recorded in 76.9% of individuals, with minor abrasions (47.4%) and fin nicks (39.9%) being the most common, followed by amputations (15.3%) and lacerations (14.2%). Only 2.4% of scars were likely inflicted by boat propellers, and only 3.4% of injuries were recorded as bites by predators. KA had a higher proportion of scarred sharks (83.7%) compared to CB (73.7%). The long-term presence and high re-sighting rates of juvenile whale sharks in CB and KA highlight their importance as key habitats within the BHS. While most sightings of whale sharks in the BHS occurred inside marine protected areas, the relatively high percentage of individuals with injuries apparently related to negative interactions with fisheries and tourism underscore the need for improved management to ensure the well-being of this fully protected species in Indonesia.

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Image: Figure 5 from the paper showing map of the proportion of total variance in the cumulative impact scores that is explained by the interactive effects. Darker areas indicate locations where stressor interactions led to greater variance in the cumulative impact scores.

Incorporating stressor interactions into marine spatial cumulative impact assessments

Stockbridge, J, AR Jones, CJ Brown, MJ Doubell, BM Gillanders. 2025. Ecological Applications 35: e3056.

Human-induced stressors are impacting the oceans and reducing the biodiversity of marine ecosystems. The many stressors affecting marine environments do not act in isolation. However, their cumulative impact is difficult to predict. Most of the available methods for quantifying cumulative impacts on marine ecosystems sum the impact of individual stressors to estimate cumulative impact. We demonstrate how experimental evidence from interacting stressors can be accounted for in cumulative impact assessments. We adapted a widely used additive model to incorporate nonadditive stressor interactions into a marine spatially explicit cumulative impact assessment for seagrasses. We combined experimental data on the impact of multiple stressors with spatial data on stressor intensity to test whether stressor interactions impact seagrasses in a case study region in South Australia. We also assessed how uncertainty about cumulative impacts changes when uncertainty in stressor interactions is included in the impact mapping. The results from an additive spatial cumulative impact assessment model were compared with results from the model incorporating interactions. Cumulative effects from the interaction model were more variable than those produced by the additive model. Five of the 15 stressor interactions that we tested produced impacts that significantly deviated from those predicted by an additive model. Areas of our study region that showed the largest discrepancies between the additive and interactive outputs were also associated with higher uncertainty. Our study demonstrates that the inclusion of stressor interactions changes the pattern and intensity of modeled spatial cumulative impact. Additive models have the potential to misrepresent cumulative impact intensity and do not provide the opportunity for targeted mitigation measures when managing the interactive effects of stressors. Appropriate inclusion of interacting stressor data may have implications for the identification of key stressors and the subsequent spatial planning and management of marine ecosystems and biodiversity.

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A systematic review of the current state of marine functional connectivity research

Tanner SE, AM Sturrock, R Ozturk, S Smolinski, Y Terzi, P Reis-Santos … AM Darnaude. 2025. Marine Ecology Progress Series 764, 237-257.

Marine functional connectivity underpins biodiversity and ecosystem functions, en suring resilience in marine and land–sea interface ecosystems. Research on this topic has ad vanced rapidly in recent decades, as reflected in the growing body of primary literature and the increasing number of reviews covering a variety of topics and methodologies. Here, we systematically extracted and analysed information from 215 reviews across the entire field to synthesize the current state of marine functional connectivity research, highlighting the main topics, methods, taxa, geographic areas, and future research priorities. Word co-occurrence and network analyses revealed imbalances in review topics, with certain habitats (e.g. coral reefs), taxa (e.g. fish), and geo graphic areas (e.g. North Atlantic) receiving disproportionate attention. These disparities likely arise from variations in funding, field site accessibility, public interest, and/or delays in adopting new concepts and methodologies. Research priorities were broadly grouped into 2 themes: (1) ‘Methods’, highlighting the need to integrate and advance sampling, modelling, and ana lysis techniques, and (2) ‘Ecology and Application’, stressing the need to understand connectivity drivers, particularly the impacts of climate change, and to integrate connectivity knowledge into marine conservation and management. There was also a third overarching theme emphasizing the importance of expanding spatial and temporal coverage of connectivity knowledge and data by embracing new technologies, growing collaborative networks and targeting understudied habitats, areas, and taxa. Tackling the identified research priorities will further improve our ability to quantify connectivity patterns and drivers, and facilitate efforts to actively apply this knowledge and data in marine management and conservation.

Image: Figure 5 from paper showing the main research priorities identified by the 215 reviews were broadly categorized into 2 main themes: ‘Methods’ (green) and ‘Ecology and Application’ (blue), with ‘Scales and Coverage’ sitting at the intersection between the 2 main themes. The 2 main themes were each represented by 3 subcategories

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Image: Graphical abstract from paper.

Long-distance migrations of catfishes in two large tropical rivers: The Ayeyarwady and Mekong Rivers

Vu, AV, LJ Baumgartner, J Conallin, Z Lunn, N Chan, IG Cowx, M Mallen-Cooper, GS Doran, BM Gillanders, JD Thiem, CM Kewish, K Limburg. 2025. Fisheries Research 291, 107562.

Understanding fish migration ecology is crucial for fisheries management. In this study, trace element and strontium isotope ratios were analysed in otoliths (ear-stones) of four economically important catfish species (Pangasiidae): Pangasius krempfi and P. mekongensis in the Mekong River, and P. pangasius and Pangasius sp. in the Ayeyarwady River to understand their migratory behaviour. Our findings showed that all four catfish species exhibited long-distance migrations: specifically, growth occurred in marine and brackish environments but migrations to fresh water were undertaken for spawning (anadromy). We identified cyclical variation in otolith elemental concentrations, suggesting these catfishes either migrated repeatedly between brackish and marine environments, or remained in estuarine areas where water chemistry varied seasonally. Additionally, evidence of multiple migration strategies was found among these catfishes. Regardless of species or river system there was consistent evidence supporting long-distance migrations that extended up to 3000 km on a return trip between feeding (marine) and spawning grounds (freshwater). To maintain viable populations of these long-distance migratory catfishes, ensuring river-to-sea connectivity is essential for the completion of their life cycles. Local and regional management plans should be developed to regulate anthropogenic pressures (e.g. dams and fishing) along their migration routes and current or planned water infrastructure should address the requirement for unimpeded bi-directional movement.

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Image: Sampling in the Ayeyarwady River

Spatial variability of water chemistry in the Ayeyarwady River Basin, Myanmar

Vu, AV, JC Conallin, LJ Stoot, GS Doran, LJ Baumgartner, KE Doyle, N Ning, Z Lunn, N Chan, NN Tun, AM Swe, BM Gillanders. 2025. Pacific Conservation Biology 31.

Context – Understanding chemical properties and biogeochemical changes can help us answer difficult ecological questions. Water chemistry is often dynamic in large tropical rivers, particularly in deltas where sea tides and river hydrological regimes are extremely influential.

 

Aims – This study assessed the spatial variability of water chemistry by measuring the elemental concentrations of seven trace elements and strontium isotopes (87Sr:86Sr) in the Ayeyarwady River Basin in Myanmar.

 

Methods – Inductively Coupled Plasma Optical Emission Spectroscopy and multi-collector inductively coupled plasma mass spectrometry were used to quantify concentrations of trace elements and strontium isotopes at 50 sampling sites, covering 1700 km of the Ayeyarwady River. Data was grouped into regions for statistical analyses.

 

Key results – Three elements (Sr, Ca, and Mg) showed distinct longitudinal concentration profiles, which were higher at the coast but consistently lower in freshwater. For example, elemental concentrations at coastal areas were 22-, 63-, and 150-times higher than in freshwater further upstream for Ca, Sr, and Mg, respectively. Although, longitudinal concentration profiles of 87Sr:86Sr ratios varied along the Ayeyarwady River, they were not significantly different among regions.

 

Conclusions – Longitudinal profiles of dissolved elements varied significantly. In particular, three elements (Sr, Ca, and Mg) are good indicators to differentiate between marine and freshwater in the Ayeyarwady River.

 

Implications – Our findings provide important baseline information on water chemistry for future fish otolith (inner ear of bony fish) chemistry studies to track fish migrations in the basin.

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Image: Figure 2 from paper showing summary rationale for statistical analyses investigating individual-level, intra- and interspecific growth synchrony of Etelis spp. within and among Exclusive Economic Zones (EEZs) of the Indo-Pacific. Numbers relate to case studies for extrinsic modelling. Green shapes show the outline of New Caledonia and Tonga (only the main island of Tongatapu represented) EEZs.

Local and regional-scale climate variability drives complex patterns of growth synchrony and asynchrony in deep-sea snappers across the Indo-Pacific

Widdrington, JB, P Reis-Santos, JI MacDonald, BR Moore, SJ Nicol, JR Morrongiello, BM Gillanders. 2025. Global Change Biology 31: e70051.

Climatic variation can play a critical role in driving synchronous and asynchronous patterns in the expression of life history characteristics across vast spatiotemporal scales. The synchronisation of traits, such as an individual's growth rate, under environmental stress may indicate a loss of phenotypic diversity and thus increased population vulnerability to stochastic deleterious events. In contrast, synchronous growth under favourable ecological conditions and asynchrony during unfavourable conditions may help population resilience and buffer against the negative implications of future environmental variability. Despite the significant implications of growth synchrony and asynchrony to population productivity and persistence, little is known about its causes and consequences either within or among fish populations. This is especially true for long-lived deep-sea species that inhabit environments characterised by large-scale interannual and decadal changes, which could propagate growth synchrony across vast distances. We developed otolith growth chronologies for three deep-sea fishes (Etelis spp.) over 65° of longitude and 20° of latitude across the Indo-Pacific region. Using reconstructed time series of interannual growth from six distinct Exclusive Economic Zones (EEZs), we assessed the level of spatial synchrony at the individual-, population- and species-scale. Across five decades of data, complex patterns of synchronous and asynchronous growth were apparent for adult populations within and among EEZs of the Pacific Ocean, mediated by shifts in oceanographic phenomena such as the Pacific Decadal Oscillation. Overall, our results indicate that the degree of synchrony in biological traits at depth depends on life history stage, spatiotemporal scales of environmental variability and the influence of ecological factors such as competition and dispersal. By determining the magnitude and timing of spatially synchronous growth at depth and its links to environmental variability, we can better understand fluctuations in deep-sea productivity and its vulnerability to future environmental stressors, which are key considerations for sustainability.

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Image: Figure 3 from paper - Visualisation of temporal variation (anomalies) in relative annual growth (estimated by Best Linear Unbiased Predictors (BLUP) of each species intrinsic growth model) for Lutjanus sebae (top, 1950 – 2020) and Etelis boweni (bottom, 1973 – 2013). Blue lines represent adult growth and red lines represent juvenile growth within each species. Dashed vertical lines and arrows indicate shifts to phases of faster or slower average growth in L. sebae adults (1975, 1990 and 2011). Shaded blue and red areas represent the standard error.

Otolith growth chronologies reveal distinct environmental sensitivities between and within shallow- and deep-water snappers

Widdrington, JB, P Reis Santos, JR Morrongiello, JI Macdonald, CB Wakefield, SJ Newman, SJ Nicol, BM Gillanders. 2025. Reviews in Fish Biology and Fisheries 35: 217-240.

Fish growth underpins individual fitness and population-level metrics, with fluctuations linked to environmental variability. Growth chronologies derived from otolith increment analysis are a powerful proxy to understand population responses to environmental change and productivity. Yet, long-term patterns of growth and their environmental drivers are better understood for shallow-water species compared to deep-water inhabitants. Additionally, focus is largely on adults, disregarding the potential influence of juvenile growth which is critical to size- and age-at-maturity. Here, we investigate the long-term growth patterns of two commercially important snapper species separated by depth in northwestern Australia’s coastal shelf waters, the shallow-water Lutjanus sebae (70 year chronology, 1950–2020) and the deep-water Etelis boweni (41 year chronology, 1973–2013). Annually-resolved otolith growth chronologies revealed distinct environmental sensitivities within (juveniles vs adults) and among (shallow- vs deep-water habitats) species. Within species, juveniles and adults responded differently to shared environmental stimuli, highlighting the importance of understanding the impacts of environmental effects and sensitivities for different life-history stages. Across species, L. sebae exhibited highly variable growth tied to local climate signals such as sea surface temperature and rainfall, while E. boweni displayed more stable growth patterns that only responded to interannual and decadal shifts in the environment (e.g. Pacific Decadal Oscillation). Our results highlight potential vulnerabilities of shallow-water species to future environmental perturbations compared to species residing at depth, as they are likely to encounter more extreme climate variability under future oceanic conditions. This study contributes valuable insights into understanding and managing the impacts of future environmental variability on fisheries sustainability, emphasising the need for continued research across species and habitats.

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Image: part of figure 4 from paper showing temporal variation (anomalies) in relative annual Sr:Ca (above) and Ba:Ca (below) fluctuations [estimated by Best Linear Unbiased Predictors (BLUP) from the optimal species-specific intrinsic models per EEZ] for E. coruscans in Tonga (left) and Wallis and Futuna (right) (1993–2014). Blue and purple lines represent sub-adult (lighter) and adult (darker) Sr:Ca variations. Red lines represent sub-adult (lighter) and adult (darker) Ba:Ca variations. Shaded areas represent the standard error.

Otolith-derived chemical chronologies reveal distinct patterns in physiology and environmental life histories of deep-sea snappers

Widdrington, JB, P Reis Santos, JI Macdonald, SJ Nicol, BM Gillanders. 2025. Marine Environmental Research 212, 107493.

Otolith chemical approaches are widely used to inform fisheries management, supporting the identification of population structure, connectivity, and natal origins. Chemical transects combined with fish age and growth data can reveal individual life histories, highlighting movement patterns and environmental influences within populations. Scaling these distinct variations to the population-level through novel chronological approaches could further boost our understanding of long-term physiological and environmental processes, and their interactions across regions and species. Yet, the application of such chemical approaches in deep-sea fishes remains limited. Here, we reconstructed individual life history patterns by integrating otolith strontium (Sr:Ca), barium (Ba:Ca), magnesium (Mg:Ca), and manganese (Mn:Ca) chemical profiles with age for two deep-sea eteline species (Etelis boweni, E. coruscans) across three Exclusive Economic Zones (EEZs) of the Pacific Ocean. We then built novel chemical chronologies of Sr:Ca and Ba:Ca to assess population-level responses and explore intrinsic and extrinsic drivers of variation among species and regions. At the individual-level, our results revealed an ontogenetic change in environment around the age of three, before the onset of sexual maturity. At the population-level, long-term fluctuations in chemical variation were associated with large-scale environmental shifts, with some evidence for regional and species differences. Overall, we showed the value of otolith chemistry to uncover individual- and population-scale responses to environmental variability in deep-sea systems. Importantly, these otolith based approaches hold promise for understudied, long-lived species and regions where long-term data are limited.

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Image: Graphical abstract from paper.

A field and laboratory manual for sampling, processing and reporting microplastics in coastal and marine environments

Wootton, N, P Reis-Santos, R Przeslawski, TM Adyel, M Blewitt, B Clarke, T Crutchett, A Ghose, S Hajbane, M Hamann, BD Hardesty, R Hossain, JL Lavers, SC Leterme, FDL Leusch, SK Lynch, M MacGregor, CA Motti, W Noble, A Obrien, T Palanisami, ED Okoffo, K Perera, P Puskic, JR Hollis, L Roman, V Sahajwalla, MFM Santana, A Snigirova, EM Tuuri, SP Wilson, S Ziajahromi, BM Gillanders. 2025. Frontiers in Marine Science 12, 1674412.

Global interest in microplastics is increasing, with numerous organisations collecting data on microplastics in the environment. However, disparate sampling, analysis, and reporting methods limit our ability to integrate data, hindering a global understanding of microplastic occurrence, effects and dynamics. Drawing on international directives and collaborations, we present a comprehensive guideline of harmonised and standardised field and laboratory approaches for microplastics in marine and coastal environments. We aim to ensure data consistency and comparability, incorporating the latest methodological developments for investigating and monitoring microplastics in four environmental matrices: sediment, water, biota, and air. A participatory approach brought together 40 researchers with diverse experience, reflecting a broad range of regional and international research. We provide best practice recommendations for sample processing to isolate, quantify and characterise microplastics, along with effective quality assurance and quality control measures. We also include reporting and data release recommendations, to ensure consistency and comparability across datasets. This guideline is endorsed by Ocean Best Practices System. By following these guidelines, and incorporating workflows supporting Findable, Accessible, Interoperable, and Reusable (FAIR) data, diverse stakeholders and practitioners can generate harmonised data essential for decision-making, facilitating a collective ability to synthesise global datasets and support action on microplastics.

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Image: Graphical abstract from paper.

Microplastic presence in dried and fresh fish from seafood markets in Sri Lanka

Wootton, N, V Silva, D Giuretis, P Reis-Santos, BM Gillanders. 2025. Marine and Freshwater Research 76: MF24270.

Context. Microplastics have been found in aquatic ecosystems globally, including in many marine organisms. Despite this, understanding the occurrence of microplastics in seafood products prepared for human consumption has received less attention. Aims. This study aims to determine the abundance and type of microplastic in dried and fresh fish purchased from seafood markets. Methods. Four locally harvested species of anchovies and sardines were sampled from seafood markets across Sri Lanka. These pelagic species are popular seafood items and are commonly consumed whole. We analysed fresh (gastrointestinal tracts, and whole body) and dried fish (whole body) under the microscope for microplastic presence (>38 μm, < 5mm), followed by polymer validation. Key results. Across all fish sampled (N=215), 82.3% had microplastic (3.64  0.26 MPs/ind), with fibre shaped pieces making up more than 95% of all microplastic particles. Overall, contamination was higher in fresh fish compared to whole dried fish. And, acrylic resin was the most common polymer. Conclusions. Microplastics were found in nearly all fresh fish and almost half the dry fish from Sri Lanka, confirming the pervasive nature of microplastic contamination. Implications. Differences in contamination levels in popular seafood products demonstrate how preparation and consumption habits can influence microplastic intake.

Near Calperun Station, SA

Near Calperun Station, SA

Giant Australian cuttlefish

Giant Australian cuttlefish

Flinders Chase

Flinders Chase

Tourville Bay

Tourville Bay

Streaky Bay

Streaky Bay

Kangaroo Island

Kangaroo Island

Routeburn Track

Routeburn Track

White Island

White Island

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