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Human society is dependent on nature 1,2 , but whether our ecological foundations are at risk remains unknown in the absence of systematic monitoring of species' populations 3 . Knowledge of species fluctuations is particularly inadequate in the marine realm 4 . Here we assess the population trends of 1,057 common shallow reef species from multiple phyla at 1,636 sites around Australia over the past decade. Most populations decreased over this period, including many tropical fishes, temperate invertebrates (particularly echinoderms) and southwestern Australian macroalgae, whereas coral populations remained relatively stable. Population declines typically followed heatwave years, when local water temperatures were more than 0.5 °C above temperatures in 2008. Following heatwaves 5,6 , species abundances generally tended to decline near warm range edges, and increase near cool range edges. More than 30% of shallow invertebrate species in cool latitudes exhibited high extinction risk, with rapidly declining populations trapped by deep ocean barriers, preventing poleward retreat as temperatures rise. Greater conservation effort is needed to safeguard temperate marine ecosystems, which are disproportionately threatened and include species with deep evolutionary roots. Fundamental among such efforts, and broader societal needs to efficiently adapt to interacting anthropogenic and natural pressures, is greatly expanded monitoring of species' population trends 7,8 ., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Over 2000km of Western Australian coastline experienced a significant marine heat wave in February and March 2011. Seawater temperature anomalies of +2-4 °C were recorded at a number of locations and satellite-derived SSTs were the highest on record. Here, we present seawater temperatures from southwestern Australia and describe, in detail, the marine climatology of Cockburn Sound; a large, multiple-use coastal embayment. We compared temperature and dissolved oxygen levels in 2011 with data from routine monitoring conducted from 2002-2010. A significant warming event, 2-4 °C in magnitude, persisted for >8 weeks, and seawater temperatures at 10 to 20m depth were significantly higher than those recorded in the previous 9 yr. Dissolved oxygen levels were depressed at most monitoring sites, being †2mgl-1 lower than usual in early March 2011. Ecological responses to short-term extreme events are poorly understood, but evidence from elsewhere along the Western Australian coastline suggests that the heat wave was associated with high rates of coral bleaching, fish, invertebrate and macroalgae mortalities, and algal blooms. However, more ecological information from Cockburn Sound and other multiple-use embayments is urgently needed. The 2011 heat wave provided insights into conditions that may become more prevalent in Cockburn Sound, and elsewhere, if the intensity and frequency of short-term extreme events increases as predicted. [ABSTRACT FROM AUTHOR]

South eastern Australia is a global warming hotspot, and is also home to ~70% of Australia's population and one of Australia's largest fisheries—the South East Scalefish and Shark Fishery. This fishery spans shelf to deep waters, subtropical to temperate waters, employs many gears, and interacts with over 100 species. Despite following best practice fisheries management principles, including taking an ecosystem perspective to overall fisheries interactions, management interventions have failed to arrest or recover the decline of some focal species. Using an Atlantis ecosystem model developed for the fishery over the past 20 years, this paper presents simulations that suggest climate change may be a major contributor to the trajectories seen for a number of species—such as jackass morwong (Nemadactylus macropterus), blue warehou (Seriolella brama), and gemfish (Rexea solandri). This kind of climate influence poses many challenges for fisheries management into the future, raising questions about what to do when climate change undermines or overrides fisheries management actions and objectives. [ABSTRACT FROM AUTHOR]

Southeastern Australia's marine waters are notably warming, surpassing global averages. This region has emerged as a strategic location for researching planktic microfossils, particularly dinoflagellate cysts, in modern and Late Quaternary sediments, offering crucial insights into the biophysical properties of mid-latitude waters. This study examined cyst distribution in marine sediment cores near Maria Island, Tasmania, southeastern Australia, up to 9000 years before present (kyrs BP). Dominant cysts included Protoceratium reticulatum, Protoperidinium spp. (P. avellana, P. conicum, P. oblongum, P. subinerme, P. shanghaiense), and Spiniferites spp. (S. bulloideus, S. hyperacanthus, S. membranaceus, S. mirabilis, S. pachydermus, and S. ramosus). Inshore, Spiniferites spp. constituted a higher proportion (up to 61%), while offshore was dominated by P. reticulatum (up to 80%). Impagidinium spp. and Nematosphaeropsis labyrinthus were exclusively found offshore and displayed increased abundance from ∼6 kyrs BP, suggesting a shift from a shallow to a deep-water habitat. Alexandrium tamarense species complex cysts were present over 140 years inshore and approaching 9 kyrs BP offshore, indicating a longstanding endemic presence. Gymnodinium catenatum cysts were detected exclusively inshore from ∼50 years ago, indicating a relatively recent bloom phenomenon. The East Australian Current's limited southward reach is suggested by the absence of the warm-water cyst-producing taxon Lingulodinium polyedra. Similarly, the non-detection of the cold-water species Spiniferites antarctica and Impagidinium pallidum reflects Subtropical Front boundaries against subantarctic incursions from the south. In contrast to coccolithophores in the same core, no noticeable shift from cold to warm-water dinoflagellate cyst species was observed. This documentation of dinoflagellate cysts aids in predicting environmental impacts on local communities and beyond. [ABSTRACT FROM AUTHOR]

Background: Conservation planning and the design of marine protected areas (MPAs) requires spatially explicit information on the distribution of ecological features. Most species of marine mammals range over large areas and across multiple planning regions. The spatial distributions of marine mammals are difficult to predict using habitat modelling at ecological scales because of insufficient understanding of their habitat needs, however, relevant information may be available from surveys conducted to inform mandatory stock assessments., Methodology and Results: We use a 20-year time series of systematic aerial surveys of dugong (Dugong dugong) abundance to create spatially-explicit models of dugong distribution and relative density at the scale of the coastal waters of northeast Australia (∼136,000 km(2)). We interpolated the corrected data at the scale of 2 km * 2 km planning units using geostatistics. Planning units were classified as low, medium, high and very high dugong density on the basis of the relative density of dugongs estimated from the models and a frequency analysis. Torres Strait was identified as the most significant dugong habitat in northeast Australia and the most globally significant habitat known for any member of the Order Sirenia. The models are used by local, State and Federal agencies to inform management decisions related to the Indigenous harvest of dugongs, gill-net fisheries and Australia's National Representative System of Marine Protected Areas., Conclusion/significance: In this paper we demonstrate that spatially-explicit population models add value to data collected for stock assessments, provide a robust alternative to predictive habitat distribution models, and inform species conservation at multiple scales.

Saline groundwater is being pumped from a number of locations in rural Western Australia to prevent secondary salinity impacting farmland, rural infrastructure and areas with high conservation value. Aquaculture may offset the costs of groundwater pumping, and the suitability of groundwater for finfish aquaculture is being assessed through bioassays. There are marked spatial variations in the ionic composition of saline ground water in Western Australia and this paper describes two bioassays investigating a saline, potassium-deficient water source that resulted in mortalities in juvenile barramundi, Lates calcarifer (Bloch). Histopathological examination revealed severe degeneration and necrosis of skeletal muscles, marked hyperplasia of branchial chloride cells and renal tubular necrosis. Clinical chemistry findings included hypernatraemia and hyperchloridaemia of the blood plasma and lowered muscle potassium levels. It is concluded that the principal cause of death was skeletal myopathy induced by low water potassium levels.

Marine microalgae have received much attention as a sustainable source of the two health beneficial omega-3-fatty acids docosahexaenoic acid (DHA, C22:6) and eicosapentaenoic acid (EPA, C20:5). However, photoautotrophic monocultures of microalgae can only produce either DHA or EPA enriched biomass. An alternative may be the photoautotrophic co-cultivation of Tisochrysis lutea as DHA-producer with Microchloropsis salina for simultaneous EPA production to obtain EPA- and DHA-rich microalgae biomass in a nutritionally balanced ratio. Photoautotrophic co-cultivation processes of T. lutea and M. salina were studied, applying scalable and fully controlled lab-scale gas-lift flat-plate photobioreactors with LED illumination for dynamic climate simulation of a repeated sunny summer day in Australia [day–night cycles of incident light (PAR) and temperature]. Monocultures of both marine microalgae were used as reference batch processes. Differences in the autofluorescence of both microalgae enabled the individual measurement, of cell distributions in co-culture, by flow cytometry. The co-cultivation of T. lutea and M. salina in artificial sea water with an inoculation ratio of 1:3 resulted in a balanced biomass production of both microalgae simultaneously with a DHA:EPA ratio of almost 1:1 (26 mgDHA gCDW−1, and 23 mgEPA gCDW−1, respectively) at harvest after depletion of the initially added fertilizer. Surprisingly, more microalgae biomass was produced within 8 days in co-cultivation with an increase in the cell dry weight (CDW) concentration by 31%, compared to the monocultures with the same amount of light and fertilizer. What is more, DHA-content of the microalgae biomass was enhanced by 33% in the co-culture, whereas EPA-content remained unchanged compared to the monocultures. [ABSTRACT FROM AUTHOR]

We describe the Australian Shark-Incident Database, formerly known as the Australian Shark-Attack File, which contains comprehensive reports of 1,196 shark bites that have occurred in Australia over 231 years (1791–2022). Data were collated by the Taronga Conservation Society Australia using purpose-designed questionnaires provided to shark-bite victims or witnesses, media reports, and information provided by the department responsible for fisheries in each Australian state (including the Northern Territory). The dataset includes provoked and unprovoked bites from fresh, brackish, and marine waters in Australia. Data span 22 suspected shark species. This dataset will be publicly available, and can be used by analysts to decipher environmental, biological, and social patterns of shark bites in Australia. The information will aid scientists, conservationists, authorities, and members of the public to make informed decisions when implementing or selecting mitigation measures. Measurement(s) Shark bite incidents Technology Type(s) survey Factor Type(s) none Sample Characteristic - Organism Elasmobranchii Sample Characteristic - Environment ocean Sample Characteristic - Location Australia [ABSTRACT FROM AUTHOR]

Multi-decadal ocean time-series are fundamental baselines for assessing the impacts of environmental change, however, compiling and quality controlling historic data from multiple sources remains challenging. Here we aggregate, document, and release a number of long time-series temperature products and climatologies compiled from data obtained at 4 monitoring sites around Australia where sub-surface ocean temperature has been recorded nominally weekly to monthly since the 1940s/50s. In recent years, the sampling was augmented with data obtained from moored sensors, vertical profiles and satellite-derived data. The temperature data have been quality controlled, and combined using a rigorously tested methodology. We have packaged the multi-decadal, multi-depth, multi-platform temperature time-series at each site and produced a range of daily temperature climatologies from different data combinations and time periods. The 17 data products are provided as CF-compliant NetCDF files and will be updated periodically. The long-term temperature time-series will be useful for studies of ocean temperature variability, trends, anomalies and change. The data collection is supported by Australia's Integrated Marine Observing System and data are open-access. Measurement(s) temperature of water • temperature of sea surface Technology Type(s) ocean time series station • satellite • ship-based water sampling • ship-based CTD profiles Sample Characteristic - Environment coastal sea water • sea water environment • continental shelf Sample Characteristic - Location Australia • Tasman Sea coastal waters of continental Australia • Western Australia [ABSTRACT FROM AUTHOR]

Population genetic data can provide valuable information on the demography of a species. For rare and elusive marine megafauna, samples for generating the data are traditionally obtained from tissue biopsies, which can be logistically difficult and expensive to collect and require invasive sampling techniques. Analysis of environmental DNA (eDNA) offers an alternative, minimally invasive approach to provide important genetic information. Although eDNA approaches have been studied extensively for species detection and biodiversity monitoring in metabarcoding studies, the potential for the technique to address population‐level questions remains largely unexplored. Here, we applied "eDNA haplotyping" to obtain estimates of the intraspecific genetic diversity of a whale shark (Rhincodon typus) aggregation at Ningaloo reef, Australia. Over 2 weeks, we collected seawater samples directly behind individual sharks prior to taking a tissue biopsy sample from the same animal. Our data showed a 100% match between mtDNA sequences recovered in the eDNA and tissue sample for all 28 individuals sampled. In the seawater samples, >97% of all reads were assigned to six dominant haplotypes, and a clear dominant signal (~99% of sample reads) was recovered in each sample. Our study demonstrates accurate individual‐level haplotyping from seawater eDNA. When DNA from one individual clearly dominates each eDNA sample, it provides many of the same opportunities for population genetic analyses as a tissue sample, potentially removing the need for tissue sampling. Our results show that eDNA approaches for population‐level analyses have the potential to supply critical demographic data for the conservation and management of marine megafauna. [ABSTRACT FROM AUTHOR]

The absence of chronic toxicity data for tropical marine waters has limited our ability to derive appropriate water quality guideline values for metals in tropical regions. To aid environmental management, temperate data are usually extrapolated to other climatic (e.g., tropical) regions. However, differences in climate, water chemistry, and endemic biota between temperate and tropical systems make such extrapolations uncertain. Chronic nickel (Ni) toxicity data were compiled for temperate (24 species) and tropical (16 species) marine biota and their sensitivities to Ni compared. Concentrations to cause a 10% effect for temperate biota ranged from 2.9 to 20 300 µg Ni/L, with sea urchin larval development being the most sensitive endpoint. Values for tropical data ranged from 5.5 to 3700 µg Ni/L, with copepod early–life stage development being the most sensitive test. There was little difference in temperate and tropical marine sensitivities to Ni, with 5% hazardous concentrations (95% confidence interval) of 4.4 (1.8–17), 9.6 (1.7–26), and 5.8 (2.8–15) µg Ni/L for temperate, tropical, and combined temperate and tropical species, respectively. To ensure greater taxonomic coverage and based on guidance provided in Australia and New Zealand, it is recommended that the combined data set be used as the basis to generate a jurisdiction‐specific water quality guideline of 6 µg Ni/L for 95% species protection applicable to both temperate and tropical marine environments. Environ Toxicol Chem 2020;39:2540–2551. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Several regions of the world, including the east coast of Australia, are characterized by the occurrence of low‐pressure systems with a range of different dynamical structures, including tropical, extratropical, and hybrid cyclones. Future changes in the occurrence of cyclones are better understood if storms are classified according to their dynamical structure. Therefore, we apply a classification of cyclones according to their cold‐core or warm‐core structure to an ensemble of regional climate model simulations. First, we show that historical simulations reproduce well the reanalysis results in terms of cyclone classification. We then show that once cyclone classification is applied, projections of future cyclone activity become more robust, including a decrease in the occurrence of both cold‐core and warm‐core cyclones. Finally, we show that in a warmer climate warm‐core hybrid cyclone activity could increase close to the coast, while the associated rainfall and wind are projected to increase. Plain Language Summary: Cyclones in the tropics derive their energy from the temperature difference between warm ocean waters and the atmosphere and their interior is warmer than the environment (warm core), while cyclones in the midlatitudes derive their energy from differences in the atmospheric temperature and density at different locations and their interior is colder than the environment (cold core). In subtropical regions both types of cyclone can form. Also in those regions cyclones known as hybrid cyclones form, with mixed tropical‐extratropical features, such as a partial lower tropospheric warm core and a partial upper tropospheric cold core. This study is focused on cyclones along the eastern coast of Australia. Here we show that dividing cyclones in different classes according to their thermal structure provides a better framework to interpret changes in cyclone activity at subtropical latitudes. This study has two main results. First, classifying cyclones adds value to climate projection robustness. A large number of models agree on the decrease in the occurrence of both cold‐core and warm‐core cyclones. The study also indicates increased occurrence of hybrid cyclones close to the Australian coast. Second, the study shows evidence of future changes in cyclone‐related impacts, such as an increase in the associated rainfall. Key Points: A physically based classification of hybrid cyclones is applied to an ensemble of regional climate model simulationsThe cyclone classification method adds value to the projections of future cyclone activity, making them more robustResults indicate future changes (2060–2079) toward more intense impacts associated with hybrid cyclones [ABSTRACT FROM AUTHOR]

Algal species which are ubiquitous along the coastlines of many countries reflect the environmental conditions of the coastal seawater and may serve as useful biomonitors of anthropogenic pollution. Heavy metal concentrations of ten elements (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) of potential environmental concern were determined in seawater, sediments and twelve species of benthic marine macroalgae from four locations (Glenelg, Port Adelaide, Port Broughton and Port Pirie) along the South Australian coastline. The four sites chosen represented varying degrees of metal contamination, where the capacity for benthic macroalgae to accumulate heavy metals from the environment was evaluated. Spatial differences in heavy metal concentration in both seawaters and sediments were observed at all sites with the highest concentrations of heavy metals including Cd (125 μg g), Pb (2,425 μg g) and Zn (7,974 μg g) found in the finer sediment fractions (<250 μm) of Port Pirie. While all algal species studied ( Acrosorium polyneurum, Anotrichium tenue, Cystophora Cephalornithos Cystophora monillifera, Cystophora monilliformis, Dictyopteris australis, Gelidium micropterum, Gracilaria, Hormophysa Cuneiformis, Sargassum cinctum, Scaberia agardhii and Ulva lactuca) accumulated metals to varying degrees, Blindigia marginata was a good biomonitor species for a number of metals including Cd, Co, Cr, Fe, Pb and Zn, exhibiting both relatively high total metal concentrations and significant concentration factors. [ABSTRACT FROM AUTHOR]

Recent anthropogenic influences on freshwater habitats are forcing anuran populations to rapidly adapt to high magnitude changes in environmental conditions or face local extinction. We examined the effects of ecologically relevant elevated salinity levels on larval growth, metamorphosis and survival of three species of Australian anuran; the spotted marsh frog (Limnodynastes tasmaniensis), the painted burrowing frog (Neobatrachus sudelli) and the green and golden bell frog (Litoria aurea), in order to better understand the responses of these animals to environmental change. Elevated salinity (16% seawater) negatively impacted on the survival of L. tasmaniensis (35% survival) and N sudelli (0% survival), while reduced salinity had a negative impact on L. aurea. (16% seawater: 85% survival; 0.4% seawater: 35% survival). L. aurea tadpoles survived in salinities much higher than previously reported for this species, indicating the potential for inter-populations differences in salinity tolerance. In L. tasmaniensis and L. aurea, development to metamorphosis was fastest in low and high salinity treatments suggesting it is advantageous for tadpoles to invest energy in development in both highly favourable and developmentally challenging environments. We propose that this response might either maximise potential lifetime fecundity when tadpoles experience favourable environments, or, facilitate a more rapid escape from pond environments where there is a reduced probability of survival. [ABSTRACT FROM AUTHOR]

Two areas within Sydney Harbour were surveyed in 2002 with a helicopter-borne time-domain electromagnetic system to test its potential for bathymetric mapping in shallow seawater. As delivered, the data were improperly calibrated. Therefore a re-calibration was performed to reconcile the measured data with ‘ground truth’. Synthetic electromagnetic transients were computed for two-layer models representing the seawater and the sediment overlying bedrock at a number of locations within the survey area. The seawater depth in the models varied between 3 m and 70 m. The measured and calculated data were compared at each delay time, and were found to be linearly related. The slope and intercept of the line of best fit were used to correct all the measured data. Inversion of the corrected time-domain electromagnetic data generally resolved the bathymetry to submetre accuracy down to depths of about 55 m. [ABSTRACT FROM AUTHOR]

Measurements of the partial pressure of CO2 in surface seawaterwere made in the Southern Ocean south of Australia during four cruises in January to February 1969, December 1983 to January 1984, December 1994 to January 1995 and January 2002. The spatial distribution offor the four cruises showed the same pattern north of the Sub-Antarctic Front (SAF), while year-to-year changes were noted south of the SAF. We evaluated the long-term trend of therepresentative of the zone between oceanographic fronts by taking into account changes in the seasonal variation inand the long-term increase of the sea-surface temperature (SST) of the Southern Hemisphere. The observed growth rate ofwas 0.7± 0.1μatm yr−1 at its minimum, which was observed at the SST of 15°C north of the Subtropical Front (STF), 1.0± 0.5μatm yr−1 in the Sub-Antarctic Zone (SAZ) between STF and SAF, 1.5± 0.4μatm yr−1 in the Polar Frontal Zone (PFZ) between SAF and the Polar Front (PF) and 1.8± 0.2μatm yr−1 in the Polar Zone (PZ) between PF and 62°S, determined as the northern edge of the Seasonal Sea Ice Zone (SSIZ) on the basis of surface salinity and satellite images. These increases were caused by the uptake of anthropogenic CO2 as well as variations in the thermodynamic temperature effect, ocean transport and biological activity. In the SSIZ between 62 and 66.5°S, we could not clearly evaluate the long-term trend ofdue to the remarkable CO2 drawdown due to biological activity in January 2002. The relatively low growth rates ofclose to the STF and in the SAZ are probably associated with the formation of Subtropical Mode Water and Sub-Antarctic Mode Water in their respective zones. Between the north of the STF and the PZ, the growth rate of total dissolved inorganic carbon was calculated to be about 0.5–0.8μmol kg−1 yr−1 via the buffer factor. [ABSTRACT FROM AUTHOR]

Regression analysis on data collected from Port Phillip Bay and Western Port, Australia in 1979 shows that there is a significant equilibrium relationship between total recoverable lead in seawater and its concentrations in the mussel Mytilus edulis ( P<0.001). The concentration of lead in seawater should not exceed 1.27 μg l if the mussel is not to reach a lead concentration of 2.5 mg kg wet weight, a value frequently used as a food standard for human consumption. When a lead value of 2.5 mg kg wet weight is reached, the concentration factor by mussels for lead from seawater is 1969. The critical value of 1.27 μg l could be used as a marine water-quality criterion for lead in waters where mussels are harvested. [ABSTRACT FROM AUTHOR]