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Southern Bluefin Tuna (SBT), Thunnus maccoyii, is ranched off Port Lincoln, South Australia and is Australia's second largest economic finfish aquaculture industry. The biggest threats to SBT health identified by the industry are the blood flukes Cardicola forsteri and C. orientalis (Trematoda: Aporocotylidae). Melanomacrophage centres (MMCs) are aggregations of pigmented macrophage like cells present in spleen, kidney and liver of teleost fish. The aim of this study was to quantify MMCs in SBT anterior kidney, liver and spleen to investigate changes in relation to Cardicola spp. Infection. Samples were collected at the end of ranching from pontoons where SBT were treated with PZQ and pontoons with untreated SBT. SBT MMC percentage of surface area cover was highest in SBT spleen and lowest in the liver. Significant positive correlations were identified between SBT MMC area and SBT size in all three organs (p < 0.05). MMC area and parasite infection showed significant positive correlations in the kidney and spleen for Cardicola spp. gill egg counts, and in the kidney for C. forsteri DNA from SBT hearts and gills (p < 0.05). MMCs area increased with increased intensity of Cardicola spp. Infection and MMCs have the potential to be used as an indicator to assess health effects that Cardicola spp. have on SBT. • Melanomacrophage centres (MMCs) had a larger area and darker pigmentation in the kidney and spleen compared to the liver. • Positive correlations were identified between MMC area and SBT size. • Positive correlations were found between SBT MMC area and Cardicola spp. DNA and egg counts. • Some parasite eggs were encapsulated in hepatic MMCs. [ABSTRACT FROM AUTHOR]

Expanded polystyrene (EPS) pollution in the marine environment is a pressing issue in Queensland, Australia due to a recent flood that scattered hundreds of EPS-containing pontoons along the coastline, causing severe ecological damage. To assist in the clean-up effort and provide crucial data for developing management guidelines, this study investigates the environmental performance of different end-of-life (EoL) disposal/recycling methods, including (i) landfill; (ii) on-site mechanical re-processing using a thermal densifier (MR); and (iii) on-site dissolution/precipitation using d -limonene (DP). Applying the life cycle assessment framework, the results showed that DP was the most environmentally favourable option. Its impacts in climate change (GWP), acidification (TAP), and fossil fuel depletion (FFD) were 612 kg CO 2 eq, 4.3 kg SO 2 eq, and 184.7 kg oil eq, respectively. For comparison, the impacts of landfilling EPS in these categories were found to be 700 kg CO 2 eq, 3.5 kg SO 2 eq, and 282 kg oil eq, respectively. Landfill also contributed considerably to eutrophication potential (MEP), at 3.77 kg N eq. Impacts from MR were most significant due to the need to transport the densifier unit to the site. The analysis also revealed that the transportation of personnel and heavy machinery to the site, was the biggest contributor to impacts in the EoL stage. Its impacts in GWP, TAP, MEP, and FFD were 1369.8 kg CO 2 eq, 6.5 kg SO 2 eq, 0.2189 kg N eq, and 497.7 kg oil eq, respectively. Monte Carlo analysis showed that the conclusions made from these results were stable and reliable. Limitations of this model and recommendations for future investigations were also discussed in this work. [Display omitted] • Transportation imposed the highest impacts during disposal of missing pontoons. • Mechanical re-processing had highest impacts. • d -limonene dissolution showed the best environmental performance. • Further research is needed to optimise d -limonene dissolution process. • Recovery of PS is desirable, but not feasible. [ABSTRACT FROM AUTHOR]

The modern day seascape is a mix of natural habitats (saltmarsh, mangroves, seagrass, unvegetated beaches), but increasingly is being replaced with hard engineering structures (e.g. floating pontoons) that have resulted in novel habitats available for flora and fauna. While these engineered structures provide new marine habitat resources, from the viewpoint of biodiversity, they effectively support a sub-set of species found in natural habitats. Unlike previous studies that have used divers for fish visual census, we used a remotely operated vessel with an underwater camera to examine the fish community using floating pontoons in a marina facility in tropical central Queensland, Australia. The camera filmed continuously the edge and underside of pontoons (both surveys covered similar pontoon linear distances – July (winter) 430m; November (summer) 485m; 2021). Fifteen fish species representing 14 families were recorded, with more species observed during summer compared to the winter survey. Remarkably, across both surveys of the 243 fishes individuals that were recorded, 166 (68%) appeared upside-down in videos (i.e., oriented to the underside of the pontoon). Engaging a behaviour of swimming upside-down has been acknowledged in natural habitats elsewhere; some coral reef species living in caves or reef ledges orientate themselves to the cave ceiling or overhanging ledge to increase prey capture rate. However, this is the first study to record fishes exhibiting the same behaviour. We conclude that our less invasive video survey approach provided the opportunity to observe fishes in a state of natural behaviour, orientating themselves towards the pontoon substrate, which is probably simply a response of adhering to basic characteristic modes, i.e., it is the orientation relative to the substrate that is important, rather than their orientation in space per se. Indeed marina pontoons provide an additional feature in already habitat complex estuaries; these data add to why we need to consider the ecosystem services offered by marine infrastructure, and the plasticity of fish to adapt to new environments in an expanding blue economy. [Display omitted] • Pontoons in marinas are an obvious marine habitat in modern day seascape. • ROV revealed nearly all fish were upside-down, orientated to the pontoon substrate. • This behavior could be a response of adhering to basic characteristic modes, such as accessing food and shelter. • The placidity of fish to adopt to new marine environments is demonstrated here. [ABSTRACT FROM AUTHOR]

Abstract: We present results from a suite of methods using in situ temperature and salinity data, and satellite altimetric observations to obtain an enhanced set of mean fields of temperature, salinity (down to 2000-m depth) and steric height (0/2000m) for a time-specific period (1992–2007). Firstly, the improved global sampling resulting from the introduction of the Argo program, enables a representative determination of the large-scale mean oceanic structure. However, shortcomings in the coverage remain. High variability western boundary current eddy fields, continental slope and shelf boundaries may all be below their optimal sampling requirements. We describe a simple method to supplement and improve standard spatial interpolation schemes and apply them to the available data within the waters surrounding Australia (100°E–180°W; 50°S–10°N). This region includes a major current system, the East Australian Current (EAC), complex topography, unique boundary currents such as the Leeuwin Current, and large ENSO related interannual variability in the southwest Pacific. We use satellite altimetry sea level anomalies (SLA) to directly correct sampling errors in in situ derived mean surface steric height and subsurface temperature and salinity fields. The surface correction is projected through the water column (using an empirical model) to modify the mean subsurface temperature and salinity fields. The errors inherent in all these calculations are examined. The spatial distribution of the barotropic–baroclinic balance is obtained for the region and a ‘baroclinic factor’ to convert the altimetry SLA into an equivalent in situ height is determined. The mean fields in the EAC region are compared with independent estimates on repeated XBT sections, a mooring array and full-depth CTD transects. [ABSTRACT FROM AUTHOR]

In the marine environment, artificial structures are not, in general, managed for their value as habitat and are often built with no a priori expectation as to the assemblages which may colonise them. It may, however, become increasingly important to consider the value of such structures as habitat when decisions are made with respect to the management of artificial structures. This study investigates the role marinas play as habitat for fish by examining the distribution of fish associated with these urban developments and how this distribution relates to the physical characteristics of marinas. Assemblages of fish associated with marinas in waterways around Sydney were sampled in August and December 2002 and May 2003. Counts were done around structures present at marinas, i.e. pontoons and pilings and in the open water immediately adjacent to these structures. Within marinas, spatial patterns were particular to the types of fish examined. Large mobile species, such as Acanthopagrus australis and Girella tricuspidata, moved between structures and the open water between them. Smaller species, such as Trachinops taeniatus and Microcanthus strigatus, were found only in the immediate vicinity of these structures. At a larger spatial scale, assemblages of fish varied markedly between different marinas. This variability could not, however, be attributed to the depth of water, the age or size of marinas, nor the type of material with which marinas were constructed (i.e. pontoons or jetties). [Copyright &y& Elsevier]

The parasitic blood flukes Cardicola forsteri and C. orientalis are an ongoing health concern for Southern Bluefin Tuna Thunnus maccoyii (SBT) ranched in Australia. In this study we compared the effect of treatment, company, and ranching year on blood fluke infections in ranched SBT. SBT were sampled during the 2018 and 2019 ranching seasons from praziquantel (PZQ) treated pontoons and untreated pontoons managed by two companies. Severity of infection was diagnosed by several criteria including adult fluke counts from hearts, egg counts from gill filaments and the use of specific quantitative polymerase chain reaction (qPCR) for detection of C. forsteri and C. orientalis ITS-2 DNA in SBT hearts and gills. PZQ treatment remains highly effective against C. forsteri infection. Prevalence and intensity of Cardicola spp. infection was lower in 2019 than 2018 for Company A in treated pontoons at week 12 and week 17 of ranching, and lower for Company A than Company B in untreated pontoons at month 5 of ranching. Results indicate re-infection may be less likely in the environment near Company A pontoons, and consistent years of treatment may have lowered the parasite load in the environment. qPCR demonstrated higher sensitivity when comparing diagnostic methods for C. forsteri in heart, and higher specificity when comparing diagnostic methods for Cardicola spp. in gills. Continuing to monitor blood fluke infections in ranched SBT can help to detect changes in drug efficacy over time and help industry to develop a best practice for treatment. [ABSTRACT FROM AUTHOR]