The fatty acid content and composition of the Antarctic krill Euphausia superba Dana, 1850 were investigated using samples collected by a commercial fishing vessel. This dataset allowed comparison between seasons, years (2013–2016), and different fishing locations. Quantities of omega 3 fatty acids 20:5n-3 and 22:6n-3 (mg/g dry mass; DM) were highest in autumn and decreased through winter to reach a spring low. Quantities of the flagellate marker 18:4n-3 and diatom marker 16:1n-7c were variable and did not display the same seasonal fluctuations. In summer, krill had high percentages (% total fatty acids) of 20:5n-3 and 22:6n-3, total PUFA, and low 18:1n-9c/18:1n-7c ratios, indicating a more herbivorous diet. Krill became more omnivorous from autumn to spring, indicated by increasing ratios of 18:1n-9c/18:1n-7c and percentages of Σ 20:1 + 22:1 isomers. Bacterial fatty acids (Σ C15 + C17 + C19 isomers) were minor components year-round (0.9–1.8 %). Seasonal levels of herbivory and omnivory differed between years, and levels of specific fatty acid ratios differed between fishing locations. The fatty acid 18:4n-3 was a major driver of variability in krill fatty acid composition, with no obvious seasonal driver. This is the first study to report krill fatty acid data during all four seasons over consecutive years. This large-scale study highlights the value of using fisheries samples to examine seasonal and annual fluctuations in krill diet and condition.

This record provides an overview of the scope of the NESP Marine Biodiversity Hub project "Identification of near-shore habitats of juvenile white sharks in south-western Australia". No data outputs were generated by this project. -------------------- In 2018, CSIRO provided the first estimate of adult abundance for the southern-western Australian white shark (Carcharodon carcharias) population. At the time, total population abundance could not be estimated because of limited information on the juvenile life-history stage. This project investigated whether juvenile white sharks from this population use near-shore habitats near the head of the Great Australian Bight. It investigated credible anecdotal evidence of juvenile white shark presence in the region and was designed as a pilot study to inform future survey and project development. The project reviewed existing sources of evidence and undertook unmanned aerial vehicle (AUV) surveys in near-shore habitats within and around the Nuyts Archipelago Marine Park. Thirty-five UAV flights were completed during 2018 and 2019, covering approximately 7.5 km². No white sharks were identified in the UAV footage, although several other marine species and shorebirds were observed. Additional evidence from scientific surveys indicated that the Head of Bight and surrounding marine park areas may be important habitat for white sharks across multiple life stages. The project included engagement with the Yalata Land Management Indigenous Ranger team, who were consulted during project planning and survey activities. The findings informed future project development by assessing the value of further on-water activities, expanded UAV surveys and targeted monitoring in the Great Australian Bight region.

Antarctic krill (Euphausia superba) are a keystone species in the Southern Ocean, but little is known about how they will respond to climate change. Ocean acidification, caused by sequestration of carbon dioxide into ocean surface waters (pCO2), is known to alter the lipid biochemistry of some organisms. This can have cascading effects up the food chain. In a year-long laboratory experiment adult krill were exposed to ambient seawater pCO2 levels (400 μatm), elevated pCO2 levels that mimicked near-future ocean acidification (1000, 1500 and 2000 μatm) and an extreme pCO2 level (4000 μatm). The laboratory light regime mimicked the seasonal Southern Ocean photoperiod and krill received a constant food supply. Total lipid mass (mg g -1 DM) of adult krill was unaffected by near-future levels of seawater pCO2. Fatty acid composition (%) and fatty acid ratios associated with immune responses and cell membrane fluidity were also unaffected by near-future pCO2, apart from an increase in 18:3n-3/18:2n-6 ratios in krill in 1500 μatm pCO2 in winter and spring. Extreme pCO2 had no effect on krill lipid biochemistry during summer. During winter and spring, krill in extreme pCO2 had elevated levels of omega-6 fatty acids (up to 1.2% increase in 18:2n-6, up to 0.8% increase in 20:4n-6 and lower 18:3n-3/18:2n-6 and 20:5n-3/20:4n-6 ratios), and showed evidence of increased membrane fluidity (up to three-fold increase in phospholipid/sterol ratios). These results indicate that the lipid biochemistry of adult krill is robust to near-future ocean acidification.

The AUStralian Tidal Energy (AUSTEn) project was a three year project (2018 - 2020) funded by the Australian Renewable Energy National Agency (agreement number G00902) led by the Australian Maritime College (University of Tasmania), in partnership with CSIRO and University of Queensland. The project had a strong industry support (Atlantis Resources Limited, MAKO Tidal Turbines Ltd, Spiral Energy Corporation Ltd). The aim of the project was to assess the technical and economic feasibility of tidal energy in Australia, based on the best understanding of resource achievable. For further information and output of the project, please visit the AUSTEn project website www.austen.org.au.

This record provides an overview of the scope and research output of the NESP Marine Biodiversity Hub project "A standardised national assessment of the state of coral and rocky reef biodiversity". For specific data outputs from this project, please see child records associated with this metadata. -------------------- This project will involve integration of a national suite of reef biota Underwater Visual Census (UVC) monitoring datasets (Reef Life Survey (RLS), University of Tasmania (UTAS), Australian Institute for Marine Science (AIMS), Parks Victoria (PV), SA Department of environment, water and natural resources (DEWNR)) to provide a comprehensive update to the state of Australian Reefs report for the next national State of the Environment Report. Maps and indicator trends will show changes in the health of rocky and coral reefs nationally from 2005 to 2020. The update will include addition of a new index which summarises the population trajectories for 600-1000 reef species nationally. Individual species trajectories will provide the only threat status information for the majority of these species, assisting future listing of previously unassessed species if significant declines are detected. Planned Outputs • Maps and trends in SoE indicators • Raw data underlying SoE analyses (data use agreement must be signed with AIMS for access to that data) • Various scientific papers

This record provides an overview of the scope and research output of the NESP Marine Biodiversity Hub project "Estimation of population abundance and mixing of southern right whales in the Australian and New Zealand regions". For specific data outputs from this project, please see child records associated with this metadata. -------------------- A comprehensive understanding of the population abundance and degree of spatial connectivity of southern right whales (Eubalaena australis) in Australian waters is currently lacking. This limits assessments of the species recovery and understanding of the nature and degree of difference between the south-eastern and south-western Australian populations. This project brought together existing photo-identification datasets, including records held in the Australian Right Whale Photo-Identification Catalogue (ARWPIC), to support a national assessment of southern right whale population dynamics and connectivity. It estimated total Australian population abundance, investigated links between whales using breeding areas along the eastern, southern and western coasts of Australia, and assessed future data collection needs for ongoing monitoring. The project supported evaluation of progress against the Conservation Management Plan for southern right whales and contributed to more coordinated conservation planning for the species at regional and national scales.

Sea urchins have the capacity to destructively overgraze kelp beds and cause a wholesale shift to an alternative and stable ‘urchin barren’ state. However, their destructive grazing behaviour can be highly labile and contingent on behavioural shifts at the individual and local population level. Changes in supply of allochthonous food sources, i.e. availability of drift-kelp, is often suggested as a proximate trigger of change in sea urchin grazing behaviour, yet field tests of this hypothesis are rare. Here we conduct a suite of in situ behavioural surveys and manipulative experiments within kelp beds and on urchin barrens to examine foraging movements and evidence for a behavioural switch to an overgrazing mode by the Australian sea urchin Heliocidaris erythrogramma (Echinometridae). Tracking of urchins using time-lapse photography revealed urchin foraging to broadly conform to a random-walk-model within both kelp beds and on barren grounds, while at the individual level there was a tendency towards local ‘homing’ to proximate crevices. However, consistent with locally observed ‘mobile feeding fronts’ that can develop at the barrens-kelp interface, urchins were experimentally inducible to show directional movement toward newly available kelp. Furthermore, field assays revealed urchin grazing rates to be high on both simulated drift-kelp and attached kelp thalli on barren grounds, however drift-kelp but not attached kelp was consumed at high rates within kelp beds. Time-lapse tracking of urchin foraging before/ after the controlled addition of drift-kelp on barrens revealed a reduction in foraging movement across the reef surface when drift-kelp was captured. Collectively results indicate that the availability of drift-kelp is a pivotal trigger in determining urchin feeding modes, which is demonstrably passive and cryptic in the presence of a ready supply of drift-kelp. Recovery of kelp beds therefore appears possible if a sustained influx of drift-kelp was to inundate urchin barrens, particularly on reefs where local urchin densities and where grazing pressure is close to the threshold enabling kelp bed recovery.

Cyclone data was used to develop a spatial model using the intensity and to determine whether Sea Surface Temperature or Tropical Cyclone Heat Potential contributes to the North Indian Ocean cyclone intensity and, if so, how?