This record provides an overview of the NESP Marine and Coastal Hub Emerging Priorities project "National assessment of harmful algal bloom preparedness and future needs". No data outputs are planned for this project. -------------------- The 2025 South Australian harmful algal bloom (HAB) highlighted major gaps in Australia’s preparedness for large-scale marine HAB events, including limitations in surveillance capability, forecasting systems, coordination arrangements and long-term response planning. While HABs are not new to Australia, the scale, duration and ecological impacts of the South Australian event demonstrated the need for a broader national assessment of HAB science capability and policy readiness. This project will review Australia’s current capability for HAB surveillance, forecasting, response and management across environmental and seafood-safety domains. It will examine existing monitoring systems, research capability, early-warning approaches, coordination arrangements and operational policy settings across Commonwealth, state and territory jurisdictions. The review will consider lessons from the South Australian bloom alongside national and international approaches to HAB preparedness and management, including monitoring technologies, forecasting systems and risk mitigation strategies. It will also consider relevant recommendations from the Australian Senate inquiry into the South Australian algal bloom and broader national policy frameworks, including the draft Sustainable Ocean Plan. Project outputs will include an assessment of current national HAB capability, identification of critical knowledge and operational gaps, and recommendations for improving HAB preparedness, surveillance, forecasting, coordination and response capacity in Australia. Outputs • Final technical report [written]

This record provides an overview of the NESP Marine and Coastal Hub Emerging Priorities project "Learning from the field: a rapid assessment of the composition and ecotoxicology of the harmful algal bloom in South Australia". For specific data outputs from this project, please see child records associated with this metadata. -------------------- A severe harmful algal bloom (HAB) involving Karenia species has affected large areas of the South Australian coastline, including Gulf St Vincent, Spencer Gulf and Investigator Strait. The species composition, toxicity and ecological impact pathways of the bloom remain poorly understood, limiting the ability of agencies to respond to ongoing and future bloom events. This Emerging Priorities project will conduct a rapid investigation of the composition, toxicity and variability of the South Australian Karenia bloom across sites, depths and bloom stages. Broadscale water sampling will target areas of bloom spread and prolonged exposure, with sampling locations adjusted using satellite chlorophyll maps and field observations. The project will combine microscopy, qPCR-based species identification and abundance estimates, rotifer bioassays, and brevetoxin screening. Rotifer assays will provide a rapid comparative indicator of aquatic toxicity, while qPCR will identify and quantify Karenia species in the same samples, allowing toxicity results to be linked with species composition and bloom development. Selected field samples and cultured strains will also be screened for brevetoxins in collaboration with allied HAB research initiatives. Outputs will include baseline information on bloom toxicity and variability, qPCR-linked species composition data, a rapid rotifer assay method, and a foundational dataset linking Karenia community structure with toxicological response. The findings will support SA DEW, Commonwealth agencies and other research users in understanding bloom impact pathways, improving future HAB response, and informing long-term monitoring and marine environmental management. Outputs • Integrated harmful algal bloom field, water-quality and toxicology dataset across Gulf St Vincent, Spencer Gulf and Investigator Strait [dataset] • Karenia species composition and abundance dataset derived from microscopy and qPCR analyses [dataset] • Toxicity assessment dataset incorporating rotifer bioassays and brevetoxin screening results [dataset] • Final technical report [written]

This record provides an overview of the NESP Marine and Coastal Hub Emerging Priorities project "A trophic-ecology based tool to assess and manage HAB impacts on marine ecosystems". For specific data outputs from this project, please see child records associated with this metadata. -------------------- South Australia’s 2025 harmful algal bloom (HAB) caused mortality across multiple trophic levels, from primary producers to top predators. This highlighted the need for tools that assess reef ecosystem condition and recovery using food-web structure, not only species counts or biomass estimates. This Emerging Priorities project will develop a trophic integrity framework for assessing subtidal reef condition across South Australia’s marine estate. The framework will support development of a Normalised Reef Status Index (NRSI) based on relative biomass across trophic levels, using biodiversity datasets from Reef Life Survey and the Australian Temperate Reef Collaboration, along with stereo-BRUV surveys and long-term habitat, plankton and water-quality monitoring. The project will model relationships between reef condition and environmental, disturbance and management drivers, enabling assessment of the 2025 HAB and marine heatwave impacts, recovery trajectories, and areas most vulnerable to future events. It will integrate existing and new biodiversity datasets with trophic and spatial analyses to provide a science-based assessment of subtidal reef condition. A web-based decision-support tool will be used to visualise reef condition, disturbance impacts and recovery, and to explore management options such as spatial protection, habitat restoration, fishing closures and rezoning. A technical report with management recommendations will support the SA HAB Science Program, state and Commonwealth agencies, marine park management, and public engagement. Outputs • Quantitative models linking trophic integrity indicators (including the NRSI) with environmental and management drivers [modelling framework] • Spatial prediction and vulnerability maps identifying reef areas most affected by the 2025 HAB and areas most susceptible to future disturbance events [dataset] • Interactive web-based decision-support dashboard for visualising reef condition, disturbance impacts and recovery trajectories, with scenario-testing functionality [tool] • Final technical report [written]

This record provides an overview of the NESP Marine and Coastal Hub Emerging Priorities project "Assessing impacts of harmful algal bloom events on South Australian benthic habitats". For specific data outputs from this project, please see child records associated with this metadata. -------------------- In early 2025, South Australia experienced an unprecedented harmful algal bloom (HAB) dominated by Karenia species, with high concentrations in Gulf St Vincent and Spencer Gulf. These gulfs support diverse benthic habitats, iconic biodiversity, and important commercial and recreational fisheries. The rapid development of the bloom and challenges associated with accessing affected areas limited timely assessment of impacts to benthic ecosystem. This Emerging Priorities project will assess HAB impacts by repeating recent benthic surveys at impacted sites across both gulfs. The project will take advantage of existing pre-bloom baseline data, allowing robust before-after comparisons with minimal confounding by seasonal or inter-annual trends. The assessment will integrate towed-camera habitat imagery, stereo-BRUV fish assemblage surveys, benthic trawl data and environmental measurements. Towed-camera resurveys will provide post-bloom imagery, and visual and quantitative assessments of habitat condition. Repeat stereo-BRUV surveys will assess changes in relative abundance, richness and composition of fish and larger invertebrate communities across seagrass and sand habitats. The findings will inform the South Australian HAB Science Program, support development of HAB-related coastal habitat monitoring, and provide evidence for state and Commonwealth agencies to prioritise future monitoring, research and management actions. Outputs • Post-HAB benthic imagery [imagery] • Quantitative assessment of impacts on benthic habitat and fish communities [dataset] • Final technical report [written]

Southeastern Australia's marine waters are undergoing a trend of increased warming, surpassing the global average. This area has emerged as an alluring location for research on planktic microfossils, particularly dinoflagellate cysts, which are abundant in contemporary and Late Quaternary sediments. The composition of dinoflagellate cyst assemblages offers valuable information about the physical and biogeochemical properties of mid-latitude waters in this region. This study presents an analysis of cyst assemblages from marine sediment cores from waters inshore and offshore Maria Island, Tasmania, southeast Australia, up to 9 kyrs BP. The dominant cysts were Protoceratium reticulatum, Protoperidinium spp. (P. avellana, P. conicum, P.minutum, 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. were more abundant (up to 61%), while P. reticulatum was dominant (up to 80%) at the offshore site. Impagidinium spp. and Nematosphaeropsis labyrinthus were exclusively detected offshore, with their increasing occurrence from 6 kyrs BP to present suggesting a transition from shallow coastal to stable deep-water habitat. Cysts of the Alexandrium tamarense complex were detected over the past 140 years and 9 kyrs BP at the inshore and offshore sites respectively, indicating an endemic long-term presence. Low abundances of Gymnodinium catenatum cysts were detected exclusively inshore from 50 years ago to present, suggesting recent bloom events. The limited southward penetration of the East Australian Current is indicated by the lack of warm-water cyst taxa such as Lingulodinium machaerophorum. Unlike coccolithophores, previously studied in the same sediment core, no discernible shift from cold to warm-water dinoflagellate cyst species was observed. The documentation of dinoflagellate cyst assemblages presented in this study will aid in predicting the effects of climate change, eutrophication, and introduction of novel species on local and broader community dynamics.