Understanding benthic biodiversity across depth gradients is critical for conservation of Antarctic marine ecosystems. As part of the TEMPO voyage conducted by the Australian Antarctic Division in 2021, we characterise East Antarctic benthic communities from shallow shelf environments to abyssal depths exceeding 4,000 m. We combined environmental DNA (eDNA) metabarcoding using four mitochondrial markers targeting animals, mammals, fishes, and krill with underwater imagery to provide complementary biodiversity assessments across this depth range. While imagery provided visual documentation of benthic communities and substrate composition, eDNA consistently detected higher species richness. We identified spatial hotspots of elevated alpha and beta diversity coinciding with areas of enhanced current convergence, potentially associated with seafloor current and topography. Interestingly, baleen whale eDNA was detected at abyssal depths, suggesting the possible presence of whale falls on the seafloor. Ordination analyses revealed variable benthic communities across depth zones in both datasets. Procrustes analysis revealed substantial incongruence between eDNA and imagery community matrices, suggesting these methods capture complementary facets of benthic biodiversity. Community composition in both datasets was significantly structured by depth and substrate, though environmental variables were strongly intercorrelated across the depth gradient, precluding attribution to individual drivers. Together, these complementary datasets provide an unprecedented biodiversity overview of East Antarctic benthic environments and highlight the value of multi-marker eDNA approaches for deep-sea ecological assessment.

Microorganisms underpin Antarctic biogeochemical cycling and ecosystem resilience, yet marine microbial diversity across East Antarctica remains poorly characterised. Addressing biodiversity gaps in previously unstudied regions is essential for understanding heterogeneity around Antarctica and assessing vulnerability to environmental change. The Bunger Hills, one of the continent’s largest ice-free oases, has been the focus of terrestrial sediment geochemistry, sedimentology, and epishelf lake research, but lacks molecular assessments of marine sediment microbial communities despite increasing environmental pressures. In contrast, marine sediment microbiomes near Casey Research Station, approximately 450 km east, have been well studied. We characterised bacterial community composition of marine sediment across 13 sites in the Bunger Hills, alongside a control site at Casey Research Station. Using 16S rRNA gene amplicon sequencing, we evaluated spatial structuring, habitat specificity, and seawater–sediment connectivity across regions. Microbial assemblages differed between the Bunger Hills and Casey Station, with greater within-site heterogeneity in the Bunger Hills. Differential abundance analyses identified 166 bacterial families that varied between locations. Furthermore, there was limited taxonomic overlap between bacterial communities in sediments and seawater, reflecting distinct ecological niches. These findings provide the first molecular baseline of marine microbial diversity in the Bunger Hills and position this understudied region within a broader East Antarctic context. Establishing this baseline is critical for detecting ecological shifts from climate-driven change and improving predictions of Antarctic ecosystem responses.

Antarctic seafloor biodiversity is unique, more than half of its species are endemic. However, the distribution of this biodiversity is poorly understood, and missing baseline data is hindering informed management and conservation. For this research project, we combined information extracted from seafloor images with environmental variables and used statistical models to, for the first time, predictively map the distribution of seafloor biodiversity on the entire Antarctic continental shelf. We identify hotspots of morphospecies richness and epifaunal cover, and show biodiversity hotspots are most prevalent in shallow, cold, food-rich environments with strong seafloor currents and little sedimentation. The colder half of the Antarctic continental shelf hosts 84% of seafloor biodiversity hotspots, highlighting its potential vulnerability to ocean warming. We assess spatial management and show only 14% of hotspots occur within existing marine protected areas. Identifying areas considered important for multiple components of the marine ecosystem, a key consideration in spatial management, reveals predicted seafloor biodiversity hotspots overlap 21-times more than expected at random with pelagic conservation priority areas identified from seabird and mammal tracks. We assess changes in future environmental conditions and highlight vulnerable vs more resilient areas on the Antarctic continental shelf. Our analysis reveals new seafloor biodiversity hotspots and provides managers and stakeholders with new information critical to conserve one of the most unique marine ecosystems on Earth.

Dispersal between populations is a fundamental mechanism that maintains genetic connectivity across species ranges. In the Southern Ocean, a large part of the benthos shows direct development, seeming to negate the possibility of dispersal via larval movement. Yet, genetic connectivity is observed between distant populations. Passive dispersal processes have been widely proposed as potential mechanisms underlying this connectivity. However, dispersal distances of Southern Ocean invertebrates over generational timescales remain unknown, leaving the mechanisms underlying connectivity to be evaluated. Here, we examine genome-wide single nucleotide polymorphisms of a direct developing circum-Antarctic sea slug of the Doris “kerguelenensis” cryptic species complex (species 29), in samples across the Palmer Archipelago (0-50km) and Western Antarctic Peninsula (~600km). We detected mostly short (n=48) and some long (n=9) geographic distances (0-5km and >30km respectively) separating close-kin pairs, indicating that long-distance dispersal mechanisms occur generationally. Short distances between full-sibling dyads (n=3) indicated full-siblings remain spatially aggregated. Thus, the longer distances separating more distantly related kin suggest the passive dispersal of egg masses during early development. Our results demonstrate how direct developing benthic invertebrates might be dispersing across the Southern Ocean. Understanding dispersal capacity in Southern Ocean species is critical for assessing resilience to climate driven environmental change.

The Antarctic and sub-Antarctic remain largely free from non-native marine species but are vulnerable to their introduction, with vessel biofouling identified as the primary vector for Southern Ocean introductions. We investigated the potential for eDNA sampling to be used to detect the transport of biofouling species within the internal seawater systems and niche areas of a vessel. eDNA samples were collected whilst underway from the uncontaminated seawater intake, moon pool and raw water systems across three voyages of the icebreaker RSV Nuyina in the 2024-25 and the 2025-26 season to Antarctica and Heard Island. Samples were amplified with three mitochondrial metabarcoding markers targeting animals broadly and molluscs and arthropods more specifically, to gain a wide overview of taxa present. 58 known biofouling species were identified across the three voyages, with some taxa detected throughout the voyages whilst others were only detected in a subset of samples. Taxa detected included the mussel Mytilus galloprovincialis and crab Carcinus maenas, both of which have invasive life-histories and may be capable of surviving in current sub-Antarctic and future Antarctic conditions. Our findings highlight the potential for the transport of biofouling species within these niche areas on vessels despite best-practice biofouling management being implemented.

The Kunming-Montreal Global Biodiversity Framework (KMGBF) prioritises that “the integrity, connectivity and resilience of all ecosystems are maintained, enhanced, or restored” with explicit reference to genetic diversity. Heard Island and McDonald Islands (HIMI) arise from the Kerguelen Plateau. The plateau's unique volcanic geological history and oceanographic position, intercepting the Antarctic Circumpolar Current, contributes to a highly productive region. This supports a biodiverse benthic ecosystem, including a lucrative fishery. A marine reserve was implemented in 2002, which now covers 92% of the HIMI Exclusive Economic Zone and contributes towards Australia’s 30x30 KMGBF target.

Despite this, research is limited regarding the genetic diversity and connectivity of the benthos within HIMI and how this diversity compares to the broader Southern Ocean. This lack of baseline data, which underpins their resilience to climate change, has major implications for conservation of the benthos.

Here, using five echinoderm and two cephalopod taxa we evaluate the diversity within and outside the reserve boundaries and provide the first comprehensive insight into the genetic diversity and connectivity of the HIMI benthos.

This dataset enhances our understanding of the HIMI benthos, supporting key priorities outlined within the Australian Antarctic Science Decadal Strategy which will inform future HIMI reserve management plans.

Antarctic marine coastal environments harbour high levels of biodiversity, yet most of what we know about marine biodiversity in East Antarctic comes from a tiny handful of places. One of the aims of the Biodiversity of East Antarctica: Underwater and Terrestrial (BEAUT) project is to expand and enhance our knowledge of biodiversity in Antarctic coastal ecosystems. Biodiversity information is critical in establishing baselines for assessing ecosystem responses to environmental change. During the 2024/25 season, in collaboration with the SAEF Marine Drivers project, we conducted the first strategic sampling campaign of the Bunger Hills marine ecosystem. This area is unique on the Antarctic coast as is it is a seasonally sea ice free marine system bordered by a permanent ice shelf rather than sea ice, sandwiched between the Bunger Hills ice free landmass and several glaciers. We conducted an extensive sampling program using ROV’s, grabs and other methods to describe and quantify biodiversity and community structure to understand drivers of biodiversity and ecological processes in this area. A range of communities were sampled including marine sediment macrofauna and meiofauna, bacterial, epibenthic and zooplankton, as well as a range of environmental variables. Preliminary findings of this work will be presented, which contributes to increasing our understanding of biodiversity patterns in East Antarctica.