Over the past fifty years, Eastern Tasmanian waters have experienced rapid warming, primarily due to the extension of the East Australian Current. This has driven expansion of warm-water biota and decline of those adapted to cooler conditions, including phytoplankton. Presently, plankton monitoring, including diatoms along Eastern Tasmania, spans <100 years. This study reconstructed diatom communities throughout a sediment core spanning 9,000 years before present (9 kyrs BP), using microfossil analysis and molecular techniques, including sedimentary ancient DNA (sedaDNA) and NRS 18S rRNA from a 10-year water column archive at the Maria Island IMOS NRS mooring. Microfossil analysis revealed a dominance of strongly silicified benthic taxa (Campylodiscus, Diploneis, Paralia, Pyxidicula, Triceratium). Notably, Paralia sulcata showed a shift ~6 kyrs BP from small to larger cells, possibly reflecting a transition from a coastal to shelf ecosystem. However, microfossils underrepresented lightly silicified planktonic diatoms. Molecular methods detected higher diatom diversity, though up to 50% of sedaDNA reads remained unclassified due to reference library limitations. Lightly silicified planktonic genera (Chaetoceros, Corethron, Lithodesmium, Rhizosolenia) were identified only via molecular approaches and comprised 73% of sedaDNA and 88% of 18S rRNA records. Of 10 shared diatom families, 5, 15, and 4 were unique to microscopy, sedaDNA, and 18S rRNA, respectively. SedaDNA also captured greater benthic diversity. Our findings revealed limitations in reconstructing historic diatom assemblages from sediment cores. Microfossils faced constraints due to difficulties in morphological identification and preservation biases. In contrast, sedaDNA analysis yielded finer taxonomic resolution, provided access to high-quality reference sequence libraries were available.

This dataset has been superseded by https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/0145df96-3847-474b-8b63-a66f0e03ff54 (Victorian Statewide Marine Habitat Map 2023). The Victorian Benthic Habitats - Gippsland Lakes (CBICS) is a synthesis of all existing benthic habitat characterisations of the Gippsland Lakes Region which have been reclassified to conform to the Combined Biotope Classification Scheme (CBiCS). The study area for this layer is defined as Jack Smith Lake in the west to Mallacoota in the east.

This dataset has been superseded by https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/0145df96-3847-474b-8b63-a66f0e03ff54 (Victorian Statewide Marine Habitat Map 2023). The Victorian Benthic Habitats - Port Phillip Bay (CBICS) is a synthesis of all existing benthic habitat characterisations of the embayment which have been reclassified to conform to the Combined Biotope Classification Scheme (CBiCS). Base information for the synthesised dataset were sourced from data provided by: Marine and Freshwater Resources Institute, Queenscliff, Victoria Institute for Sustainability and Innovation, Victoria University, Melbourne. Parks Victoria, Victorian Government Deakin University, Victoria Department of Environment, Land, Water and Planning, Victorian Government

This dataset has been superseded by https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/0145df96-3847-474b-8b63-a66f0e03ff54 (Victorian Statewide Marine Habitat Map 2023). The Victorian Benthic Habitats - Western Port Bay (CBICS) is a synthesis of all existing benthic habitat characterisations of the embayment which have been reclassified to conform to the Combined Biotope Classification Scheme (CBiCS). Base layers for the synthesised dataset were sourced from data provided by: Marine and Freshwater Resources Institute, Queenscliff, Victoria Institute for Sustainability and Innovation, Victoria University, Melbourne. Parks Victoria, Victorian Government Deakin University, Victoria Department of Environment, Land, Water and Planning, Victorian Government