Seagrass beds are a dominant marine ecosystem of Tayaritja (the Furneaux Group of Islands) in the north-eastern waters off Tasmania. Historical coarse mapping has indicated extensive beds of Posidonia, Amphibolis, Heterozostera, and Zostera species, potentially comprising some of the largest and deepest seagrass extents found in temperate Australian waters. However, limited data on the distribution and ecological value of these seagrass habitats represents a significant knowledge gap in understanding Australia's wetland natural assets. This project mapped the extent, ecological composition, population structure, and blue carbon value of seagrass beds around Tayaritja, in partnership with the Tasmanian Aboriginal Centre. This record specifically describes the seagrass population genetics component of the project. Leaf tissue samples were collected from four seagrass species: Amphibolis antarctica, Heterozostera nigricaulis, Posidonia australis and Zostera muelleri. Samples were collected from multiple sites around Tayaritja Sea Country and processed for genome-wide SNP genotyping using the DArTseq platform. The dataset includes population-level genetic summary statistics, associated DArT metadata and reports, and raw sequence data used to support assessment of genetic diversity, clonality, population structure and connectivity among sampled seagrass populations. See the "Lineage" section of this record for full methodology. ***EMBARGO NOTE*** Data is currently embargoed until 31/12/2026. Please contact the NESP Data Wrangler (Southern node) to discuss access options: Emma.Flukes@utas.edu.au

Changes in seagrass coverage in Cockburn Sound from 1967 to 1999 were assessed from aerial photographs using modern mapping methods with the aim of accurately determining the magnitude of change in hectares of seagrasses between 1967 and 1999.