Australian Seagrass Occurence - Aggregated data product (1967 - ongoing) (NESP MaC 5.9, IMOS)

The Australian Seagrass Aggregated Data Product harmonises disparate seagrass datasets from providers across Australia into a single, standardised resource suitable for ecological assessment, long-term monitoring and habitat modelling. Seagrass observations across contributing datasets were acquired using a combination of direct field surveys and in water observational methods, selected according to site accessibility, water clarity and survey objectives. Intertidal meadows were commonly mapped using on foot low tide surveys, with observers delineating meadow boundaries and recording species presence using handheld GNSS units. Shallow subtidal and nearshore habitats were assessed through boat based transects, snorkel and photo quadrat surveys, supplemented in some state monitoring programs by underwater video, differential global positioning system (DGPS), bathyscope observations, and side scan sonar to verify habitat boundaries and species occurrence.Repeat aerial and satellite remote sensing surveys provided comprehensive spatial coverage for regional and long term mapping programs. Many legacy datasets, including NSW estuarine macrophytes and the Cockburn Sound historical time series, were derived from purpose flown aerial photography acquired under optimal water clarity conditions and subsequently digitised or classified into habitat polygons with field based validation. More recent datasets incorporated UAV (drone) orthomosaics to produce centimetre scale mapping of shallow reef flat meadows, alongside high resolution multispectral satellite imagery (WorldView 2, IKONOS and QuickBird 2) and medium resolution PlanetScope imagery to model seagrass distribution, species composition and biomass across broader spatial extents.Source data were contributed by institutions including the Institute for Marine and Antarctic Studies (IMAS), James Cook University’s Centre for Tropical Water and Aquatic Research (TropWATER), state government agencies in New South Wales, Queensland, Western Australia, South Australia, Victoria, Northern Territory and Tasmania, and research organisations including CSIRO, The Australian Institute of Marine Science (AIMS), The University of Western Australia (UWA) and The University of Queensland (UQ). Data was accessed primarily through Seamap Australia’s GeoServer infrastructure and institutional repositories. The geographic coverage spans the full extent of Australian coastal waters, with particularly dense data coverage in the Great Barrier Reef, Torres Strait, Gulf of Carpentaria, Hervey Bay, Moreton Bay, Cockburn Sound, and temperate southern coastlines including Tasmania and Victoria. The product records presence and absence of 13 seagrass species, including Cymodocea rotundata, C. serrulata, Enhalus acoroides, Halophila capricornia, H. decipiens, H. ovalis, H. spinulosa, H. tricostata, Halodule uninervis, Syringodium isoetifolium, Thalassodendron ciliatum, Thalassia hemprichii and Zostera muelleri subsp. capricorni. Source datasets differ widely in schema, geometry formats, temporal encodings, and species representations. All inputs are validated, normalised, All taxa have been mapped to the Codes for Australian Aquatic Biota (CAAB, 2024) controlled vocabulary and aligned with the World Register of Marine Species (WoRMS) taxonomy and transformed into a unified long‑format Parquet dataset. Each record is tagged with enhanced metadata, including links to Australian Marine Parks and Commonwealth marine regions, along with a H3 spatial index (resolution 15, ~1m2) to support subsetting and temporal/spatial analysis.