Benthic sediment sampling surveys in inner Darwin Harbour (GA0358) and shallow water areas in and around Bynoe Harbour (GA059) were undertaken in the period from 29 May to 16 August 2017. Partners involved in the surveys included Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and the Department of Environment and Natural Resources within the Northern Territory Government (NT DENR) (formerly the Department of Land and Resource Management (DLRM)). These surveys forms part of a four year (2014-2018) science program aimed at improving knowledge about the marine environments in the regions around Darwin and Bynoe harbour’s through the collection and collation of baseline data that will enable the creation of thematic habitat maps to underpin marine resource management decisions. This project is being led by the Northern Territory Government and is funded by the INPEX-led Ichthys LNG Project, in collaboration with - and co-investment from GA and AIMS. The program builds upon an NT Government project (2010-2011) which saw the collection of baseline data (multibeam echosounder data, sediment samples and video transects) from inner Darwin Harbour (Siwabessy et al. 2015). Here we present an account of the field methods and data summaries (location maps and comprehensive metadata) for the collection of 285 seabed sediment samples designated for grain size and inorganic elemental analyses, and organic matter concentration, source and reactivity measures. Metadata is also provided for seagrass and hardground observations. The seagrass observation data have been incorporated into DENR’s seagrass database. The baseline environmental datasets acquired during these surveys will be merged with like datasets from three other surveys conducted (i.e. GA0351/SOL6187, GA4452/SOL6432 and GA0356) as part of the overall project to create a set of interpolated maps of abiotic parameters with full coverage for the region. Some of the maps will be integrated into final habitat mapping products. Baseline data from the surveys will also be made publically available via the Geoscience Australia website ( http://www.ga.gov.au/ ).

This resource contains a predicted seabed gravel content grid for the greater Darwin Harbour region as part of a baseline seabed mapping program of Darwin Harbour and Bynoe Harbour. This project was funded through offset funds provided by an INPEX-led Ichthys LNG Project to the Northern Territory Government's Department of Environment and Natural Resources (NTG-DENR) with co-investment from Geoscience Australia (GA) and the Australian Institute of Marine Science (AIMS). The intent of this program is to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline data that enable the creation of thematic habitat maps and information to underpin marine resource management decisions. The predicted seabed gravel content grid was derived from a compilation of multiple surveys undertaken by GA, AIMS and NTG-DENR between 2011 and 2017, including GA0333 (Siwabessy et al., 2015), GA0341 (Siwabessy et al., 2015), GA0351/SOL6187 (Siwabessy et al., 2016), GA4452/SOL6432 (Siwabessy et al., 2017), GA0356 (Radke et al., 2017), and GA0358 and GA0359 (Radke et al., 2018), adding to those from a previous survey GA0333 collected by GA, AIMS and NTG-DENR. This dataset provides spatially continuous predictions of seabed %gravel (>2000 µm) content for the Darwin and Bynoe harbour region, northern Australian marine margin. Data are presented in 10 m resolution raster grids format and ascii text file. Predictions are based on 395 samples and 14 environmental variables derived from high resolution multibeam sonar bathymetry and backscatter data. Accuracy of predictions is high, with a VEcv = 59% for gravel; and the predictive accuracy has been increased by 68.4% for gravel in comparison with the commonly used method (i.e., IDW). Absences in predictions occur in this dataset as a result of non-availability associated with predictive variables. This dataset supersedes previous predictions of mud content for the Darwin and Bynoe harbour region with demonstrated improvements in predictive accuracy.

This resource contains a predicted seabed sand content grid for the greater Darwin Harbour region as part of a baseline seabed mapping program of Darwin Harbour and Bynoe Harbour. This project was funded through offset funds provided by an INPEX-led Ichthys LNG Project to the Northern Territory Government's Department of Environment and Natural Resources (NTG-DENR) with co-investment from Geoscience Australia (GA) and the Australian Institute of Marine Science (AIMS). The intent of this program is to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline data that enable the creation of thematic habitat maps and information to underpin marine resource management decisions. The predicted seabed sand content grid was derived from a compilation of multiple surveys undertaken by GA, AIMS and NTG-DENR between 2011 and 2017, including GA0333 (Siwabessy et al., 2015), GA0341 (Siwabessy et al., 2015), GA0351/SOL6187 (Siwabessy et al., 2016), GA4452/SOL6432 (Siwabessy et al., 2017), GA0356 (Radke et al., 2017), and GA0358 and GA0359 (Radke et al., 2018), adding to those from a previous survey GA0333 collected by GA, AIMS and NTG-DENR. This dataset provides spatially continuous predictions of seabed %sand (63-2000 µm) content for the Darwin and Bynoe harbour region, northern Australian marine margin. Data are presented in 10 m resolution raster grids format and ascii text file. Predictions are based on 395 samples and seven environmental variables derived from high resolution multibeam sonar bathymetry and backscatter data. Accuracy of predictions is high, with a VEcv = 39% for sand; and the predictive accuracy has been increased by 84.8% for sand in comparison with the commonly used method (i.e., IDW). Absences in predictions occur in this dataset as a result of non-availability associated with predictive variables. This dataset supersedes previous predictions of sand content for the Darwin and Bynoe harbour region with demonstrated improvements in predictive accuracy.

This resource contains a predicted seabed mud content grid for the greater Darwin Harbour region as part of a baseline seabed mapping program of Darwin Harbour and Bynoe Harbour. This project was funded through offset funds provided by an INPEX-led Ichthys LNG Project to the Northern Territory Government's Department of Environment and Natural Resources (NTG-DENR) with co-investment from Geoscience Australia (GA) and the Australian Institute of Marine Science (AIMS). The intent of this program is to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline data that enable the creation of thematic habitat maps and information to underpin marine resource management decisions. The predicted seabed mud content grid was derived from a compilation of multiple surveys undertaken by GA, AIMS and NTG-DENR between 2011 and 2017, including GA0333 (Siwabessy et al., 2015), GA0341 (Siwabessy et al., 2015), GA0351/SOL6187 (Siwabessy et al., 2016), GA4452/SOL6432 (Siwabessy et al., 2017), GA0356 (Radke et al., 2017), and GA0358 and GA0359 (Radke et al., 2018), adding to those from a previous survey GA0333 collected by GA, AIMS and NTG-DENR. This dataset provides spatially continuous predictions of seabed %mud (< 63 µm) content for the Darwin and Bynoe harbour region, northern Australian marine margin. Data are presented in 10 m resolution raster grids format and ascii text file. Predictions are based on 395 samples and nine environmental variables derived from high resolution multibeam sonar bathymetry and backscatter data. Accuracy of predictions is very high, with a VEcv = 62% for mud; and the predictive accuracy has been increased by 198.3% for mud in comparison with the commonly used method (i.e., IDW). Absences in predictions occur in this dataset as a result of non-availability associated with predictive variables. This dataset supersedes previous predictions of mud content for the Darwin and Bynoe harbour region with demonstrated improvements in predictive accuracy.