This record describes multibeam echosounder data collected on RV Investigator voyage IN2024_V03, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 2)." The voyage took place between May 01, 2024 and May 31, 2024 (AEST), departing from Hobart and returning to Sydney. The Kongsberg EM710 MKII multibeam echosounder was used to acquire seafloor bathymetry and backscatter information and watercolumn backscatter between the shelf areas of eastern Australia from Hobart, TAS to Sydney, NSW. The EM710 MKII provides a 0.5° by 1° transmit and receive angular resolution respectively. The echosounder's nominal frequency range is from 40 to 100 kHz. Data are stored in *.all raw format for bathymetry and backscatter and *.wcd format for watercolumn backscatter at CSIRO. There are 1,705 files totalling 174GB of raw data in this dataset. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format are corrected for motion and position. GPS tide was computed using PosMV data and then set to vertical datum EGM2008 model for approximate mean sea-level and applied to the processed data. Processed data has had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry grids in geotiff format. Additional information regarding this dataset, including further information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes multibeam echosounder data collected on RV Investigator voyage IN2024_V03, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 2)." The voyage took place between May 01, 2024 and May 31, 2024 (AEST), departing from Hobart and returning to Sydney. The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter between the shelf areas of eastern Australia from Hobart, TAS to Sydney, NSW. The EM122 provides a 1 degree by 1 degree angular resolution. The echosounder's nominal frequency is 12 kHz. Data are stored in *.all raw format for bathymetry and backscatter and *.wcd format for watercolumn backscatter at CSIRO. There are 62 files totalling 6.01GB of raw data in this dataset. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format are corrected for motion and position. GPS tide was computed using PosMV data and then set to vertical datum EGM2008 model for approximate mean sea-level and applied to the processed data. Processed data has had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry grids in geotiff format. Additional information regarding this dataset, including further information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2024_V03, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 2)." The voyage took place between May 01, 2024 and May 31, 2024 (AEST), departing from Hobart and returning to Sydney. The Simrad EK60 split beam echosounders for 18kHz and Simrad EK80 split beam echosounders for 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 1500 m, between the shelf areas of eastern Australia from Hobart, TAS to Sydney, NSW. All frequencies were logged continuously for the extent of the voyage. The frequencies 70kHz & 120kHz were set to passive for small periods of mapping during the voyage. Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 688 files totalling 64.3 GB of raw data in this dataset. No post processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes sub bottom profiler data collected on RV Investigator voyage IN2024_V03, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 2)." The voyage took place between May 01, 2024 and May 31, 2024 (AEST), departing from Hobart and returning to Sydney. The Kongsberg SBP120 (sub bottom profiler) was used to acquire data containing the specular reflections at different sediment interfaces below the seafloor. The SBP120 provides a 3° by 3° angular resolution. The echosounder's frequency sweep range is from 2.5 to 7 kHz. The SBP120 was logged continuously for the extent of the voyage. Data are stored in *.raw (1368 files 30.5 GB) raw and *.seg (1352 files 30.2 GB) segy formats at CSIRO. The segy format data had a real time processing stream applied, which applies gain, a gain correction, matched filter with replica shaping, an attribute calculation for instantaneous amplitude and time variable gain. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request

This data set contains the imagery collected on the Marine National Facility (MNF) RV Investigator voyage IN2024_V03, titled ‘Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 2) ." The voyage took place between May 01, 2024 and May 31, 2024 (AEST), departing from Hobart and returning to Sydney, collecting imagery of benthic habitats together with oceanographic data. Instrument(s) used to collect this data: MNF Deep Towed camera (DTC) Datasets include: Video (oblique forward view) Stereo stills (oblique forward view) Navigational data

This dataset is focusing on using environmental DNA (eDNA) to measure offshore marine biodiversity in Southeast Australia. The eDNA samples were collected during two SEA-MES voyages aboard the RV Investigator: IN2023_V05 (July 2023) and IN2024_V03 (May 2024). Sampling sites spanned the continental shelf, from Tasmania to Batemans Bay, NSW, with water collected from both surface and bottom depths via Niskin bottles and a deep-tow camera system. A total of over 100 CTD deployments were conducted across these sites, providing comprehensive spatial coverage. The dataset includes processed eDNA metabarcoding results, containing sequence read counts and taxonomic data derived from DNA sequences, with a focus on fish but extending across the full tree of life, including bacteria, invertebrates, and vertebrates. Over 180 million sequences were generated, using a variety of markers such as mtDNA 16S (fish), mtDNA COI Leray (metazoans), and V4 18S (eukaryotes). This dataset is valuable for understanding marine biodiversity in southeast Australia and advancing offshore eDNA techniques.

This dataset comprises the Multi-net plankton sampling collected during the SEA-MES program across four RV Investigator voyages (IN2023_V05, IN2024_V03, IN2024_V05, IN2025_V04). A total of 173 Multi-net operations were conducted, using 100 µm and 500 µm mesh nets to collect depth-stratified samples through the water column, capturing both day and night to assess diel vertical migration. The dataset includes 560 samples from 100 µm nets and 140 samples from 500 µm nets, providing information on zooplankton composition, biomass, and community structure, including 58,246 individuals from 105 genera and 70 families identified to date. These data provide a detailed view of pelagic biodiversity across the south-eastern continental shelf and upper slope of Australia.

This record describes Hydrology (HYD) data collected from the Marine National Facility (MNF) RV Investigator voyage IN2024_V03, titled: "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 2)." The voyage took place between May 1 and May 31, 2024, departing from Hobart (TAS) and arriving in Sydney (NSW) Hydrology samples were collected from Niskin bottles sampled at various depths during Conductivity-Temperature-Depth (CTD) deployments. Parameters analysed were salinity, dissolved oxygen, phosphate, silicate, nitrate plus nitrite and ammonium. This dataset has been processed (quality-controlled), and archived at the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC) in Hobart. Additional information regarding this dataset is contained in the Voyage Report and Data Processing Report.

This record describes the Underway (UWY) data collected from the Marine National Facility (MNF) RV Investigator voyage IN2024_V03, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 2)." The voyage took place between May 01, 2024 and May 31, 2024 (AEST), departing from Hobart and returning to Sydney. Standard Underway data is continuously recorded, consisting of: (1) Navigation data (NAV): Latitude, Longitude, Speed, Heading, Course Over Ground, Gyros, and Doppler Log (dual GPS instrument). (2) Thermosalinograph (TSG): Water Salinity, Flow-Rate, Temperature, Fluorescence, pCO2 and Optode/Oxygen. (3) Atmospheric (MET): Humidity, Wind Speed and Direction (vane and ultrasonic), Radiometer/Sea Surface Temperature, Pyranometer/Solar Radiation, Photosynthetically Active Radiation (PAR), Air Temperature, Air Pressure, Rain, Ozone and Trace Gases (port and starboard instruments). The quality-controlled RV Investigator underway meteorological and SST data are supplied to the IMOS AODN and other global data repositories and distributors, and made available for satellite SST validation by the Australian Bureau of Meteorology (BoM). Near real-time, unprocessed data are available via the link "Visualisation tool for Underway Data." This dataset has been processed (quality-controlled), and archived by the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC). Data are available at time intervals of 5 sec (NetCDF format), 5 sec, 10 sec, 1 min and 5 min (ASCII format). Note: not all variables are quality controlled; please check for existing QC flags in the datasets. Additional information regarding this dataset is contained in the Voyage Summary and/or the Data Processing Reports for this voyage.

This record describes the End of Voyage (EOV) data archive from the Marine National Facility (MNF) RV Investigator voyage IN2024_V03, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 2) ." The voyage took place between May 01, 2024 and May 31, 2024 (AEST), departing from Hobart and returning to Sydney. For further information please refer to the voyage documentation links. Instruments used and data collected include: Regular measurements: Lowered ADCP (LADCP), Acoustic Doppler Current Profiler (ADCP; 75 KHz), Disdrometer, Radon sensor, CTD, Hydrochemistry, Fisheries Echosounder (EK80), Multibeam Echosounder (EM710, EM122), Sub-bottom Profiler (SBP120), GPS Positioning System, Doppler Velocity Log, Thermosalinographs (TSG), Fluorometer, Oxygen Optode, pCO2, Atmospheric Temperature, Humidity, Pressure, Wind and Rain sensors, Photosynthetically Active Radiation (PAR) sensor, Precision Infrared Radiometer (PIR), Precision Spectral Pyranometer (PSP), ITI Trawl Net, Starboard and Portside Radiometers, Air Sampler, Ultra Short BaseLine Underwater Positioning System (USBL), Weather Radar. Voyage-specific measurements: Deep Towed Camera (DTC), Multiple Plankton Sampler (HydroBIOS Multinet), Demersal Trawl, Rectangular Midwater Trawl (RMT), Wildlife Observations (seabirds, cetaceans and seals). The archive for the IN2024_V03 EOV raw data is curated by the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC) in Hobart, with a permanent archive at the CSIRO Data Access Portal (https://data.csiro.au/), providing access to voyage participants and processors of the data collected on the voyage. All voyage documentation is available electronically to MNF support via the local network. Applications to access voyage documentation by non-CSIRO participants can be made via data-requests-hf@csiro.au All processed data from this voyage are made publicly available through the MNF Data Trawler (in the related links)