This dataset includes the biogeochemical (BGC) parameters collected and analysed from the National Reference Stations (NRS) excluding the biological compositional data which can be accessed through other products. Nine Sites are included in the IMOS NRS field sampling stations. Maria Island (TAS), Kangaroo Island (SA), Esperance (WA, discontinued 2013), Rottnest Island (WA), Ningaloo (WA, discontinued 2013), Darwin (NT), Yongala (QLD), North Stradbroke Island (QLD) and Port Hacking (NSW). All data included in this product are obtained from water samples collected from small vessels. Parameters in this product include salinity, carbon, alkalinity, oxygen, pigments (from High Performance Liquid Chromatography - HPLC), picoplankton cells count (from flow cytometry), secchi depth, total suspended matter (inorganic and organic components) and nutrients, comprising of ammonium, nitrate, phosphate and silicate. Over the course of the long-term monitoring program some parameters have been discontinued, others introduced and depths at which samples have been taken may have changed. Therefore, there may not be a continuous time series for each parameter, it is advised to consult the IMOS NRS Biogeochemical Operations Manual (Davies & Sommerville 2020) for more details.
Data is also available in this collection from other projects which collect and analyse samples in similar methods to the NRS. The biogeochemical data from South Australian Research and Development Institutes' (SARDI) sampling at non IMOS stations is included along with the nutrient and picoplankton data from the Coastal Sampling Station at Botany Bay (https://imos.org.au/facilities/facilities/microbial-coastal-sampling). The data from Port Philip Bay and Great Barrier Reef (GBR) sites for this project is provided in other collections.
This dataset supersedes the following collections: "IMOS National Reference Station (NRS) - Total Suspended Solids (TSS) and Secchi Depth" - https://catalogue-imos.aodn.org.au/geonetwork/srv/api/records/f439db64-5551-15d1-e043-08114f8ce23c ; "IMOS National Reference Station (NRS) - Picoplankton flow cytometry" - https://catalogue-imos.aodn.org.au/geonetwork/srv/api/records/fa93c66e-0e55-7e1d-e043-08114f8c1b76 ; "IMOS National Reference Station (NRS) - Salinity, Carbon, Alkalinity, Oxygen and Nutrients (Silicate, Ammonium, Nitrite/Nitrate, Phosphate)" - https://catalogue-imos.aodn.org.au/geonetwork/srv/api/records/fa93c66e-0e56-7e1d-e043-08114f8c1b76 and "IMOS National Reference Station (NRS) - Phytoplankton HPLC Pigment Composition Analysis" - https://catalogue-imos.aodn.org.au/geonetwork/srv/api/records/f48531e2-f182-56ca-e043-08114f8c7f2e (collections were removed from the AODN Portal in February 2022, and the data has been archived).
Maintenance and Update Frequency: asNeeded
Statement: Water samples are collected off small vessels at the IMOS National Reference Stations. The depth of the sample varies at each station. The sampling methods are fully described in the IMOS NRS Biogeochemical Operations Manual (Davies & Sommerville 2020). The analysis and quality control (QC) procedures performed at CSIRO are also described in this manual.
Triplicate samples are collected at 10 m intervals to have a nutrient distribution across the water column. For consistency across NRS stations, all samples are unfiltered and frozen. The averaged value for each depth is supplied here.
Carbon, alkalinity and dissolved oxygen
Carbon, alkalinity and dissolved oxygen represent important data to monitor the ‘marine biological pump’. Alkalinity and dissolved inorganic carbon (DIC) samples are returned to CSIRO Hobart for analyses. Measurements of carbon are provided in the form of dissolved inorganic carbon (DIC). Sample for DIC, alkalinity and dissolved oxygen are taken at 10 m intervals. While DIC and alkalinity samples are provided for all NRS, samples for dissolved oxygen are collected only at Maria Island (MAI) and Rottnest Island (ROT) stations.
Secchi disk and total suspended solid (TSS)
Secchi disk values provided by this collection represent the limit of visibility in the water column. These values are derived by the average of two depths, the depth the disk is just no longer visible, and the depth the disk becomes visible again. Total suspended solid (TSS) were collected in duplicate, now they are collected in triplicate with a blank. The averaged value of these measurements, accounting for the blank when present, is provided for total TSS, organic and inorganic TSS fraction.
Flow cytometry cells count
Flow cytometry analyses are performed to count specific phytoplankton cells, in this case Prochlorococcus, Synechococcus and Picoeukaryotes. The values provided by this product are derived by an average of two replicate for each sample.
High Performance Liquid Chromatography (HPLC)
HPLC analyses are performed to obtain phytoplankton pigment observation, from which it is possible to estimate the taxonomic composition of phytoplankton assemblages. These samples are currently collected at the surface and at the same depth as the shallowest water quality monitor (WQM) on the mooring, an average is provided here.
Statement: Sampling information at South Australian shelf and gulf sites - partially described in Van Ruth P.D., Patten N.L., Doubell M.J., Chapman P., Redondo Rodriguez A., Middleton J. 2018. Seasonal and event-scale variations in the influence of upwelling on enrichment and primary productivity in the eastern Great Australian Bight. Deep-Sea Research Part II, 157-158; 36-45. https://doi.org/10.1016/j.dsr2.2018.09.008
Statement: ATTRIBUTE STATEMENT: StationName - Name of the station where sample was collected TripCode - Unique code for the sampling trip SampleDate_Local - Sampling date (Local) SampleDate_UTC - Sampling date (UTC) Latitude - Nominal latitude (North) of the station where sample was collected (Degrees) Longitude - Nominal longitude (East) of the station where sample was collected (Degrees) Depth_m - Depth below surface of the water body where the sample was collected.
The dataset also includes a field which corresponds to unique sample identifiers that are assigned by the Australian Microbiome (AM) Initiative for corresponding water samples with microbial DNA sequencing data. These data handles resolve to the Bioplatforms Australia Data Portal the raw and processed DNA sequencing data pertaining to these samples is hosted. Please see the https://catalogue-imos.aodn.org.au/geonetwork/srv/api/records/d014c510-d49c-4e2d-8798-2e6e0e88a705 for further information.
Statement: The ’All Biogeochemical Parameters’ product only includes data from the National Reference Stations. This product combines all replicates to ensure one value per sampling trip for each depth. Raw data from the National Reference Stations, including all replicates, and data from SARDIs other moorings and from the Coastal Sampling Project are accessible through the raw products.
Australia’s Integrated Marine Observing System (IMOS) is enabled by the National Collaborative Research Infrastructure Strategy (NCRIS). It is operated by a consortium of institutions as an unincorporated joint venture, with the University of Tasmania as Lead Agent.
Environment Protection Authority Victoria (EPA), Victorian Government
University of Technology, Sydney (UTS)
The University of New South Wales (UNSW)