This dataset comprises the phytoplankton abundance and biovolume measurements from samples collected at the Integrated Marine Observing Systems (IMOS) National Reference Stations (NRS) and other repeatedly sampled stations. For information on using the data from the NRS stations please refer to Eriksen et al. 2019. It is advised that anyone using this data should read this methodology or contact the project contact person to understand the nuances of each sampling and analysis chain. The Southern Ocean Time Series (SOTS) phytoplankton data are collected and analysed as per Eriksen 2018.
The data are made available in binned products for ease of use. As taxonomy changes over time and the ability of analysts improves with training more and more species can be identified over time. The products account for these changes and for real absences from the samples. A 0 abundance means that the species was looked for and not seen, null (empty cell) means that the species was not looked for in that sample. The products are therefore applicable for use in time series analysis.
There are a total of 10 products to choose from.
Phytoplankton data are available as either abundance or biovolume, and each of these at 4 levels of binning:
Raw product (includes all data)
Species product (includes all data where species have been identified)
Genus product (includes all data binned to genus level)
Higher taxonomic group (includes all data binned to functional groups)
Derived indices – NRS only (useful indices at sample level for NRS data)
Depth Binned CTD Data – NRS only (NRS CTD data binned to 1m and matched to TripCode).
Plankton abundances were originally provided on the AODN Portal only as raw data, in flat table form (with each species recorded in a separate row), without any adjustments for taxonomy changes or real absences.
The first version of the "analysis-ready" products were first published on 04/04/2019. However, they were removed again in November 2020 because technical issues prevented them from being regularly updated.
This dataset supersedes the previous "IMOS National Reference Station (NRS) - Phytoplankton Abundance and Biovolume" - https://catalogue-imos.aodn.org.au/geonetwork/srv/api/records/dfef238f-db69-3868-e043-08114f8c8a94 (collection was removed from the AODN Portal in December 2021, and the data has been archived).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 described in Eriksen et al. 2019.
The SOTS data comes from the Southern Ocean Time Series project. The location is a fixed mooring with samples taken at various depths at regular intervals, methodologies and quality control procedures are described in Eriksen et al., 2020. The SOTS sub-facility publish Annual reports which include 'Sample' reports - which describe the 3 main types of samples and associated composition measurements, from shipboard sensor and sample measurements made during the service visits of the moorings.
1. Sediment trap samples collected by the Subantarctic Zone (SAZ) mooring.
2. Water samples collected by the RAS water sampler deployed on either the Pulse or Southern Ocean Flux Station (SOFS) mooring, and collected by the TM sampler deployed on the SOFS mooring.
3. Samples collected with other devices during the SOTS service voyages, e.g. from CTD Niskin bottles, in-situ pumps, continuous plankton recorders, and nets.
Note that not all these sample types were collected in any given year.
Data sampling is being conducted as part of a larger IMOS monitoring program. The zooplankton samples are analysed at the Plankton Ecology Lab at CSIRO Marine and Atmospheric Research, Queensland. The samples are settled in a 1000 ml measuring cylinder for 24 hours. The top 900ml is siphoned off once settled and the remainder is transferred into a 100ml measuring cyclinder and left to settle for 24 hours. Once settled the top 90 ml is siphoned off from these samples and the remainder is transfered into a sample jar. This is gently agitated and a 1ml sample is taken and transferred into a Segdwick rafter. The whole sample is scanned at 100x magnification to count large cells. The sample is then counted at 200x magnification to count up to 200 cells of one taxa or up to 400 squares of the Sedgwick rafter. Finally, the sample is counted at 640x magnification for small flagellates, up to 200 cells of one taxa or 20 sqaures on the Sedgwick rafter. These counts are then converted to cells / l and ml / l and the analysis data is exported to IMOS.
** All raw files and background information files can be accessed here - http://imos-data.s3-website-ap-southeast-2.amazonaws.com/?prefix=IMOS/BGC_DB/harvested_from_CSIRO/ **
Statement: For NRS stations only - Derived Indices
This index includes the total mass of living organisms in sea water collected with a 100-micron mesh net. Thus, values provided by this parameter comprise the organic carbon from the plankton.
Abundance is measured here as total number of elements (or individuals) for a specific taxon in sea water. This derived product is provided for phytoplankton (total number of cells), zooplankton and copepods (total number of animals).
Mean total length of copepods
This index provides the mean total length of copepod in the sample.
Mean volume of cells
This index provides the mean volume of a phytoplankton cell in the sample, calculated from the individual cell size, cell morphology and cell abundance.
Total phytoplankton carbon
Total mass of phytoplankton as carbon is calculated using standard conversion factors of biovolume to carbon for each cell, then summed (Montagnes-Berges 1994, Menden-Deuer & Lessard 2000, Verity & Langdon 1984, Vogt et al 2012, Caron et al 1995).
No of species in sample
Provided for copepods, phytoplankton, diatoms, dinoflagellates as an indicator of richness.
The Shannon diversity index is a statistical metric used to quantify rarity and commonness of species in a population. Indeed, Shannon diversity accounts for both species richness (the number of species present) and species abundance (the number of individuals per species) in the analysed population. This index is provided for copepods, phytoplankton, diatoms and dinoflagellates.
Shannon evenness provides a measure of biodiversity in the population analysed. The Shannon evenness index is derived from the Shannon diversity index, dividing Shannon diversity by its maximum. Thus, Shannon evenness can vary between 0 and 1, where 1 represents a complete evenness of the species in the analysed population. In this product the Shannon evenness index is provided for copepods, phytoplankton, diatoms and dinoflagellates.
Mixed layer depth (MLD)
Mixed layer depth (MLD) is derived from the Conductivity-Temperature-Depth (CTD) measurements, provided in the Depth binned CTD product. MLD is calculated and provided here in two different forms, from temperature and from salinity, following Condie and Dunn, 2006 methodology.
Deep chlorophyll maximum (DCM)
The deep chlorophyll maximum (DCM) represents the region below the sea water surface where the maximum concentration of chlorophyll occurs. For this specific product the DCM is provided as the depth (m) in which the maximum fluorescence value was recorded by the fluorometer installed on the CTD.
Sea surface components: temperature (CDTSST), chlorophyll-a (CDTChla) and salinity (CDTSalinity)
These indices are the mean values of the top ten metres of the water column and represent surface conditions measured at the time the sample was collected.
Chemistry: SiO4, PO4, NH4, NO3, NO2, O2, DIC and alkalinity
These are water column average values calculated from all the samples taken across multiple depths.
The mean value of chlorophyll-a plus divinyl chlorophyll-a from the pigments data as an indication of chlorophyll-a availability for phytoplankton.
Statement: ATTRIBUTE STATEMENT: Project - Name of the project the sample was collected for StationName - Name of the station where sample was collected StationCode - IMOS site code for station Latitude - Nominal latitude (North) of the station where sample was collected (Decimal degrees, WSG84 datum) Longitude - Nominal longitude (East) of the station where sample was collected (Decimal degrees, WSG84 datum) TripCode - Unique code for the sampling trip SampleTime_UTC - UTC date and time of sample collection SampleTime_local - Local date and time of sample collection Year_local - Year of sample collection Month_local - Month of sample collection Day_local - Day of month of sample collection (local time) Time_local24hr - Local 24hr time of sample collection SampleDepth_m - Depth of sample collection, or “integrated”, or “water column” CTDSST_degC - Temperature of the water column at 10m depth, from matching CTD cast CTDChlaSurf_mgm3 - Artificial chlorophyll concentration at 10m depth, computed from bio-optical sensor on matching CTD cast CTDSalinity_psu - Derived salinity of the water column at 10m depth, from matching CTD cast [taxonomic level name] (e.g., “Noctiluca scintillans”) - Taxonomic level abundance (plankton) or biovolume (phytoplankton) Method - Light microscopy or SEM, plus preservation methods
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