Phytoplankton samples collected on the CLIVAR voyage of the Aurora Australis, 2001

• Other Authors: AADC (originator), AU/AADC > Australian Antarctic Data Centre, Australia (resourceProvider)
• Format: Dataset
• Language: unknown
• Published: Australian Ocean Data Network
• Subjects: biota; oceans; PHYTOPLANKTON; EARTH SCIENCE; BIOLOGICAL CLASSIFICATION; PROTISTS; PLANKTON; CTD > Conductivity Temperature Depth; NISKIN BOTTLES; R/V AA > R/V Aurora Australis; SHIPS; AMD/AU; AMD; CEOS; OCEAN > SOUTHERN OCEAN; GEOGRAPHIC REGION > POLAR; Antarctic; Southern Ocean; The Antarctic; Antarc*; Antarctica; aurora australis; Sea ice
• Online Access: https://researchdata.edu.au/phytoplankton-samples-collected-australis-2001/1698246; https://data.aad.gov.au/metadata/records/ASAC_1343_phytoplankton_samples; https://data.aad.gov.au/aadc/biodiversity/display_collection.cfm?collection_id=158; https://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_1343_phytoplankton_samples; https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=AAS_1343

Taken from the methods section of the attached paper: Sampling Strategy Eight CTD stations were visited cruising southwards; two stations at 63.9 degrees S (SIZ), 60.9 degrees S (SAZ) were re-visited after 11 and 17 days from the first sampling, respectively. A station at 51 degrees S was sampled for phytoplankton determination during the northbound transect. The stations at 63.9 degrees S were covered by sea ice (CTD 85: ~40-45%; CTD 127: ~25-30%) at the time of sampling. At 64.9 degrees S (CTD 122) sampling was carried out in ice-free (less than 15%) but ice-melt water. Water samples were collected with Niskin bottles from four standard depths (5, 25, 50 and 70m) at all sites except at 46.9 and 48.8 degrees S (CTD 15 and 23) where they were collected at 10, 30, and 60 m. The same standard depths were chosen for the assessment of new production. At stations between 53.7 and 64.9 degrees S (CTD 50-73, 85-122) additional samples were obtained from 90-100 m. At CTD 50, teh depth of 150 m was included, and at CTD 64, the depths of 130, 170, and 200 m were also sampled. Depths below 70 m were sampled at the occasion of collecting diatoms and particles exported from the mixed layer. Since the mean mixed layer depth was 70 m, we mainly concentrate on phytoplankton data analysis from the upper 70 m water column. Locations of sampling sites for ASAC project 40/1343 on voyage 3 of the Aurora Australis in the 2001/2002 season. The dataset also contains information on chlorophyll, carotenoids, coccolithophorids and species indentification and counts. The data can be accessed via the Biodiversity Database at the provided URL. From the abstract of the referenced publication: Variations of phytoplankton assemblages were studied in November-December 2001, in surface waters of the Southern Ocean along a transect between the Sub-Antarctic Zone (SAZ) and the Seasonal Ice Zone (SIZ; 46.9-64.9 degrees S; 142-143 degrees E; CLIVAR-SR3 cruise). Two regions had characteristic but different phytoplankton assemblages. Nanoflagellates (less than 20 microns) and pico-plankton (~2 microns) occurred in similar concentrations along the transect, but were dominant in the SAZ, Sub-Antarctic Front (SAF), Polar Front Zone (PFZ) and the Inter-Polar Front Zone (IPFZ), (46.9-56.9 degrees S). Along the entire transect their average cell numbers in the upper 70 m of water column, varied from 300,000 to 1,100,000 cells per litre. Larger cells (greater than 20 microns), diatoms and dinoflagellates, were more abundant in the Antarctic Zone-South (AZ-S) and the SIZ (60.9-64.9 degrees S). In AZ-S and SIZ diatoms ranged between 270,000 and 1,200,000 cells per litre, dinoflagellates from 31,000 to 102,000 cells per litre. A diatom bloom was in progress in the AZ-S showing a peak of 1,800,000 cells per litre. Diatoms were dominated by Pseudo-nitzschia spp., Fragilariopsis spp., and Chaetoceros spp. Pseudo-nitzschia spp. outnumbered other diatoms in the AZ-S. Fragilariopsis spp. were most numerous in the SIZ. Dinoflagellates contained autotrophs (eg Prorocentrum) and heterotrophs (Gyrodinium/Gymnodinium, Protoperidinium). Diatoms and dinoflagellates contributed most to the cellular carbon: 11-25 and 17-124 micrograms of carbon per litre, respectively. Small cells dominated in the northern region characterised by the lowest N-uptake and new production of the transect. Larger diatom cells were prevalent in the southern area with higher values of N-uptake and new production. Diatom and nanoflagellate cellular carbon contents were highly correlated with one another, with primary production, and productivity related parameters. They contributed up to 75% to the total autotrophic C biomass. Diatom carbon content was significantly correlated to nitrate uptake and particle export, but not to ammonium uptake, while flagellate carbon was well correlated to ammonium uptake, but not to export. Diatoms have contributed highly to particle export along the latitudinal transect, while flagellates played a minor role in the export. This work was completed as part of ASAC projects 40 and 1343. See also the related metadata record, "Spring Phytoplankton Assemblages in the Southern Ocean Between Australia and Antarctica".