Data

Phytoplankton Biogeochemistry Logbooks from the Denman Marine Voyage of the RSV Nuyina, 2025

Australian Antarctic Division

Latour, P. ; LATOUR, PAULINE

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ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rfr_id=info%3Asid%2FANDS&rft_id=info:doi10.26179/j743-j410&rft.title=Phytoplankton Biogeochemistry Logbooks from the Denman Marine Voyage of the RSV Nuyina, 2025&rft.identifier=10.26179/j743-j410&rft.publisher=Australian Antarctic Data Centre&rft.description=These data were collected on voyage 3 of the RSV Nuyina in the 2024/2025 season. The voyage was colloquially known as the Denman Marine Voyage, as it operated in the vicinity of the Denman Glacier.During the Denman Marine Voyage, the aim of the Biology team was to study the parameters controlling phytoplankton growth near the Denman Glacier and within the Shackleton Polynya. Phytoplankton are microscopic single cell organisms playing key roles in the carbon cycle – through photosynthesis, and in supporting marine ecosystems, by being at the base of most oceanic food webs. In the Southern Ocean, phytoplankton is generally limited by iron, a trace metal present in very low concentrations. However, primary productivity tends to increase strongly near shelfs, where iron supply is much larger. Historical satellite recordings have repeatedly shown higher phytoplankton growth in the Shackleton polynya compared to the waters near the Denman Glacier. To study this, we sampled the CTD for multiple biological parameters (photophysiology, community composition, chlorophyll concentrations, particulate organic carbon, biogenic silica, carbon uptake and bacterial production), associated with trace metal measurements from nearby TMR deployments. We also performed bioassay incubations at two ‘process stations’, one near the Denman Glacier and one within the Shackleton polynya, where we incubated natural phytoplankton communities under modified conditions (e.g., different light or metal levels). Additional underway and opportunistic samples were performed when encountering features of interest (e.g., subsurface iceberg meltwater, aerosols).This dataset contains data of extracted chlorophyll-a (Chl-a) concentrations and photophysiology measured through Fast Repetition Rate Fluorometry (FRRF). Further sample analyses will provide data on particulate organic carbon (POC), biogenic silica (BSi), community composition (through flow cytometry, pigments measurements and microscopy for phytoplankton taxonomy), primary productivity (through use of 14C) and bacterial production (through 3H-leucine). Progress Code: completedStatement: Chlorophyll-a samples were collected from the CTD/TMR, underway system or bioassay incubations by filtering ~1L of seawater through a 25mm GF/F filter. Filters were kept at -20°C until analyses. Samples were measured after pigment extraction in 90% acetone for 18 to 24h at -20°C, onto a Turner trilogy fluorometer (Holm-Hansen et al. 1965). Results were blank corrected using 90% acetone from the batch of extraction. Samples for photophysiology were collected from the CTD/TMR, underway system and bioassay incubations. Photophysiology was studied using a Fast Repetition Rate Fluorometer (450 nm excitation; Chelsea) after low light (&rft.creator=Latour, P. &rft.creator=LATOUR, PAULINE &rft.date=2025&rft.coverage=westlimit=93.6; southlimit=-66.2; eastlimit=142; northlimit=-47&rft.coverage=westlimit=93.6; southlimit=-66.2; eastlimit=142; northlimit=-47&rft_rights=These data are not yet publicly available for download.&rft_rights=Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/legalcode&rft_rights=This data set conforms to the CCBY Attribution License (http://creativecommons.org/licenses/by/4.0/). Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=AAS_4630_voyage_202425030_DMV_Phytoplankton_Biogeochemistry when using these data.&rft_rights=This metadata record is publicly available.&rft_subject=oceans&rft_subject=biota&rft_subject=EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > PIGMENTS > CHLOROPHYLL&rft_subject=EARTH SCIENCE > BIOLOGICAL CLASSIFICATION > PROTISTS > PLANKTON > PHYTOPLANKTON&rft_subject=EARTH SCIENCE > BIOSPHERE > ECOSYSTEMS > AQUATIC ECOSYSTEMS > PLANKTON > PHYTOPLANKTON&rft_subject=EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > BIOGEOCHEMICAL CYCLES&rft_subject=PHYSIOLOGY&rft_subject=BIOLOGICAL SAMPLING&rft_subject=DENMAN&rft_subject=DMV&rft_subject=FLUOROMETERS > FLUOROMETERS&rft_subject=NISKIN BOTTLES&rft_subject=R/V Nuyina > R/V Nuyina&rft_subject=AMD/AU&rft_subject=AMD&rft_subject=CEOS&rft_subject=OCEAN > SOUTHERN OCEAN > EAST ANTARCTIC CONTINENTAL SHELF&rft_subject=OCEAN > SOUTHERN OCEAN&rft_subject=CONTINENT > ANTARCTICA > DENMAN GLACIER&rft_subject=GEOGRAPHIC REGION > POLAR&rft.type=dataset&rft.language=English Access the data

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These data are not yet publicly available for download.

This data set conforms to the CCBY Attribution License (http://creativecommons.org/licenses/by/4.0/). Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=AAS_4630_voyage_202425030_DMV_Phytoplankton_Biogeochemistry when using these data.

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These data were collected on voyage 3 of the RSV Nuyina in the 2024/2025 season. The voyage was colloquially known as the "Denman Marine Voyage", as it operated in the vicinity of the Denman Glacier.

During the Denman Marine Voyage, the aim of the Biology team was to study the parameters controlling phytoplankton growth near the Denman Glacier and within the Shackleton Polynya. Phytoplankton are microscopic single cell organisms playing key roles in the carbon cycle – through photosynthesis, and in supporting marine ecosystems, by being at the base of most oceanic food webs. In the Southern Ocean, phytoplankton is generally limited by iron, a trace metal present in very low concentrations. However, primary productivity tends to increase strongly near shelfs, where iron supply is much larger. Historical satellite recordings have repeatedly shown higher phytoplankton growth in the Shackleton polynya compared to the waters near the Denman Glacier. To study this, we sampled the CTD for multiple biological parameters (photophysiology, community composition, chlorophyll concentrations, particulate organic carbon, biogenic silica, carbon uptake and bacterial production), associated with trace metal measurements from nearby TMR deployments. We also performed bioassay incubations at two ‘process stations’, one near the Denman Glacier and one within the Shackleton polynya, where we incubated natural phytoplankton communities under modified conditions (e.g., different light or metal levels). Additional underway and opportunistic samples were performed when encountering features of interest (e.g., subsurface iceberg meltwater, aerosols).

This dataset contains data of extracted chlorophyll-a (Chl-a) concentrations and photophysiology measured through Fast Repetition Rate Fluorometry (FRRF). Further sample analyses will provide data on particulate organic carbon (POC), biogenic silica (BSi), community composition (through flow cytometry, pigments measurements and microscopy for phytoplankton taxonomy), primary productivity (through use of 14C) and bacterial production (through 3H-leucine).

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Progress Code: completed

Statement: Chlorophyll-a samples were collected from the CTD/TMR, underway system or bioassay incubations by filtering ~1L of seawater through a 25mm GF/F filter. Filters were kept at -20°C until analyses. Samples were measured after pigment extraction in 90% acetone for 18 to 24h at -20°C, onto a Turner trilogy fluorometer (Holm-Hansen et al. 1965). Results were blank corrected using 90% acetone from the batch of extraction. Samples for photophysiology were collected from the CTD/TMR, underway system and bioassay incubations. Photophysiology was studied using a Fast Repetition Rate Fluorometer (450 nm excitation; Chelsea) after low light (<2 µmol photons m-2 s-1) acclimation of natural phytoplankton communities for 20-30min. Fast Repetition Rate Fluorometry was used to determine the maximum photochemical efficiency (Fv/Fm) and functional absorption cross section (σPSII) of photosystem II (PSII). After the low light acclimation period, samples were exposed to 120 flashes of light every 2 μsec (saturation sequence) to saturate PSII and the first stable electron acceptor, QA, after which the time interval between flashes was increased exponentially (relaxation sequence) for 60 flashes. Fv/Fm (where Fv = Fm − Fo) was calculated from Fo and Fm, which refer to the minimum and maximum fluorescence, respectively, in the dark-acclimated state. Fv/Fm and σPSII were determined from the mean of 200 iterations of the fluorescence induction and relaxation protocol measured at 450 nm.

Data time period: 2025-03-02 to 2025-04-24