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  • 1
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    Meteorology and oceanography of the Atlantic sector of the Southern Ocean—a review of German achievements from the last decade (2016)
    Springer
    Details
    Publication Date: 2023-03-09
    Description: In the early 1980s, Germany started a new era of modern Antarctic research. The Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) was founded and important research platforms such as the German permanent station in Antarctica, today called Neumayer III, and the research icebreaker Polarstern were installed. The research primarily focused on the Atlantic sector of the Southern Ocean. In parallel, the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) started a priority program ‘Antarctic Research’ (since 2003 called SPP-1158) to foster and intensify the cooperation between scientists from different German universities and the AWI as well as other institutes involved in polar research. Here, we review the main findings in meteorology and oceanography of the last decade, funded by the priority program. The paper presents field observations and modelling efforts, extending from the stratosphere to the deep ocean. The research spans a large range of temporal and spatial scales, including the interaction of both climate components. In particular, radiative processes, the interaction of the changing ozone layer with large-scale atmospheric circulations, and changes in the sea ice cover are discussed. Climate and weather forecast models provide an insight into the water cycle and the climate change signals associated with synoptic cyclones. Investigations of the atmospheric boundary layer focus on the interaction between atmosphere, sea ice and ocean in the vicinity of polynyas and leads. The chapters dedicated to polar oceanography review the interaction between the ocean and ice shelves with regard to the freshwater input and discuss the changes in water mass characteristics, ventilation and formation rates, crucial for the deepest limb of the global, climate-relevant meridional overturning circulation. They also highlight the associated storage of anthropogenic carbon as well as the cycling of carbon, nutrients and trace metals in the ocean with special emphasis on the Weddell Sea.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    The physiological response of an Antarctic key phytoplankton species to low iron and manganese concentrations (2023)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2024-03-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Iron (Fe) and manganese (Mn) availability and the divergent requirements of phytoplankton species were recently shown to be potential important drivers of Southern Ocean community composition. Knowledge about Antarctic phytoplankton species requirements for Fe and Mn remains, however, scarce. By performing laboratory experiments and additional calculations of the photosynthetic electron transport, we investigated the response of the ecologically important species 〈italic toggle="no"〉Phaeocystis antarctica〈/italic〉 under a combination of different Fe and Mn concentrations. Fe deprivation alone provoked typical physiological characteristics of Fe limitation in 〈italic toggle="no"〉P. antarctica〈/italic〉 (e.g., lowered growth and photosynthetic efficiency). In comparison, under Mn deprivation alone, the growth and carbon production of 〈italic toggle="no"〉P. antarctica〈/italic〉 were not impacted. Its tolerance to cope with low Mn concentrations resulted from an efficient photoacclimation strategy, including a higher number of active photosystems II through which fewer electrons were transported. This strategy allowed us to maintain similar high growth and carbon production rates as FeMn‐enriched cells. Due to its low Mn requirement, 〈italic toggle="no"〉P. antarctica〈/italic〉 performed physiologically as Fe‐deprived cells under the combined depletion of Fe and Mn. Hence, our study reveals that different from other Southern Ocean phytoplankton species, 〈italic toggle="no"〉P. antarctica〈/italic〉 possesses a high capacity to cope with natural low Mn concentrations, which can facilitate its dominance over others, potentially explaining its ecological success across the Southern Ocean.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.1594/PANGAEA.944462
    Keywords: ddc:577.7 ; Southern Ocean ; Antarctic phytoplankton ; Trace metal ; photophysiology ; carbon fixation
    Language: English
    Type: doc-type:article
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    CITATION GEO-LEO
  • 3
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    Ocean acidification decreases the light-use efficiency in an Antarctic diatom under dynamic but not constant light, link to supplementary data (2015)
    PANGAEA
    In:  Supplement to: Hoppe, Clara Jule Marie; Holtz, Lena-Maria; Trimborn, Scarlett; Rost, Björn (2015): Ocean acidification decreases the light-use efficiency in an Antarctic diatom under dynamic but not constant light. New Phytologist, 207(1), 159-171, https://doi.org/10.1111/nph.13334
    Details
    Publication Date: 2023-04-05
    Description: There is increasing evidence that different light intensities strongly modulate the effects of ocean acidification (OA) on marine phytoplankton. The aim of the present study was to investigate interactive effects of OA and dynamic light, mimicking natural mixing regimes. The Antarctic diatom Chaetoceros debilis was grown under two pCO2 (390 and 1000 latm) and light conditions (constant and dynamic), the latter yielding the same integrated irradiance over the day. To characterize interactive effects between treatments, growth, elemental composition, primary production and photophysiology were investigated. Dynamic light reduced growth and strongly altered the effects of OA on primary production, being unaffected by elevated pCO2 under constant light, yet significantly reduced under dynamic light. Interactive effects between OA and light were also observed for Chl production and particulate organic carbon (POC) quotas. Response patterns can be explained by changes in the cellular energetic balance. While the energy transfer efficiency from photochemistry to biomass production (Phi_e,C) was not affected by OA under constant light, it was drastically reduced under dynamic light. Contrasting responses under different light conditions need to be considered when making predictions regarding a more stratified and acidified future ocean.
    Type: Dataset
    Format: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, 48.3 kBytes
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    DATA PANGAEA
  • 4
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    Responses of a natural phytoplankton community from the Drake Passage to two predicted climate change scenarios (2022)
    PANGAEA
    Details
    Publication Date: 2023-04-05
    Description: Contrasting models predict two different climate change scenarios for the Southern Ocean (SO), forecasting either less or stronger vertical mixing of the water column. To investigate the responses of SO phytoplankton to these future conditions, we sampled a natural diatom dominated (63%) community from today's relatively moderately mixed Drake Passage waters with both low availabilities of iron (Fe) and light. The phytoplankton community was then incubated at these ambient open ocean conditions (low Fe and low light, moderate mixing treatment), representing a control treatment. In addition, the phytoplankton was grown under two future mixing scenarios based on current climate model predictions. Mixing was simulated by changes in light and Fe availabilities. The two future scenarios consisted of a low mixing scenario (low Fe and higher light, low mixing treatment) and a strong mixing scenario (high Fe and low light, strong mixing treatment). In addition, communities of each mixing scenario were exposed to ambient and low pH, the latter simulating ocean acidification (OA). The effects of the scenarios on particulate organic carbon (POC) production, trace metal to carbon ratios, photophysiology and the relative numerical contribution of diatoms and nanoflagellates were assessed. During the first growth phase, at ambient pH both future mixing scenarios promoted the numerical abundance of diatoms (~75%) relative to nanoflagellates. This positive effect, however, vanished in response to OA in the communities of both future mixing scenarios (~65%), with different effects for their productivity. At the end of the experiment, diatoms remained numerically the most abundant phytoplankton group across all treatments (~80%). In addition, POC production was increased in the two future mixing scenarios under OA. Overall, this study suggests a continued numerical dominance of diatoms as well as higher carbon fixation in response to both future mixing scenarios under OA, irrespective of different changes in light and Fe availability.
    Keywords: Carbon, organic, particulate, net production; Carbon, organic, particulate, net production, standard deviation; CO2; compiled data; diatoms; DrakePassage; Experiment/study setup; Experimental treatment; Growth phase; iron; Iron/Carbon ratio; Iron/Carbon ratio, standard deviation; Light; mixing; Multiple stressors; Ocean acidification; pH; Photochemical quantum yield; Photochemical quantum yield, standard deviation; Pigments, light harvesting/light protective ratio; Pigments, light harvesting/light protective ratio, standard deviation; Scenario; Southern Ocean
    Type: Dataset
    Format: text/tab-separated-values, 168 data points
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    DATA PANGAEA
  • 5
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    Open Ocean and coastal phytoplankton communities of western Antarctic Peninsula and Drake Passage waters (2015)
    PANGAEA
    In:  Supplement to: Trimborn, Scarlett; Hoppe, Clara Jule Marie; Taylor, Bettina B; Bracher, Astrid; Hassler, Christel S (2015): Physiological characteristics of open ocean and coastal phytoplankton communities of Western Antarctic Peninsula and Drake Passage waters. Deep Sea Research Part I: Oceanographic Research Papers, 98, 115-124, https://doi.org/10.1016/j.dsr.2014.12.010
    Details
    Publication Date: 2023-04-05
    Description: Photophysiological processes as well as uptake characteristics of iron and inorganic carbon were studied in inshore phytoplankton assemblages of the Western Antarctic Peninsula (WAP) and offshore assemblages of the Drake Passage. Chlorophyll a concentrations and primary productivity decreased from in- to offshore waters. The inverse relationship between low maximum quantum yields of photochemistry in PSII (Fv/Fm) and large sizes of functional absorption cross sections (sigma PSII) in offshore communities indicated iron-limitation. Congruently, the negative correlation between Fv/Fm values and iron uptake rates across our sampling locations suggest an overall better iron uptake capacity in iron-limited pelagic phytoplankton communities. Highest iron uptake capacities could be related to relative abundances of the haptophyte Phaeocystis antarctica. As chlorophyll a-specific concentrations of humic-like substances were similarly high in offshore and inshore stations, we suggest humic-like substances may play an important role in iron chemistry in both coastal and pelagic phytoplankton assemblages. Regarding inorganic carbon uptake kinetics, the measured maximum short-term uptake rates (Vmax(CO2)) and apparent half-saturation constants (K1/2(CO2)) did not differ between offshore and inshore phytoplankton. Moreover, Vmax(CO2) and K1/2(CO2) did not exhibit any CO2-dependent trend over the natural pCO2 range from 237 to 507 µatm. K1/2(CO2) strongly varied among the sampled phytoplankton communities, ranging between 3.5 and 35.3 µmol/L CO2. While in many of the sampled phytoplankton communities, the operation of carbon-concentrating mechanisms (CCMs) was indicated by low K1/2(CO2) values relative to ambient CO2 concentrations, some coastal sites exhibited higher values, suggesting down-regulated CCMs. Overall, our results demonstrate a complex interplay between photophysiological processes, iron and carbon uptake of phytoplankton communities of the WAP and the Drake Passage.
    Keywords: AWI_PhyOce; Physical Oceanography @ AWI
    Type: Dataset
    Format: application/zip, 2 datasets
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    DATA PANGAEA
  • 6
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    Nitrate and silicate responses of a natural phytoplankton community from the Drake Passage to different climate change scenarios (2022)
    PANGAEA
    Details
    Publication Date: 2023-04-05
    Description: Contrasting models predict two different climate change scenarios for the Southern Ocean (SO), forecasting either less or stronger vertical mixing of the water column. To investigate the responses of SO phytoplankton to these future conditions, we sampled a natural diatom dominated (63%) community from today's relatively moderately mixed Drake Passage waters with both low availabilities of iron (Fe) and light. The phytoplankton community was then incubated at these ambient open ocean conditions (low Fe and low light, moderate mixing treatment), representing a control treatment. In addition, the phytoplankton was grown under two future mixing scenarios based on current climate model predictions. Mixing was simulated by changes in light and Fe availabilities. The two future scenarios consisted of a low mixing scenario (low Fe and higher light, low mixing treatment) and a strong mixing scenario (high Fe and low light, strong mixing treatment). In addition, communities of each mixing scenario were exposed to ambient and low pH, the latter simulating ocean acidification (OA). The effects of the scenarios on particulate organic carbon (POC) production, trace metal to carbon ratios, photophysiology and the relative numerical contribution of diatoms and nanoflagellates were assessed. During the first growth phase, at ambient pH both future mixing scenarios promoted the numerical abundance of diatoms (~75%) relative to nanoflagellates. This positive effect, however, vanished in response to OA in the communities of both future mixing scenarios (~65%), with different effects for their productivity. At the end of the experiment, diatoms remained numerically the most abundant phytoplankton group across all treatments (~80%). In addition, POC production was increased in the two future mixing scenarios under OA. Overall, this study suggests a continued numerical dominance of diatoms as well as higher carbon fixation in response to both future mixing scenarios under OA, irrespective of different changes in light and Fe availability.
    Keywords: CO2; compiled data; diatoms; DrakePassage; Experimental treatment; Incubation duration; iron; Light; mixing; Multiple stressors; Nitrate; Nitrate, standard deviation; Ocean acidification; pH; Silicate; Silicate, standard deviation; Southern Ocean
    Type: Dataset
    Format: text/tab-separated-values, 343 data points
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    DATA PANGAEA
  • 7
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    Picoeukaryote counts determined from the community sampled at station West and East (PS97) before and after exposure to different Fe and Mn availabilities (2021)
    PANGAEA
    Details
    Publication Date: 2023-10-28
    Description: Two Fe-Mn bottle amendment experiments with two natural phytoplankton communities were performed during Polarstern expedition PS97 in 2016 in the Drake Passage. At two locations, sea water was pumped (using trace metals clean techniques) from 25m depth and used to fill polycarbonate bottles after having passed through a cleaned 200 μm mesh (removing large grazers). The Control treatment was the sampled seawater without any trace metals addition while the other three treatments were enriched with either FeCl3 alone (0.5 nM; +Fe treatment) or MnCl2 alone (1 nM; +Mn treatment) or both trace metals together (+FeMn treatment). All treatments were done in triplicate 2,5L PC bottles. All incubation bottles were maintained at 30 μmol photons m-2 s-1 under a 16:8 (light:dark) hour cycle at 1 ̊C. Autotrophic picoeukaryotes were analyzed via flow cytometry. At the start and the end of the experiments, samples were preserved with 10% buffered formalin, flash-frozen in liquid nitrogen, and analyzed flow cytometrically to assess picoplankton densities. Before running the samples, 2 μL beads (Sperotech - Rainbow Fluorescent Particles (RFPs) - 2.11 μm) were added to each treatment as a size and fluorescence reference. Then picoeukaryotes were identified based on side scatter versus FL-3. Three P subgroups (0.2 – 2 μm) were differentiated according to their size : small (P1), medium (P2) and large (P3), according to sub-cluster of events.
    Keywords: ANT-XXXI/3; co-limitation; Drake Passage; Event label; Experiment; Experimental treatment; Flow cytometry; Incubation duration; Membrane pump; MP; Phytoplankton composition; Picoeukaryotes; Polarstern; Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; PS97; PS97/043-1; PS97/087-4; Scotia Sea; Southern Ocean; SPP1158; trace elements
    Type: Dataset
    Format: text/tab-separated-values, 298 data points
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    DATA PANGAEA
  • 8
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    Phytoplankton species determination and counts determined from the community sampled at station West and East (PS97) before and after exposure to different Fe and Mn availabilities (2021)
    PANGAEA
    Details
    Publication Date: 2023-10-28
    Description: Two Fe-Mn bottle amendment experiments with two natural phytoplankton communities were performed during Polarstern expedition PS97 in 2016 in the Drake Passage. At two locations, sea water was pumped (using trace metals clean techniques) from 25m depth and used to fill polycarbonate bottles after having passed through a cleaned 200 μm mesh (removing large grazers). The Control treatment was the sampled seawater without any trace metals addition while the other three treatments were enriched with either FeCl3 alone (0.5 nM; +Fe treatment) or MnCl2 alone (1 nM; +Mn treatment) or both trace metals together (+FeMn treatment). All treatments were done in triplicate 2,5L PC bottles. All incubation bottles were maintained at 30 μmol photons m-2 s-1 under a 16:8 (light:dark) hour cycle at 1 ̊C. To determine the effects of the different treatments on the microplankton composition for the two Fe-Mn enrichment experiments, unfiltered seawater was collected at the start and the end of both experiments for later analysis via light microscopy in the home laboratory. Briefly, samples were fixed with hexamine-buffered formalin solution (2% final concentration) and Lugol's solution (1% final concentration) and stored at 2 °C in the dark until taxonomic analysis. All samples were allowed to settle in Utermöhl sedimentation chambers for at least 24 hours and were analyzed on an inverted light microscope, according to the method of Utermöhl (1958). Species were counted and identified according to taxonomic literature. Each aliquot was examined until at least 400 cells had been counted.
    Keywords: ANT-XXXI/3; Chaetoceros sp.; co-limitation; Drake Passage; Event label; Experiment; Experimental treatment; Fragilariopsis sp.; Incubation duration; Light microscopy (Utermöhl 1958); Membrane pump; MP; Phaeocystis antarctica; Phytoplankton composition; Polarstern; Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; PS97; PS97/043-1; PS97/087-4; Pseudo-nitzschia sp.; Scotia Sea; Southern Ocean; SPP1158; trace elements
    Type: Dataset
    Format: text/tab-separated-values, 180 data points
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    DATA PANGAEA
  • 9
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    Chlorophyll a, primary production and nutrients during POLARSTERN cruise ANT-XXVIII/2 (2017)
    PANGAEA
    In:  Supplement to: Hoppe, Clara Jule Marie; Klaas, Christine; Ossebaar, Sharyn; Soppa, Mariana A; Cheah, Wee; Laglera, Luis Miguel; Santos-Echeandía, Juan; Rost, Björn; Wolf-Gladrow, Dieter A; Bracher, Astrid; Hoppema, Mario; Strass, Volker H; Trimborn, Scarlett (2017): Controls of primary production in two phytoplankton blooms in the Antarctic Circumpolar Current. Deep Sea Research Part II: Topical Studies in Oceanography, 138, 63-73, https://doi.org/10.1016/j.dsr2.2015.10.005
    Details
    Publication Date: 2023-10-18
    Description: The Antarctic Circumpolar Current has a high potential for primary production and carbon sequestration through the biological pump. In the current study, two large-scale blooms observed in 2012 during a cruise with R.V. Polarstern were investigated with respect to phytoplankton standing stocks, primary productivity and nutrient budgets. While net primary productivity was similar in both blooms, chlorophyll a -specific photosynthesis was more efficient in the bloom closer to the island of South Georgia (39 °W, 50 °S) compared to the open ocean bloom further east (12 °W, 51 °S). We did not find evidence for light being the driver of bloom dynamics as chlorophyll standing stocks up to 165 mg/m² developed despite mixed layers as deep as 90 m. Since the two bloom regions differ in their distance to shelf areas, potential sources of iron vary. Nutrient (nitrate, phosphate, silicate) deficits were similar in both areas despite different bloom ages, but their ratios indicated more pronounced iron limitation at 12 °W compared to 39 °W. While primarily the supply of iron and not the availability of light seemed to control onset and duration of the blooms, higher grazing pressure could have exerted a stronger control toward the declining phase of the blooms.
    Type: Dataset
    Format: application/zip, 3 datasets
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    DATA PANGAEA
  • 10
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    Nutrient concentrations during POLARSTERN cruise ANT-XXVIII/2 (2017)
    PANGAEA
    Details
    Publication Date: 2023-10-18
    Keywords: ANT-XXVIII/3; Area/locality; CTD/Rosette; CTD-RO; Date/Time of event; DEPTH, water; Elevation of event; Event label; Latitude of event; Longitude of event; Nitrate; Phosphate; Polarstern; PS79; PS79/087-2; PS79/088-1; PS79/092-1; PS79/093-1; PS79/095-3; PS79/096-1; PS79/101-1; PS79/102-1; PS79/103-1; PS79/104-1; PS79/105-1; PS79/106-1; PS79/107-1; PS79/108-1; PS79/109-1; PS79/110-1; PS79/111-1; PS79/112-1; PS79/114-2; PS79/115-1; PS79/116-1; PS79/117-1; PS79/118-1; PS79/119-3; PS79/120-1; PS79/121-1; PS79/122-2; PS79/123-1; PS79/124-1; PS79/125-1; PS79/126-1; PS79/127-2; PS79/128-10; PS79/137-7; PS79/144-2; PS79/145-1; PS79/146-1; PS79/147-1; PS79/148-1; PS79/149-1; PS79/150-1; PS79/151-1; PS79/152-1; PS79/153-1; PS79/154-1; PS79/155-1; PS79/156-1; PS79/157-1; PS79/158-1; PS79/159-1; PS79/160-1; PS79/161-1; PS79/162-2; PS79/163-1; PS79/164-1; Silicate; South Atlantic Ocean
    Type: Dataset
    Format: text/tab-separated-values, 2589 data points
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    DATA PANGAEA
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