scholarly journals Modeling Iron and Light Controls on the Summer Phaeocystis antarctica Bloom in the Amundsen Sea Polynya

2019 ◽  
Vol 33 (5) ◽  
pp. 570-596 ◽  
Author(s):  
Hilde Oliver ◽  
Pierre St‐Laurent ◽  
Robert M. Sherrell ◽  
Patricia L. Yager
Keyword(s):  
Amundsen Sea ◽  
Phaeocystis Antarctica

scholarly journals Characteristics of methanesulfonic acid, non-sea-salt sulfate and organic carbon aerosols over the Amundsen Sea, Antarctica

2020 ◽  
Vol 20 (9) ◽  
pp. 5405-5424 ◽  
Author(s):  
Jinyoung Jung ◽  
Sang-Bum Hong ◽  
Meilian Chen ◽  
Jin Hur ◽  
Liping Jiao ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Southern Ocean ◽  
Methanesulfonic Acid ◽  
Austral Summer ◽  
Sea Salt ◽  
Water Soluble ◽  
Fluorescence Excitation ◽  
Amundsen Sea ◽  
Phaeocystis Antarctica ◽  
Seawater Samples

Abstract. To investigate the characteristics of particulate methanesulfonic acid (MSA(p)), non-sea-salt sulfate (nss SO42-) and organic carbon (OC) aerosols, aerosol and seawater samples were collected over the Southern Ocean (43–70∘ S) and the Amundsen Sea (70–75∘ S) during the ANA06B cruise conducted in the austral summer of 2016 aboard the Korean icebreaker IBR/V Araon. Over the Southern Ocean, the atmospheric MSA(p) concentration was low (0.10±0.002 µg m−3), whereas its concentration increased sharply up to 0.57 µg m−3 in the Amundsen Sea where Phaeocystis antarctica (P. antarctica), a producer of dimethylsulfide (DMS), was the dominant phytoplankton species. Unlike MSA(p), the mean nss SO42- concentration in the Amundsen Sea was comparable to that in the Southern Ocean. Water-soluble organic carbon (WSOC) concentrations over the Southern Ocean and the Amundsen Sea varied from 0.048 to 0.16 and 0.070 to 0.18 µgC m−3, with averages of 0.087±0.038 and 0.097±0.038 µgC m−3, respectively. For water-insoluble organic carbon (WIOC), its mean concentrations over the Southern Ocean and the Amundsen Sea were 0.25±0.13 and 0.26±0.10 µgC m−3, varying from 0.083 to 0.49 and 0.12 to 0.38 µgC m−3, respectively. WIOC was the dominant organic carbon species in both the Southern Ocean and the Amundsen Sea, accounting for 73 %–75 % of the total aerosol organic carbon. WSOC/Na+ and WIOC/Na+ ratios in the fine-mode aerosol particles were higher, especially in the Amundsen Sea where biological productivity was much higher than the Southern Ocean. The fluorescence properties of water-soluble organic aerosols investigated using a fluorescence excitation–emission matrix coupled with parallel factor analysis (EEM–PARAFAC) revealed that protein-like components were dominant in our marine aerosol samples, representing 69 %–91 % of the total intensity. Protein-like components also showed a significant positive relationship with the relative biomass of diatoms; however, they were negatively correlated with the relative biomass of P. antarctica. These results suggest that the protein-like component is most likely produced as a result of biological processes of diatoms in the Amundsen Sea.

scholarly journals Particle flux on the continental shelf in the Amundsen Sea Polynya and Western Antarctic Peninsula

Elem Sci Anth ◽  
2015 ◽  
Vol 3 ◽  
Author(s):  
Hugh W. Ducklow ◽  
Stephanie E. Wilson ◽  
Anton F. Post ◽  
Sharon E. Stammerjohn ◽  
Matthew Erickson ◽  
...  
Keyword(s):  
Time Series ◽  
Antarctic Peninsula ◽  
Particle Flux ◽  
Phytoplankton Bloom ◽  
Bacterial Respiration ◽  
Polar Regions ◽  
Western Antarctic Peninsula ◽  
Amundsen Sea ◽  
Incubation Experiments ◽  
Phaeocystis Antarctica

Abstract We report results from a yearlong, moored sediment trap in the Amundsen Sea Polynya (ASP), the first such time series in this remote and productive ecosystem. Results are compared to a long-term (1992–2013) time series from the western Antarctic Peninsula (WAP). The ASP trap was deployed from December 2010 to December 2011 at 350 m depth. We observed two brief, but high flux events, peaking at 8 and 5 mmol C m−2 d−1 in January and December 2011, respectively, with a total annual capture of 315 mmol C m−2. Both peak fluxes and annual capture exceeded the comparable WAP observations. Like the overlying phytoplankton bloom observed during the cruise in the ASP (December 2010 to January 2011), particle flux was dominated by Phaeocystis antarctica, which produced phytodetrital aggregates. Particles at the start of the bloom were highly depleted in 13C, indicating their origin in the cold, CO2-rich winter waters exposed by retreating sea ice. As the bloom progressed, microscope visualization and stable isotopic composition provided evidence for an increasing contribution by zooplankton fecal material. Incubation experiments and zooplankton observations suggested that fecal pellet production likely contributed 10–40% of the total flux during the first flux event, and could be very high during episodic krill swarms. Independent estimates of export from the surface (100 m) were about 5–10 times that captured in the trap at 350 m. Estimated bacterial respiration was sufficient to account for much of the decline in the flux between 50 and 350 m, whereas zooplankton respiration was much lower. The ASP system appears to export only a small fraction of its production deeper than 350 m within the polynya region. The export efficiency was comparable to other polar regions where phytoplankton blooms were not dominated by diatoms.

scholarly journals Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica

Elem Sci Anth ◽  
2016 ◽  
Vol 4 ◽  
Author(s):  
C.M. Williams ◽  
A.M. Dupont ◽  
J. Loevenich ◽  
A.F. Post ◽  
J. Dinasquet ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
Phytoplankton Bloom ◽  
Net Primary Production ◽  
Growth Efficiency ◽  
Bacterial Respiration ◽  
Pump Efficiency ◽  
Amundsen Sea ◽  
Coastal System ◽  
Chl A ◽  
Phaeocystis Antarctica

Abstract Heterotrophic bacteria play a key role in marine carbon cycling, and understanding their activities in polar systems is important for considering climate change impacts there. One goal of the ASPIRE project was to examine the relationship between the phytoplankton bloom and bacterial heterotrophy in the Amundsen Sea Polynya (ASP). Bacterial abundance, production (BP), respiration, growth efficiency, and extracellular enzyme activity (EEA) were compared to nutrient and organic matter inventories, chlorophyll a (Chl a), viral and microzooplankton abundance, and net primary production (NPP). Bacterial production and respiration clearly responded (0.04–4.0 and 10–53 µg C L−1 d−1, respectively) to the buildup of a massive Phaeocystis antarctica bloom (Chl a: 0.2–22 µg L−1), with highest rates observed in the central polynya where Chl a and particulate organic carbon (POC) were greatest. The highest BP rates exceeded those reported for the Ross Sea or any other Antarctic coastal system, yet the BP:NPP ratio (2.1–9.4%) was relatively low. Bacterial respiration was also high, and growth efficiency (2–27%; median = 10%) was similar to oligotrophic systems. Thus, the integrated bacterial carbon demand (0.8–2.8 g C m−2 d−1) was a high fraction (25–128%; median = 43%) of NPP during bloom development. During peak bloom, activity was particle-associated: BP and EEA correlated well with POC, and size fractionation experiments showed that the larger size fraction (> 3 µm) accounted for a majority (∼ 75%) of the BP. The community was psychrophilic, with a 5x reduction in BP when warmed to 20°C. In deeper waters, respiration remained relatively high, likely fueled by the significant downward particle flux in the region. A highly active, particle-associated, heterotrophic microbial community clearly responded to the extraordinary phytoplankton bloom in the ASP, likely limiting biological pump efficiency during the early season.

scholarly journals Microzooplankton distribution in the Amundsen Sea Polynya (Antarctica) during an extensive Phaeocystis antarctica bloom

2019 ◽  
Vol 170 ◽  
pp. 1-10 ◽  
Author(s):  
Rasmus Swalethorp ◽  
Julie Dinasquet ◽  
Ramiro Logares ◽  
Stefan Bertilsson ◽  
Sanne Kjellerup ◽  
...  
Keyword(s):  
Amundsen Sea ◽  
Phaeocystis Antarctica

scholarly journals Sea ice algal biomass and physiology in the Amundsen Sea, Antarctica

Elem Sci Anth ◽  
2014 ◽  
Vol 2 ◽  
Author(s):  
Kevin R. Arrigo ◽  
Zachary W. Brown ◽  
Matthew M. Mills
Keyword(s):  
Sea Ice ◽  
Photosynthetic Apparatus ◽  
Snow Accumulation ◽  
Visible Radiation ◽  
Microalgal Biomass ◽  
Amundsen Sea ◽  
Developed Surface ◽  
Phaeocystis Antarctica ◽  
Important Food Source ◽  
Time Of Year

Abstract Sea ice covers approximately 5% of the ocean surface and is one of the most extensive ecosystems on the planet. The microbial communities that live in sea ice represent an important food source for numerous organisms at a time of year when phytoplankton in the water column are scarce. Here we describe the distributions and physiology of sea ice microalgae in the poorly studied Amundsen Sea sector of the Southern Ocean. Microalgal biomass was relatively high in sea ice in the Amundsen Sea, due primarily to well developed surface communities that would have been replenished with nutrients during seawater flooding of the surface as a result of heavy snow accumulation. Elevated biomass was also occasionally observed in slush, interior, and bottom ice microhabitats throughout the region. Sea ice microalgal photophysiology appeared to be controlled by the availability of both light and nutrients. Surface communities used an active xanthophyll cycle and effective pigment sunscreens to protect themselves from harmful ultraviolet and visible radiation. Acclimation to low light microhabitats in sea ice was facilitated by enhanced pigment content per cell, greater photosynthetic accessory pigments, and increased photosynthetic efficiency. Photoacclimation was especially effective in the bottom ice community, where ready access to nutrients would have allowed ice microalgae to synthesize a more efficient photosynthetic apparatus. Surprisingly, the pigment-detected prymnesiophyte Phaeocystis antarctica was an important component of surface communities (slush and surface ponds) where its acclimation to high light may precondition it to seed phytoplankton blooms after the sea ice melts in spring.

scholarly journals Phaeocystis antarctica blooms strongly influence bacterial community structures in the Amundsen Sea polynya

2014 ◽  
Vol 5 ◽  
Author(s):  
Tom O. Delmont ◽  
Katherine M. Hammar ◽  
Hugh W. Ducklow ◽  
Patricia L. Yager ◽  
Anton F. Post
Keyword(s):  
Bacterial Community ◽  
Community Structures ◽  
Amundsen Sea ◽  
Phaeocystis Antarctica

scholarly journals Microzooplankton distribution in the Amundsen Sea Polynya (Antarctica) during an extensivePhaeocystis antarcticabloom

2018 ◽  
Author(s):  
Rasmus Swalethorp ◽  
Julie Dinasquet ◽  
Ramiro Logares ◽  
Stefan Bertilsson ◽  
Sanne Kjellerup ◽  
...  
Keyword(s):  
Food Web ◽  
Phytoplankton Community ◽  
Heterotrophic Nanoflagellates ◽  
Amundsen Sea ◽  
Production Studies ◽  
Rrna Sequencing ◽  
Phaeocystis Antarctica ◽  
Summer Bloom ◽  
Coastal Phytoplankton

AbstractIn Antarctica, summer is a time of extreme environmental shifts resulting in large coastal phytoplankton blooms fueling the food web. Despite the importance of the microbial loop in remineralizing biomass from primary production, studies of how microzooplankton communities respond to such blooms in the Southern Ocean are rather scarce. Microzooplankton (ciliates and dinoflagellates) communities were investigated combining microscopy and 18S rRNA sequencing analyses in the Amundsen Sea Polynya during an extensive summer bloom ofPhaeocystis antarctica. The succession of microzooplankton was further assessed during a 15-day induced bloom microcosm experiment. Dinoflagellates accounted for up to 58% the microzooplankton biomassin situwithGymnodiniumspp.,Protoperidiumspp. andGyrodiniumspp. constituting 87% of the dinoflagellate biomass.Strombilidiumspp.,Strombidiumspp. and tintinids represented 90% of the ciliates biomass.Gymnodinium,Gyrodiniumand tintinnids are known grazers ofPhaeocystis,suggesting that this prymnesiophyte selected for the key microzooplankton taxa. Availability of other potential prey, such as diatoms, heterotrophic nanoflagellates and bacteria, also correlated to changes in microzooplankton community structure. Overall, both heterotrophy and mixotrophy appeared to be key trophic strategies of the dominant microzooplankton observed, suggesting that they influence carbon flow in the microbial food web through top-down control on the phytoplankton community.

scholarly journals A Joint Inversion Estimate of Antarctic Ice Sheet Mass Balance Using Multi-Geodetic Data Sets

2019 ◽  
Vol 11 (6) ◽  
pp. 653 ◽  
Author(s):  
Chunchun Gao ◽  
Yang Lu ◽  
Zizhan Zhang ◽  
Hongling Shi
Keyword(s):  
Mass Balance ◽  
Joint Inversion ◽  
Ice Sheet ◽  
Mass Change ◽  
West Antarctica ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
Forward Models ◽  
Uplift Rates ◽  
The Antarctic

Many recent mass balance estimates using the Gravity Recovery and Climate Experiment (GRACE) and satellite altimetry (including two kinds of sensors of radar and laser) show that the ice mass of the Antarctic ice sheet (AIS) is in overall decline. However, there are still large differences among previously published estimates of the total mass change, even in the same observed periods. The considerable error sources mainly arise from the forward models (e.g., glacial isostatic adjustment [GIA] and firn compaction) that may be uncertain but indispensable to simulate some processes not directly measured or obtained by these observations. To minimize the use of these forward models, we estimate the mass change of ice sheet and present-day GIA using multi-geodetic observations, including GRACE and Ice, Cloud and land Elevation Satellite (ICESat), as well as Global Positioning System (GPS), by an improved method of joint inversion estimate (JIE), which enables us to solve simultaneously for the Antarctic GIA and ice mass trends. The GIA uplift rates generated from our JIE method show a good agreement with the elastic-corrected GPS uplift rates, and the total GIA-induced mass change estimate for the AIS is 54 ± 27 Gt/yr, which is in line with many recent GPS calibrated GIA estimates. Our GIA result displays the presence of significant uplift rates in the Amundsen Sea Embayment of West Antarctica, where strong uplift has been observed by GPS. Over the period February 2003 to October 2009, the entire AIS changed in mass by −84 ± 31 Gt/yr (West Antarctica: −69 ± 24, East Antarctica: 12 ± 16 and the Antarctic Peninsula: −27 ± 8), greater than the GRACE-only estimates obtained from three Mascon solutions (CSR: −50 ± 30, JPL: −71 ± 30, and GSFC: −51 ± 33 Gt/yr) for the same period. This may imply that single GRACE data tend to underestimate ice mass loss due to the signal leakage and attenuation errors of ice discharge are often worse than that of surface mass balance over the AIS.

Seabird hotspots on icebergs in the Amundsen Sea, Antarctica

Polar Biology ◽  
2017 ◽  
Vol 41 (1) ◽  
pp. 111-114 ◽  
Author(s):  
Claude R. Joiris
Keyword(s):  
Amundsen Sea
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