scholarly journals A global compilation of dissolved iron measurements: focus on distributions and processes in the Southern Ocean

2012 ◽  
Vol 9 (6) ◽  
pp. 2333-2349 ◽  
Author(s):  
A. Tagliabue ◽  
T. Mtshali ◽  
O. Aumont ◽  
A. R. Bowie ◽  
M. B. Klunder ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Future Research ◽  
Ocean Water ◽  
Missing Measurements ◽  
Antarctic Region ◽  
Dissolved Iron ◽  
Limiting Nutrient ◽  
Modelling Studies ◽  
The Antarctic ◽  
Subantarctic Region

Abstract. Due to its importance as a limiting nutrient for phytoplankton growth in large regions of the world's oceans, ocean water column observations of concentration of the trace-metal iron (Fe) have increased markedly over recent decades. Here we compile >13 000 global measurements of dissolved Fe (dFe) and make this available to the community. We then conduct a synthesis study focussed on the Southern Ocean, where dFe plays a fundamental role in governing the carbon cycle, using four regions, six basins and five depth intervals as a framework. Our analysis highlights depth-dependent trends in the properties of dFe between different regions and basins. In general, surface dFe is highest in the Atlantic basin and the Antarctic region. While attributing drivers to these patterns is uncertain, inter-basin patterns in surface dFe might be linked to differing degrees of dFe inputs, while variability in biological consumption between regions covaries with the associated surface dFe differences. Opposite to the surface, dFe concentrations at depth are typically higher in the Indian basin and the Subantarctic region. The inter-region trends can be reconciled with similar ligand variability (although only from one cruise), and the inter-basin difference might be explained by differences in hydrothermal inputs suggested by modelling studies (Tagliabue et al., 2010) that await observational confirmation. We find that even in regions where many dFe measurements exist, the processes governing the seasonal evolution of dFe remain enigmatic, suggesting that, aside from broad Subantarctic – Antarctic trends, biological consumption might not be the major driver of dFe variability. This highlights the apparent importance of other processes such as exogenous inputs, physical transport/mixing or dFe recycling processes. Nevertheless, missing measurements during key seasonal transitions make it difficult to better quantify and understand surface water replenishment processes and the seasonal Fe cycle. Finally, we detail the degree of seasonal coverage by region, basin and depth. By synthesising prior measurements, we suggest a role for different processes and highlight key gaps in understanding, which we hope can help structure future research efforts in the Southern Ocean.

scholarly journals A global compilation of over 13 000 dissolved iron measurements: focus on distributions and processes in the Southern Ocean

2011 ◽  
Vol 8 (6) ◽  
pp. 11489-11527 ◽  
Author(s):  
A. Tagliabue ◽  
T. Mtshali ◽  
O. Aumont ◽  
A. R. Bowie ◽  
M. B. Klunder ◽  
...  
Keyword(s):  
Biological Activity ◽  
Southern Ocean ◽  
Water Mass ◽  
Future Research ◽  
Ocean Water ◽  
Missing Measurements ◽  
Analysis Techniques ◽  
Dissolved Iron ◽  
Deep Waters ◽  
Limiting Nutrient

Abstract. Due to its importance as a limiting nutrient for phytoplankton growth in large regions of the world's oceans, ocean water column observations of concentration of the trace-metal iron (Fe) have increased markedly over recent decades. Here we compile > 13 000 global measurements of dissolved Fe (dFe) and make this available to the community. We then conduct a synthesis study focussed on the Southern Ocean, where dFe plays a fundamental role in governing the carbon cycle, using four regions, six basins and five depth intervals as a framework. Our analysis reveals the importance of biological activity and dFe inputs in governing the inter-region and inter-basin differences in surface dFe, respectively. In deep waters, the major controls of inter-region and inter-basin dFe variability are ligand distributions and deep dFe inputs or water mass characteristics, respectively. We find that even in regions where many dFe measurements exist, the processes governing the seasonal evolution of dFe remain enigmatic, suggesting that, aside from broad sub-Antarctic-Antarctic trends, biological activity might not the major driver of dFe variability. Nevertheless, missing measurements during key seasonal transitions make it difficult to better quantify and understand surface water replenishment processes and the seasonal Fe cycle. Statistical differences exist in the measured dFe between measurements taken over the period 1989–2002 and 2003–2008, which may reflect progress in clean sampling and analysis techniques. Finally, we detail the degree of seasonal coverage by region, basin and depth. By synthesising prior measurements we suggest a role for different processes and highlight key gaps in understanding, which we hope can help structure future research efforts in the Southern Ocean.

Benthic hydroids (Cnidaria, Hydrozoa) from the Weddell Sea (Antarctica)

Zootaxa ◽  
2019 ◽  
Vol 4570 (1) ◽  
pp. 1
Author(s):  
JOAN J. SOTO ÀNGEL ◽  
ÁLVARO L. PEÑA CANTERO
Keyword(s):  
Southern Ocean ◽  
New Records ◽  
Weddell Sea ◽  
Reproductive Phenology ◽  
Antarctic Region ◽  
Bathymetric Range ◽  
Eastern Sector ◽  
Number Of Species ◽  
The Antarctic

Hydrozoans are a conspicuous component of Antarctic benthic communitites. Recent taxonomic effort has led to a substantial increase in knowledge on the diversity of benthic hydroids from some areas of the Southern Ocean, including the Weddell Sea, the largest sea in the Antarctic region. However, the study of many hydrozoan taxa are still pending, and the diversity in this huge region is expected to be higher than currently known. In order to contribute to the knowledge of taxonomy, ecology and distribution of these cnidarians, a study of unpublished material collected by several German Antarctic expeditions aboard the RV Polarstern in the eastern sector of the Weddell Sea has been conducted. A total of 77 species belonging to 22 families and 28 genera of benthic hydroids have been inventoried, constituting the most prolific collection hitherto analyzed. Most species (81%) belong to Leptothecata, but the observed share of Anthoathecata (19%) is higher than in previous Antarctic hydrozoan studies. Symplectoscyphidae was the most speciose family with 16 representatives (22%), followed by Haleciidae with 10 (14%) and Staurothecidae with 8 (11%). The number of species known in the area was increased with 27 new records, including several species rarely documented. As a result, the Weddell Sea becomes the second Antarctic region in terms of hydrozoan diversity, with 89 species known to date. Novel data on the use of substrate, reproductive phenology, and bathymetric range are provided for the inventoried species. 

scholarly journals Seasonal modulation of phytoplankton biomass in the Southern Ocean

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Lionel A. Arteaga ◽  
Emmanuel Boss ◽  
Michael J. Behrenfeld ◽  
Toby K. Westberry ◽  
Jorge L. Sarmiento
Keyword(s):  
Southern Ocean ◽  
Phytoplankton Biomass ◽  
Light Availability ◽  
Key Factors ◽  
Division Rate ◽  
Very Large Array ◽  
Dissolved Iron ◽  
Environmental Properties ◽  
Limiting Nutrient

Abstract Over the last ten years, satellite and geographically constrained in situ observations largely focused on the northern hemisphere have suggested that annual phytoplankton biomass cycles cannot be fully understood from environmental properties controlling phytoplankton division rates (e.g., nutrients and light), as they omit the role of ecological and environmental loss processes (e.g., grazing, viruses, sinking). Here, we use multi-year observations from a very large array of robotic drifting floats in the Southern Ocean to determine key factors governing phytoplankton biomass dynamics over the annual cycle. Our analysis reveals seasonal phytoplankton accumulation (‘blooming’) events occurring during periods of declining modeled division rates, an observation that highlights the importance of loss processes in dictating the evolution of the seasonal cycle in biomass. In the open Southern Ocean, the spring bloom magnitude is found to be greatest in areas with high dissolved iron concentrations, consistent with iron being a well-established primary limiting nutrient in this region. Under ice observations show that biomass starts increasing in early winter, well before sea ice begins to retreat. The average theoretical sensitivity of the Southern Ocean to potential changes in seasonal nutrient and light availability suggests that a 10% change in phytoplankton division rate may be associated with a 50% reduction in mean bloom magnitude and annual primary productivity, assuming simple changes in the seasonal magnitude of phytoplankton division rates. Overall, our results highlight the importance of quantifying and accounting for both division and loss processes when modeling future changes in phytoplankton biomass cycles.

An account of the Mysidacea (Crustacea, Malacostraca) of the Southern Ocean

1998 ◽  
Vol 10 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Angelika Brandt ◽  
Ute Mühlenhardt-Siegel ◽  
Volker Siegel
Keyword(s):  
Southern Ocean ◽  
Present State ◽  
Distribution Patterns ◽  
Taxonomic Diversity ◽  
Shelf Break ◽  
Bathymetric Distribution ◽  
Antarctic Region ◽  
Magellan Region ◽  
Antarctic Shelf ◽  
The Antarctic

An inventory of Antarctic and Subantarctic mysid fauna is presented, together with a summary of the present state of knowledge of species and their taxonomic diversity, geographic and bathymetric distribution patterns. Fifty nine species of Mysidacea (Crustacea, Peracarida) are now known. Of these, 37 were reported for the Antarctic region and 31 for the Magellan region; six species occur further north in the Southern Ocean, but south of 40°S. 51% of the Antarctic Mysidacea are endemic, and the figure for the Magellan region is 48%. Most of the species live hyperbenthically, but some also occur bathy- or mesopelagically. Mysidetes has the most species in the Southern Ocean, and Eucopia australis is the species with the widest bathymetric distribution (600–6000 m depth). It is concluded that an emergence of species onto the Antarctic shelf in the Neogene was quite unlikely, because none of the mysid species is a true deepsea species, and most species occur on the shelf or at the shelf break. It is more probable that present day species colonized the Southern Ocean via shallower waters. The examples of the distribution of different genera suggest that the Mysidacea of the Southern Ocean probably had various geographical origins.

scholarly journals First Record of a living Platycopida (Crustacea, Ostracoda) from Antarcticwaters and a Discussion on Cytherella serratula (Brady, 1880)

Zootaxa ◽  
2008 ◽  
Vol 1866 (1) ◽  
pp. 349 ◽  
Author(s):  
SIMONE N. BRANDÃO
Keyword(s):  
New Species ◽  
Southern Ocean ◽  
Intraspecific Variation ◽  
Late Cretaceous ◽  
First Record ◽  
Review Of The Literature ◽  
Antarctic Region ◽  
Fossil Species ◽  
O2 Concentration ◽  
The Antarctic

Previous records of Platycopida (Ostracoda) from the Antarctic region of the Southern Ocean include only a few fossil species from the Late Cretaceous to the Palaeocene: Cytherelloidea megaspirocostata Majoran & Widmark, 1998, [sic] Cytherella serratula (Brady, 1880), plus seven species left in open nomenclature. The present study documents the first record of a living platycopid from the Antarctic region and describes Cytherella rwhatleyi sp. nov. as new. Comparison among specimens collected at stations 60° longitude and 10° of latitude apart from each other show that very little intraspecific variation in outline and ornamentation of the valves, as well as on the hemipenis is presented by this new species. Otherwise, clear differences on valve and hemipenis are observed between different species (herein, Jellinek & Swanson 2003). Review of the literature indicates that several species (with great differences in valve outline and ornamentation) have been erroneously assigned to Cytherella serratula (Brady, 1880) demonstrating that this so-called cosmopolitan taxon is in truth most probably restricted to bathyal depths of the Northwestern Atlantic. Finally, the abundances of Cytherella rwhatleyi sp. nov. in the samples studied herein (considering O2 concentration measurements) contradict the proposed relationship between Platycopida and O2 concentration in water masses (Whatley et al. 2003).

scholarly journals A catalogue of the Antarctic and sub-Antarctic Phoxocephalidae (Crustacea: Amphipoda: Gammaridea) with taxonomic, distribution and ecological data

Zootaxa ◽  
2008 ◽  
Vol 1752 (1) ◽  
pp. 1 ◽  
Author(s):  
GLORIA M. ALONSO DE PINA ◽  
MARTIN RAUSCHERT ◽  
CLAUDE DE BROYER
Keyword(s):  
Southern Ocean ◽  
Taxonomic Status ◽  
Ecological Data ◽  
Bathymetric Distribution ◽  
Antarctic Region ◽  
Substrate Preferences ◽  
West Antarctic ◽  
Ecological Literature ◽  
The Antarctic ◽  
Extensive List

An up-to-date catalogue of Antarctic and sub-Antarctic Phoxocephalidae is presented, including 35 species. Extensive list of bibliographical references with synonymy, detailed information on geographic and bathymetric distribution, ecological data, museum locations of type-material, remarks on taxonomic and biogeographical status, are provided for each species. The catalogue is based on taxonomic and ecological literature until 31 December 2006. Additional unpublished records of species from the Antarctic and sub-Antarctic collections held at the Alfred Wegener Institut für Polarund Meeresforschung, Bremerhaven, and at the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Buenos Aires, have been included. The taxonomic status of all the Southern Ocean species has been checked. Species allocated to the genera Paraphoxus and Parharpinia, and Fuegiphoxus uncinatus require further study to clarify or confirm the genus allocation. Most of the Southern Ocean phoxocephalids have a wide bathymetric distribution, equally present in the Antarctic and sub-Antarctic regions. The highest species richness is found above 200 meters depth in the sub-Antarctic region. Of 35 phoxocephalid species reported, 25 are endemic to the Southern Ocean s.l., 15 are endemic to the Antarctic region and 6 are endemic to the sub-Antarctic region, the latter distributed only in the Magellan province. Endemicity at genus level attains 22% for the whole Southern Ocean, with 3 genera restricted to the Magellan province and one genus to the West Antarctic, Magellan and sub-Antarctic islands provinces. Habitat and substrate preferences, dietary and burrowing behaviours are scarcely known for most of the phoxocephalid species from the Southern Ocean.

scholarly journals Antarctic meltwater-induced dynamical changes in phytoplankton in the Southern Ocean

2021 ◽  
Author(s):  
Ji-Hoon Oh ◽  
Kyung Min Noh ◽  
Hyung-Gyu Lim ◽  
Emilia Kyung Jin ◽  
Sang-Yoon Jun ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Regime Shift ◽  
Nitrate Concentration ◽  
Chlorophyll Concentration ◽  
Iron Concentration ◽  
Freshwater Flux ◽  
Iron Availability ◽  
Dissolved Iron ◽  
Marginal Sea ◽  
The Antarctic

Abstract IIt has been suggested that the freshwater flux due to the recent melting of the Antarctic ice-sheet/shelf will suppress ventilation in the Southern Ocean. In this study, we performed idealized earth system simulations to examine the impacts of Antarctic meltwater on surface phytoplankton biomass in the Antarctic Ocean. The enhanced stratification due to the meltwater leads to a decrease in the surface nitrate concentration but an increase in the surface dissolved iron concentration. These changes are associated with the reduced upwelling of nitrate-rich deep water and the trapped iron exported from the terrestrial sediment. Because of the limited iron availability in the Southern Ocean, the trapped iron in surface water enhances the chlorophyll concentration in the open ocean. However, in the marginal sea along the Antarctic coastline where the iron is relatively sufficient, a nitrate reduction induces a chlorophyll decrease, indicating a regime shift from iron-limited to nitrate-limited conditions.

scholarly journals Delivering 21st century Antarctic and Southern Ocean science

2016 ◽  
Vol 28 (6) ◽  
pp. 407-423 ◽  
Author(s):  
M.C. Kennicutt ◽  
Y.D. Kim ◽  
M. Rogan-Finnemore ◽  
S. Anandakrishnan ◽  
S.L. Chown ◽  
...  
Keyword(s):  
Southern Ocean ◽  
21St Century ◽  
Numerical Models ◽  
Future Research ◽  
Sample Collection ◽  
Data Accessibility ◽  
Ocean Science ◽  
Antarctic Research ◽  
Remote Sensing And Sensors ◽  
The Antarctic

AbstractThe Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high priority Antarctic research in the 21st century. The ARC project addressed the challenges of enabling technologies, facilitating access, providing logistics and infrastructure, and capitalizing on international co-operation. Technological requirements include: i) innovative automated in situ observing systems, sensors and interoperable platforms (including power demands), ii) realistic and holistic numerical models, iii) enhanced remote sensing and sensors, iv) expanded sample collection and retrieval technologies, and v) greater cyber-infrastructure to process ‘big data’ collection, transmission and analyses while promoting data accessibility. These technologies must be widely available, performance and reliability must be improved and technologies used elsewhere must be applied to the Antarctic. Considerable Antarctic research is field-based, making access to vital geographical targets essential. Future research will require continent- and ocean-wide environmentally responsible access to coastal and interior Antarctica and the Southern Ocean. Year-round access is indispensable. The cost of future Antarctic science is great but there are opportunities for all to participate commensurate with national resources, expertise and interests. The scope of future Antarctic research will necessitate enhanced and inventive interdisciplinary and international collaborations. The full promise of Antarctic science will only be realized if nations act together.

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