scholarly journals Carbon Mineralization Pathways in Antarctic Shelf Sediments, East Antarctic Peninsula

2020 ◽  
Author(s):  
Marwa Baloza ◽  
Susann Henkel ◽  
Sabine Kasten ◽  
Moritz Holtappels
Keyword(s):  
Antarctic Peninsula ◽  
Carbon Mineralization ◽  
Shelf Sediments ◽  
Antarctic Shelf

scholarly journals Fe-binding organic ligands in coastal and frontal regions of the western Antarctic Peninsula

2021 ◽  
Vol 18 (15) ◽  
pp. 4587-4601
Author(s):  
Indah Ardiningsih ◽  
Kyyas Seyitmuhammedov ◽  
Sylvia G. Sander ◽  
Claudine H. Stirling ◽  
Gert-Jan Reichart ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Organic Ligand ◽  
Open Ocean ◽  
Organic Ligands ◽  
Western Antarctic Peninsula ◽  
Southern Boundary ◽  
Complexation Capacity ◽  
Electrochemical Approach ◽  
Shelf Sediments

Abstract. Organic ligands are a key factor determining the availability of dissolved iron (DFe) in the high-nutrient low-chlorophyll (HNLC) areas of the Southern Ocean. In this study, organic speciation of Fe is investigated along a natural gradient of the western Antarctic Peninsula, from an ice-covered shelf to the open ocean. An electrochemical approach, competitive ligand exchange – adsorptive cathodic stripping voltammetry (CLE-AdCSV), was applied. Our results indicated that organic ligands in the surface water on the shelf are associated with ice-algal exudates, possibly combined with melting of sea ice. Organic ligands in the deeper shelf water are supplied via the resuspension of slope or shelf sediments. Further offshore, organic ligands are most likely related to the development of phytoplankton blooms in open ocean waters. On the shelf, total ligand concentrations ([Lt]) were between 1.2 and 6.4 nM eq. Fe. The organic ligands offshore ranged between 1.0 and 3.0 nM eq. Fe. The southern boundary of the Antarctic Circumpolar Current (SB ACC) separated the organic ligands on the shelf from bloom-associated ligands offshore. Overall, organic ligand concentrations always exceeded DFe concentrations (excess ligand concentration, [L′] = 0.8–5.0 nM eq. Fe). The [L′] made up to 80 % of [Lt], suggesting that any additional Fe input can be stabilized in the dissolved form via organic complexation. The denser modified Circumpolar Deep Water (mCDW) on the shelf showed the highest complexation capacity of Fe (αFe'L; the product of [L′] and conditional binding strength of ligands, KFe'Lcond). Since Fe is also supplied by shelf sediments and glacial discharge, the high complexation capacity over the shelf can keep Fe dissolved and available for local primary productivity later in the season upon sea-ice melting.

scholarly journals A large population of king crabs in Palmer Deep on the west Antarctic Peninsula shelf and potential invasive impacts

2011 ◽  
Vol 279 (1730) ◽  
pp. 1017-1026 ◽  
Author(s):  
Craig R. Smith ◽  
Laura J. Grange ◽  
David L. Honig ◽  
Lieven Naudts ◽  
Bruce Huber ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Large Population ◽  
Ecological Impacts ◽  
Remotely Operated Vehicle ◽  
The West ◽  
Cold Temperatures ◽  
West Antarctic ◽  
Antarctic Shelf ◽  
West Antarctic Peninsula ◽  
The Antarctic

Lithodid crabs (and other skeleton-crushing predators) may have been excluded from cold Antarctic continental shelf waters for more than 14 Myr. The west Antarctic Peninsula shelf is warming rapidly and has been hypothesized to be soon invaded by lithodids. A remotely operated vehicle survey in Palmer Deep, a basin 120 km onto the Antarctic shelf, revealed a large, reproductive population of lithodids, providing the first evidence that king crabs have crossed the Antarctic shelf. DNA sequencing and morphology indicate the lithodid is Neolithodes yaldwyni Ahyong & Dawson, previously reported only from Ross Sea waters. We estimate a N. yaldwyni population density of 10 600 km −2 and a population size of 1.55 × 10 6 in Palmer Deep, a density similar to lithodid populations of commercial interest around Alaska and South Georgia. The lithodid occurred at depths of more than 850 m and temperatures of more than 1.4°C in Palmer Deep, and was not found in extensive surveys of the colder shelf at depths of 430–725 m. Where N. yaldwyni occurred, crab traces were abundant, megafaunal diversity reduced and echinoderms absent, suggesting that the crabs have major ecological impacts. Antarctic Peninsula shelf waters are warming at approximately 0.01°C yr −1 ; if N. yaldwyni is currently limited by cold temperatures, it could spread up onto the shelf (400–600 m depths) within 1–2 decades. The Palmer Deep N. yaldwyni population provides an important model for the potential invasive impacts of crushing predators on vulnerable Antarctic shelf ecosystems.

scholarly journals Annotated and illustrated list of echinoderms collected during the Colombian scientific expeditions to the Antarctica (2016-2019)

2021 ◽  
Vol 50 (SuplEsp) ◽  
pp. 85-108
Author(s):  
Giomar Borrero ◽  
Daniela Yepes
Keyword(s):  
Geographical Distribution ◽  
Antarctic Peninsula ◽  
Sea Cucumber ◽  
Base Line ◽  
Antarctic Shelf ◽  
The Antarctic ◽  
First Time ◽  
Oceanographic Conditions

I n order to contribute to the base line of knowledge that is being built of the Gerlache Strait and the adjacent areas, the echinoderms collected during the Scientific Expeditions from Colombia to Antarctica carried out between 2016 and 2019 as part of the project “Biodiversity and oceanographic conditions of the Gerlache Strait, Biogerlache-Antártica” are presented. Eleven stations between 54 and 523 m deep were sampled, using sediment dredgers that captured incidentally some individuals from the mega and macro-epifauna, which were separated, reviewed and identified. Twentynine (29) individuals were obtained in five of the sampled stations, belonging to 13 morphotypes. Ophiuroidea was the richest class (five morphotypes), followed by Holothuroidea (four), Asteroidea (two) and Crinoidea (two). Morphological and distribution comments are presented, as well as general and detailed images of each morphotype. Among the contributions to the inventory of echinoderms in the area, it is highlighted the sea cucumber genus Taeniogyrus Semper, 1867 that is registered for the first time for the Antarctic peninsula and the crinoid species Anthometrina adriani (Bell, 1908) that extends its geographical distribution, confined to the high-Antarctic shelf, up to the Gerlache Strait ( 64° 39 ‘S).

A high resolution relative paleointensity record from the Gerlache-Boyd paleo-ice stream region, northern Antarctic Peninsula

2006 ◽  
Vol 66 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Verónica Willmott ◽  
Eugene W. Domack ◽  
Miquel Canals ◽  
Stefanie Brachfeld
Keyword(s):  
Antarctic Peninsula ◽  
Mineral Assemblage ◽  
Western Antarctic Peninsula ◽  
Suitable Material ◽  
Relative Paleointensity ◽  
Shelf Sediments ◽  
Tephra Layers ◽  
Absolute Dating ◽  
Bransfield Basin

AbstractHerein we document and interpret an absolute chronological dating attempt using geomagnetic paleointensity data from a post-glacial sediment drape on the western Antarctic Peninsula continental shelf. Our results demonstrate that absolute dating can be established in Holocene Antarctic shelf sediments that lack suitable material for radiocarbon dating. Two jumbo piston cores of 10-m length were collected in the Western Bransfield Basin. The cores preserve a strong, stable remanent magnetization and meet the magnetic mineral assemblage criteria recommended for reliable paleointensity analyses. The relative paleomagnetic intensity records were tuned to published absolute and relative paleomagnetic stacks, which yielded a record of the last ∼8500 years for the post-glacial drape. Four tephra layers associated with documented eruptions of nearby Deception Island have been dated at 3.31, 3.73, 4.44, and 6.86 ± 0.07 ka using the geomagnetic paleointensity method. This study establishes the dual role of geomagnetic paleointensity and tephrochronology in marine sediments across both sides of the northern Antarctic Peninsula.

scholarly journals Iron cycling and stable Fe isotope fractionation in Antarctic shelf sediments, King George Island

2018 ◽  
Vol 237 ◽  
pp. 320-338 ◽  
Author(s):  
Susann Henkel ◽  
Sabine Kasten ◽  
Jan F. Hartmann ◽  
Adrián Silva-Busso ◽  
Michael Staubwasser
Keyword(s):  
Isotope Fractionation ◽  
King George Island ◽  
Iron Cycling ◽  
Shelf Sediments ◽  
Antarctic Shelf

scholarly journals Temperature characteristics of bacterial sulfate reduction in continental shelf and slope sediments

2012 ◽  
Vol 9 (8) ◽  
pp. 3425-3435 ◽  
Author(s):  
J. E. Sawicka ◽  
B. B. Jørgensen ◽  
V. Brüchert
Keyword(s):  
Deep Sea ◽  
Carbon Mineralization ◽  
Temperature Response ◽  
Short Term ◽  
Temperature Characteristics ◽  
Sulfate Reducing ◽  
Shelf Sediments ◽  
Mineralization Processes ◽  
Response Profiles

Abstract. The temperature responses of sulfate-reducing microbial communities were used as community temperature characteristics for their in situ temperature adaptation, their origin, and dispersal in the deep sea. Sediments were collected from a suite of coastal, continental shelf, and slope sediments from the southwest and southeast Atlantic and permanently cold Arctic fjords from water depths ranging from the intertidal zone to 4327 m. In situ temperatures ranged from 8 °C on the shelf to −1 °C in the Arctic. Temperature characteristics of the active sulfate-reducing community were determined in short-term incubations with 35S-sulfate in a temperature gradient block spanning a temperature range from 0 to 40 °C. An optimum temperature (Topt) between 27 °C and 30 °C for the South Atlantic shelf sediments and for the intertidal flat sediment from Svalbard was indicative of a psychrotolerant/mesophilic sulfate-reducing community, whereas Topt ≤20 °C in South Atlantic slope and Arctic shelf sediments suggested a predominantly psychrophilic community. High sulfate reduction rates (20–50%) at in situ temperatures compared to those at Topt further support this interpretation and point to the importance of the ambient temperature regime for regulating the short-term temperature response of sulfate-reducing communities. A number of cold (<4 °C) continental slope sediments showed broad temperature optima reaching as high as 30 °C, suggesting the additional presence of apparently mesophilic sulfate-reducing bacteria. Since the temperature characteristics of these mesophiles do not fit with the permanently cold deep-sea environment, we suggest that these mesophilic microorganisms are of allochthonous origin and transported to this site. It is likely that they were deposited along with the mass-flow movement of warmer shelf-derived sediment. These data therefore suggest that temperature response profiles of bacterial carbon mineralization processes can be used as community temperature characteristics, and that mixing of bacterial communities originating from diverse locations carrying different temperature characteristics needs to be taken into account to explain temperature response profiles of bacterial carbon mineralization processes in sediments.

scholarly journals Sources of Fe-binding organic ligands in surface waters of the western Antarctic Peninsula

2020 ◽  
Author(s):  
Indah Ardiningsih ◽  
Kyyas Seyitmuhammedov ◽  
Sylvia G. Sander ◽  
Claudine H. Stirling ◽  
Gert-Jan Reichart ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Organic Ligand ◽  
Open Ocean ◽  
Organic Ligands ◽  
Western Antarctic Peninsula ◽  
Southern Boundary ◽  
Complexation Capacity ◽  
Electrochemical Approach ◽  
Shelf Sediments

Abstract. Organic ligands are a key factor determining the availability of dissolved iron (DFe) in the high nutrient low chlorophyll (HNLC) areas of the Southern Ocean. In this study, organic speciation of Fe is investigated along a natural gradient of the western Antarctic Peninsula, from an ice covered shelf to the open ocean. An electrochemical approach, competitive ligand exchange – adsorptive cathodic stripping voltammetry (CLE-AdCSV) was applied. Our results indicated that organic ligands in surface water on the shelf are associated with ice-algal exudates, possibly combined with melting of sea-ice. Organic ligands in deeper shelf water are supplied via resuspension of slope or shelf sediments. Further offshore, organic ligands are most likely related to the development of phytoplankton blooms in open ocean waters. On the shelf, total ligand concentrations ([Lt]) were between 1.2 nM eq. Fe and 6.4 nM eq. Fe. The organic ligands offshore ranged between 1.0 and 3.0 nM eq. Fe. The southern boundary of the Antarctic Circumpolar Current (SB ACC) separated the organic ligands on the shelf from bloom-associated ligands offshore. Overall, organic ligand concentrations always exceeded DFe concentration (excess ligand concentration, [L'] = 0.8–5.0 nM eq. Fe). The [L'] made up to 80 % of [Lt], suggesting that any additional Fe input can be stabilized in the dissolved form via organic complexation. The denser modified Circumpolar Deep Water (mCDW) on the shelf showed the highest complexation capacity of Fe (αFe'L; the product of [L'] and conditional binding strength of ligands, KFe'Lcond). Since Fe is also supplied by shelf sediments and glacial discharge, the high complexation capacity over the shelf can keep Fe dissolved and available for local primary productivity later in the season, upon sea ice melting.

Sign in / Sign up

Export Citation Format

Share Document