1
|
Change and variability in Antarctic coastal exposure, 1979-2020. Nat Commun 2022; 13:1164. [PMID: 35246526 PMCID: PMC8897499 DOI: 10.1038/s41467-022-28676-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 01/17/2022] [Indexed: 11/08/2022] Open
Abstract
Increased exposure of Antarctica’s coastal environment to open ocean and waves due to loss of a protective sea-ice “buffer” has important ramifications for ice-shelf stability, coastal erosion, important ice-ocean-atmosphere interactions and shallow benthic ecosystems. Here, we introduce a climate and environmental metric based on the ongoing long-term satellite sea-ice concentration record, namely Coastal Exposure Length. This is a daily measure of change and variability in the length and incidence of Antarctic coastline lacking any protective sea-ice buffer offshore. For 1979–2020, ~50% of Antarctica’s ~17,850-km coastline had no sea ice offshore each summer, with minimal exposure in winter. Regional summer/maximum contributions vary from 45% (Amundsen-Bellingshausen seas) to 58% (Indian Ocean and Ross Sea), with circumpolar annual exposure ranging from 38% (2019) to 63% (1993). The annual maximum length of Antarctic coastal exposure decreased by ~30 km (~0.32%) per year for 1979–2020, composed of distinct regional and seasonal contributions. A new metric measuring the exposure of the Antarctic coastline to full open-ocean conditions reveals strong regional and seasonal change and variability occurred over the past four decades due to the loss and/or gain of an offshore sea-ice buffer.
Collapse
|
2
|
Pryer HV, Hawkings JR, Wadham JL, Robinson LF, Hendry KR, Hatton JE, Kellerman AM, Bertrand S, Gill‐Olivas B, Marshall MG, Brooker RA, Daneri G, Häussermann V. The Influence of Glacial Cover on Riverine Silicon and Iron Exports in Chilean Patagonia. GLOBAL BIOGEOCHEMICAL CYCLES 2020; 34:e2020GB006611. [PMID: 33519063 PMCID: PMC7818384 DOI: 10.1029/2020gb006611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 09/27/2020] [Accepted: 11/12/2020] [Indexed: 06/12/2023]
Abstract
Glaciated environments have been highlighted as important sources of bioavailable nutrients, with inputs of glacial meltwater potentially influencing productivity in downstream ecosystems. However, it is currently unclear how riverine nutrient concentrations vary across a spectrum of glacial cover, making it challenging to accurately predict how terrestrial fluxes will change with continued glacial retreat. Using 40 rivers in Chilean Patagonia as a unique natural laboratory, we investigate how glacial cover affects riverine Si and Fe concentrations, and infer how exports of these bioessential nutrients may change in the future. Dissolved Si (as silicic acid) and soluble Fe (<0.02 μm) concentrations were relatively low in glacier-fed rivers, whereas concentrations of colloidal-nanoparticulate (0.02-0.45 μm) Si and Fe increased significantly as a function of glacial cover. These colloidal-nanoparticulate phases were predominately composed of aluminosilicates and Fe-oxyhydroxides, highlighting the need for size-fractionated analyses and further research to quantify the lability of colloidal-nanoparticulate species. We also demonstrate the importance of reactive particulate (>0.45 μm) phases of both Si and Fe, which are not typically accounted for in terrestrial nutrient budgets but can dominate riverine exports. Dissolved Si and soluble Fe yield estimates showed no trend with glacial cover, suggesting no significant change in total exports with continued glacial retreat. However, yields of colloidal-nanoparticulate and reactive sediment-bound Si and Fe were an order of magnitude greater in highly glaciated catchments and showed significant positive correlations with glacial cover. As such, regional-scale exports of these phases are likely to decrease as glacial cover disappears across Chilean Patagonia, with potential implications for downstream ecosystems.
Collapse
Affiliation(s)
- Helena V. Pryer
- Bristol Glaciology Centre, Department of Geographical SciencesUniversity of BristolBristolUK
- School of Earth SciencesUniversity of BristolBristolUK
| | - Jon R. Hawkings
- Department of Earth, Ocean and Atmospheric SciencesFlorida State UniversityTallahasseeFLUSA
- German Research Centre for Geosciences GFZPotsdamGermany
| | - Jemma L. Wadham
- Bristol Glaciology Centre, Department of Geographical SciencesUniversity of BristolBristolUK
| | | | | | | | - Anne M. Kellerman
- Department of Earth, Ocean and Atmospheric SciencesFlorida State UniversityTallahasseeFLUSA
| | | | - Beatriz Gill‐Olivas
- Bristol Glaciology Centre, Department of Geographical SciencesUniversity of BristolBristolUK
| | - Matthew G. Marshall
- Bristol Glaciology Centre, Department of Geographical SciencesUniversity of BristolBristolUK
| | | | - Giovanni Daneri
- Centro de Investigación en Ecosistemas de la PatagoniaCoyhaiqueChile
- COPAS Sur‐AustralUniversidad de ConcepciónConcepciónChile
| | - Vreni Häussermann
- Huinay Scientific Field StationPontificia Universidad Católica de ValparaísoValparaísoChile
| |
Collapse
|
3
|
Thomsen S, Hansen MH, Lillethorup JP, Tirsgaard FS, Flytkjær A, Melvad C, Rysgaard S, Carlson DF. An affordable and miniature ice coring drill for rapid acquisition of small iceberg samples. HARDWAREX 2020; 7:e00101. [PMID: 35495204 PMCID: PMC9041166 DOI: 10.1016/j.ohx.2020.e00101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Icebergs account for approximately half of the freshwater flux from the Greenland Ice Sheet and they can impact marine ecosystems by releasing nutrients and sediments into the ocean as they drift and melt. Parameterizing iceberg fluxes of nutrients and sediments to fjord and ocean waters remains a difficult task due to the complexity of ice-ocean interactions and is complicated by a lack of observations. Acquiring iceberg samples can be difficult and dangerous, as icebergs can break apart and roll without warning. Here we present open source design files for a small, lightweight ice coring drill that can be reproduced using modern computer numerical control (CNC) machining and 3D printing technology. This ice core drill can rapidly acquire small ice samples from icebergs and bergy bits using a standard commercial, off-the-shelf battery-operated hand drill. Design files and a recent field expedition to Northwest Greenland are described. Ice core collection required only 30 s, thereby minimizing risks to scientists.
Collapse
Affiliation(s)
| | | | | | | | - Adam Flytkjær
- School of Engineering, Aarhus University, Aarhus, Denmark
| | - Claus Melvad
- School of Engineering, Aarhus University, Aarhus, Denmark
| | - Søren Rysgaard
- Arctic Research Centre, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Daniel F. Carlson
- Arctic Research Centre, Department of Bioscience, Aarhus University, Aarhus, Denmark
- Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL, USA
- Institute of Coastal Research, Helmholtz-Zentrum Geesthacht, Centre for Materials and Coastal Research, Geesthacht, Germany
| |
Collapse
|
4
|
Delord K, Kato A, Tarroux A, Orgeret F, Cotté C, Ropert-Coudert Y, Cherel Y, Descamps S. Antarctic petrels 'on the ice rocks': wintering strategy of an Antarctic seabird. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191429. [PMID: 32431861 PMCID: PMC7211841 DOI: 10.1098/rsos.191429] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 02/17/2020] [Indexed: 06/11/2023]
Abstract
There is a paucity of information on the foraging ecology, especially individual use of sea-ice features and icebergs, over the non-breeding season in many seabird species. Using geolocators and stable isotopes, we defined the movements, distribution and diet of adult Antarctic petrels Thalassoica antarctica from the largest known breeding colony, the inland Svarthamaren, Antarctica. More specifically, we examined how sea-ice concentration and free-drifting icebergs affect the distribution of Antarctic petrels. After breeding, birds moved north to the marginal ice zone (MIZ) in the Weddell sector of the Southern Ocean, following its northward extension during freeze-up in April, and they wintered there in April-August. There, the birds stayed predominantly out of the water (60-80% of the time) suggesting they use icebergs as platforms to stand on and/or to rest. Feather δ15N values encompassed one full trophic level, indicating that birds fed on various proportions of crustaceans and fish/squid, most likely Antarctic krill Euphausia superba and the myctophid fish Electrona antarctica and/or the squid Psychroteuthis glacialis. Birds showed strong affinity for the open waters of the northern boundary of the MIZ, an important iceberg transit area, which offers roosting opportunities and rich prey fields. The strong association of Antarctic petrels with sea-ice cycle and icebergs suggests the species can serve, year-round, as a sentinel of environmental changes for this remote region.
Collapse
Affiliation(s)
- K. Delord
- Centre d'Etudes Biologiques de Chizé, UMR 7372 du CNRS-La Rochelle Université, 79360 Villiers-en-Bois, France
| | - A. Kato
- Centre d'Etudes Biologiques de Chizé, UMR 7372 du CNRS-La Rochelle Université, 79360 Villiers-en-Bois, France
| | - A. Tarroux
- Norwegian Institute for Nature Research, Fram Centre, 9296 Tromsø, Norway
- Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway
| | - F. Orgeret
- Centre d'Etudes Biologiques de Chizé, UMR 7372 du CNRS-La Rochelle Université, 79360 Villiers-en-Bois, France
- Department of Zoology, Nelson Mandela, University, Port Elizabeth, South Africa
| | - C. Cotté
- Laboratoire d'Océanographie et du Climat, Expérimentation et Approches Numériques, Institut Pierre Simon Laplace, Université Pierre et Marie Curie, Centre National de la Recherche Scientifique, Paris, France
- Sorbonne Universités (UPMC, Univ Paris 06)-CNRS-IRD-MNHN, LOCEAN Laboratory, Paris, France
| | - Y. Ropert-Coudert
- Centre d'Etudes Biologiques de Chizé, UMR 7372 du CNRS-La Rochelle Université, 79360 Villiers-en-Bois, France
| | - Y. Cherel
- Centre d'Etudes Biologiques de Chizé, UMR 7372 du CNRS-La Rochelle Université, 79360 Villiers-en-Bois, France
| | - S. Descamps
- Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway
| |
Collapse
|
5
|
Hopwood MJ, Carroll D, Höfer J, Achterberg EP, Meire L, Le Moigne FAC, Bach LT, Eich C, Sutherland DA, González HE. Highly variable iron content modulates iceberg-ocean fertilisation and potential carbon export. Nat Commun 2019; 10:5261. [PMID: 31748607 PMCID: PMC6868171 DOI: 10.1038/s41467-019-13231-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 10/29/2019] [Indexed: 11/17/2022] Open
Abstract
Marine phytoplankton growth at high latitudes is extensively limited by iron availability. Icebergs are a vector transporting the bioessential micronutrient iron into polar oceans. Therefore, increasing iceberg fluxes due to global warming have the potential to increase marine productivity and carbon export, creating a negative climate feedback. However, the magnitude of the iceberg iron flux, the subsequent fertilization effect and the resultant carbon export have not been quantified. Using a global analysis of iceberg samples, we reveal that iceberg iron concentrations vary over 6 orders of magnitude. Our results demonstrate that, whilst icebergs are the largest source of iron to the polar oceans, the heterogeneous iron distribution within ice moderates iron delivery to offshore waters and likely also affects the subsequent ocean iron enrichment. Future marine productivity may therefore be not only sensitive to increasing total iceberg fluxes, but also to changing iceberg properties, internal sediment distribution and melt dynamics.
Collapse
Affiliation(s)
- Mark J Hopwood
- GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
| | - Dustin Carroll
- Moss Landing Marine Laboratories, San José State University, Moss Landing, CA, USA
| | - Juan Höfer
- Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile
| | | | - Lorenz Meire
- Royal Netherlands Institute for Sea Research, and Utrecht University, Yerseke, The Netherlands
- Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk, Greenland
| | - Frédéric A C Le Moigne
- Mediterranean Institute of Oceanography, UM110, CNRS, IRD, Aix Marseille Université Marseille, Marseille, France
| | - Lennart T Bach
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
| | - Charlotte Eich
- Royal Netherlands Institute for Sea Research, and University of Amsterdam, Texel, The Netherlands
| | | | - Humberto E González
- Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
| |
Collapse
|
6
|
Wadham JL, Hawkings JR, Tarasov L, Gregoire LJ, Spencer RGM, Gutjahr M, Ridgwell A, Kohfeld KE. Ice sheets matter for the global carbon cycle. Nat Commun 2019; 10:3567. [PMID: 31417076 PMCID: PMC6695407 DOI: 10.1038/s41467-019-11394-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 07/09/2019] [Indexed: 11/09/2022] Open
Abstract
The cycling of carbon on Earth exerts a fundamental influence upon the greenhouse gas content of the atmosphere, and hence global climate over millennia. Until recently, ice sheets were viewed as inert components of this cycle and largely disregarded in global models. Research in the past decade has transformed this view, demonstrating the existence of uniquely adapted microbial communities, high rates of biogeochemical/physical weathering in ice sheets and storage and cycling of organic carbon (>104 Pg C) and nutrients. Here we assess the active role of ice sheets in the global carbon cycle and potential ramifications of enhanced melt and ice discharge in a warming world.
Collapse
Affiliation(s)
- J L Wadham
- University of Bristol, Bristol, BS8 1TH, UK.
| | - J R Hawkings
- National High Magnetic Field Lab and Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL, 32306, USA
- German Research Centre for Geosciences GFZ, 14473, Potsdam, Germany
| | - L Tarasov
- Memorial University, St. John's, NF, A1B 3X9, Canada
| | | | - R G M Spencer
- National High Magnetic Field Lab and Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL, 32306, USA
| | | | - A Ridgwell
- University of California, Riverside, CA, 94720, USA
| | - K E Kohfeld
- Simon Fraser University, Burnaby, BC, 8888, Canada
| |
Collapse
|
7
|
St Pierre KA, St Louis VL, Lehnherr I, Gardner AS, Serbu JA, Mortimer CA, Muir DCG, Wiklund JA, Lemire D, Szostek L, Talbot C. Drivers of Mercury Cycling in the Rapidly Changing Glacierized Watershed of the High Arctic's Largest Lake by Volume (Lake Hazen, Nunavut, Canada). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:1175-1185. [PMID: 30596413 DOI: 10.1021/acs.est.8b05926] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Across the Arctic, glaciers are melting and permafrost is thawing at unprecedented rates, releasing not only water to downstream aquatic systems, but also contaminants like mercury, archived in ice over centuries. Using concentrations from samples collected over 4 years and calibrated modeled hydrology, we calculated methylmercury (MeHg) and total mercury (THg) mass balances for Lake Hazen, the world's largest High Arctic lake by volume, for 2015 and 2016. Glacial rivers were the most important source of MeHg and THg to Lake Hazen, accounting for up to 53% and 94% of the inputs, respectively. However, due to the MeHg and THg being primarily particle-bound, Lake Hazen was an annual MeHg and THg sink. Exports of MeHg and THg out the Ruggles River outflow were consequently very low, but erosion and permafrost slumping downstream of the lake increased river MeHg and THg concentrations significantly before entering coastal waters in Chandler Fjord. Since 2001, glacial MeHg and THg inputs to Lake Hazen have increased by 0.01 and 0.400 kg yr-1, respectively, in step with dramatic increases in glacial melt. This study highlights the potential for increases in mercury inputs to arctic ecosystems downstream of glaciers despite recent reductions in global mercury emissions.
Collapse
Affiliation(s)
- K A St Pierre
- Department of Biological Sciences , University of Alberta , Edmonton , Alberta T6G 2E9 , Canada
| | - V L St Louis
- Department of Biological Sciences , University of Alberta , Edmonton , Alberta T6G 2E9 , Canada
| | - I Lehnherr
- Department of Geography , University of Toronto Mississauga , Mississauga , Ontario L5L 1C6 , Canada
| | - A S Gardner
- NASA Jet Propulsion Laboratory , California Institute of Technology , Pasadena , California 91109 , United States
| | - J A Serbu
- Department of Biological Sciences , University of Alberta , Edmonton , Alberta T6G 2E9 , Canada
| | - C A Mortimer
- Department of Earth and Atmospheric Sciences , University of Alberta , Edmonton , Alberta T6G 2E3 Canada
| | - D C G Muir
- Environment and Climate Change Canada , Canadian Centre for Inland Waters , Burlington , Ontario , L7S 1A1 , Canada
| | - J A Wiklund
- Department of Biology , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
| | - D Lemire
- Department of Geography , University of Toronto Mississauga , Mississauga , Ontario L5L 1C6 , Canada
| | - L Szostek
- Department of Biological Sciences , University of Alberta , Edmonton , Alberta T6G 2E9 , Canada
| | - C Talbot
- Environment and Climate Change Canada , Canadian Centre for Inland Waters , Burlington , Ontario , L7S 1A1 , Canada
| |
Collapse
|
8
|
Joiris CR. Hotspots of kittiwakes Rissa tridactyla tridactyla on icebergs off southwest Greenland in autumn. Polar Biol 2018. [DOI: 10.1007/s00300-018-2356-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
9
|
Grefe I, Fielding S, Heywood KJ, Kaiser J. Nitrous oxide variability at sub-kilometre resolution in the Atlantic sector of the Southern Ocean. PeerJ 2018; 6:e5100. [PMID: 30002961 PMCID: PMC6037155 DOI: 10.7717/peerj.5100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 06/05/2018] [Indexed: 11/20/2022] Open
Abstract
The Southern Ocean is an important region for global nitrous oxide (N2O) cycling. The contribution of different source and sink mechanisms is, however, not very well constrained due to a scarcity of seawater data from the area. Here we present high-resolution surface N2O measurements from the Atlantic sector of the Southern Ocean, taking advantage of a relatively new underway setup allowing for collection of data during transit across mesoscale features such as frontal systems and eddies. Covering a range of different environments and biogeochemical settings, N2O saturations and sea-to-air fluxes were highly variable: Saturations ranged from 96.5% at the sea ice edge in the Weddell Sea to 126.1% across the Polar Frontal Zone during transit to South Georgia. Negative sea-to-air fluxes (N2O uptake) of up to −1.3 µmol m−2 d−1 were observed in the Subantarctic Zone and highest positive fluxes (N2O emission) of 14.5 µmol m−2 d−1 in Stromness Bay, coastal South Georgia. Although N2O saturations were high in areas of high productivity, no correlation between saturations and chlorophyll a (as a proxy for productivity) was observed. Nevertheless, there is a clear effect of islands and shallow bathymetry on N2O production as inferred from supersaturations.
Collapse
Affiliation(s)
- Imke Grefe
- Centre for Ocean and Atmospheric Sciences, University of East Anglia, Norwich, United Kingdom.,Current affiliation: Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom
| | | | - Karen J Heywood
- Centre for Ocean and Atmospheric Sciences, University of East Anglia, Norwich, United Kingdom
| | - Jan Kaiser
- Centre for Ocean and Atmospheric Sciences, University of East Anglia, Norwich, United Kingdom
| |
Collapse
|
10
|
|
11
|
Dinasquet J, Richert I, Logares R, Yager P, Bertilsson S, Riemann L. Mixing of water masses caused by a drifting iceberg affects bacterial activity, community composition and substrate utilization capability in the Southern Ocean. Environ Microbiol 2017; 19:2453-2467. [PMID: 28429510 DOI: 10.1111/1462-2920.13769] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 04/15/2017] [Indexed: 11/29/2022]
Abstract
The number of icebergs produced from ice-shelf disintegration has increased over the past decade in Antarctica. These drifting icebergs mix the water column, influence stratification and nutrient condition, and can affect local productivity and food web composition. Data on whether icebergs affect bacterioplankton function and composition are scarce, however. We assessed the influence of iceberg drift on bacterial community composition and on their ability to exploit carbon substrates during summer in the coastal Southern Ocean. An elevated bacterial production and a different community composition were observed in iceberg-influenced waters relative to the undisturbed water column nearby. These major differences were confirmed in short-term incubations with bromodeoxyuridine followed by CARD-FISH. Furthermore, one-week bottle incubations amended with inorganic nutrients and carbon substrates (a mix of substrates, glutamine, N-acetylglucosamine, or pyruvate) revealed contrasting capacity of bacterioplankton to utilize specific carbon substrates in the iceberg-influenced waters compared with the undisturbed site. Our study demonstrates that the hydrographical perturbations introduced by a drifting iceberg can affect activity, composition, and substrate utilization capability of marine bacterioplankton. Consequently, in a context of global warming, increased frequency of drifting icebergs in polar regions holds the potential to affect carbon and nutrient biogeochemistry at local and possibly regional scales.
Collapse
Affiliation(s)
- Julie Dinasquet
- Department of Natural Sciences, Linnaeus University, Kalmar, Sweden.,Marine Biological Section, University of Copenhagen, Helsingør, Denmark
| | - Inga Richert
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden.,Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Microbial Ecosystem Services Group, Leipzig, Germany
| | | | - Patricia Yager
- Department of Marine Sciences, University of Georgia, Athens, GA, USA
| | - Stefan Bertilsson
- Department of Ecology and Genetics, Limnology and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Lasse Riemann
- Marine Biological Section, University of Copenhagen, Helsingør, Denmark
| |
Collapse
|
12
|
Climatically sensitive transfer of iron to maritime Antarctic ecosystems by surface runoff. Nat Commun 2017; 8:14499. [PMID: 28198359 PMCID: PMC5316877 DOI: 10.1038/ncomms14499] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 01/06/2017] [Indexed: 11/12/2022] Open
Abstract
Iron supplied by glacial weathering results in pronounced hotspots of biological production in an otherwise iron-limited Southern Ocean Ecosystem. However, glacial iron inputs are thought to be dominated by icebergs. Here we show that surface runoff from three island groups of the maritime Antarctic exports more filterable (<0.45 μm) iron (6–81 kg km−2 a−1) than icebergs (0.0–1.2 kg km−2 a−1). Glacier-fed streams also export more acid-soluble iron (27.0–18,500 kg km−2 a−1) associated with suspended sediment than icebergs (0–241 kg km−2 a−1). Significant fluxes of filterable and sediment-derived iron (1–10 Gg a−1 and 100–1,000 Gg a−1, respectively) are therefore likely to be delivered by runoff from the Antarctic continent. Although estuarine removal processes will greatly reduce their availability to coastal ecosystems, our results clearly indicate that riverine iron fluxes need to be accounted for as the volume of Antarctic melt increases in response to 21st century climate change. Glacially-derived iron fertilizes the Southern Ocean ecosystem, but the quantities transported by runoff from Antarctica are unknown. Here, the authors show significant fluxes associated with surface meltwater runoff, and demonstrate that a marked increase in export can be expected in response to climate warming.
Collapse
|
13
|
Learman DR, Henson MW, Thrash JC, Temperton B, Brannock PM, Santos SR, Mahon AR, Halanych KM. Biogeochemical and Microbial Variation across 5500 km of Antarctic Surface Sediment Implicates Organic Matter as a Driver of Benthic Community Structure. Front Microbiol 2016; 7:284. [PMID: 27047451 PMCID: PMC4803750 DOI: 10.3389/fmicb.2016.00284] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 02/22/2016] [Indexed: 02/01/2023] Open
Abstract
Western Antarctica, one of the fastest warming locations on Earth, is a unique environment that is underexplored with regards to biodiversity. Although pelagic microbial communities in the Southern Ocean and coastal Antarctic waters have been well-studied, there are fewer investigations of benthic communities and most have a focused geographic range. We sampled surface sediment from 24 sites across a 5500 km region of Western Antarctica (covering the Ross Sea to the Weddell Sea) to examine relationships between microbial communities and sediment geochemistry. Sequencing of the 16S and 18S rRNA genes showed microbial communities in sediments from the Antarctic Peninsula (AP) and Western Antarctica (WA), including the Ross, Amundsen, and Bellingshausen Seas, could be distinguished by correlations with organic matter concentrations and stable isotope fractionation (total organic carbon; TOC, total nitrogen; TN, and δ13C). Overall, samples from the AP were higher in nutrient content (TOC, TN, and NH4+) and communities in these samples had higher relative abundances of operational taxonomic units (OTUs) classified as the diatom, Chaetoceros, a marine cercozoan, and four OTUs classified as Flammeovirgaceae or Flavobacteria. As these OTUs were strongly correlated with TOC, the data suggests the diatoms could be a source of organic matter and the Bacteroidetes and cercozoan are grazers that consume the organic matter. Additionally, samples from WA have lower nutrients and were dominated by Thaumarchaeota, which could be related to their known ability to thrive as lithotrophs. This study documents the largest analysis of benthic microbial communities to date in the Southern Ocean, representing almost half the continental shoreline of Antarctica, and documents trophic interactions and coupling of pelagic and benthic communities. Our results indicate potential modifications in carbon sequestration processes related to change in community composition, identifying a prospective mechanism that links climate change to carbon availability.
Collapse
Affiliation(s)
- Deric R Learman
- Department of Biology, Institute for Great Lakes Research, Central Michigan University Mt. Pleasant, MI, USA
| | - Michael W Henson
- Department of Biological Sciences, Louisiana State University Baton Rouge, LA, USA
| | - J Cameron Thrash
- Department of Biological Sciences, Louisiana State University Baton Rouge, LA, USA
| | - Ben Temperton
- Department of Biosciences, University of Exeter Exeter, UK
| | - Pamela M Brannock
- Department of Biological Sciences, Auburn University Auburn, AL, USA
| | - Scott R Santos
- Department of Biological Sciences, Auburn University Auburn, AL, USA
| | - Andrew R Mahon
- Department of Biology, Institute for Great Lakes Research, Central Michigan University Mt. Pleasant, MI, USA
| | | |
Collapse
|
14
|
Diatoms (Bacillariophyceae) associated with free-drifting Antarctic icebergs: taxonomy and distribution. Polar Biol 2016. [DOI: 10.1007/s00300-015-1791-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
15
|
A preliminary model of iron fertilisation by baleen whales and Antarctic krill in the Southern Ocean: Sensitivity of primary productivity estimates to parameter uncertainty. Ecol Modell 2016. [DOI: 10.1016/j.ecolmodel.2015.10.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
16
|
Summer social structure of crabeater seal Lobodon carcinophaga in the Amundsen Sea, Antarctica. Polar Biol 2015. [DOI: 10.1007/s00300-015-1778-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
17
|
Hawkings JR, Wadham JL, Tranter M, Raiswell R, Benning LG, Statham PJ, Tedstone A, Nienow P, Lee K, Telling J. Ice sheets as a significant source of highly reactive nanoparticulate iron to the oceans. Nat Commun 2014; 5:3929. [PMID: 24845560 PMCID: PMC4050262 DOI: 10.1038/ncomms4929] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 04/22/2014] [Indexed: 11/22/2022] Open
Abstract
The Greenland and Antarctic Ice Sheets cover ~\n10% of global land surface, but are rarely considered as active components of the global iron cycle. The ocean waters around both ice sheets harbour highly productive coastal ecosystems, many of which are iron limited. Measurements of iron concentrations in subglacial runoff from a large Greenland Ice Sheet catchment reveal the potential for globally significant export of labile iron fractions to the near-coastal euphotic zone. We estimate that the flux of bioavailable iron associated with glacial runoff is 0.40–2.54 Tg per year in Greenland and 0.06–0.17 Tg per year in Antarctica. Iron fluxes are dominated by a highly reactive and potentially bioavailable nanoparticulate suspended sediment fraction, similar to that identified in Antarctic icebergs. Estimates of labile iron fluxes in meltwater are comparable with aeolian dust fluxes to the oceans surrounding Greenland and Antarctica, and are similarly expected to increase in a warming climate with enhanced melting. Glacial meltwaters may help fertilize the iron-limited Polar Oceans, yet the contribution is poorly constrained. Hawkings et al. monitor iron fluxes during a full-melt season in Greenland, and propose that ice sheets provide highly reactive and potentially bioavailable iron, comparable with aeolian dust fluxes.
Collapse
Affiliation(s)
- Jon R Hawkings
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - Jemma L Wadham
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - Martyn Tranter
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - Rob Raiswell
- Cohen Biogeochemistry Laboratory, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - Liane G Benning
- Cohen Biogeochemistry Laboratory, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - Peter J Statham
- School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK
| | - Andrew Tedstone
- School of Geoscience, University of Edinburgh, Edinburgh EH8 9XP, UK
| | - Peter Nienow
- School of Geoscience, University of Edinburgh, Edinburgh EH8 9XP, UK
| | - Katherine Lee
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - Jon Telling
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| |
Collapse
|
18
|
Calving fluxes and basal melt rates of Antarctic ice shelves. Nature 2013; 502:89-92. [PMID: 24037377 DOI: 10.1038/nature12567] [Citation(s) in RCA: 401] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 08/07/2013] [Indexed: 11/08/2022]
Abstract
Iceberg calving has been assumed to be the dominant cause of mass loss for the Antarctic ice sheet, with previous estimates of the calving flux exceeding 2,000 gigatonnes per year. More recently, the importance of melting by the ocean has been demonstrated close to the grounding line and near the calving front. So far, however, no study has reliably quantified the calving flux and the basal mass balance (the balance between accretion and ablation at the ice-shelf base) for the whole of Antarctica. The distribution of fresh water in the Southern Ocean and its partitioning between the liquid and solid phases is therefore poorly constrained. Here we estimate the mass balance components for all ice shelves in Antarctica, using satellite measurements of calving flux and grounding-line flux, modelled ice-shelf snow accumulation rates and a regional scaling that accounts for unsurveyed areas. We obtain a total calving flux of 1,321 ± 144 gigatonnes per year and a total basal mass balance of -1,454 ± 174 gigatonnes per year. This means that about half of the ice-sheet surface mass gain is lost through oceanic erosion before reaching the ice front, and the calving flux is about 34 per cent less than previous estimates derived from iceberg tracking. In addition, the fraction of mass loss due to basal processes varies from about 10 to 90 per cent between ice shelves. We find a significant positive correlation between basal mass loss and surface elevation change for ice shelves experiencing surface lowering and enhanced discharge. We suggest that basal mass loss is a valuable metric for predicting future ice-shelf vulnerability to oceanic forcing.
Collapse
|
19
|
Smith KL, Sherman AD, Shaw TJ, Sprintall J. Icebergs as unique Lagrangian ecosystems in polar seas. ANNUAL REVIEW OF MARINE SCIENCE 2012; 5:269-287. [PMID: 22809193 DOI: 10.1146/annurev-marine-121211-172317] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Global warming and its disproportionate impact on polar regions have led to increased iceberg populations. Southern Ocean studies in the northwest Weddell Sea have verified substantial delivery of terrestrial material accompanied by increased primary production and faunal abundance associated with free-drifting icebergs. It is hypothesized that input and utilization of macro- and micronutrients are promoted by conditions unique to free-drifting icebergs, leading to increased production, grazing, and export of organic carbon. In Arctic regions, increased freshwater input from meltwater acts to stratify and stabilize the upper water column. As has been observed in the Southern Ocean, Arctic-region icebergs should drive turbulent upwelling and reduce stratification, potentially leading to increased nitrate delivery to the local ecosystem. Increasing populations of icebergs in polar regions can potentially be important in mediating the drawdown and sequestration of CO(2) and can thus impact the oceanic carbon cycle.
Collapse
Affiliation(s)
- K L Smith
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA.
| | | | | | | |
Collapse
|
20
|
de Jong J, Schoemann V, Lannuzel D, Croot P, de Baar H, Tison JL. Natural iron fertilization of the Atlantic sector of the Southern Ocean by continental shelf sources of the Antarctic Peninsula. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jg001679] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
21
|
Ingels J, Vanreusel A, Brandt A, Catarino AI, David B, De Ridder C, Dubois P, Gooday AJ, Martin P, Pasotti F, Robert H. Possible effects of global environmental changes on Antarctic benthos: a synthesis across five major taxa. Ecol Evol 2012; 2:453-85. [PMID: 22423336 PMCID: PMC3298955 DOI: 10.1002/ece3.96] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 11/11/2011] [Accepted: 11/23/2011] [Indexed: 11/25/2022] Open
Abstract
Because of the unique conditions that exist around the Antarctic continent, Southern Ocean (SO) ecosystems are very susceptible to the growing impact of global climate change and other anthropogenic influences. Consequently, there is an urgent need to understand how SO marine life will cope with expected future changes in the environment. Studies of Antarctic organisms have shown that individual species and higher taxa display different degrees of sensitivity to environmental shifts, making it difficult to predict overall community or ecosystem responses. This emphasizes the need for an improved understanding of the Antarctic benthic ecosystem response to global climate change using a multitaxon approach with consideration of different levels of biological organization. Here, we provide a synthesis of the ability of five important Antarctic benthic taxa (Foraminifera, Nematoda, Amphipoda, Isopoda, and Echinoidea) to cope with changes in the environment (temperature, pH, ice cover, ice scouring, food quantity, and quality) that are linked to climatic changes. Responses from individual to the taxon-specific community level to these drivers will vary with taxon but will include local species extinctions, invasions of warmer-water species, shifts in diversity, dominance, and trophic group composition, all with likely consequences for ecosystem functioning. Limitations in our current knowledge and understanding of climate change effects on the different levels are discussed.
Collapse
Affiliation(s)
- Jeroen Ingels
- Marine Biology Department, Ghent UniversityKrijgslaan 281 S8, 9000 Ghent, Belgium
| | - Ann Vanreusel
- Marine Biology Department, Ghent UniversityKrijgslaan 281 S8, 9000 Ghent, Belgium
| | - Angelika Brandt
- Zoological Museum Hamburg, University of HamburgMartin-Luther-King-Platz 3, 20146 Hamburg, Germany
| | - Ana I Catarino
- Marine Biology Laboratory, Université Libre de BruxellesCP160/15, Avenue F.D. Roosevelt 50, 1050 Brussels, Belgium
| | - Bruno David
- Biogeosciences, The University of BurgundyUMR CNRS 5561, Bd Gabriel 6,21000 Dijon, France
| | - Chantal De Ridder
- Marine Biology Laboratory, Université Libre de BruxellesCP160/15, Avenue F.D. Roosevelt 50, 1050 Brussels, Belgium
| | - Philippe Dubois
- Marine Biology Laboratory, Université Libre de BruxellesCP160/15, Avenue F.D. Roosevelt 50, 1050 Brussels, Belgium
| | - Andrew J Gooday
- Ocean Biogeochemistry & Ecosystems Research Group, National Oceanography CentreEuropean Way, Southampton SO14 3ZH, United Kingdom
| | - Patrick Martin
- Royal Belgian Institute of Natural SciencesRue Vautier 29, 1000 Brussels, Belgium
| | - Francesca Pasotti
- Marine Biology Department, Ghent UniversityKrijgslaan 281 S8, 9000 Ghent, Belgium
| | - Henri Robert
- Royal Belgian Institute of Natural SciencesRue Vautier 29, 1000 Brussels, Belgium
| |
Collapse
|
22
|
Ferrario ME, Cefarelli AO, Robison B, Vernet M. THALASSIONEIS SIGNYENSIS (BACILLARIOPHYCEAE) FROM NORTHWEST WEDDELL SEA ICEBERGS, AN EMENDATION OF THE GENERIC DESCRIPTION(1). JOURNAL OF PHYCOLOGY 2012; 48:222-230. [PMID: 27009666 DOI: 10.1111/j.1529-8817.2011.01097.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We offer an emended description of the genus Thalassioneis based on new observations of the type species, T. signyensis Round, from material sampled in the northwest Weddell Sea. Specimens from algal communities attached to submerged flanks of several icebergs were collected with a remote-operated vehicle (ROV-Phantom DS 2). The analyses were carried out by LM and SEM. Fresh material and frustules without organic matter allowed us to observe details not included in the original description such as type and structure of colonies and chloroplasts. The frustule shows an asymmetry with respect to the location of the apical pore fields, one of them situated on the valvar face and the other one displaced toward the mantle; the former is involved in joining contiguous cells to form long chains. Furthermore, we present details on the ultrastructure of the cingulum that consists of three to four open copulae with one or more rows of poroids. A brief discussion on the habit and ecology of this taxon, which may be endemic to the northwest Weddell Sea, is also presented. A comparison with similar genera, such as Brandinia, Creania, Fossula, Fragilaria, Rimoneis, Synedropsis, and Ulnaria, is included with an evaluation of morphological characteristics useful to differentiate them.
Collapse
Affiliation(s)
- Martha E Ferrario
- División Científica Ficología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina CONICET, Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917 1033, Buenos Aires, ArgentinaDivisión Científica Ficología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, ArgentinaMonterey Bay Aquarium Research Institute, Moss Landing, California 95039, USAIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0218, USA
| | - Adrián O Cefarelli
- División Científica Ficología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina CONICET, Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917 1033, Buenos Aires, ArgentinaDivisión Científica Ficología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, ArgentinaMonterey Bay Aquarium Research Institute, Moss Landing, California 95039, USAIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0218, USA
| | - Bruce Robison
- División Científica Ficología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina CONICET, Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917 1033, Buenos Aires, ArgentinaDivisión Científica Ficología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, ArgentinaMonterey Bay Aquarium Research Institute, Moss Landing, California 95039, USAIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0218, USA
| | - María Vernet
- División Científica Ficología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina CONICET, Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917 1033, Buenos Aires, ArgentinaDivisión Científica Ficología, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, ArgentinaMonterey Bay Aquarium Research Institute, Moss Landing, California 95039, USAIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0218, USA
| |
Collapse
|
23
|
Limpert E, Stahel WA. Problems with using the normal distribution--and ways to improve quality and efficiency of data analysis. PLoS One 2011; 6:e21403. [PMID: 21779325 PMCID: PMC3136454 DOI: 10.1371/journal.pone.0021403] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 06/01/2011] [Indexed: 02/02/2023] Open
Abstract
Background The Gaussian or normal distribution is the most established model to characterize quantitative variation of original data. Accordingly, data are summarized using the arithmetic mean and the standard deviation, by ± SD, or with the standard error of the mean, ± SEM. This, together with corresponding bars in graphical displays has become the standard to characterize variation. Methodology/Principal Findings Here we question the adequacy of this characterization, and of the model. The published literature provides numerous examples for which such descriptions appear inappropriate because, based on the “95% range check”, their distributions are obviously skewed. In these cases, the symmetric characterization is a poor description and may trigger wrong conclusions. To solve the problem, it is enlightening to regard causes of variation. Multiplicative causes are by far more important than additive ones, in general, and benefit from a multiplicative (or log-) normal approach. Fortunately, quite similar to the normal, the log-normal distribution can now be handled easily and characterized at the level of the original data with the help of both, a new sign, x/, times-divide, and notation. Analogous to ± SD, it connects the multiplicative (or geometric) mean * and the multiplicative standard deviation s* in the form * x/s*, that is advantageous and recommended. Conclusions/Significance The corresponding shift from the symmetric to the asymmetric view will substantially increase both, recognition of data distributions, and interpretation quality. It will allow for savings in sample size that can be considerable. Moreover, this is in line with ethical responsibility. Adequate models will improve concepts and theories, and provide deeper insight into science and life.
Collapse
Affiliation(s)
| | - Werner A. Stahel
- Seminar for Statistics, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
- * E-mail:
| |
Collapse
|
24
|
Spatial characterization of the meltwater field from icebergs in the Weddell Sea. Proc Natl Acad Sci U S A 2011; 108:5492-7. [PMID: 21444769 DOI: 10.1073/pnas.0909306108] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We describe the results from a spatial cyberinfrastructure developed to characterize the meltwater field around individual icebergs and integrate the results with regional- and global-scale data. During the course of the cyberinfrastructure development, it became clear that we were also building an integrated sampling planning capability across multidisciplinary teams that provided greater agility in allocating expedition resources resulting in new scientific insights. The cyberinfrastructure-enabled method is a complement to the conventional methods of hydrographic sampling in which the ship provides a static platform on a station-by-station basis. We adapted a sea-floor mapping method to more rapidly characterize the sea surface geophysically and biologically. By jointly analyzing the multisource, continuously sampled biological, chemical, and physical parameters, using Global Positioning System time as the data fusion key, this surface-mapping method enables us to examine the relationship between the meltwater field of the iceberg to the larger-scale marine ecosystem of the Southern Ocean. Through geospatial data fusion, we are able to combine very fine-scale maps of dynamic processes with more synoptic but lower-resolution data from satellite systems. Our results illustrate the importance of spatial cyberinfrastructure in the overall scientific enterprise and identify key interfaces and sources of error that require improved controls for the development of future Earth observing systems as we move into an era of peta- and exascale, data-intensive computing.
Collapse
|
25
|
Dehner CA, Barton L, Maurice PA, DuBois JL. Size-dependent bioavailability of hematite (α-Fe2O3) nanoparticles to a common aerobic bacterium. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:977-83. [PMID: 21174456 DOI: 10.1021/es102922j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The size-dependent bioavailability of hematite (α-Fe(2)O(3)) nanoparticles to obligate aerobic Pseudomonas mendocina bacteria was examined using the natural siderophore-producing wild type strain and a siderophore(-) mutant strain. Results showed that Fe from hematite less than a few tens of nm in size appears to be considerably more bioavailable than Fe associated with larger particles. This increased bioavailability is related to the total available particle surface area, and depends in part on greater accessibility of the Fe to the chelating siderophore(s). Greater bioavailability is also related to mechanism(s) that depend on cell/nanomineral proximity, but not on siderophores. Siderophore(-) bacteria readily acquire Fe from particles <10 nm but must be in direct physical proximity to the nanomineral; the bacteria neither produce a diffusible Fe-mobilizing agent nor accumulate a reservoir of dissolved Fe in supernatant solutions. Particles <10 nm appear to be capable of penetrating the outer cell wall, offering at least one possible pathway for Fe acquisition. Other cell-surface-associated molecules and/or processes could also be important, including a cell-wall associated reducing capability. The increased bioavailability of <10 nm particles has implications for both biogeochemical Fe cycling and applications involving engineered nanoparticles, and raises new questions regarding biogenic influences on adsorbed contaminants.
Collapse
Affiliation(s)
- Carolyn A Dehner
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 62223, USA
| | | | | | | |
Collapse
|
26
|
Chever F, Bucciarelli E, Sarthou G, Speich S, Arhan M, Penven P, Tagliabue A. Physical speciation of iron in the Atlantic sector of the Southern Ocean along a transect from the subtropical domain to the Weddell Sea Gyre. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jc005880] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- F. Chever
- Université Européenne de Bretagne Bretagne France
- LEMAR, UMR 6539 Université de Brest, CNRS, IRD, UBO, IUEM, Technopôle Brest Iroise Plouzane France
| | - E. Bucciarelli
- Université Européenne de Bretagne Bretagne France
- LEMAR, UMR 6539 Université de Brest, CNRS, IRD, UBO, IUEM, Technopôle Brest Iroise Plouzane France
| | - G. Sarthou
- Université Européenne de Bretagne Bretagne France
- LEMAR, UMR 6539 Université de Brest, CNRS, IRD, UBO, IUEM, Technopôle Brest Iroise Plouzane France
| | - S. Speich
- Laboratoire de Physique des Océans, UMR 6523 IFREMER, CNRS, IRD, UBO Plouzane France
| | - M. Arhan
- Laboratoire de Physique des Océans, UMR 6523 IFREMER, CNRS, IRD, UBO Plouzane France
| | - P. Penven
- Laboratoire de Physique des Océans, UMR 6523 IFREMER, CNRS, IRD, UBO Plouzane France
| | - A. Tagliabue
- LSCE, UMR 1572 IPSL, CEA, CNRS, UVSQ Gif‐sur‐Yvette France
- LOCEAN, UMR 7159 IPSL, UPMC, MHNH, IRD, CNRS Paris France
| |
Collapse
|
27
|
Diversity of the diatom genus Fragilariopsis in the Argentine Sea and Antarctic waters: morphology, distribution and abundance. Polar Biol 2010. [DOI: 10.1007/s00300-010-0794-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
28
|
Lannuzel D, Schoemann V, de Jong J, Pasquer B, van der Merwe P, Masson F, Tison JL, Bowie A. Distribution of dissolved iron in Antarctic sea ice: Spatial, seasonal, and inter-annual variability. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jg001031] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
29
|
van Beek P, Souhaut M, Reyss JL. Measuring the radium quartet (228Ra, 226Ra, 224Ra, 223Ra) in seawater samples using gamma spectrometry. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2010; 101:521-529. [PMID: 20106569 DOI: 10.1016/j.jenvrad.2009.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 11/03/2009] [Accepted: 12/15/2009] [Indexed: 05/28/2023]
Abstract
Radium isotopes are widely used in marine studies (eg. to trace water masses, to quantify mixing processes or to study submarine groundwater discharge). While 228Ra and 226Ra are usually measured using gamma spectrometry, short-lived Ra isotopes (224Ra and 223Ra) are usually measured using a Radium Delayed Coincidence Counter (RaDeCC). Here we show that the four radium isotopes can be analyzed using gamma spectrometry. We report 226Ra, 228Ra, 224Ra, 223Ra activities measured using low-background gamma spectrometry in standard samples, in water samples collected in the vicinity of our laboratory (La Palme and Vaccarès lagoons, France) but also in seawater samples collected in the plume of the Amazon river, off French Guyana (AMANDES project). The 223Ra and 224Ra activities determined in these samples using gamma spectrometry were compared to the activities determined using RaDeCC. Activities determined using the two techniques are in good agreement. Uncertainties associated with the 224Ra activities are similar for the two techniques. RaDeCC is more sensitive for the detection of low 223Ra activities. Gamma spectrometry thus constitutes an alternate method for the determination of short-lived Ra isotopes.
Collapse
Affiliation(s)
- P van Beek
- LEGOS, Laboratoire d'Etudes en Géophysique et Océanographie Spatiales (CNRS/CNES/IRD/UPS), Observatoire Midi Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France.
| | | | | |
Collapse
|
30
|
Raiswell R, Benning LG, Tranter M, Tulaczyk S. Bioavailable iron in the Southern Ocean: the significance of the iceberg conveyor belt. GEOCHEMICAL TRANSACTIONS 2008; 9:7. [PMID: 18513396 PMCID: PMC2440735 DOI: 10.1186/1467-4866-9-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Accepted: 05/30/2008] [Indexed: 05/24/2023]
Abstract
Productivity in the Southern Oceans is iron-limited, and the supply of iron dissolved from aeolian dust is believed to be the main source from outside the marine reservoir. Glacial sediment sources of iron have rarely been considered, as the iron has been assumed to be inert and non-bioavailable. This study demonstrates the presence of potentially bioavailable Fe as ferrihydrite and goethite in nanoparticulate clusters, in sediments collected from icebergs in the Southern Ocean and glaciers on the Antarctic landmass. Nanoparticles in ice can be transported by icebergs away from coastal regions in the Southern Ocean, enabling melting to release bioavailable Fe to the open ocean. The abundance of nanoparticulate iron has been measured by an ascorbate extraction. This data indicates that the fluxes of bioavailable iron supplied to the Southern Ocean from aeolian dust (0.01-0.13 Tg yr(-1)) and icebergs (0.06-0.12 Tg yr(-1)) are comparable. Increases in iceberg production thus have the capacity to increase productivity and this newly identified negative feedback may help to mitigate fossil fuel emissions.
Collapse
Affiliation(s)
- Rob Raiswell
- Earth and Biosphere Institute, School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK
| | - Liane G Benning
- Earth and Biosphere Institute, School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK
| | - Martyn Tranter
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK
| | - Slawek Tulaczyk
- Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, USA
| |
Collapse
|
31
|
Hochella MF, Lower SK, Maurice PA, Penn RL, Sahai N, Sparks DL, Twining BS. Nanominerals, mineral nanoparticles, and Earth systems. Science 2008; 319:1631-5. [PMID: 18356515 DOI: 10.1126/science.1141134] [Citation(s) in RCA: 343] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Minerals are more complex than previously thought because of the discovery that their chemical properties vary as a function of particle size when smaller, in at least one dimension, than a few nanometers, to perhaps as much as several tens of nanometers. These variations are most likely due, at least in part, to differences in surface and near-surface atomic structure, as well as crystal shape and surface topography as a function of size in this smallest of size regimes. It has now been established that these variations may make a difference in important geochemical and biogeochemical reactions and kinetics. This recognition is broadening and enriching our view of how minerals influence the hydrosphere, pedosphere, biosphere, and atmosphere.
Collapse
Affiliation(s)
- Michael F Hochella
- Center for NanoBioEarth, Department of Geosciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA 24061-0420, USA.
| | | | | | | | | | | | | |
Collapse
|