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51. Co-occurrence of Fe and P stress in natural populations of the marine diazotroph Trichodesmium

Author

Held, Noelle A., Webb, Eric A., McIlvin, Matthew M., Hutchins, David A., Cohen, Natalie R., Moran, Dawn M., Kunde, Korinna, Lohan, Maeve C., Mahaffey, Claire, Woodward, E. Malcolm S., and Saito, Mak A.

Abstract

Trichodesmium is a globally important marine microbe that provides fixed nitrogen (N) to otherwise N-limited ecosystems. In nature, nitrogen fixation is likely regulated by iron or phosphate availability, but the extent and interaction of these controls are unclear. From metaproteomics analyses using established protein biomarkers for nutrient stress, we found that iron–phosphate co-stress is the norm rather than the exception for Trichodesmium colonies in the North Atlantic Ocean. Counterintuitively, the nitrogenase enzyme was more abundant under co-stress as opposed to single nutrient stress. This is consistent with the idea that Trichodesmium has a specific physiological state during nutrient co-stress. Organic nitrogen uptake was observed and occurred simultaneously with nitrogen fixation. The quantification of the phosphate ABC transporter PstA combined with a cellular model of nutrient uptake suggested that Trichodesmium is generally confronted by the biophysical limits of membrane space and diffusion rates for iron and phosphate acquisition in the field. Colony formation may benefit nutrient acquisition from particulate and organic sources, alleviating these pressures. The results highlight that to predict the behavior of Trichodesmium, both Fe and P stress must be evaluated simultaneously.

Published
2020

55. Increasing picocyanobacteria success in shelf waters contributes to long‐term food web degradation

Author

Schmidt, Katrin, primary, Birchill, Antony J., additional, Atkinson, Angus, additional, Brewin, Robert J. W., additional, Clark, James R., additional, Hickman, Anna E., additional, Johns, David G., additional, Lohan, Maeve C., additional, Milne, Angela, additional, Pardo, Silvia, additional, Polimene, Luca, additional, Smyth, Tim J., additional, Tarran, Glen A., additional, Widdicombe, Claire E., additional, Woodward, E. Malcolm S., additional, and Ussher, Simon J., additional

Published
2020
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60. Supplementary material to "Co-occurrence of Fe and P stress in natural populations of the marine diazotroph Trichodesmium"

Author

Held, Noelle A., primary, Webb, Eric A., additional, McIlvin, Matthew M., additional, Hutchins, David A., additional, Cohen, Natalie R., additional, Moran, Dawn M., additional, Kunde, Korinna, additional, Lohan, Maeve C., additional, Mahaffey, Claire M., additional, Woodward, E. Malcolm S., additional, and Saito, Mak A., additional

Published
2020
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64. Seasonal iron depletion in temperate shelf seas

Author

Birchill, Antony J., Milne, Angela, Woodward, E. Malcolm S., Harris, Carolyn, Annett, Amber, Rusiecka, Dagmara, Achterberg, Eric P., Gledhill, Martha, Ussher, Simon J., Worsfold, Paul J., Geibert, Walter, and Lohan, Maeve C.

Abstract

Our study followed the seasonal cycling of soluble (SFe), colloidal (CFe), dissolved (DFe), total dissolvable (TDFe), labile particulate (LPFe), and total particulate (TPFe) iron in the Celtic Sea (NE Atlantic Ocean). Preferential uptake of SFe occurred during the spring bloom, preceding the removal of CFe. Uptakeand export of Fe during the spring bloom, coupled with a reduction in vertical exchange, led to Fe deplete surface waters (

Published
2017

66. Radium-228-derived ocean mixing and trace element inputs in the South Atlantic.

Author

Yu-Te Hsieh, Geibert, Walter, Woodward, E. Malcolm S., Wyatt, Neil J., Lohan, Maeve C., Achterberg, Eric P., and Henderson, Gideon M.

Subjects
OCEANIC mixing, EUPHOTIC zone, TRACE elements, MARINE productivity, CONTINENTAL shelf, OCEAN, DUST
Abstract

Trace elements play important roles as micronutrients in modulating marine productivity in the global ocean. The South Atlantic around 40°S is a prominent region of high productivity and a transition zone between the nitrate-depleted Subtropical Gyre and the iron-limited Southern Ocean. However, the sources and fluxes of trace elements to this region remain unclear. In this study, the distribution of the naturally occurring radioisotope 228Ra in the water column of the South Atlantic (Cape Basin and Argentine Basin) has been investigated along a 40°S zonal transect to estimate ocean mixing and trace element supply to the surface ocean. Ra-228 profiles have been used to determine the horizontal and vertical mixing rates in the near-surface open ocean. In the Argentine Basin, horizontal mixing from the continental shelf to the open ocean shows an eddy diffusion of Kx = 1.7 ± 1.4 (106 cm² s-1) and an integrated advection velocity w = 0.6 ± 0.3 cm s-1. In the Cape Basin, horizontal mixing is Kx = 2.7 ± 0.8 (107 cm² s-1) and vertical mixing Kz = 1.0 - 1.5 cm² s-1 in the upper 600 m layer. Three different approaches (228Ra-diffusion, 228Ra-advection and 228Ra/TE-ratio) have been applied to estimate the dissolved trace-element fluxes from shelf to open ocean. These approaches bracket the possible range of off-shelf fluxes from the Argentine margin to be: 3.8 - 22 (x10³) nmol Co m-2 d-1, 7.9 - 20 (x104) nmol Fe m-2 d-1 and 2.7 - 6.5 (x104) nmol Zn m-2 d-1. Off-shelf fluxes from the Cape margin are: 4.3 - 6.2 (x10³) nmol Co m-2 d-1, 1.2 - 3.1 (x104) nmol Fe m-2 d-1 and 0.9 - 1.2 (x104) nmol Zn m-2 d-1. On average, at 40°S in the Atlantic, vertical mixing supplies 0.4 - 1.2 nmol Co m-2 d-1, 3.6 - 11 nmol Fe m-2 d-1, and 13 - 16 nmol Zn m-2 d-1 to the euphotic zone. Compared with atmospheric dust and continental shelf inputs, vertical mixing is a more important source for supplying dissolved trace elements to the surface 40°S Atlantic. It is insufficient, however, to provide the trace elements removed by biological uptake. Other inputs (e.g. particulate, or from [ABSTRACT FROM AUTHOR]

Published
2020
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67. Seasonal cycling of zinc and cobalt in the Southeast Atlantic along the GEOTRACES GA10 section.

Author

Wyatt, Neil J., Milne, Angela, Achterberg, Eric P., Browning, Thomas J., Bouman, Heather A., Woodward, E. Malcolm S., and Lohan, Maeve C.

Subjects
WATER, BIOLOGICAL interfaces, WATER springs, STOICHIOMETRY, SPRING, CYCLING competitions
Abstract

We report the distributions of dissolved zinc (dZn) and cobalt (dCo) in sub-tropical and sub-Antarctic waters of the Southeast Atlantic Ocean during austral spring 2010 and summer 2011/12. A strong seasonal signal was observed in sub-tropical surface waters with early spring mixed-layer dZn and dCo concentrations of 3.16 ± 1.35 nM and 39 ± 9 pM, respectively, compared with summer values depleted well below these levels by biological activity. The elevated spring mixed-layer dZn concentrations resulted from an apparent offshore transport of elevated dZn at depths between 20-50 m, derived from lithogenic inputs from the Agulhas Bank. In contrast, open-ocean sub-Antarctic surface waters displayed largely consistent inter-seasonal mixed-layer dZn and dCo concentrations of 0.11 ± 0.08 nM and 11 ± 5 pM, respectively. The vertical distributions of dZn and dCo in the upper water column were similar to that of phosphate (PO43-), with positive linear relationships during each of the seasons and across dynamic biogeochemical regimes, suggesting surface biological drawdown and shallow remineralisation of these metals in this region largely influences their distribution. The ecological stoichiometries for dZn and dCo, calculated from the linear regression with PO43-, suggest a greater overall use of dZn relative to dCo in the upper water column of the Southeast Atlantic with an inter-seasonal Zn:Co ratio ranging between 9 and 29. Sub-tropical surface water Zn:Co ratios were found to decrease between spring and summer indicating a preferential removal of dZn relative to dCo between seasons. In this paper we investigate how the seasonal influences of external input and phytoplankton succession may relate to the distribution of dZn and dCo, and variation in Zn:Co ecological stoichiometry, across two distinct ecological regimes in the Southeast Atlantic. [ABSTRACT FROM AUTHOR]

Published
2020
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70. Seasonal iron depletion in temperate shelf seas

Author

Birchill, Antony J., primary, Milne, Angela, additional, Woodward, E. Malcolm S., additional, Harris, Carolyn, additional, Annett, Amber, additional, Rusiecka, Dagmara, additional, Achterberg, Eric P., additional, Gledhill, Martha, additional, Ussher, Simon J., additional, Worsfold, Paul J., additional, Geibert, Walter, additional, and Lohan, Maeve C., additional

Published
2017
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71. Return of naturally sourced Pb to Atlantic surface waters

Author

Bridgestock, Luke, van de Flierdt, Tina, Rehkämper, Mark, Paul, Maxence, Middag, Rob, Milne, Angela, Lohan, Maeve C., Baker, Alex R., Chance, Rosie, Khondoker, Roulin, Strekopytov, Stanislav, Humphreys-Williams, Emma, Achterberg, Eric P., Rijkenberg, Micha J. A., Gerringa, Loes J. A., de Baar, Hein J. W., and Natural Environment Research Council (NERC)

Subjects
TRACE-METAL CHEMISTRY, ANTHROPOGENIC LEAD, Science & Technology, Science, WESTERN NORTH-ATLANTIC, MEDITERRANEAN-SEA, Article, Multidisciplinary Sciences, DRY DEPOSITION, TRANSATLANTIC DUST TRANSPORT, SAHARAN DUST, PARTICULATE MATTER, ISOTOPIC EVIDENCE, MARINE AEROSOLS, Science & Technology - Other Topics
Abstract

Anthropogenic emissions completely overwhelmed natural marine lead (Pb) sources during the past century, predominantly due to leaded petrol usage. Here, based on Pb isotope measurements, we reassess the importance of natural and anthropogenic Pb sources to the tropical North Atlantic following the nearly complete global cessation of leaded petrol use. Significant proportions of up to 30–50% of natural Pb, derived from mineral dust, are observed in Atlantic surface waters, reflecting the success of the global effort to reduce anthropogenic Pb emissions. The observation of mineral dust derived Pb in surface waters is governed by the elevated atmospheric mineral dust concentration of the North African dust plume and the dominance of dry deposition for the atmospheric aerosol flux to surface waters. Given these specific regional conditions, emissions from anthropogenic activities will remain the dominant global marine Pb source, even in the absence of leaded petrol combustion., Anthropogenic lead (Pb) has overwhelmed natural Pb sources for over a century, yet the phasing out of leaded petrol in the early 2000s has renewed hope. Here, Bridgestock et al. use Pd isotopes to reassess the origins of Pd deposited in the tropical North Atlantic and reveal a significant natural source.

Published
2016

76. The GEOTRACES Intermediate Data Product 2014

Author

Mawji, Edward, primary, Schlitzer, Reiner, additional, Dodas, Elena Masferrer, additional, Abadie, Cyril, additional, Abouchami, Wafa, additional, Anderson, Robert F., additional, Baars, Oliver, additional, Bakker, Karel, additional, Baskaran, Mark, additional, Bates, Nicholas R., additional, Bluhm, Katrin, additional, Bowie, Andrew, additional, Bown, Johann, additional, Boye, Marie, additional, Boyle, Edward A., additional, Branellec, Pierre, additional, Bruland, Kenneth W., additional, Brzezinski, Mark A., additional, Bucciarelli, Eva, additional, Buesseler, Ken, additional, Butler, Edward, additional, Cai, Pinghe, additional, Cardinal, Damien, additional, Casciotti, Karen, additional, Chaves, Joaquin, additional, Cheng, Hai, additional, Chever, Fanny, additional, Church, Thomas M., additional, Colman, Albert S., additional, Conway, Tim M., additional, Croot, Peter L., additional, Cutter, Gregory A., additional, de Baar, Hein J.W., additional, de Souza, Gregory F., additional, Dehairs, Frank, additional, Deng, Feifei, additional, Dieu, Huong Thi, additional, Dulaquais, Gabriel, additional, Echegoyen-Sanz, Yolanda, additional, Lawrence Edwards, R., additional, Fahrbach, Eberhard, additional, Fitzsimmons, Jessica, additional, Fleisher, Martin, additional, Frank, Martin, additional, Friedrich, Jana, additional, Fripiat, François, additional, Galer, Stephen J.G., additional, Gamo, Toshitaka, additional, Solsona, Ester Garcia, additional, Gerringa, Loes J.A., additional, Godoy, José Marcus, additional, Gonzalez, Santiago, additional, Grossteffan, Emilie, additional, Hatta, Mariko, additional, Hayes, Christopher T., additional, Heller, Maija Iris, additional, Henderson, Gideon, additional, Huang, Kuo-Fang, additional, Jeandel, Catherine, additional, Jenkins, William J., additional, John, Seth, additional, Kenna, Timothy C., additional, Klunder, Maarten, additional, Kretschmer, Sven, additional, Kumamoto, Yuichiro, additional, Laan, Patrick, additional, Labatut, Marie, additional, Lacan, Francois, additional, Lam, Phoebe J., additional, Lannuzel, Delphine, additional, le Moigne, Frederique, additional, Lechtenfeld, Oliver J., additional, Lohan, Maeve C., additional, Lu, Yanbin, additional, Masqué, Pere, additional, McClain, Charles R., additional, Measures, Christopher, additional, Middag, Rob, additional, Moffett, James, additional, Navidad, Alicia, additional, Nishioka, Jun, additional, Noble, Abigail, additional, Obata, Hajime, additional, Ohnemus, Daniel C., additional, Owens, Stephanie, additional, Planchon, Frédéric, additional, Pradoux, Catherine, additional, Puigcorbé, Viena, additional, Quay, Paul, additional, Radic, Amandine, additional, Rehkämper, Mark, additional, Remenyi, Tomas, additional, Rijkenberg, Micha J.A., additional, Rintoul, Stephen, additional, Robinson, Laura F., additional, Roeske, Tobias, additional, Rosenberg, Mark, additional, van der Loeff, Michiel Rutgers, additional, Ryabenko, Evgenia, additional, Saito, Mak A., additional, Roshan, Saeed, additional, Salt, Lesley, additional, Sarthou, Géraldine, additional, Schauer, Ursula, additional, Scott, Peter, additional, Sedwick, Peter N., additional, Sha, Lijuan, additional, Shiller, Alan M., additional, Sigman, Daniel M., additional, Smethie, William, additional, Smith, Geoffrey J., additional, Sohrin, Yoshiki, additional, Speich, Sabrina, additional, Stichel, Torben, additional, Stutsman, Johnny, additional, Swift, James H., additional, Tagliabue, Alessandro, additional, Thomas, Alexander, additional, Tsunogai, Urumu, additional, Twining, Benjamin S., additional, van Aken, Hendrik M., additional, van Heuven, Steven, additional, van Ooijen, Jan, additional, van Weerlee, Evaline, additional, Venchiarutti, Celia, additional, Voelker, Antje H.L., additional, Wake, Bronwyn, additional, Warner, Mark J., additional, Woodward, E. Malcolm S., additional, Wu, Jingfeng, additional, Wyatt, Neil, additional, Yoshikawa, Hisayuki, additional, Zheng, Xin-Yuan, additional, Xue, Zichen, additional, Zieringer, Moritz, additional, and Zimmer, Louise A., additional

Published
2015
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82. Identifying the provenance of Leach’s storm petrels in the North Atlantic using polychlorinated biphenyl signatures derived from comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry

Author

Megson, David, primary, Brown, Thomas A., additional, Johnson, Glenn W., additional, O’Sullivan, Gwen, additional, Bicknell, Anthony W.J., additional, Votier, Stephen C., additional, Lohan, Maeve C., additional, Comber, Sean, additional, Kalin, Robert, additional, and Worsfold, Paul J., additional

Published
2014
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86. Multiple trophic levels fueled by recirculation in the Columbia River plume

Author

Kudela, Raphael M., primary, Horner-Devine, Alexander R., additional, Banas, Neil S., additional, Hickey, Barbara M., additional, Peterson, Tawnya D., additional, McCabe, Ryan M., additional, Lessard, Evelyn J., additional, Frame, Elizabeth, additional, Bruland, Kenneth W., additional, Jay, David A., additional, Peterson, Jay O., additional, Peterson, William T., additional, Kosro, P. Michael, additional, Palacios, Sherry L., additional, Lohan, Maeve C., additional, and Dever, Edward P., additional

Published
2010
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94. Supplementary Material from Coastal ocean and shelf-sea biogeochemical cycling of trace elements and isotopes: lessons learned from GEOTRACES

Author

Charette, Matthew A., Lam, Phoebe J., Lohan, Maeve C., Kwon, Eun Young, Hatje, Vanessa, Jeandel, Catherine, Shiller, Alan M., Cutter, Gregory A., Thomas, Alex, Boyd, Philip W., Homoky, William B., Milne, Angela, Thomas, Helmuth, Andersson, Per S., Porcelli, Don, Tanaka, Takahiro, Geibert, Walter, Dehairs, Frank, and Garcia-Orellana, Jordi

Subjects
13. Climate action, Astrophysics::High Energy Astrophysical Phenomena, Physics::Atomic Physics, 14. Life underwater, Nuclear Experiment, Physics::Atmospheric and Oceanic Physics, Physics::Geophysics
Abstract

Description and derivation of equation used to derive trace element and isotope fluxes from the continental margin

95. Paired dissolved and particulate phase Cu isotope distributions in the South Atlantic

Author

Little, Susan H., Archer, Corey, Milne, Angela, Schlosser, Christian, Achterberg, Eric P., Lohan, Maeve C., and Vance, Derek

Subjects
Particulate, South Atlantic, GEOTRACES, 13. Climate action, Copper isotopes, 14. Life underwater, Dissolved
Abstract

Copper (Cu) is both an essential micronutrient and toxic to photosynthesizing microorganisms at low concentrations. Its dissolved vertical distribution in the oceans is unusual, being neither a nutrient-type nor scavenged-type element. This distribution is attributed to biological uptake in the surface ocean with remineralisation at depth, combined with strong organic complexation by dissolved ligands, scavenging onto particles, and benthic sedimentary input. We present coupled dissolved and particulate phase Cu isotope data along the UK-GEOTRACES South Atlantic section, alongside higher resolution dissolved and particulate phase Cu concentration measurements. Our dissolved phase isotope data contribute to an emerging picture of homogeneous deep ocean δ65Cu, at about +0.65‰ (relative to NIST SRM 976). We identify two pools of Cu in the particulate phase: a refractory, lithogenic pool, at about 0‰, and a labile pool accessed via a weak acidic leach, at about +0.4‰. These two pools are comparable to those previously observed in sediments. We observe deviations towards lighter δ65Cu values in the dissolved phase associated with local enrichments in particulate Cu concentrations along the continental slopes, and in the surface ocean. Copper isotopes are thus a sensitive indicator of localised particle-associated benthic or estuarine Cu inputs. The measurement of Cu isotopes in seawater is analytically challenging, and we call for an intercalibration exercise to better evaluate the potential impacts of UV-irradiation, storage time, and different analytical procedures., Chemical Geology, 502, ISSN:0009-2541, ISSN:1872-6836

96. Supplementary Material from Coastal ocean and shelf-sea biogeochemical cycling of trace elements and isotopes: lessons learned from GEOTRACES

Author

Charette, Matthew A., Lam, Phoebe J., Lohan, Maeve C., Kwon, Eun Young, Hatje, Vanessa, Jeandel, Catherine, Shiller, Alan M., Cutter, Gregory A., Thomas, Alex, Boyd, Philip W., Homoky, William B., Milne, Angela, Thomas, Helmuth, Andersson, Per S., Porcelli, Don, Tanaka, Takahiro, Geibert, Walter, Dehairs, Frank, and Garcia-Orellana, Jordi

Subjects
13. Climate action, Astrophysics::High Energy Astrophysical Phenomena, Physics::Atomic Physics, 14. Life underwater, Nuclear Experiment, Physics::Atmospheric and Oceanic Physics, Physics::Geophysics
Abstract

Description and derivation of equation used to derive trace element and isotope fluxes from the continental margin

97. Vitamin B12 and iron colimitation of phytoplankton growth in the Ross Sea.

Author

Bertrand, Erin M., Saito, Mak A., Rose, Julie M., Riesselman, Christina R., Lohan, Maeve C., Noble, Abigail E., Lee, Peter A., and DiTullio, Giacomo R.

Subjects
IRON, VITAMIN B12, MARINE phytoplankton, ARCHAEBACTERIA, BACTERIA
Abstract

Primary production in the Ross Sea, one of the most productive areas in the Southern Ocean, has previously been shown to be seasonally limited by iron. In two of three bottle incubation experiments conducted in the austral summer, significantly higher chlorophyll a (Chl a) concentrations were measured upon the addition of iron and B12, relative to iron additions alone. Initial bacterial abundances were significantly lower in the two experiments that showed phytoplankton stimulation upon addition of B12 and iron relative to the experiment that did not show this stimulation. This is consistent with the hypothesis that the bacteria and archaea in the upper water column are an important source of B12 to marine phytoplankton. The addition of iron alone increased the growth of Phaeocystis antarctica relative to diatoms, whereas in an experiment where iron and B12 stimulated total phytoplankton growth, the diatom Pseudonitzschia subcurvata went from comprising approximately 70% of the phytoplankton community to over 90%. Cobalt additions, with and without iron, did not alter Chl a biomass relative to controls and iron additions alone in the Ross Sea. Iron and vitamin B12 plus iron treatments caused reductions in the DMSP (dimethyl sulfoniopropionate) : Chl a ratio relative to the control and B12 treatments, consistent with the notion of an antioxidant function for DMSP. These results demonstrate the importance of a vitamin to phytoplankton growth and community composition in the marine environment. [ABSTRACT FROM AUTHOR]

Published
2007
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