iron limitation; DOC; bacteria; Southern Ocean; phytoplankton; recycling; EPS; bioavailability
Rickli Jörg, Janssen David J., Hassler Christel, Ellwood Michael J., Jaccard Samuel L. (2019), Chromium biogeochemistry and stable isotope distribution in the Southern Ocean, in Geochimica et Cosmochimica Acta
Ellwood Michael J., Hassler Christel, Moisset Sophie, Pascal Ludovic, Danza Francesco, Peduzzi Sandro, Tonolla Mauro, Vance Derek (2019), Iron isotope transformations in the meromictic Lake Cadagno, in Geochimica et Cosmochimica Acta
, 255, 205-221.
Blanco‐Ameijeiras Sonia, Cabanes Damien J. E., Hassler Christel S. (2019), Towards the development of a new generation of whole‐cell bioreporters to sense iron bioavailability in oceanic systems – learning from the case of Synechococcus sp. PCC 7002 iron bioreporter, in Journal of Applied Microbiology
Moisset Sophie A.M., Cabanes Damien J.E., Blanco-Ameijeiras Sonia, Hassler Christel S. (2019), Response of phytoplankton from the metalimnetic chlorophyll maximum to macro- and micro-nutrients amendments in Lake Geneva, in Journal of Great Lakes Research
, 45(2), 290-299.
Zitoun Rebecca, Hassler Christel, Clearwater Susan J., Thompson Karen J., Albert Anathea, Sander Sylvia G. (2019), Investigating the fate of copper in a laboratory‐based toxicity test with embryos of Mytilus galloprovincialis : Copper mass balance of a closed bioassay, in Environmental Toxicology and Chemistry
, 38(3), 561-574.
Zitoun Rebecca, Clearwater Susan J., Hassler Christel, Thompson Karen J., Albert Anathea, Sander Sylvia G. (2019), Copper toxicity to blue mussel embryos (Mytilus galloprovincialis), in Science of The Total Environment
, 653, 300-314.
Davies Claire H., Ajani Penelope, Armbrecht Linda, Atkins Natalia, Baird Mark E., Beard Jason, Bonham Pru, Burford Michele, Clementson Lesley, Coad Peter, Crawford Christine, Dela-Cruz Jocelyn, Doblin Martina A., Edgar Steven, Eriksen Ruth, Everett Jason D., Furnas Miles, Harrison Daniel P., Hassler Christel, Henschke Natasha, Hoenner Xavier, Ingleton Tim, Jameson Ian, Keesing John, et al. (2018), A database of chlorophyll a in Australian waters, in Scientific Data
, 5(1), 180018-180018.
Biller Steven J., Berube Paul M., Dooley Keven, Williams Madeline, Satinsky Brandon M., Hackl Thomas, Hogle Shane L., Coe Allison, Bergauer Kristin, Bouman Heather A., Browning Thomas J., De Corte Daniele, Hassler Christel, Hulston Debbie, Jacquot Jeremy E., Maas Elizabeth W., Reinthaler Thomas, Sintes Eva, Yokokawa Taichi, Chisholm Sallie W. (2018), Marine microbial metagenomes sampled across space and time, in Scientific Data
, 5(1), 180176-180176.
Berube Paul M., Biller Steven J., Hackl Thomas, Hogle Shane L., Satinsky Brandon M., Becker Jamie W., Braakman Rogier, Collins Sara B., Kelly Libusha, Berta-Thompson Jessie, Coe Allison, Bergauer Kristin, Bouman Heather A., Browning Thomas J., De Corte Daniele, Hassler Christel, Hulata Yotam, Jacquot Jeremy E., Maas Elizabeth W., Reinthaler Thomas, Sintes Eva, Yokokawa Taichi, Lindell Debbie, Stepanauskas Ramunas, et al. (2018), Single cell genomes of Prochlorococcus, Synechococcus, and sympatric microbes from diverse marine environments, in Scientific Data
, 5(1), 180154-180154.
Blanco-Ameijeiras Sonia, Moisset Sophie A M, Trimborn Scarlett, Campbell Douglas A, Heiden Jasmin P, Hassler Christel S (2018), Elemental Stoichiometry and Photophysiology Regulation of Synechococcus sp. PCC7002 Under Increasing Severity of Chronic Iron Limitation, in Plant and Cell Physiology
, 59(9), 1803-1816.
Schlitzer Reiner, Anderson Robert F., Dodas Elena Masferrer, Lohan Maeve, Geibert Walter, Tagliabue Alessandro, Bowie Andrew, Jeandel Catherine, Maldonado Maria T., Landing William M., Cockwell Donna, Abadie Cyril, Abouchami Wafa, Achterberg Eric P., Agather Alison, Aguliar-Islas Ana, van Aken Hendrik M., Andersen Morten, Archer Corey, Auro Maureen, de Baar Hein J., Baars Oliver, Baker Alex R., Bakker Karel, et al. (2018), The GEOTRACES Intermediate Data Product 2017, in Chemical Geology
, 493, 210-223.
Ellwood Michael J., Bowie Andrew R., Baker Alex, Gault-Ringold Melanie, Hassler Christel, Law Cliff S., Maher William A., Marriner Andrew, Nodder Scott, Sander Sylvia, Stevens Craig, Townsend Ashley, van der Merwe Pier, Woodward E. Malcolm S., Wuttig Kathrin, Boyd Philip W. (2018), Insights Into the Biogeochemical Cycling of Iron, Nitrate, and Phosphate Across a 5,300 km South Pacific Zonal Section (153°E-150°W), in Global Biogeochemical Cycles
, 32(2), 187-207.
CH7 Kasparian J. Hassler C.S. et al. (2017), Assessing the Dynamic of organic aerosols over the North Atlantic Ocean, in Nature Scientific Reports.
, 7, 45476.
CH6 Moneesha S. Ellwood M.J.E. Sinoir M. Hassler C.S. (2017), Dissolved zinc isotope as a tool to investigate zinc biogeochemical cycling in the Tasman Sea., in Marine Chemistry
, 192, 1.
CH9 Cabanes D.J.E. Norman L. Santos-Echeandia J. Iversen M.H. Trimborn S. Laglera L.M. H (2017), First evaluation on the role of salp fecal pellets on iron biogeochemistry., in Frontiers in Marine Sciences
CH4 Trimborn S. Brenneis T. Hoppe C.J.M. Laglera L. Norman L. Santos-Echeandia J. Völkner C. (2017), Iron sources alter the response of Southern Ocean phytoplankton to ocean acidification., in Marine Ecology Progress Series
, 578, 35.
CH5 Blanco-Ameijeiras S. Cosi C. Hassler C.S. (2017), Long-term acclimation to iron limitation reveals new insights in metabolism regulation of Synechococcus sp. PCC7002., in Frontier Marine Sciences
Buck K.N. Lohan M.C. Sander S.G. Hassler C. Pizeta I. (2017), Organic ligands – A key control of trace metal biogeochemistry in the ocean., in Frontier in Marine Science
CH8 Hassler C.S. van den Berg C. Boyd P.W (2017), Using a regional classification to provide a more inclusive examination of the ocean biogeochemistry of iron-binding ligands, in Frontiers in Marine Sciences
The Southern Ocean (SO) plays a critical role on atmospheric CO2 sink mediated by the physical, biological and microbial pumps and thus affects our climate. The SO is the largest oceanic iron-limited region, and unsurprisingly it has been extensively studied. However, how iron limitation takes places and its consequences for the efficiency of the biological carbon pump mediated by phytoplankton remain mostly unresolved. The lack of understanding of the link between iron chemistry and its bioavailability as well as the key drivers and processes at play, significantly prevents advances in this research area. Because iron is mostly associated with organic ligands and limits the growth of phytoplankton in most of the SO, the biogeochemistry of Fe and carbon are closely inter-related. Moreover, the labile dissolved organic compounds excreted by phytoplankton are rapidly consumed by heterotrophic bacteria to fuel carbon export mediated by the microbial carbon pump. It is thus evident that both carbon pumps are inter-related with the production and recycling of organic carbon and bioavailable Fe acting as critical connectors in the SO. However, the link between these pumps is mostly conceptual and controlling mechanisms remain unknown. As this connection is critical for the functioning of this ecosystem including its footprint on our climate, it is urgent to learn how these pumps are connected and controlled.This project addresses specific aspects related to this major gap of knowledge by investigating pathways involved in the production/recycling of carbon and iron in surface water. This will be achieved by combining experiments at sea and in the laboratory. For this purpose, marine dissolved organic compounds (DOC) from various origins will be isolated and characterized. Here, we will isolate and characterize DOC from iron-limited and iron replete regions chosen to represent the biochemical variability encountered across the SO. Moreover, DOC produced by key biological players from the SO will be isolated and studied; including DOC excreted by bacteria, phytoplankton and grazers. Moreover, DOC sensitivity to photo- and viral degradations - two important transformation pathways - will be quantified. An extensive and unique analytical matrix is proposed to resolve key properties and functional groups in DOC as well as its iron binding properties, likely identifying, for the first time, the “dark matter” constituting DOC compounds involved in Fe binding as well as binding mechanism. The comparison of the various DOC compositions will identify whether a unique chemical traceable signature is associated with specific origin or transformation pathways. The impact on the microbial pump will be inferred from DOC lability whereas the impact on the biological pump will be inferred from iron bioavailability (55Fe bioaccumulation), pigments, photo-physiology and POC analyses.Finally, this project explores a novel research area: the role of viruses in the degradation of marine DOC and its impact for both the biological and the microbial pumps. Marine viruses constitutively bear enzymes that are efficient in passively degrading their hosts carbohydrates in solution, whose impact has never been addressed. Given the high concentration and diversity of viruses in the ocean, and the facts that carbohydrate constitute up to 50 % of marine DOC and can affect iron chemistry, this study might totally revisit the role of viruses in marine biogeochemistry and result in seminal publications. Important collaborative efforts on highly specialised techniques are put at play to solve the complexity of marine DOC and Fe-binding ligands. Major breakthrough in the field of marine biogeochemistry is thus expected as well as solid contributions to international research programs, such as SCOR and GEOTRACES. Being related to climate, ecosystem functioning and biodiversity, this project benefits to the scientific community at large.