Nicolas Cassar | Scholars@Duke

Nicolas Cassar
Associate Professor of Biogeochemistry in the Division of Earth & Ocean Sciences

Nicolas Cassar's research focuses on environmental biogeochemistry and physiology, with the objective of constraining the mechanisms governing carbon cycling and climate. Current research interests include ocean carbon cycles and productivity; carbon acquisition mechanisms in marine phytoplankton and implications for climate change and paleo-CO2 reconstruction; and global carbon cycle and ocean-atmosphere fluxes. His scientific approach is interdisciplinary, integrating field observations, laboratory experiments, modeling and theory.

Current Appointments & Affiliations

Associate Professor of Biogeochemistry in the Division of Earth & Ocean Sciences, Earth and Ocean Sciences, Nicholas School of the Environment 2014
Sr. Associate Dean for Research and Doctoral Programs, Nicholas School of the Environment, Duke University 2019

Contact Information

Box 90328, Durham, NC 27708
Grainger Hall, 9 Circuit Drive (Eh5118), Nicholas School of the Environment, Durham, NC 27708
nicolas.cassar@duke.edu (919) 681-8865
Cassar Lab

Background
Education, Training, & Certifications
- Ph.D., University of Hawaii at Manoa 2003
- B.S., McGill University (Canada) 1997
Duke Appointment History
- Assistant Professor, Marine Science and Conservation, Nicholas School of the Environment 2012 - 2015
- Assistant Professor of Biogeochemistry, Earth and Ocean Sciences, Nicholas School of the Environment 2009 - 2014
Recognition
In the News
- FEB 21, 2019 Nicholas School of the Environment
  
  Coastal Waters Are Unexpected Hotspots for Nitrogen Fixation
Awards & Honors
- Faculty Early Career Development (CAREER) Program. National Science Foundation. 2014
Expertise
Subject Headings
Global Scholarship
- Research
  - Australia (Country)
Research
Selected Grants
- Biological and physical drivers of O2 saturation and net community production variability at the Western Antarctic Peninsula awarded by National Science Foundation 2017 - 2020
- CAREER: Method development for high-resolution underway N2 fixation measurements awarded by National Science Foundation 2014 - 2020
- The Biogeochemical Compass: Navigating the Flows of Energy and Matter within the Southern Ocean awarded by Antarctic Circumnavigation Expedition 2016 - 2019
- Quantifying the carbon export potential of the marine microbial community: Coupling of biogenic rates and fluxes with genomics at the ocean surface awarded by University of North Carolina - Chapel Hill 2017 - 2019
- Derivation of a Global Net Community Assessment of Regulating Factors Using in-Situ Measurements & Remotely Sensed Prop. awarded by National Aeronautics and Space Administration 2013 - 2017
- Dynamics of Dissolved Inorganic Carbon (DIC), Biological Oxygen Production and Dinitrogen Fixation in the Coastal Ocean awarded by NC Sea Grant 2016 - 2017
- Physiological and Ecosystem Structure Forcings on Carbon Fluxes in the Southern Ocean Mixed Layer awarded by National Science Foundation 2011 - 2015
- EAGER: Method development for the assessment of spatiotemporal Variablility on Non symbiotic N2 fixation: Acetylene Redu awarded by National Science Foundation 2011 - 2013
Publications & Artistic Works
Selected Publications
- Academic Articles
  - Berthelot H, Duhamel S, L'Helguen S, Maguer J-F, Wang S, Cetinić I, Cassar N. NanoSIMS single cell analyses reveal the contrasting nitrogen sources for small phytoplankton. The Isme Journal. 2019 Mar;13(3):651-662. PubMed Central PMCID: 30323264. Full Text
  - Lin Y, Gifford S, Ducklow H, Schofield O, Cassar N. Towards Quantitative Microbiome Community Profiling Using Internal Standards. Applied and Environmental Microbiology. 2019 Mar;85(5). PubMed Central PMCID: 30552195. Full Text
  - Tang W, Li Z, Cassar N. Machine Learning Estimates of Global Marine Nitrogen Fixation. Journal of Geophysical Research: Biogeosciences. 2019 Mar 1;124(3):717-730. Full Text
  - Tang W, Wang S, Fonseca-Batista D, Dehairs F, Gifford S, Gonzalez AG, Gallinari M, Planquette H, Sarthou G, Cassar N. Revisiting the distribution of oceanic N2 fixation and estimating diazotrophic contribution to marine production. Nature Communications. 2019 Feb 19;10(1):831-null. PubMed Central PMCID: 30783106. Full Text
  - Li Z, Cassar N. Theoretical Considerations on Factors Confounding the Interpretation of the Oceanic Carbon Export Ratio. Global Biogeochemical Cycles. 2018 Nov;32(11):1644-1658. Full Text
  - Nevison C, Munro D, Lovenduski N, Cassar N, Keeling R, Krummel P, Tjiputra J. Net Community Production in the Southern Ocean: Insights From Comparing Atmospheric Potential Oxygen to Satellite Ocean Color Algorithms and Ocean Models. Geophysical Research Letters. 2018 Oct 16;45(19):10-559. Full Text
  - Ducklow HW, Stukel MR, Eveleth R, Doney SC, Jickells T, Schofield O, Baker AR, Brindle J, Chance R, Cassar N. Spring-summer net community production, new production, particle export and related water column biogeochemical processes in the marginal sea ice zone of the Western Antarctic Peninsula 2012-2014. Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences. 2018 Jun;376(2122). PubMed Central PMCID: 29760119. Full Text
  - Wang S, Lin Y, Gifford S, Eveleth R, Cassar N. Linking patterns of net community production and marine microbial community structure in the western North Atlantic. The Isme Journal. 2018 May;12(11):2582-2595. PubMed Central PMCID: 29934639. Full Text
  - Moreno CM, Lin Y, Davies S, Monbureau E, Cassar N, Marchetti A. Examination of gene repertoires and physiological responses to iron and light limitation in Southern Ocean diatoms. Polar Biology. 2018 Apr 1;41(4):679-696. Full Text
  - Cassar N, Tang W, Gabathuler H, Huang K. Method for High Frequency Underway N2 Fixation Measurements: Flow-Through Incubation Acetylene Reduction Assays by Cavity Ring Down Laser Absorption Spectroscopy (FARACAS). Analytical Chemistry. 2018 Feb 6;90(4):2839-2851. PubMed Central PMCID: 29338196. Full Text
  - Simonin M, Colman BP, Tang W, Judy JD, Anderson SM, Bergemann CM, Rocca JD, Unrine JM, Cassar N, Bernhardt ES. Plant and Microbial Responses to Repeated Cu(OH)2 Nanopesticide Exposures Under Different Fertilization Levels in an Agro-Ecosystem. Frontiers in Microbiology. 2018 Jan;9:1769-null. PubMed Central PMCID: 30108580. Full Text
  - Li Z, Cassar N. A mechanistic model of an upper bound on oceanic carbon export as a function of mixed layer depth and temperature. Biogeosciences. 2017 Nov 14;14(22):5015-5027. Full Text
  - Lin Y, Cassar N, Marchetti A, Moreno C, Ducklow H, Li Z. Specific eukaryotic plankton are good predictors of net community production in the Western Antarctic Peninsula. Scientific reports. 2017 Nov;7(1):14845-. PubMed PMID: 29093494. Full Text
  - Eveleth R, Cassar N, Doney SC, Munro DR, Sweeney C. Biological and physical controls on O 2 /Ar, Ar and pCO 2 variability at the Western Antarctic Peninsula and in the Drake Passage. Deep Sea Research Part Ii: Topical Studies in Oceanography. 2017 May 1;139:77-88. Full Text
  - Eveleth R, Cassar N, Sherrell RM, Ducklow H, Meredith MP, Venables HJ, Lin Y, Li Z. Ice melt influence on summertime net community production along the Western Antarctic Peninsula. Deep Sea Research Part Ii: Topical Studies in Oceanography. 2017 May 1;139:89-102. Full Text
  - Erickson ZK, Thompson AF, Cassar N, Sprintall J, Mazloff MR. An advective mechanism for deep chlorophyll maxima formation in southern Drake Passage. Geophysical Research Letters. 2016 Oct 28;43(20):10-855. Full Text
  - Li Z, Cassar N, Huang K, Ducklow H, Schofield O. Interannual variability in net community production at the Western Antarctic Peninsula region (1997–2014). Journal of Geophysical Research: Oceans. 2016 Jul 1;121(7):4748-4762. Full Text
  - Bender ML, Tilbrook B, Cassar N, Jonsson B, Poisson A, Trull TW. Ocean productivity south of Australia during spring and summer. Deep Sea Research Part I: Oceanographic Research Papers. 2016 Jun 1;112:68-78. Full Text
  - Li Z, Cassar N. Satellite estimates of net community production based on O 2 /Ar observations and comparison to other estimates. Global Biogeochemical Cycles. 2016 May 1;30(5):735-752. Full Text
  - Huang K, Cassar N, Jonsson B, Cai WJ, Bender ML. An Ultrahigh Precision, High-Frequency Dissolved Inorganic Carbon Analyzer Based on Dual Isotope Dilution and Cavity Ring-Down Spectroscopy. Environmental Science & Technology. 2015 Jul;49(14):8602-8610. Full Text Link to Item
  - Shadwick EH, Tilbrook B, Cassar N, Trull TW, Rintoul SR. Summertime physical and biological controls on O2 and CO2 in the Australian Sector of the Southern Ocean. Journal of Marine Systems. 2015 Jul;147:21-28. Full Text Link to Item
  - Marchetti A, Catlett D, Hopkinson BM, Ellis K, Cassar N. Marine diatom proteorhodopsins and their potential role in coping with low iron availability. The Isme Journal. 2015 May. Full Text Link to Item
  - Cassar N, Wright SW, Thomson PG, Trull TW, Westwood KJ, de Salas M, Davidson A, Pearce I, Davies DM, Matear RJ. The relation of mixed-layer net community production to phytoplankton community composition in the Southern Ocean. Global Biogeochemical Cycles. 2015 Apr;29(4):446-462. Full Text Link to Item
  - Shadwick EH, Tilbrook B, Cassar N, Trull TW, Rintoul SR. Summertime physical and biological controls on O<inf>2</inf> and CO<inf>2</inf> in the Australian Sector of the Southern Ocean. Journal of Marine Systems. 2015;147:21-28. Full Text
  - Cassar N, Nevison CD, Manizza M. Correcting oceanic O2/Ar-net community production estimates for vertical mixing using N2O observations. Geophysical Research Letters. 2015 Dec 28;41(24):8961-8970. Full Text Link to Item
  - Eveleth R, Timmermans M-L, Cassar N. Physical and biological controls on oxygen saturation variability in the upper Arctic Ocean. Journal of Geophysical Research: Oceans. 2014 Nov;119(11):7420-7432. Full Text Link to Item
  - Ulfsbo A, Cassar N, Korhonen M, van Heuven S, Hoppema M, Kattner G, Anderson LG. Late summer net community production in the central Arctic Ocean using multiple approaches. Global Biogeochemical Cycles. 2014 Oct;28(10):1129-1148. Full Text Link to Item
  - Rutgers van der Loeff MM, Cassar N, Nicolaus M, Rabe B, Stimac I. The influence of sea ice cover on air-sea gas exchange estimated with radon-222 profiles. Journal of Geophysical Research: Oceans. 2014 May;119(5):2735-2751. Full Text Link to Item
  - Chang C-H, Johnson NC, Cassar N. Neural network-based estimates of Southern Ocean net community production from in situ O2/Ar and satellite observation: a methodological study. Biogeosciences. 2014;11:3279-3297. Full Text Link to Item
  - Roedenbeck C, Bakker DCE, Metzl N, Olsen A, Sabine C, Cassar N, Reum F, Keeling RF, Heimann M. Interannual sea-air CO2 flux variability from an observation-driven ocean mixed-layer scheme. Biogeosciences. 2014;11(17):4599-4613. Full Text Link to Item
  - Huang K, Cassar N, Wanninkhof RH, Bender ML. An isotope dilution method for high-frequency measurements of dissolved inorganic carbon concentration in the surface ocean. Limnology and Oceanography: Methods. 2014 Dec 30;11(NOV):572-583. Full Text Link to Item
  - Castro-Morales K, Cassar N, Shoosmith DR, Kaiser J. Biological production in the Bellingshausen Sea from oxygen-to-argon ratios and oxygen triple isotopes. Biogeosciences. 2013 Apr 5;10(4):2273-2291. Full Text Link to Item
  - Li Z, Li L, Song K, Cassar N. Estimation of phytoplankton size fractions based on spectral features of remote sensing ocean color data. Journal of Geophysical Research: Oceans. 2013;118(3):1445-1458. Full Text Link to Item
  - Jean M-E, Cassar N, Setzer C, Bellenger JP. Short-term N2 fixation kinetics in a moss-associated cyanobacteria. Environmental Science & Technology. 2012 Aug;46(16):8667-8671. Full Text Link to Item
  - Bhattachan A, D'Odorico P, Baddock MC, Zobeck TM, Okin GS, Cassar N. The Southern Kalahari: a potential new dust source in the Southern Hemisphere?. Environmental Research Letters. 2012 Apr 10;7(2). Full Text Link to Item
  - Hamme RC, Cassar N, Lance VP, Vaillancourt RD, Bender ML, Strutton PG, Moore TS, DeGrandpre MD, Sabine CL, Ho DT, Hargreaves BR. Dissolved O2/Ar and other methods reveal rapid changes in productivity during a Lagrangian experiment in the Southern Ocean. Journal of Geophysical Research: Oceans. 2012 Apr;117(C4). Full Text Link to Item
  - Huang K, Ducklow H, Vernet M, Cassar N, Bender ML. Export production and its regulating factors in the West Antarctica Peninsula region of the Southern Ocean. Global Biogeochemical Cycles. 2012 Apr;26(2). Full Text Link to Item
  - Nevison CD, Keeling RF, Kahru M, Manizza M, Mitchell BG, Cassar N. Estimating net community production in the Southern Ocean based on atmospheric potential oxygen and satellite ocean color data. Global Biogeochemical Cycles. 2012 Mar;26(1). Full Text Link to Item
  - Cassar , Bellenger JP, Jackson RB, Karr J, Barnett BA. N2 fixation estimates in real-time by cavity ring-down laser absorption spectroscopy. Oecologia. 2012;168(2):335-342. Full Text Link to Item
  - Bender ML, Kinter S, Cassar N, Wanninkhof R. Evaluating gas transfer velocity parameterizations using upper ocean radon distributions. Journal of Geophysical Research: Oceans. 2011 Feb 9;116(C2). Full Text Link to Item
  - Cassar N, DiFiore PJ, Barnett BA, Bender ML, Bowie AR, Tilbrook B, Petrou K, Westwood KJ, Wright SW, Lefevre D. The influence of iron and light on net community production in the Subantarctic and Polar Frontal Zones. Biogeosciences. 2011 Feb 9;8(2):227-237. Full Text Link to Item
  - Stanley RHR, Kirkpatrick JB, Cassar N, Barnett BA, Bender ML. Net community production and gross primary production rates in the Western Equatorial Pacific. Global Biogeochemical Cycles. 2010 Oct 12;24(4). Full Text Link to Item
  - Boye M, Achterberg E, Bown J, Bucciarelli E, Cardinal D, Cassar N, Cavagna A-J, Chever F, Dehairs F, Fine RA, Happell J, Joubert W, Le Moigne F, Masque P, Monteiro P, Planchon F, Sarthou G, Verdeny E, Wake B, Waldron H. A first look at GEOTRACES issues from the IPY BONUS GOODHOPE cruise in the Southern Ocean. Geochimica Et Cosmochimica Acta. 2009 Jun 1;73(13):A152-A152. Link to Item
  - Cassar N, Barnett B, Bender ML, Kaiser J, Hamme RC, Tilbrook B. Continuous high-frequency dissolved O2/Ar measurements by Equilibrator Inlet Mass Spectrometry (EIMS). Analytical Chemistry. 2009 Feb 4;81(5):1855-1864. Full Text Link to Item
  - Cassar N, McKinley GA, Bender ML, Mika R, Battle M. An improved comparison of atmospheric Ar/N2 time-series and paired ocean-atmosphere model predictions. Journal of Geophysical Research: Atmospheres. 2008 Nov 16;113(D21). Full Text Link to Item
  - Nevison CD, Mahowald NM, Doney SC, Lima ID, Cassar N. Impact of variable air-sea O2 and CO2 fluxes on atmospheric potential oxygen (APO) and land-ocean carbon sink partitioning. Biogeosciences. 2008 Jun 2;5:875-889. Full Text Link to Item
  - Cassar N, Bender ML, Barnett BA, Fan S, Moxim WJ, Levy II H, Tilbrook B. The Southern Ocean biological response to aeolian iron deposition. Science. 2007 Aug 24;317(5841):1067-1070. Full Text Link to Item
  - Cassar N, Laws EA. Potential contribution of beta-carboxylases to photosynthetic carbon isotope fractionation in a marine diatom. Phycologia. 2007 May;46(3):307-314. Full Text Link to Item
  - Cassar N, Laws EA, Popp BN. Carbon isotopic fractionation by the marine diatom Phaeodactylum tricornutum under nutrients and light-limited growth conditions. Geochemica Et Cosmochimica Acta. 2006 Nov 1;70(21):5323-5335. Full Text Link to Item
  - Bender ML, Ho DT, Hendricks MB, Mika R, Battle MO, Tans PP, Conway TJ, Sturtevant B, Cassar N. Atmospheric O2/N2 changes, 1993-2002: Implications for the partitioning of fossil fuel CO2 sequestration. Global Biogeochemical Cycles. 2005 Dec 7;19(4). Full Text Link to Item
  - Cassar N, Laws EA, Bidigare RR, Popp BN. Bicarbonate uptake by Southern Ocean phytoplankton. Global Biogeochemical Cycles. 2004 Jun 1;18(2). Full Text
  - Cassar N, Laws EA, Bidigare RR, Popp BN. Bicarbonate uptake by Southern Ocean phytoplankton. Global Biogeochemical Cycles. 2004 Jun;18(2):n/a-n/a. Full Text
  - Cassar N, Laws EA, Popp BN, Bidigare RR. Sources of inorganic carbon for photosynthesis in a strain of Phaeodactylum tricornutum. Limnology and Oceanography. 2002;47(4):1192-1197. Link to Item
  - Laws EA, Popp BN, Cassar N, Tanimoto J. 13C discrimination patterns in oceanic phytoplankton: The likely influence of CCMs and the implications for palaeoreconstructions. Functional Plant Biology. 2002;29:1-11. (Academic Article)
  - Laws EA, Popp BN, Cassar N, Tanimoto J. C discrimination patterns in oceanic phytoplankton: Likely influence of Co- concentrating mechanisms, and implications for palaeoreconstructions. Functional Plant Biology. 2002;29(2-3):323-333.
  - Laws EA, Popp BN, Cassar N, Tanimoto J. 13C discrimination patterns in oceanic phytoplankton: likely influence of CO2 concentrating mechanisms, and implications for palaeoreconstructions. Functional Plant Biology : Fpb.. 2002 Jan;29(2/3):323-333. PubMed Central PMCID: AGR:IND23274183. Full Text
  - Berner RA, Petsch ST, Lake JA, Beerling DJ, Popp BN, Lane RS, Laws EA, Westley MB, Cassar N, Woodward FI, Quick WP. Isotope fractionation and atmospheric oxygen: Implications for Phanerozoic O2 Evolution. Science. 2000 Mar;287(5458):1630-1633. Full Text Link to Item
  - De Vaugelas J, Meinesz A, Antolic B, Ballesteros E, Belsher T, Cassar N, Ceccherelli G, Cinelli F, Cottalorda JM, Fradà Orestano C, Grau AM, Jaklin A, Morucci C, Relini M, Sandulli R, Span A, Tripaldi G, Van Klaveren P, Zavodnik N, Zuljevic A. Standardization proposal for the mapping of Caulerpa taxifolia expansion in the Mediterranean Sea. Oceanologica Acta. 1999 Jan 1;22(1):85-94. Full Text
- Reports
  - Bender ML, Cassar N, Mika R. Atmospheric O2/N2 and Ar/N2 studies at Cape Grim. 2006.
  - Meinesz A, Cottalorda JM, Chiaverni D, Cassar N, Vaugelas DJ. Suivi de l’invasion de l’algue tropicale Caulerpa taxifolia en Méditerranée: situation au 31.12.1997. Sophia Antipolis, Nice; 1998.
- Conference Papers
  - Thompson AF, Cassar N. Physical-biogeochemical coupling in the southern ocean. 2015 Dec 1:6-null.
- Theses and Dissertations
  - Cassar N. Carbon-Concentrating Mechanisms and beta-Carboxylation: their potential contribution to marine photosynthetic carbon isotope fractionation. Laws E, editor. 2003. (PhD Thesis) Link to Item
Teaching & Mentoring
Recent Courses
- ENVIRON 362S: Changing Oceans 2019
- EOS 364S: Changing Oceans 2019
- EOS 393: Research Independent Study 2019
- EOS 394: Research Independent Study 2019
- EOS 791: Independent Study 2019
- EOS 525: Fundamentals of Water Biogeochemistry and Pollution 2018

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Education, Training, & Certifications

Duke Appointment History

In the News

Awards & Honors

Subject Headings

Global Scholarship

Research

Selected Grants

Selected Publications

Academic Articles

Reports

Conference Papers

Theses and Dissertations

Recent Courses