Color photo of Robert Letscher, EOS ASSISTANT PROFESSOR and ASSISTANT DIRECTOR of the Ocean Process Analysis Laboratory.

Robert Letscher

Associate Professor
Assistant Director - Ocean Process Analysis Laboratory
Phone: (603) 862-1008
Office: Morse Hall, Durham, NH 03824
Websites:
Associate Professor of Chemical Oceanography
Earth Sciences
Assistant Director, Ocean Process Analysis Laboratory


I am a marine biogeochemist meaning I work to uncover and quantify the interrelated chemical, biological, and physical processes occurring within the ocean that result in transformations of the important bioactive elements carbon, nitrogen, phosphorus, and oxygen. My focus is understanding the production, transformation, and fate of biologically produced organic matter and the related cycling of chemical nutrients in the sea. My research program studies these processes at the largest scales – the global ocean, annual to millennial. I am particularly interested in studying the low nutrient ecosystems of the ocean subtropics. Covering 60% of the Earth’s surface they are the world’s largest biome, responsible for a quarter of all biological productivity. My group uses a variety of techniques and tools including collection of new chemical observations at sea, development of ocean biogeochemistry within Earth System Models, laboratory experiments, and analysis of data from autonomous platforms such as BGC-Argo.

Courses Taught

  • ESCI 400: Freshman Field Seminar
  • ESCI 501: Introduction to Oceanography
  • ESCI 747/847: Aqueous Geochemistry
  • ESCI 752/852: Chemical Oceanography
  • ESCI 795/895: Top/Ocean Biogeochemistry
  • ESCI 896: Topics/Deep Ocean Circulation
  • INCO 590: Student Research Experience
  • INCO 790: Advanced Research Experience
  • OCE 999: Doctoral Research

Education

  • Ph.D., University of Miami
  • B.S., University of Miami

Research Interests

  • Biogeochemistry
  • Ocean Modeling
  • Oceanography

Selected Publications

  • Curran, K., Villareal, T. A., & Letscher, R. T. (2025). A time series analysis of transparent exopolymer particle distributions and C : N stoichiometry in the subtropical North Pacific: a key process in net community production and preformed nitrate anomalies?. Biogeosciences, 22(14), 3515-3531. doi:10.5194/bg-22-3515-2025

  • Yu, J., Krumhardt, K. M., Keith Moore, J., Letscher, R. T., Wang, S., Wiseman, N. A., . . . Martiny, A. C. (2025). Simulating Marine Ecosystem Dynamics and Biogeochemical Cycling With Multiple Plankton Functional Types. Journal of Advances in Modeling Earth Systems, 17(7). doi:10.1029/2024ms004521

  • Liang, Z., Letscher, R. T., & Knapp, A. N. (2025). Oligotrophic Ocean New Production Supported by Lateral Transport of Dissolved Organic Nutrients. Global Biogeochemical Cycles, 39(6). doi:10.1029/2024gb008345

  • Letscher, R. T., Smethie, W. M., & Hansell, D. A. (2025). Centennial‐Scale Storage of DOC Within Arctic Ocean Deep Waters Controlled by Subzero Temperatures. Global Biogeochemical Cycles, 39(4). doi:10.1029/2024gb008428

  • Letscher, R. T., & Aluwihare, L. I. (2024). A simple method for the quantification of amidic bioavailable dissolved organic nitrogen in seawater. Limnology and Oceanography: Methods, 22(7), 451-463. doi:10.1002/lom3.10622

  • Letscher, R. T., Primeau, F., & Moore, J. K. (2016). Nutrient budgets in the subtropical ocean gyres dominated by lateral transport. NATURE GEOSCIENCE, 9(11), 815-+. doi:10.1038/NGEO2812

  • Letscher, R. T., & Moore, J. K. (2015). Preferential remineralization of dissolved organic phosphorus and non-Redfield DOM dynamics in the global ocean: Impacts on marine productivity, nitrogen fixation, and carbon export. GLOBAL BIOGEOCHEMICAL CYCLES, 29(3), 325-340. doi:10.1002/2014GB004904

  • Letscher, R. T., Moore, J. K., Teng, Y. -C., & Primeau, F. (2015). Variable C: N: P stoichiometry of dissolved organic matter cycling in the Community Earth System Model. BIOGEOSCIENCES, 12(1), 209-221. doi:10.5194/bg-12-209-2015

  • Letscher, R. T., Hansell, D. A., Carlson, C. A., Lumpkin, R., & Knapp, A. N. (2013). Dissolved organic nitrogen in the global surface ocean: Distribution and fate. GLOBAL BIOGEOCHEMICAL CYCLES, 27(1), 141-153. doi:10.1029/2012GB004449

  • Letscher, R. T., Hansell, D. A., & Kadko, D. (2011). Rapid removal of terrigenous dissolved organic carbon over the Eurasian shelves of the Arctic Ocean. MARINE CHEMISTRY, 123(1-4), 78-87. doi:10.1016/j.marchem.2010.10.002

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  • Most Cited Publications