The vastness of the ocean presents a daunting challenge for scientists: How can we interpret trends in ocean ecosystems when the measurements we make are few and far between? In the open sea, most scientists have historically relied on ships to transport them to locations where they spend only a short time capturing a snapshot of ocean conditions below the sea surface. In the coastal zone, where conditions may change hourly, most sampling is done once a month at most. Far offshore, processes that drive ecosystem structure and function often work on a seasonal time scale. Closer to the coast, similar processes operate much more rapidly. The problems this presents leads to a conclusion that all ocean scientists agree on: the ocean is grossly undersampled!

Current records of fundamental properties such as oxygen, pH, nutrients, or chlorophyll describe a range of ocean states. However, the sample-to-sample variability observed in ocean time series may not reflect actual trends at any given location and time because so few measurements are collected. This limited sampling provides little scientific insight into the processes that actually underlie the snapshot observations.

Developing new tools and techniques to overcome these challenges is a major driver of the Chemical Sensor Team’s activities. Application of this approach in Elkhorn Slough, near MBARI in Central California, highlights some of the advances in understanding when sampling resolution is more closely matched to environmental processes. Opportunities for deploying analogous sensor suites in the vast expanse of the Southern Ocean provide another perspective on how we can address the fundamental problem of “being there”.

Know Your Ocean

Periodic table of elements in the ocean

Ocean currents, chemistry, and biology influence the distribution of elements in the ocean. This periodic table explores the elements occurring in the Atlantic and Pacific oceans.


Former Lab Members

  • Thomas P Chapin (former postdoctoral fellow/now USGS)
  • Zanna Chase (former Postdoctoral Fellow/now at University of Tasmania)
  • Steve Fitzwater (former Research Technician/deceased)
  • Patrick Gibson (former Postdoctoral Fellow)
  • Todd Martz (former Postdoctoral Fellow/now at Scripps Institution of Oceanography)
  • Joe Needoba (former Postdoctoral Fellow/now at Oregon Health and Science University)



Stoer, A. C., Y. Takeshita, T. L. Maurer, C. Begouen Demeaux, H. C. Bittig, E. Boss, H. Claustre, C. Gordon, B.J. Greenan, K. S. Johnson, E. Organelli, R. Sauzède, C. M. Schmechtig, and K. Fennel. 2023. A census of quality-controlled Biogeochemical-Argo float measurements. Frontiers in Marine Science10.

Chen, H., F.A. Haumann, L.D. Talley, K.S. Johnson, and J.L. Sarmiento. 2022. The deep ocean's carbon exhaust. Global Biogeochemical Cycles, 36(7): 1–21.

Roemmich, D., L. Talley, N. Zilberman, E. Osborne, K.S. Johnson, L. Barbero, H.C. Bittig, N. Briggs, A.J. Fassbender, G.C. Johnson, B.A. King, E. McDonagh, S. Purkey, S. Riser, T. Suga, Y. Takeshita, V. Thierry, and S. Wijffels. 2021. The Technological, Scientific, and Sociological Revolution of Global Subsurface Ocean Observing. Oceanography, 34: 2–8.

Huang, Y., A.J. Fassbender, J.S. Long, S. Johannessen, and M.B. Bif. 2022. Partitioning the export of distinct biogenic carbon pools in the Northeast Pacific Ocean using a biogeochemical profiling float. Global Biogeochemical Cycles, 36: 1–19.

Maurer, T.L., J.N. Plant, and K.S. Johnson. 2021. Delayed-mode quality control of oxygen, nitrate, and pH data on SOCCOM biogeochemical profiling floats. Frontiers in Marine Science, 8: 1–20.