The oceans teem with marine microbes that move at the mercy of currents. All of these viruses, bacteria, and eukaryotic protists (e.g. algae) are invisible to the naked eye, but are appreciable to biogeochemical cycles1. That is just so WILD!
Below are the research projects I’m involved with that are dedicated to studying these amazing lifeforms and the processes they influence.
The Northwest Atlantic Ocean is a region characterized by both massive seasonal phytoplankton blooms 2 and deep convective overturning events that can physically deliver organic carbon produced by phytoplankton to depth, 3 4, where it can be sequestered on the timescales of ocean circulaiton. The region is consequently important in regulating the flux of atmospheric CO2 into the ocean.
The NAAMES program was comprised of four field campaigns in the Northwest Atlantic involving coordinated ship, aircraft, remote sensing, autonomous in situ sensing efforts. It was designed to resolve the dynamics and drivers of the annual phytoplankton bloom and their subsequent impacts on the atmosphere. The framework of NAAMES represented a great opportunity for us to track and assess the temporal and spatial dynamics of dissolved organic carbon (DOC), as well as the mechanisms that control its accumulation, persistence, and export.
In this paper, we combined autonomous float and ship-collected data to constrain the seasonal accumulation and export potential of DOC in the study region. We currently have a manuscript in review in which we assess the interplay between seasonal bacterioplankton-phytoplankton carbon flux and DOC accumulation and bioavailability over the large latitudinal range occupied by NAAMES.
Diaz, B., Knowles, B., Johns, C., Laber, C., Bondoc, K.G.V, Harvey, E., Lowenstein, D., Fredricks, J., Haramaty, L., Natale, F., Graff, J., Haentjens, N., Westberry, T., Baetge, N., Mojica, K., Gaube, P., Boss, E., Carlson, C., Behrenfeld, M., Van Mooy, B., Bidle, K. Seasonal mixed layer dynamics shape phytoplankton physiology, viral infection, and accumulation in the North Atlantic. Nature Communications. in press
Baetge, N., Bolaños, L., Della Penna, A., Gaube, P., Liu, S., Opalk, K., Graff, J., Giovannoni, S., Behrenfeld, M., Carlson, C. Bacterioplankton Response to Physical Stratification following Deep Convection. Elementa. in review
Baetge, N., Behrenfeld, M., Fox, J., Halsey, K., Mojica, K., Novoa, A., Stephens, B., Carlson, C. The Seasonal Flux and Fate of Dissolved Organic Carbon through the Food Web in the Westen North Atlantic. (2021). Frontiers in Microbiology.
Bolaños, L., Choi, C.J., Worden, A., Baetge, N., Carlson, C., Giovannoni, S. Seasonality of the microbial community composition in the western North Atlantic. (2021). Frontiers in Marine Science. 8:624164.
Hendrickson, B., Brooks, S., Thornton, D., Moore, R., Crosbie, E., Ziemba, L., Carlson, C., Baetge, N., Mirrielees, J., and Alsante, A. (2020). Role of Sea Surface Microlayer Properties in Cloud Formation. Frontiers in Marine Science.7:596225.
Saliba, G., Chen, C., Lewis, S., Russell. L, Quinn, P., Bates, T., Bell, T., Lawler, M., Saltzman, E., Sanchez, K., Moore, R., Shook, M., Rivellini, L., Lee, A., Baetge, N., Carlson, C., Behrenfeld, M. (2020). Seasonal Differences and Variability of Concentrations, Chemical Composition, and Cloud Condensation Nuclei of Marine Aerosol over the North Atlantic. Journal of Geophysical Research: Atmospheres, 125(19).
Baetge, N., Graff, J. R., Behrenfeld, M. J., & Carlson, C. A. (2020). Net Community Production, Dissolved Organic Carbon Accumulation, and Vertical Export in the Western North Atlantic. Frontiers in Marine Science, 7, 227.
Saliba, G., Chen, C. L., Lewis, S., Russell, L. M., Rivellini, L. H., Lee, A. K., … & Karp-Boss, L. (2019). Factors driving the seasonal and hourly variability of sea-spray aerosol number in the North Atlantic. Proceedings of the National Academy of Sciences, 116(41), 20309-20314.
Behrenfeld, M. J., Moore, R. H., Hostetler, C. A., Graff, J., Gaube, P., Russell, L. M., … & Proctor, C. (2019). The North Atlantic aerosol and marine ecosystem study (NAAMES): science motive and mission overview. Frontiers in Marine Science, 6, 122.
ACIDD was a student-led oceanographic research cruise in which I was a co-PI and Chief Scientist that sought to document the daily rhythm of microbial processes in the Santa Barbara Channel (SBC). We secured ship time through the UC Ship Funds and over the course of a year, built a remarkable team that designed and planned achievable research objectives. When one of the California’s largest recorded wildfire erupted days before our cruise, we were well prepared to respond quickly and take on a secondary objective: document and dissect the impacts of wildfire ash deposition on the marine ecosystems.
Wagner, S., Harvey, E., Baetge, N., McNair, H., Arrington, E., Stubbins, A. Investigating atmospheric inputs of dissolved black carbon to the Santa Barbara Channel during the Thomas Fire (California, USA).Journal of Geophysical Research: Biogeosciences, 126(8)
Established in 2015, BIOS-SCOPE is an ongoing research program focused on fieldwork in the vicinity of the Bermuda Atlantic Time-series Study (BATS) site, one of the few locations in the global ocean with a long history of measurements. The program combines a wide array genomic, ecological, and oceanographic approaches to assess how microbes interact with each other and with chemical compounds to shape biogeochemical patterns. Much of my involvement with the program has been in support of the research by Dr. Shuting Liu, currently a postdoctoral scholar in Dr. Carlson’s group.
Liu, S., Baetge, N., Comstock, J., Opalk, K., Parsons, R., Halewood, E., English, C., Giovannoni, S., Bolanos, L., Nelson, C., Vergin, K., Carlson, C. Stable isotope probing identifies bacterioplankton lineages capable of utilizing dissolved organic matter across a range of bioavailability. Frontiers in Marine Science, 11, 2364.
Liu, S., Parsons, R., Opalk, K., Baetge, N., Giovannoni, S., Bolaños, L. M., … & Carlson, C. A. (2020). Different carboxyl-rich alicyclic molecules proxy compounds select distinct bacterioplankton for oxidation of dissolved organic matter in the mesopelagic Sargasso Sea. Limnology and Oceanography, 65(7), 1532-1553, 1-22.
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Behrenfeld, M. J. (2010). Abandoning sverdrup’s critical depth hypothesis on phytoplankton blooms. Ecology 91, 977–989.↩
Carlson, C. A., Ducklow, H. W., and Michaels, A. F. (1994). Annual Flux of dissolved organic carbon from the euphotic zone in the northwestern Sargasso Sea. Nature 371, 405–408.↩
Dall’Olmo, G., Dingle, J., Polimene, L., Brewin, R. J. W., and Claustre, H. (2016). Substantial energy input to the mesopelagic ecosystem from the seasonal mixed-layer pump. Nat. Geosci. 9, 820–823.↩