Award: OCE-1829888

This project assessed the linkage between a major marine phytoplankter (Synechococcus) and the dissolved carbon released from it after fracturing the cells. Long-term incubation experiments of this material revealed stable fluorescence organic matter that has the ability to accumulate in the deep ocean. We also compared the community structure of bacteria and archaea in the Atlantic and Pacific Ocean at 200 m depth intervals based on the sequences of a marker gene (16S rRNA gene). On several representative depths (i.e., surface, deep chlorophyll maximum, oxygen minimum zone, mesopelagic, and bathypelagic zone), we performed ultra-deep genomic sequencing and found new groups of uncultured bacteria that are abundant in the deep ocean and can utilize organic carbon in specific ways. Similarly, the molecular composition of the dissolved organic carbon (DOC) was characterized using state-of-the art analytical tools (mass spectrometry, optical properties analysis and nuclear magnetic resonance spectroscopy) at the same locations. Results showed fundamental differences between the samples collected in the Atlantic versus the Pacific Oceans suggesting that the DOC is fundamentally different and highly dependent on locale. A masters and PhD student were trained during this project and undergraduate interns had the opportunity to participate in one major oceanic research cruise aboard the RV Atlantic Explorer. Unfortunately, the Covid-19 pandemic severely influenced our broader impact activities, but we still were able to produce a mini documentary about the work on a research vessel coordinated by our science communication intern Emily Ramirez. The results from this project have far reaching implications in better understanding the marine carbon cycle at large. Last Modified: 03/07/2023 Submitted by: Michael Gonsior