From phytoplankton’s ‘crash diet’ to eddies feeding the sea: What lipidomics can tell us about surface ocean carbon cycling

Marine microbes are key players in global biogeochemical cycles including the carbon and nutrient cycles. About half of the global primary production occurs in the surface ocean via photosynthesis by phytoplankton, which provides the basis for the transfer of organic matter and energy to marine ecosystems, supporting most marine food webs including fisheries production as well as stimulating ocean carbon sequestration. Changes in the marine environment resulting from physical and chemical processes impact microbial growth by providing access to light and nutrients. Yet, we still lack a mechanistic understanding about the effects of environmental change on marine microbial communities and with this marine ecosystem functioning, specifically at high-resolution temporal or spatial scales. During this talk, I demonstrate how the emerging field of marine microbial lipidomics provides essential insights on these processes in two case studies: (i) A combined lipidomics and metatranscriptomics approach to investigate the orchestration of phytoplankton activity involved in photosynthesis, energy storage, photoacclimation and photoprotection in the surface waters of the open oligotrophic Pacific over the day/night cycle. I present, for example, lipid biomarker evidence for how nutrient limited phytoplankton utilize a ‘crash diet’ strategy to support their cellular energy demands at night and how this could provide a strong evolutionary reinforcement for diel vertical migration by mesozooplankton. (ii) Microbial lipidome variability in and around a mesoscale eddy to investigate the effects of these ubiquitous oceanic features on surface ocean carbon cycling. I show how physical processes within eddies formed in Eastern Boundary Upwelling Systems shape small scale variations in the plankton lipidome. I further discuss the consequences of essential lipid enrichment in eddies for lateral and vertical transport processes of organic carbon as well as the potential contribution of this carbon to the maintenance of secondary productivity and carbon export offshore. In summary, we are just beginning to understand in detail the environmental factors and mechanisms affecting the planktonic lipidome but they will be crucial for predicting future changes in ecosystem functioning and the marine carbon cycle.

Zoom link: https://ubc.zoom.us/j/61227908464?pwd=eE9IaGhPZFF6OW5OSWROL3U4cmJYQT09 (link is external)

Meeting ID: 612 2790 8464

Passcode: 009405

Please note that after the seminar, the candidate will give a chalk-talk regarding their research plan over the next five years at ESB 5104 @2:30 pm, you are welcome to join as well!