PHYTOPLANKTON RESILIENCE TO GLOBAL CHANGE: BIOMARKER LESSONS FROM THE GEOLOGIC RECORD (Invited Presentation)

Microfossils preserved in the geologic record have formed the basis for the study of the evolution and demise of marine phytoplankton over Earth history. However, since only a fraction of phytoplankton produces hard fossilizable skeletons, our view of ancient marine ecosystems remains incomplete. This gap in our knowledge can be filled with the use of biomarkers, the degradation products of cell membrane lipids produced by all forms of life which can be preserved in the geologic record for up to billions of years. In this invited presentation, I provide an overview of how biomarkers records, especially when combined with microfossil records, provide a more holistic view of the response of marine planktonic ecosystem to large environmental perturbations in the geological record. I will compare the differences in ecosystem resilience to different environmental forcing, such as nutrient disruption and ocean depletion during Cretaceous oceanic anoxic events (OAEs) and mass extinction events (Permian-Triassic and Triassic-Jurassic boundary), and ocean acidification during the Cretaceous-Paleogene mass extinction. I will discuss the role of non-calcareous plankton in the recovery and sustaining of marine productivity when calcareous organisms suffered severe extinction or turnover, and how this information can inform future predictions of ecosystem response and changes in biogeochemical cycles to current and projected trends in ocean deoxygenation and acidification.