DECOUPLED SHELF-OCEAN PHYTOPLANKTON PRODUCTIVITY RESPONSES ACROSS THE PALEOCENE-EOCENE THERMAL MAXIMUM
Here we present integrated biotic and geochemical data from open ocean and shelf settings in an attempt to address these contradictions. We compare whole assemblage nannofossil abundances across the PETM from shelf deposits at Wilson Lake, New Jersey, with deep marine sections of Ocean Drilling Program Site 1209 on Shatsky Rise in the Pacific. Nannofossil assemblages at both sites display a pattern of continuous reorganization during the PETM. Assemblage shifts at Shatsky Rise demonstrate an interval of short-lived extremely high or low productivity coincident with the onset of the carbon isotope excursion, reflected by peaks in relative abundance of taxa characteristic of highly-stressed environments. In contrast, stable isotope and dinocyst records for Wilson Lake suggest that surface waters become seasonally more brackish on the New Jersey shelf across the PETM, and nannofossil assemblages confirm a transient shift to more eutrophic conditions associated with increased run-off and well-mixed surface waters. This suggests strong decoupling between the response of neritic and oceanic phytoplankton communities across the PETM.