Changes in calcareous nannoplankton assemblages during the recovery of the Paleocene Eocene Thermal Maximum (PETM)

Open Access
Grey, Jacqueline Ashley
Graduate Program:
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 09, 2017
Committee Members:
  • Timothy Bralower, Thesis Advisor
  • Mark E Patzkowsky, Committee Member
  • Peter Daniel Wilf, Committee Member
  • nannoplankton
  • Paleocene Eocene Thermal Maximum
  • PETM recovery
  • paleoecology
  • global warming
Warming and associated environmental perturbations during the Paleocene Eocene Thermal Maximum (PETM; 55.8 Mya) caused permanent changes in calcareous nannoplankton communities. Assemblages during the onset of the PETM have been studied in extraordinary detail with temperature proposed as the main control on community structure; however, few analyses have focused on the recovery stage. Thus, we lack a clear understanding of how communities responded to gradual cooling and recovery of habitats following a rapid warming event. Here, we have performed high-resolution assemblage studies of coastal sites – (Wilson Lake and CamDor cores) –and open ocean sites from a variety of latitudes (Ocean Drilling Program Sites 738, 1210, and 1263). Multivariate statistics are applied to the global data set to assess how assemblage structure changed in these different settings. Results show that assemblages and the environmental controls on assemblage structure are highly variable across oceanic settings. For example, eutrophic genera show different trends at Wilson Lake in New Jersey and CamDor in Maryland even though these sites are a few hundred miles apart. Similarly, across a variety of latitudes in the open ocean, thermophilic taxa show a variable decline in abundance. We find that nannoplankton assemblages in the onset of the event were controlled predominantly by temperature change, whereas in the recovery, a combination of temperature and nutrients drove changes, thus explaining the highly variable pattern. The assemblage organization observed during the PETM recovery set the stage for the composition of nannoplankton communities in the warm early Eocene.