Comparative Analysis of Marine Diatom Species Richness and Diversity Across the Paleocene-Eocene Thermal Maximum at Different Latitudes

Abstract

This study examines the impacts of rapid warming experienced during the Paleocene-Eocene Thermal Maximum (PETM) at approximately 56 Ma on marine diatom communities and how these effects differ based on latitude. Understanding how diatom communities have responded to rapid warming events like the PETM may provide insight into how diatom communities will be impacted by the changes occurring as a result of the current global climate change, and the potential changes to the carbon cycle and marine primary production that may result from these changes. There are differing views of whether these changes will lead to a positive or negative feedbacks in the global carbon cycle. Potential changes are assessed using statistical analyses of diatom abundance data from existing marine sediment cores from the Lomonosov Ridge, in the Central Arctic Ocean, the Blake Nose, in western North Atlantic Ocean, and the Broken Ridge in the Eastern Indian Ocean. Cluster analysis and Principal Component Analysis are performed to identify variance between datasets. Abundance data is not measured consistently at all locations, complicating comparisons between datasets. There is some evidence that diagenesis has limited diatoms preservation during the PETM in some locations. Impacts on diatom communities are assessed using species richness and species diversity calculated using the Shannon-Wiener Diversity Index. Changes observed in diatom species are assessed for a more comprehensive picture of how rapid warming impacted diatom species richness and diversity across the globe. The results of this study suggest that diatom communities were negatively affected by the rapid warming characteristic of the PETM in middle latitude locations, while the Central Arctic Ocean diatom communities showed an increase in diatom species richness and diversity. The diatom community response to rapid warming observed in the Central Arctic Ocean across the PETM may be connected to poor diatom preservation prior to the PETM or the vastly different paleogeography providing increased nutrient availability from runoff in the Central Arctic Ocean. If marine diatom communities suffer as the data suggests in middle latitude locations, then it is likely decreases in diatom species diversity and richness have the potential to lead to a positive feedback loop for further warming. However, more data is needed in high latitude locations to determine if the negative effects of rapid warming are specific to middle latitude locations.