Madeleine Lausted ’24


Ecology and Evolutionary Biology

Project Title

The History of Eastern Tropical North Pacific Oxygen Since the Last Ice Age

Presentation Link

View Madeleine's Presentation

Certificate(s): Global Health and Health Policy, French Language and Culture

High productivity and slow circulation in the Eastern Tropical North Pacific (ETNP) results in one of the world’s largest oxygen deficient zones (ODZ). Organisms there rely on nitrate for respiration via water column denitrification (WCD). Reconstructing how rates of WCD in ODZs have changed since the last glacial maximum has important implications for understanding past changes in ocean circulation and abyssal carbon storage. During WCD, the expression of a large isotope effect elevates the 15N nitrogen to 14N nitrogen ratio of nitrate supplied for primary productivity above ODZs. This allows the Sigman Lab to make inferences about the extent of WCD based on the 15N/14N of fossil-bound organic matter deposited on the ocean floor. I prepared fossil foraminifera samples from a ETNP core site to be analyzed for a new nitrogen-isotope record covering the last glacial-interglacial transition. The hands-on work strengthened my skills in microscopy. In our weekly meetings, my mentor improved my understanding of the fields of paleoclimatology and oceanography through paper readings and discussions, and of the research process in general. I look forward to exploring these fields further and drawing on this experience for my own studies and independent research.

Internship Year


Project Category

Climate and Environmental Science


Sigman Research Laboratory, Department of Geosciences, Princeton University


Daniel Sigman, Dusenbury Professor of Geological and Geophysical Sciences, Professor of Geosciences; Matthew Lacerra, Ph.D. candidate, Geosciences