Tacy Guest ’26


Ecology and Evolutionary Biology

Project Title

Investigating Nitrogen Allocation in Corals and Their Symbionts

Certificate(s): Environmental Studies

I worked with The Ward lab to standardize a method for separating coral tissue from the symbionts that live within the tissue. Coral is composed of coral tissue and single-celled photosynthetic algae symbionts called zooxanthellae. The zooxanthellae undergo photosynthesis and provide energy and fixed carbon to the coral, but little is known about how they contribute to nitrogen uptake. Understanding these relationships is critical to the future preservation of coral species. To understand the nitrogen uptake however, it is necessary to separate the coral tissue and the symbionts. While many methods exist in the literature, there is no standardized method, and the cross contamination between the tissue and the zooxanthellae in existing methods has never been quantified. I tested different variations of the method by preparing samples, assisting in cell counts and running the mass spectrometer, a machine that detects the nitrogen and carbon content of a sample. I also participated in the data analysis that followed these experiments. I practiced technical lab techniques and learned troubleshooting techniques for the mass spectrometer. I’m excited to continue working with The Ward Lab through my sophomore year and on my junior paper and senior thesis.

Internship Year


Project Category

Climate and Environmental Science


The Ward Lab, Department of Geosciences, Princeton University - Princeton, New Jersey


Bess Ward, William J. Sinclair Professor of Geosciences and the High Meadows Environmental Institute; Moriah Kunes, Ph.D. candidate, Geosciences