India Ingemi ’24
Fish Ecology From Ear Stones (Otoliths) and Coral Skeletal Material Past and Present
My goal was to determine the nitrogen isotopic baseline (δN 15 / δN 14 ratio) in the Caribbean and Pacific Ocean across the Miocene, Pliocene, and Modern epochs. I accomplished this by performing nitrogen isotope analysis on otoliths, or ear bones, from myctophids, a family of fish that live in the ocean below the zone where sunlight can reach. Otoliths contain small amounts of protein that serve as great indicators of a fish’s δN 15 / δN 14 ratio. Measuring the nitrogen content of the otoliths involved a 7-day long procedure: I first cleaned the samples using chemical reduction and oxidation to remove nonorganic bound matter, then I oxidized the organic material using persulfate and sodium hydroxide, before pH adjusting and sparging the samples, and finally performed N2O nitrogen isotope ratio spectroscopy. I found it fascinating how so much paleontological history can be garnered by comparing the δN 15 / δN 14 ratio of modern and fossil myctophid otoliths; for example, this method helps to narrow the estimated time frame of the formation of the Isthmus of Panama. Additionally, I gained valuable lab skills, including how to use a mass spectrometer and centrifuge, which are greatly applicable to my future career.
Climate and Environmental Science
Sigman Research Laboratory and The Ward Lab, Department of Geosciences, Princeton University - Princeton, New Jersey
Daniel Sigman, Dusenbury Professor of Geological and Geophysical Sciences, Professor of Geosciences; Bess Ward, William J. Sinclair Professor of Geosciences and the High Meadows Environmental Institute; Jessica Lueders-Dumont, Postdoctoral Research Fellow, Geosciences