Coral Nitrogen Isotopes as a Recorder of Natural and Human-Driven Changes in the Nutrient Conditions of Oceanic Surface Waters

2016 Faculty Research Award

Award Period: 2016-2018

Daniel Sigman, the Dusenbury Professor of Geological and Geophysical Sciences, will undertake a project at the island of Bermuda to investigate the nutrient-cycling processes recorded by the isotopes of nitrogen trapped in the skeletons of corals, as well as generate a coral nitrogen-isotope record extending back at least 100 years. This work will illuminate the cycling of nutrients on coral reefs, including the nutrition of corals and their interaction with other reef organisms. Moreover, the project will help to establish coral records as a tool for reconstructing past ocean nutrient changes, including those associated with human activities and climate change. Application of this new tool to Bermuda will test for the possibility of increased atmospheric-nitrogen deposition on the open North Atlantic due to fertilizer use and fossil-fuel burning in North America. The researchers will measure the ratios of nitrogen isotopes bound within modern corals and many other organisms, and the forms of nitrogen collected from reefs around Bermuda. Analyses also will be performed on a coral core from the outer reef at Bermuda. These studies — made possible by an ongoing collaboration with Anne Cohen at the Woods Hole Oceanographic Institution and Samantha de Putron at the Bermuda Institute of Ocean Sciences (BIOS) — will yield vital information about human impacts on ocean nutrient cycling, both in the present and in recent centuries.

Educational Impacts

PEI summer interns will have the opportunity to work in Bermuda with Princeton graduate student Victoria Luu on coral-growth experiments and the collection of reef samples. On campus, undergraduates will work on isotopic measurements of the experimental and field samples. Work on the project could result in junior and senior research topics.