Internship Journey at HMEI: Personal Accounts and Insights
In the summer of 2023, a rising college sophomore embarked on an exciting research journey, focusing on one of Earth's most significant extinction events: the Cretaceous/Paleogene (K-Pg) mass extinction. Rebecca Cho, Natural Sciences Correspondent, brings us an insightful account of this intern's groundbreaking research.
The Intern's Summer Research
The intern's research project, potentially associated with the High Meadows Environmental Institute (HMEI) Internship Program, aimed to reconstruct the marine ecological changes that occurred across the K-Pg boundary. The intern chose to join the Sigman laboratory for the summer, where they used nitrogen isotopes (δ^{15}N) preserved in planktonic foraminifera to trace and interpret these changes.
Marine Environmental Changes During the K-Pg Mass Extinction
The K-Pg mass extinction marks one of the most catastrophic events in Earth's history, leading to the loss of about 75% of all species, including non-avian dinosaurs and many marine organisms[1]. This project sought to reconstruct the marine ecological changes that occurred during this boundary by analyzing nitrogen isotopes in microscopic marine fossils called planktonic foraminifera.
Methodology
Planktonic foraminifera are single-celled organisms that live in the ocean's surface waters and whose calcium carbonate shells are abundant in marine sediments. These shells can preserve isotopic signals reflecting the nitrogen dynamics of ancient oceans. By measuring changes in nitrogen isotopic composition (δ^{15}N) through time, researchers can infer shifts in marine nitrogen cycling, including processes like denitrification, nitrogen fixation, and nutrient utilization by marine plankton.
Such isotopic analyses provide a proxy for past marine productivity, nutrient availability, and ocean oxygenation, helping to reveal how the marine ecosystem responded to the extreme environmental stressors of the K-Pg mass extinction, such as asteroid impact-induced darkness, cooling, and acidification.
Scientific Significance
The project addresses several key scientific questions:
- How did marine productivity and nutrient cycling change in response to the K-Pg extinction event?
- What was the impact on marine food webs and primary production?
- Can nitrogen isotope records help resolve the persistence, recovery, or reorganization of marine ecosystems after the extinction?
This research contributes to a broader understanding of how marine ecosystems respond to catastrophic environmental perturbations, with relevance to contemporary concerns about biodiversity loss and global change.
Broader Context
Reconstructing Earth's past climates and environments—especially during major extinction events—is an active area in paleoceanography and paleoclimatology[3]. The use of nitrogen isotopes in planktonic foraminifera is a relatively novel approach in this field, complementing more traditional proxies such as carbon and oxygen isotopes.
The Intern's Experience
During their internship, the intern developed relationships with mentors experienced in the field of geochemistry, gaining valuable insights into the world of research. The experience affirmed their interest in studying Geosciences as their concentration at Princeton.
Choosing a Lab for Research
For students seeking to embark on their own research journey, the process of choosing a lab can be daunting. The intern's decision to join the Sigman laboratory offers valuable insights into this process.
Funding and Opportunities
The HMEI Internship Program offers opportunities for students to connect their coursework with real-world research. For those interested in securing funding for their research projects, the "Funding" section provides a guide to various resources and opportunities.
Reflections on the Summer Research Internship
In the "Summer Research" section, the intern shares their reflections on their experience in the Sigman laboratory for the summer of 2023. Their account offers a unique perspective on the challenges and rewards of conducting cutting-edge research in the field of geosciences.
[1] Alvarez, L.W., Alvarez, W., Asaro, F., & Michel, H.V. (1980). Extraterrestrial cause for the Cretaceous–Tertiary extinction. Science, 208(4449), 1095-1108.
[3] Zachos, J.C., Pagani, M., Sloan, L.C., Thomas, E., and Billups, K. (2001). Trends, rhythms, and aberrations in global climate 65 Ma—A review. Climate Change, 53(3–4), 251-304.
The intern's summer research project involved reconstructing marine ecological changes during the Cretaceous/Paleogene (K-Pg) mass extinction, focusing on nitrogen isotopes in planktonic foraminifera as a proxy for past marine productivity, nutrient availability, and ocean oxygenation. This independent work was carried out under the guidance of the Sigman laboratory, offering the undergraduate student an opportunity for education-and-self-development in the field of science.
