This week’s Steinmetz Spotlight is Emma Puhalski ‘22. She is a Geoscience and Biology double major from Wilbraham, MA. Her research project focuses on stable isotope concentrations in sea ice in McMurdo Sound, Antarctica.

She writes about her work, “I am studying the stable carbon, oxygen, and nitrogen isotopes in the Antarctic sea scallop Adamussium colbecki as a proxy for past sea ice state in McMurdo Sound, Antarctica. Fluctuations in sea ice cover are major drivers of climate change, but Antarctica lacks notable proxy records of sea ice state. Bivalves record environmental conditions and can track changes in sea ice cover over time. Adamussium colbecki is a large sea scallop with a circum-Antarctic distribution and an abundant fossil record throughout the Holocene. Our group’s prior work showed that carbon (δ13C) and nitrogen (δ15N) isotopes in modern scallop shells record seasonal variation in sea ice state over time when paired with growth markers called striae. I have applied this paleoclimate proxy by analyzing A. colbecki subfossils from terraces along Explorer’s Cove (EC) and Bay of Sails (BOS), western McMurdo Sound, Antarctica. Seawater temperature proxy records suggest warmer conditions 2,000-5,000 ybp, so we expect variable δ13C stable δ15N values recording annual sea ice in shells from both sites. Preliminary results indicate that sea ice may have been persistent at both EC and BOS, which may represent a colder and more stable sea ice state for Antarctica in the past.”