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Nina Whitney, Ph.D. student in Geological and Atmospheric Sciences, was named the Gretchen L. Blechschmidt Award recipient for 2016 by the Geological Society of America (GSA).

Whitney works with Associate Professor Alan Wanamaker
on reconstructing ocean dynamics and climate in the North Atlantic Ocean. The Gulf of Maine is influenced by the warm Gulf Stream and the cold Labrador Current, making it an ideal location to study changes in North Atlantic Ocean currents.

“Understanding changes in ocean currents in the last several centuries is important because these currents have a large influence on global climate,” Whitney said. “Understanding their natural variability helps us better assess current changes and predict future changes.”

To reconstruct Gulf of Maine seawater temperatures, Whitney uses stable isotope geochemistry to unlock the marine archives of quahog (Artica islandica) shells.

“These clams are like trees in that they grow in annual increments,” Whitney said. “They can be dated and sampled at annual resolution. They are also the oldest living, non-colonial animals in the world. The oldest found so far was 507 years old.”

Until now, Whitney has been measuring oxygen isotopes in the clam shells to research changes in seawater temperature. However, since oxygen isotopes are influenced by changes in salinity, interpreting the data can be difficult.

Whitney will use the GSA award to do a pilot study on nitrogen isotopes in the shells. Nitrogen isotopes in shells are influenced both by water source and by the clams’ diet. By using compound specific nitrogen isotopes, one can theoretically determine whether the changes in nitrogen isotopes are due to changes in source water or changes in diet.

“To our knowledge, this method has never been used before in Artica islandica shells,” Whitney said. “If the technique works, we could look at changes in source water and therefore ocean current changes and the resulting climate changes, without relying on oxygen isotopes.”