Investigating the response of marine phytoplankton to iron and vitamin additions (2014)
Undergraduates: Wilton Burns, Natalie Cohen
Faculty Advisor: Adrian Marchetti
Department: Environmental Science
The nutrient and vitamin concentrations in Earth¿s oceans will likely change in the coming years due to global climate change caused by anthropogenic forcings. It is important to study how the changing environment will affect marine phytoplankton because they play an integral role in atmospheric carbon uptake through primary production. The purpose of this study was to determine how the phytoplankton community changes in the NE Pacific with the addition of iron (Fe) and vitamins (B12 and B7). Water samples were collected along the well-studied coastal to open ocean transect known as Line P, and seawater was spiked to create six different treatments: Fe, Fe and B7, Fe and B12, B12, B7, and a control group. The methods utilized in this study were light microscopy, 18S clone libraries, and flow cytometry. The light microscopy results indicate that with the addition of Fe, diatoms thrive and become the most abundant phytoplankton in the water samples. Using the Shannon Diversity Index, this study concludes that the overall diversity of the phytoplankton community decreases with time for all six treatment groups. The normalized diversity was highest in the control group after 96 hours but there was a negligible difference in diversity among the other five treatments. This indicates that the changing vitamin and Fe concentrations in the world¿s oceans will have an effect on the overall biodiversity of phytoplankton communities in Fe limited regions of the NE Pacific.