This study proposes to assess the importance of alternative pathways in the carbon and sulfur budgets of Arctic phytoplankton and to determine whether nutrient limitation and temperature control the size of the different organic pools of the carbon and sulfur budgets as well as the production rate of these different mineral pools. Phytoplankton may act as a sink for carbon dioxide and act as a source of dimethylsulfide. Large phytoplankton biomass accumulates during spring blooms in Arctic waters, where algal taxa such as diatoms and other algae dominate. Previous work by the PIs indicated that polar phytoplankton can be strong producers of dissolved organic carbon and sulfur than previously thought. The widespread distribution of these species in highly productive waters of the polar seas makes understanding the variability of this system highly critical. The PIs propose to differentiate between the production of algal mucilage and dissolved carbon pools and determine their relative importance to the total excretion of photosynthetic fixed carbon, to determine the role of Phaeocystis and diatomaceous algae in carbon and sulfur pathways, to examine the changes in partitioning of carbon and sulfur during exponential and stationary growth, and to study the role of nutrient limitation on organic carbon and sulfur production.
