Mark E. Nielsen is a postdoctoral research fellow in organismic and evolutionary biology at Harvard University. He studies the biogeochemistry of hydrothermal vents and marine sediments. Nielsen earned his PhD in oceanography from Oregon State University in 2009 and his dissertation was titled Utilization of Natural and Supplemental Biofuels for Harvesting Energy from Marine Sediments. He is an expert on the design and operation of microbial fuel cells. Prior to his graduate work, Nielsen worked as a water resource consultant in Colorado, specializing in engineering and geology in support of water rights.