 The deep water horizon accident caused a significant uncontrolled hydrocarbon release to the Gulf of Mexico, much of which was entrained in deep submerged plumes. While biodegradation of the hydrocarbons has been inferred from microbial biomass and genetics, the amount of conversion of oil and gas carbon to biomass remains uncertain. This study examines correlated depletions of nitrate, phosphate, and oxygen in the submerged plumes and concludes that a substantial portion of hydrocarbons in these plumes was converted to biomass, 0.8-2 times 10 to the power of 10 mol C. The results suggest the need for better monitoring of changes in nutrients as well as study of nutrient recycling in similar, future hydrocarbon releases. This article was authored by Alan M. Shiller and Tom Jujung.