The continental shelf adjacent to the Mississippi River is a highly productive system, often referred to as the fertile fisheries crescent. This productivity is attributed to the effects of the river, especially nutrient delivery. In the later decades of the 20th century, though, changes in the system were becoming evident. Nutrient loads were seen to be increasing and reports of hypoxia were becoming more frequent. During most recent summers, a broad area (up to 20,000 km²) of near bottom, inner shelf waters immediately west of the Mississippi River delta became hypoxic (dissolved oxygen concentrations less than 2 mg/l). In 1990, the Coastal Ocean program of the National Oceanic and Atmospheric Administration initiated the Nutrient Enhanced Coastal Ocean Productivity (NECOP) study of this area to test the hypothesis that anthropogenic nutrient addition to the coastal ocean has contributed to coastal eutrophication with a significant impact on water quality. Three major goals of the study were to determine the fate the degree to which coastal productivity in the region is enhanced by terrestrial input, to determine the impact of enhanced productivity on water quality, and to determine the fate of fixed carbon and its impact on living marine resources. NECOP involved 49 federal and academic scientists from 14 institutions from 1990 through 1996. Data aquired on research vessels Pelican, Longhorn, Gyre and Acadiana and NOAA ships Malcolm Baldridge and Chapman.