Sediment community oxygen consumption and nutrient exchange in the central and eastern North Pacific 1

Sediment community oxygen consumption (SCOC) and nutrient exchange rates (NH sub(4) super(+), NO sub(3) super(), NO sub(2) super()) were measured along a transect of five stations from the oligotrophic central North Pacific to the eutrophic upwelling off the coast of southern California. These rates were measured using a free vehicle grab respirometer at three spatial scales: intergrab (cm), intersubstation (km), and interstation (10 super(2) km). Sediment community oxygen consumption increased along a gradient of increasing surface primary productivity from west to east. Macrofaunal abundance and biomass, and surface organic carbon and total nitrogen also increased from west to east, with a trend toward larger animals at the eastern stations. Most of the variability in SCOC at both the interstation and intersubstation level is correlated with depth and macrofaunal abundance. Predictive equations for SCOC were generated using these parameters. Nitrogenous nutrient exchange rates were highly variable and showed no east- west trends.