The total daily O_2 consumption rate of the intertidal oyster reef community in Georgia, USA was found to range between 0.6 x 104and 5.0 x 104mg O_2/m2of reef surface, corresponding to a seasonal range of ambient water temperature from 9 degrees C to 30 degrees C. Oysters, nonoyster macrofauna, microbiota, and chemical oxidation were estimated to account for 48.1%, 10.0%, 21.9%, and 20.0%, respectively, of total O2consumed. Reef macrofaunal biomass averages 1,108 g/m2(ash—free dry weight) of which Crassostrea virginica comprises 87.5%. Growth of individual reef oysters, and, therefore, entire reefs, appears to be extremely slow, probably due to high maintenance costs and limited inundation time characteristic of the intertidal zone. The oyster reef community occupies only 0.06% of total marsh—water surface area in a salt marsh estuary unit (the Duplin River marsh—estuary system), but it can theoretically degrade 1% of the estimated excess annual net primary production in the system.