Simultaneous annual fluxes of carbon, nitrogen and phosphorus were studied on an
intertidal oyster reef In Bly Creek, South Carolina, USA. We observed material fluxes every 10.2 d (33
tidal cycles) over 1 yr and used regression estimation to compute annual estimates. The reef appeared to
take up 1200 g C m-' yr-' from tidal waters. It had an estimated net removal of 189 g N m-' yr-' from the
water column with the majority of this nitrogen released as ammonium (125 g N m-' y~'), and a net
uptake of 98 g P m-2 yr-l. As indicated by the C: N: P ratio of the fluxes, proportionally more phosphorus
was taken up than would be expected. Oyster reefs process carbon, nitrogen und phosphorus at high
rates and appear to function as retention mechanisms for nitrogen and phosphorus in estuaries.