FLUX OF INORGANIC NUTRIENTS AND PARTICULATE CARBON BETWEEN A SPARTINA MARITIMA SALT MARSH AND THE SWARTKOPS ESTUARY, EASTERN CAPE

Summary The flux of dissolved inorganic nutrients (NH4-N, NO2-N, NO3-N, SRP) and suspended particulates (particulate organic carbon POC, and particulate inorganic carbon PIC) was measured across the mouth of a small creek draining a portion of the intertidal Spartina salt marsh in the Swartkops estuary. Direct measurements of constituent concentration, the volume of water flowing into and out of the creek basin at discrete time intervals, and tidal height were made over full spring tide cycles on a two-weekly basis during a 12 month study period. Results show that the marsh acts as a sink for NH4-N, NO2-N, and NO3-N on an annual basis, but exports soluble reactive phosphate to the contiguous estuarine waters. The marsh also imports nominal amounts of suspended POC and PIC ( 1.5 mm) on ebb tides to the estuary. It is concluded that the marsh retains and utilizes most of its own production and functions virtually as an independent ecosystem.