The role of tall and medium Spartina alterniflora Zones in the processing of nutrients in tidal water

Abstract

A nitrogen and phosphorus nutrient exchange study was conducted on a vegetated mesohaline marsh in the Carters Creek area, Virginia. The low marsh, dominated by tall Spartina alterniflora removed NH 4 + , NO 3 − , PO 4 3− , dissolved organic nitrogen, dissolved organic phosphorus, particulate nitrogen, and particulate phosphorus from the tidal water as it traversed this zone on an annual basis, while all the nitrogen and phosphorus species were removed from the tidal water inundating the high marsh (medium S. alterniflora). Nitrite was the only nutrient which was released into the tidal water on an annual basis, this occurring in the low marsh during the fall. The low marsh functioned differently from the high marsh in that (1) most of the nitrogen and phosphorus was removed from the tidal water as it resided on the low marsh (areal basis), and (2) seasonal changes in flux direction for NH 4 + , DON, DOP, and PN were observed. The nutrients removed from the tidal water can potentially supply all of the nitrogen and phosphorus required for plant production in the low marsh and between 30 and 105 percent of the nitrogen and 60–70 percent of the phosphorous needed by the high marsh.