The Flax Pond ecosystem study: Exchanges of carbon in water between a salt marsh and Long Island Sound1

Flax Pond, a tidal marsh on the north shore of Long Island, New York, was used to examine the exchanges of carbon in its various forms between a salt marsh and the coastal waters. The marsh removed fine particulate carbon from the tidal water throughout the year; it tended to be a small source of C as total CO 2 and dissolved organic carbon during summer, and a sink for both forms in winter. The net flux of total carbon over a year, measured as total CO 2 and as particulate and dissolved organic C, was a small input into the marsh, estimated as about 51 g C m −2 . The data were consistent with others showing the marsh to be a net consumer of chlorophyll throughout the year and a strongly heterotrophic system in summer and do not support the conventional view of marshes as net sources of fixed carbon to coastal waters.