This study examines carbon flow in the Dipper Harbour salt marsh, a macrotidal system located on the north-west coast of the Bay of Fundy, New Brunswick. The vegetated marsh surface is composed of three major zones; the Spartina alterniflora-dominated low marsh, the Plantago maritima-dominated Middle marsh, and the Spartina patens-dominated high marsh. The total net primary production (NPP) of these dominant macrophytes is 860, 300 and 650 g C m$ sp{-2}$ yr$ sp{-1}$ respectively. In all plant zones, 66% of the NPP occurs in the belowground fraction. / Empirical measurements of organic matter burial indicate that the marsh sediment acts as a carbon sink, accumulating between 75 and 105 g C m$ sp{-2}$ yr$ sp{-1}$. The tidal export of aboveground plant biomass in the form of particulate organic matter accounts for a net loss of carbon ranging from 65 to 170 g C m$ sp{-2}$ yr$ sp{-1}$. An experiment examining the exchange of dissolved organic carbon (DOC) suggest a net annual export of roughly 500 g C m$ sp{-2}$ yr$ sp{-1}$. The forementioned fluxes are combined with estimates of surface gas exchange and algal productivity in order to construct a carbon budget. The budget predicts a DOC export term of 365 g C m$ sp{-2}$ yr$ sp{-1}$, which is of the same order of magnitude as that obtained from the empirical DOC data. / The results of this study show that the Plantago zone plays a significant role in the circulation of carbon in the Dipper Harbour salt marsh. This suggests that the patterns of carbon circulation in northern marshes may differ considerably from those in marshes further south where no distinct Plantago zone has been reported.

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