Aquatic Sciences Meeting, Albuquerque 2001

PC14 Estuarine, Near-shore, and Continental Shelf Processes

Date: Thursday, February 15, 2001

Location: Southwest Hall

Farris, C, N, National Park Service, Wellfleet, USA, charles_farris@nps.gov

COMPARISON OF GEOCHEMICAL WATER COLUMN SPECIES AMONG RESTRICTED MARSH BASINS IN RESPONSE TO TIDAL FLOODING REGIMES.

Flood-ebb differences in water column parameters were examined among four tidally restricted coastal marshes. All marshes showed a flood ebb cycle in total dissolved iron (TDFe) and alkalinity. When marshes were ordered by frequency and extent of inundation, the marsh with the greatest tidal incursion showed the highest levels of TDFe (26-56 uM) and minimal changes in alkalinity (2 to 2 mEq l-1). The most restricted marsh showed the lowest levels of TDFe (3.8 uM) and significantly higher alkalinity (4.7 mEq l-1). The distribution of TDFe species varied significantly as the marsh with the highest degree of inundation had the highest proportion of reduced iron (95%). The most restricted marsh had only 68% reduced iron. These chemical parameters are driven by the incursion of flooding waters into the marsh peat interstices, the presence or absence of reducing peat conditions and the developmental history of the individual basin. These parameters are both driven by and affect geochemical condition in the marsh. These results may help elucidate potential restoration trajectories of individual marshes as more natural tidal flooding regimes are established.

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Aquatic Sciences Meeting, Albuquerque 2001

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