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Marine Ecology Progress Series

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MEPS 400:3-17 (2010)  -  DOI:

Nitrogen interception and export by experimental salt marsh plots exposed to chronic nutrient addition

Lindsay D. Brin1,2,*, Ivan Valiela2, Dale Goehringer3, Brian Howes3

1Brown University, Department of Ecology & Evolutionary Biology, 80 Waterman Street, Box G-W, Providence, Rhode Island 02912, USA
2The Ecosystems Center, Marine Biological Laboratory, 7 MBL St., Woods Hole, Massachusetts 02543, USA
3School of Marine Science and Technology, University of Massachusetts, Dartmouth, 706 South Rodney French Blvd., New Bedford, Massachusetts 02744, USA

ABSTRACT: Mass balance studies conducted in the 1970s in Great Sippewissett Salt Marsh, New England, showed that fertilized plots intercepted 60 to 80% of the nitrogen (N) applied at several treatment levels every year from April to October, where interception mechanisms include plant uptake, denitrification and burial. These results pointed out that salt marshes are able to intercept land-derived N that could otherwise cause eutrophication in coastal waters. To determine the long-term N interception capacity of salt marshes and to assess the effect of different levels of N input, we measured nitrogenous materials in tidal water entering and leaving Great Sippewissett experimental plots in the 2007 growing season. Our results, from sampling over both full tidal cycles and more intensively sampled ebb tides, indicate high interception of externally added N. Tidal export of dissolved inorganic N (DIN) was small, although it increased with tide height and at high N input rates. NH4+ export was generally 2 to 3 times NO3 export, except at the highest N addition, where DIN export was evenly partitioned between NO3 and NH4+. Exports of dissolved organic N were not enhanced by N addition. Overall, export of added N was very small, <7% for all treatments, which is less than earlier estimates. Apparent enhanced tidal export of N from N-amended plots ceased when N additions ended in the fall. Nitrogen cycling within the vegetated marsh appears to limit N export, such that interception of added N remains high even after over 3 decades of external N inputs.

KEY WORDS: Spartina salt marsh · New England · Nutrient addition · Nitrogen export · Nitrogen uptake · Dissolved inorganic nitrogen · Dissolved organic nitrogen · Nitrate · Ammonium

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Cite this article as: Brin LD, Valiela I, Goehringer D, Howes B (2010) Nitrogen interception and export by experimental salt marsh plots exposed to chronic nutrient addition. Mar Ecol Prog Ser 400:3-17.

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