Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Nitrogen Cycling and Ecosystem Exchanges in a Virginia Tidal Freshwater Marsh

Scott C. Neubauer, Iris C. Anderson and Betty B. Neikirk
Estuaries
Vol. 28, No. 6 (Dec., 2005), pp. 909-922
Stable URL: http://www.jstor.org/stable/3526956
Page Count: 14
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Nitrogen Cycling and Ecosystem Exchanges in a Virginia Tidal Freshwater Marsh
Preview not available

Abstract

Tidal freshwater marshes are diverse habitats that differ both within and between marshes in terms of plant community composition, sediment type, marsh elevation, and nutrient status. Because our knowledge of the nitrogen (N) biogeochemistry of tidal freshwater systems is limited, it is difficult to assess how these marshes will respond to long-term progressive nutrient loading due to watershed development and urbanization. We present a process-based mass balance model of N cycling in Sweet Hall marsh, a pristine (i.e., how nutrient) Peltandra virginica-Pontederia cordata dominated tidal freshwater marsh in the York River estuary, Virginia. The model, which was based on a combination of field and literature data, revealed that N cycling in the system was largely conservative. The mineralization of organic N to NH4 + provided almost twice as much inorganic N as was needed to support marsh macrophyte and benthic microalgal primary production. Efficient utilization of porewater NH4 + by nitrifiers and other microbes resulted in low rates of tidal NH4 + export from the marsh and little accumulation of NH4 + in marsh porewaters. Inputs of N from the estuary and atmosphere were not critical in supporting marsh primary production, and served to balance N losses due to denitrification and burial. A comparison of these results with the literature suggests that the relative importance of tidal freshwater marsh N cycling processes, including plant productivity, organic matter mineralization, microbial immobilization, and coupled nitrification-denitrification, are largely independent of small changes in water column N loading. Although very high (millimolar) concentrations of dissolved inorganic N can affect processes including denitrification and plant productivity, the factors that cause the switch from efficient N recycling to a more open N cycle have not yet been identified.

Page Thumbnails

  • Thumbnail: Page 
909
    909
  • Thumbnail: Page 
910
    910
  • Thumbnail: Page 
911
    911
  • Thumbnail: Page 
912
    912
  • Thumbnail: Page 
913
    913
  • Thumbnail: Page 
914
    914
  • Thumbnail: Page 
915
    915
  • Thumbnail: Page 
916
    916
  • Thumbnail: Page 
917
    917
  • Thumbnail: Page 
918
    918
  • Thumbnail: Page 
919
    919
  • Thumbnail: Page 
920
    920
  • Thumbnail: Page 
921
    921
  • Thumbnail: Page 
922
    922