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Urban Runoff and Oxygen Dynamics on Marsh Platforms

PIs: William Savidge & Jack Blanton, Skidaway Institute of Oceanography, Savannah GA, USA

Support: Coastal Incentive Grant

Timeframe: 2008 - 2011

Project Locations:
Ogeechee River Estuary
Skidaway Island
Vernon River
Skidaway River

Discipline: Chemsitry & Biology

Project Objective:
Oxygen concentrations on high-tide marsh platforms have been compared for a site on the Vernon River and a site on the Skidaway River. The Vernon River site receives significant freshwater runoff from urbanized uplands via drainage canals.  The Skidaway site serves as an unimpacted control.  The objective of this work is to determine the effects of runoff on oxygen availability within an estuarine subhabitat that is a critical foraging, nursery, and refuge area for finfish and crustaceans.


  • There is no biologically significant difference in oxygen concentrations on flooded marsh platforms at the two sites
  • Oxygen concentrations are low (2-5 mg l-1) and undersaturated during the summer, but rise rapidly with declining temperatures in the fall and winter.
  • There appears to be a marked transition in the oxygen regime associated with the first autumn cold front.
  • Stormwater discharge is associated with enhanced rates of water column + sediment respiration at the Vernon River site
  • Rapid exchange of Vernon River water with the larger estuarine watershed (Little Ogeechee River, Green Island Sound) means that salinity and oxygen perturbations due to stormwater runoff are of short duration.
  • Results from this work indicate that stormwater runoff in the Vernon River has no effect on high tide marsh concentrations (relative to the Saltmarsh Ecosystem Research Facility (SERF) control site) and only a minor influence on oxygen consumption rates.

Publications or web-accessible reports:

Savidge, D. K., J. Norman, C. Smith, J. A. Amft, T. Moore, C. Edwards, and G. Voulgaris. 2010. Shelf edge tide correlated eddies along the southeastern United States. Geophys. Res. Lett., 37, L22604, doi:10.1029/2010GL045236.

Urban Runoff and Oxygen Dynamics on Salt Marsh Platforms: Status Report to DNR-CRD.  2010. http://www.skio.usg.edu/?p=research/bio/urbanrunoff

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This page was updated March 3, 2014