East coast nitrogen export Dr. Merryl Alber University of Georgia

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

malber@uga.edu https://marsci.uga.edu/directory/people/merryl-alber https://orcid.org/0000-0002-9467-4449 Georgia Coastal Ecosystems LTER Project

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

gcelter@uga.edu https://gce-lter.marsci.uga.edu/ Dr. Merryl Alber University of Georgia

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

malber@uga.edu https://marsci.uga.edu/directory/people/merryl-alber https://orcid.org/0000-0002-9467-4449 Principal investigator Dr. Sylvia C. Schaefer University of Georgia

Dept. of Marine Sciences University of Georgia Athens GA 30602-3636 USA

sylvia@uga.edu Graduate research assistant 2026

M.S. student S. Schaefer and M. Alber (UGA) completed an analysis of the relationship between watershed nitrogen input and export of N to coastal systems along the east coast of the U.S. Although global estimates of nitrogen export to coasts have been taken to be 25% of watershed input, we found that average N export was only 9% of input in southeastern estuaries, suggesting that global estimates of N export may need revision. We also identified a threshold in N export at 38°N latitude that corresponds to a reported break-point in the rate of denitrification at 10-12°C. Percent N export was strongly related to both temperature itself (R2=0.76) and a denitrification temperature factor (R2=0.74). We propose that temperature, by regulating denitrification, results in increased proportionate N export at higher latitudes.

Question 1: What are the long-term patterns of environmental forcing to the coastal zone? (more information)

LTER NSF U.S. east coast GCE denitrification export input nitrogen watershed Overall geographic extent of the research project -81.759763 -81.119291 31.771190 30.892711 2004-01-01 2006-12-31

National Science Foundation grant number OCE-9982133. Additional funding: Coastal Incentive Grant, Georgia Department of Natural Resources; Environmental Protection Agency STAR grant

estuary marsh complex Central Georgia Coast - Central Georgia coastal region from the South Newport River (northern extent) to the Satilla River (southern extent), and from the outer banks of the barrier islands (eastern extent) to approximately 35km inland (western extent) -81.759763 -81.119291 31.771190 30.892711 East coast nitrogen export https://gce-lter.marsci.uga.edu/public/resources/projects/CoastalNitroFigAlberQ1.png Schaefer, S.C. and Alber, M. 2007. Presentation: Temperature as a Control on Proportional Nitrogen Export to Coastal Ecosystems: An application of the SCOPE nitrogen budgeting method. Estuarine Research Federations 2007 Annual Meeting, 4-8 November 2007, Providence, Rhode Island. Schaefer, S.C. and Alber, M. 2007. Temperature controls a latitudinal gradient in the proportion of watershed nitrogen exported to coastal ecosystems. Biogeochemistry. 85(3):333-346. (DOI: 10.1007/s10533-007-9144-9) http://www.springerlink.com/content/u0146q6420406j04/ Schaefer, S.C. 2006 Nutrient budgets for watersheds on the southeastern Atlantic coast of the United States: temporal and spatial variation. M.S. Thesis, University of Georgia, Athens, Georgia, 105 pp. Schaefer, S.C. and Alber, M. 2006. Presentation: A latitudinal gradient in the percentage of net anthropogenic nitrogen input exported to Atlantic coast rivers. Estuaries session. Semi-annual meeting of the Southeastern Estuarine Research Societ, March 31-April 1, 2006, St. Augustine, Florida. Schaefer, S.C. and Alber, M. 2006. Poster: Temperature response of denitrification drives a latitudinal gradient in coastal export. LTER All Scientists Meeting, September 20-24, 2006, Estes Park, Colorado. Schaefer, S.C. and Alber, M. 2005. Presentation: Comparison of net anthropogenic nitrogen inputs and riverine export in estuarine watersheds of the Southeast. 2005 Estuarine Research Federation Meeting. October 16-20, 2005, Norfolk, Virginia.