Coastal Marine Ecosystems - Wetlands

Nitrogen Cycling in Coastal Salt Marshes

The salt marsh along the Gulf Coast of Florida showing the edge of the spartina grass along the water
Dr. Joel Kostka in the salt marsh in the Apalachicola National Estuarine Research Research in Florida.
Research microcosms for examining nitrogen cycling directed by microbes.

We are studying nitrogen cycling in marsh sediments of the Apalachicola National Estuarine Research Reserve (ANERR), Florida. TheANERR encompasses a productive and pristine ecosystem where the Apalachicola River reaches the Gulf of Mexico. We are studying nitrogen cycling in marsh sediments of the Apalachicola National Estuarine Research Reserve (ANERR), Florida. TheANERR encompasses a productive and pristine ecosystem where the Apalachicola River reaches the Gulf of Mexico. Pristine beaches, beautiful scenery, abundant oysters, fish, manatees, dolphins, and migratory birds make the Apalachicola Bay a valuable resource and attractive recreation destination. Prior to reaching the ocean, the Apalachicola River forms a network of distributaries and flows through an extensive system of low-salinity marshes at the boundary between the River and the Apalachicola Bay.

Our work at the FSU Coastal and Marine Laboratory involves the study of long-term nitrogen loss via denitrification (nitrogen gas production by microorganisms) and nitrogen burial in ANERR marsh sediments. Controlled environment chambers at the FSUML are used to incubate sediment cores during rate measurements. Stable isotopes and mass spectrometry are used to trace the rates and pathways of nitrogen exchange between marshes and the surrounding estuary. This research is being conducted with financial support from the NOAA Estuarine Reserves Division, graduate fellowship program for Tom Gihring, a graduate student in Dr. Kostka's laboratory.

From the Kostka Lab:


  • Tom Gihring, former Ph.D. Student
  • Tom DiChristina, Georgia Institute of Technology


J.-H. Hyun, A. C. Smith and J. E. Kostka. 2007. Relative significance of sulfate- and iron(III) reduction to organic matter mineralization and its controls in contrasting habitats of the Georgia saltmarsh. Applied Geochemistry 22:2637-2651.

S. G. Wakeham, A. P. McNichol, J.E. Kostka, and T.K. Pease. 2006. Natural-abundance radiocarbon as a tracer of assimilation of petroleum carbon by bacteria in saltmarsh sediments. Geochimica et Cosmochimica Acta 70: 1761-1771.

E. Kristensen and J.E. Kostka. 2005. Macrofaunal burrows and irrigation in marine sediment: microbiological and biogeochemical interactions. In: Interactions between Macro- and Microorganisms in Marine Sediments, E. Kristensen, J.E. Kostka, R. Haese (edit's), American Geophysical Union, Washington, DC, 390 pp.

S.L. Dollhopf, J. Hyun, A.C. Smith, H.J. Adams, S. O'Brien, and J.E. Kostka. 2005. Quantification of ammonia-oxidizing bacteria and controls of nitrification in saltmarsh sediments. Applied and Environmental Microbiology 71:240-246.

C. Koretsky, A. Roychoudhury, E. Voillier, C. Moore, J.E. Kostka, T. DiChristina, P. Van Cappellen. 2005. Salt marsh pore water geochemistry does not correlate with microbial community structure. Estuarine, Coastal, and Shelf Science 62:233.

Y. Furukawa, A.C. Smith, J.E. Kostka, J. Watkins, and C.R. Alexander. 2004. Quantification of macrobenthic impacts on diagenesis using a multicomponent inverse model in saltmarsh sediments. Limnology and Oceanography 49: 2058-2072.

B. Gribsholt, J.E. Kostka, and E. Kristensen. 2003. Impact of fiddler crabs and plant roots on sediment biogeochemistry in a Georgia salt marsh. Marine Ecology Progress Series 259: 237-251.

A. Roychoudhury, J.E. Kostka, P. Van Cappellen. 2003. Pyritization: A palaeoenvironmental and redox proxy reevalauted. Estuarine, Coastal, and Shelf Science 57:1183-1193.

A. Roychoudhury, P. Van Cappellen, J.E. Kostka, E. Voillier. 2003. Kinetics of microbially-mediated reactions: dissimilatory sulfate reduction in saltmarsh sediments (Sapelo Island, Georgia, USA). Estuarine, Coastal, and Shelf Science 56: 999-1008.

R.A. Jahnke, C.R. Alexander, and J.E. Kostka. 2003. Advective pore water input of nutrients to the Satilla River Estuary, Georgia, USA. Estuarine, Coastal and Shelf Science 56:641-653.

J.E. Kostka, B. Gribsholt, E. Petrie, D. Dalton, H. Skelton, and E. Kristensen. 2002. The rates and pathways of carbon oxidation in bioturbated saltmarsh sediments. Limnology & Oceanography 47:230-240.

J.E. Kostka, A. Roychoudhury, P. Van Cappellen. 2002. Rates and controls of anaerobic microbial respiration across spatial and temporal gradients in saltmarsh sediments. Biogeochemistry 60: 49-76.