Robert R. Twilley,
Director, Wetland Biogeochemistry
Professor, Department of Oceanography and Coastal Science
Louisiana State University.

Research Interests

My research has focused on systems ecology and biogeochemistry of coastal wetlands both in the Gulf of Mexico and throughout Latin America. Through this research I try to develop fundamentals of ecosystem science by describing biogeochemical processes (denitrification, nutrient burial, benthic nutrient fluxes) that determine the function of coastal ecosystems as either a source or sink of primary nutrients to near shore environments. I use modeling, field manipulations, and mesocosm techniques to test hypotheses of nutrient cycling in coastal ecosystems. A large part of my career has been spent determining the role of mangroves in the fate of carbon and nutrients in tropical estuaries. I just completed a project funded by Environmental Protection Agency to develop ecosystem models that will serve as methodologies to assess the response of mangrove wetlands to environmental change (see Chen and Twilley 1998). Recently I have been involved with a National Science Foundation initiative to develop ecosystem science in the area of restoration ecology (see Twilley et al. 1999 published in Marine Pollution Journal). Finally, I have been involved with the restoration and nutrient dynamics of coastal ecosystems of the Florida Coastal Everglades/LTER program funded by NSF as another experimental test of these hypotheses.

My career includes experience in a variety of marine and estuarine ecosystems in southeastern United States, and coastal environments throughout the Caribbean and Latin America. Research and teaching in mangroves and tropical estuaries has resulted in experience throughout Central and South America, as well as the Caribbean. I have directed and been involved with graduate students and courses at academic institutions in Brazil, Colombia, Mexico, Ecuador, and Venezuela. I've applied my basic research by participating in initiatives and workshops on programs to develop science for the management, valuation, and conservation of tropical wetlands and estuaries supported by IUCN (International Conservation Union), US Agency for International Development, World Wildlife Fund, World Bank, and National Research Council. Many of these ideas were published in an overview in Environmental Science and Policy, using my experience in Ecuador as a case study.

In 1999 I co-edited The Biogeochemistry of Gulf of Mexico Estuaries, in 2001 was lead author of Confronting Climate Change in the Gulf Coast Region: Prospects for Sustaining Our Ecological Heritage, and 2002 was co-author of report by the Pew Center for Global Climate Change entitled Coastal and Marine Ecosystems and Global Climate Change. Presently, I am a member of the Louisiana Framework Development Team that is developing a comprehensive restoration plan for the Louisiana Coastal Area. I am active in the Estuarine Research Federation having co-chaired the ERF’99 conference in New Orleans, and was program chair of the 2003 annual conference of the Society of Wetland Scientists. My current focus is developing ecosystem models, both conceptual and simulation, to forecast the rehabilitation of coastal and wetland ecosystems.

Selected Publications

__Bianchi, T., J. Pennock, and R.R. Twilley (eds). 1999. Biogeochemistry of Gulf of Mexico Estuaries. John Wiley and Sons, New York. 428 pp.

__Twilley, R.R., E. Barron, H.L. Gholz, M.A. Harwell, R.L. Miller, D.J. Reed, J.B. Rose, E. Siemann, R.G. Welzel and R.J. Zimmerman. 2001. Confronting Climate Change in the Gulf Coast Region: Prospects for Sustaining Our Ecological Heritage. Union of Concerned Scientists, Cambridge, MA and Ecological Society of America, Washington, DC. 82 pp.

__Twilley, R.R. 1985. The exchange of organic carbon in basin mangrove forests in a southwest Florida estuary. Estuarine, Coastal and Shelf Science 20:543-557.

__Twilley, R.R., A.E. Lugo, and C. Patterson-Zucca. 1986. Litter production and turnover in basin mangrove forests in southwest Florida. Ecology 67:670-683.

__Twilley, R.R. 1988. Coupling of mangroves to the productivity of estuarine and coastal waters, pp 155-180. In: B.O. Jansson (ed.), Coastal-Offshore Ecosystem Interactions. Springer-Verlag, Germany.

__Twilley, R.R., R.H. Chen, and T. Hargis. 1992. Carbon sinks in mangroves and their implications to carbon budget of tropical coastal ecosystems. Water, Air and Soil Pollution 64: 265-288.

__Twilley, R.R. 1995. Properties of mangrove ecosystems in relation to the energy signature of coastal environments, pp. 43-62. IN: C.A.S. Hall, (ed.), Maximum Power. University Press of Colorado, Niwot

__Twilley, R.R., M. Pozo, V.H. Garcia, V.H. Rivera-Monroy, R. Zambrano, and A. Bodero. 1997. Litter dynamics in riverine mangrove forests in the Guayas River estuary, Ecuador. Oecologia 111:109-122.

__Twilley, R.R., R, R. Gottfried, V.H. Rivera-Monroy, M. M. Armijos, A. Bodero. 1998. An approach and preliminary model of integrating ecological and economic constraints of environmental quality in the Guayas River estuary, Ecuador. Environmental Science and Policy 1:271-288.

__Twilley, R.R. and R. Chen. A water budget and hydrology model of a basin mangrove forest in Rookery Bay, Florida. 1998. Australian Journal of Freshwater and Marine Research. 49:309-323.

__Chen, R. And R. R. Twilley. 1998. A gap dynamic model of mangrove forest development along gradients of soil salinity and nutrient resources. Journal of Ecology 86:37-52.

__Chen, R. and R. R. Twilley. 1999. A simulation model of organic matter and nutrient accumulation in mangrove wetland soils. Biogeochemistry 44:93-118.

__Twilley, R.R, Rivera-Monroy, V.H., Chen, R., Botero, L. 1999. Adapting an ecological mangrove model to simulate trajectories in restoration ecology. Marine Pollution Bulletin 37:404-419.

__Rivera-Monroy, V.H., R.R. Twilley, D. Bone, D. Childers, C. Coronodo-Molina, I.C. Feller; J. Herrera-Silveira, R. Jaffe, E. Mancera, E. Rejmankaova, J. Salisbury. 2004. Conceptual Framework to Develop Long Term Ecological Research and Management Objectives in the Wider Caribbean Region. BIOSCIENCE 54:843-856.

Research Support and Proposals:

National Science Foundation/LTER Program. FCE/LTER - Florida Coastal Everglades. Subcontract with FIU. March 2000 to February 2006.

US Department of Agriculture/Environmental Protection Agency, NUMAN – Utilizing Mississippi River Diversions for Nutrient Management in a Louisiana Coastal Watershed. August 2002 through July 2005.

Environmental Protection Agency, Use of Science in Gulf of Mexico Decision Making Involving Climate Change. October 2002 through September 2005.

EPSCOR/EPA, Modeling Impacts of Climate Change on Wetland Ecosystems. June 2002 through June 2004. LA Department of Natural Resources, Conceptual Ecological Models for Planning and Evaluating the Louisiana Coastal Area Restoration Plan. R.R. Twilley, PI. June 2002 to March 2005.

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