On Rockefeller Refuge and Lacassine National Wildlife Refuge, the permanently flooded 

 freshwater impoundments were favorable to alligators (Chabreck 1960; Carbonneau 1987). In 

 certain coastal areas, deer (Odocoileus virginianus) populations have benefited from impoundments. 

 In addition to having permanent freshwater and an increased food supply, the levees provide travel 

 lanes, escape cover, and protection during floods (Chabreck 1960; Joanen et al. 1985). 



In South Carolina, brackish impoundments managed for waterfowl provide greater and more 

 diversified wildlife use than unmanaged sites. Predatory birds and alligator numbers were greater 

 in managed than in unmanaged marshes, presumably because of the high prey availability (Epstein 

 and Joyner 1986). In the impoundments during drawdown, shorebirds and wading birds were more 

 abundant than were waterfowl (Strange 1987). 



Annual drying of freshwater impoundments is essential for growth of annual plants, and periodic 

 drying of brackish impoundments is necessary to maximize production of aquatic plants. However, 

 certain groups such as alligators, mottled ducks, and aquatic organisms may be temporarily affected 

 by these programs (Davidson and Chabreck 1983). 



Water salinities in impounded marshes more often reflect the historical trends of salinity in an 

 area than do non-impounded areas (Chabreck 1960). Water hyacinth, a pest plant in Louisiana 

 fresh marshes, is curtailed in manipulated freshwater impoundments which are drained (Carney and 

 Chabreck 1977). 



Tidal marshes and associated water bodies are important nursery areas for marine fish and 

 crustaceans, and impoundment levees block the ingress and egress of these organisms. Operation 

 of water control structures to allow organisms to enter and exit impoundments has been successfully 

 practiced on Rockefeller Refuge (Davidson and Chabreck 1983). 



Marsh impoundments have certain limitations, which at times makes it necessary for landowners 

 to use other types of management. First, impoundments are costly to construct and maintain. 

 Also, without facilities for pumping water, years that are unusually wet or dry generally result in 

 poor food production. Impoundments can only be built in areas that will support a continuous 

 levee. In certain areas, such as southeastern Louisiana, the use of impoundments is limited because 

 of the fluid nature of the subsoil. 



We are currently studying the effects of water manipulation on plants and wildlife in a floating 

 freshwater marsh impoundment in southeastern Louisiana. The study will determine the feasibility 

 of water manipulation as a wildlife management tool in southeastern Louisiana, where the soil is 

 highly organic. 



LITERATURE CITED 



Alexander, C.E., M.A Boutman, and D.W. Field. 1986. An inventory of coastal wetlands of the 

 USA U.S. Department of Commerce. Washington, DC. 25 pp. 



Baldwin, W.P. 1968. Impoundments for waterfowl on South Atlantic and gulf coastal marshes. 

 Pages 127-133 in J.D. Newsom, ed. Proceedings of the marsh and estuary management 

 symposium. Louisiana State University, Baton Rouge. 



Carbonneau, D.A. 1987. Nesting ecology of an American alligator population in a freshwater 

 coastal marsh. M.S. Thesis. Louisiana State University, Baton Rouge. 53 pp. 



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