In addition to the production of foodstuff, the vegetation of the brackish 

 marsh also provides cover for the fauna. Many of the conspicuous animals (musk- 

 rat, nutria, alligator ( Al li gator mississippiensis ), birds) utilize vegetation 

 for construction of nests; all terrestrial animals may employ the vegetation 

 for concealment from predators (O'Neil, 1949; Joanen, 1969; Chabreck, 1971b^). 



The primary producers are differentially regulated by water fluxes, sedi- 

 ment, salinity, and nutrients as previously discussed. Interaction between 

 these factors results in the area's total vegetative composition being avail- 

 able to consumers. 



Consumers . The primary consumers of the brackish marsh may by catego- 

 rized as terrestrial or aquatic. Small fish and invertebrates comprise the 

 bulk of the latter category; they feed primarily upon detritus and phyto- 

 plankton. These aquatic organisms are regulated by the volume of standing 

 water; concentrations of oxygen and toxic substances may affect their physi- 

 ology. Suspended substances, salinity, and heat may modify these parameters. 

 Secondary consumers, which rely heavily on these aquatic species, include 

 alligators, mammals, and birds (Chabreck, 1971a^, 1971b^). 



Insects, waterfowl, muskrat, nutria, and other small mammals consume 

 primary producers directly. It is well established that waterfowl, muskrat, 

 and nutria prefer the rhizomes of sedges to those of marshhay cordgrass or 

 saltgrass. This preference has led to "eatouts" of large areas in the past. 

 Although detrimental to the further survival of sedges, these areas may prove 

 to be beneficial to ducks (Lynch et al., 1947; O'Neil, 1949). All of these 

 terrestrial primary consumers may utilize the vegetation for cover and/or nest 

 construction. 



Many secondary consumers - large mammals (raccoon, oppossum ( Didelphis 

 marsupial is ), armadillo ( Dasypus novemcinctus ), wolf), marsh hawks, and other 

 birds (red-wing blackbird ( Agelaius phoeniceus ), bittern, rail, crane, sand- 

 piper) - rely heavily on the terrestrial primary consumers for food. 



Although man may be considered the top carnivore in this system, his 

 activities that alter land and water characteristics are more significant than 

 his predation (Gagliano, 1973). 



Summary . The brackish marsh system is characterized by a highly produc- 

 tive grass or grass/sedge community dominated by marshhay cordgrass. Its 

 dominance can b6 suppressed only by proper regulation of fire, hydroperiod, 

 and salinity. The vegetation supports a variety of economically important 

 animals. The primary forcing functions in the system are the fluxes of water 

 (fresh and saline), which regulate the flows of nutrients, sediment, salt, and 

 heat. In addition, the water inputs determine the frequency of submergence/ 

 emergence, duration of submergence, and depth of standing water. These factors 

 are regulators of the primary producers and consumers. Management practices 

 and other human activities affect the system, primarily by altering the temporal 

 and spatial relationships of water. 



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