Palmisano, 1970; Bayley and Odum, 1976). The biological and chemical properties 

 of flooded soils are significantly different from those of aerated soils. Nutri- 

 ent regeneration is slower in saturated soils, and growth of vegetation may be 

 limited by the lack of available nutrients (Redman and Patrick, 1965; Palmisano, 

 1970). 



The goal of many management practices is to control the flow and storage 

 of water in the system. Impoundments and drawdowns are most common in this 

 marsh type. Through proper timing of water level regulation, the vegetation 

 can be controlled to favor cattle, waterfowl, fish, or other wildlife (Ensminger, 

 1963; Shiflet, 1963; Meeks, 1969; Smith, 1970). 



It must be emphasized that flowing water is the main transporter of sedi- 

 ments into and out of the system. The primary effect of decreases in water 

 flows (resulting from levees and channels) may be due to the reduced sediment 

 input rather than to the reduced nutrient input per se (Penfound and Hathaway, 

 1938; Gagliano, 1973). 



Standing water, of course, provides the necessary habitat for all aquatic 

 plants and animals. Phytoplankton and fish, for example, are totally dependent 

 upon ponds for their existence. 



Sediment . The primary source of mineral sediment in a typical fresh marsh 

 is upland drainage. As mentioned earlier, the location of the marsh (river 

 mouth) or man-induced alterations (channelization) may allow marine influences 

 in some fresh marshes. Regardless of their origin, the al lochthonous sediments 

 bear important nutrients complexed to their surfaces. 



The highly organic soils of fresh marshes indicate a predominance of peat 

 deposition over importation of mineral sediments. Chabreck (1972) and 

 Brupbacher, et al. (1973) reported average organic matter content of mucks and 

 peats from Louisiana fresh marshes as high as 66 percent. Brackish and salt 

 marshes, in comparison, were 50 and 45 percent organic, respectively. Bayley 

 and Odum (1976) found that one-seventh of the total plant biomass in a sawgrass 

 marsh is converted to peat. This accumulation of material is important in 

 counteracting the effects of subsidence in coastal areas. If the rate of peat 

 accumulation is sufficient, net land elevation may increase. This would initiate 

 a successional change in vegetation. Vegetation may also change as a consequence 

 of a change in the type of sediment deposited. Roseau cane, for example, is 

 usually found on mineral soils; cattail, however, is commonly the dominant in 

 similar systems with organic soils (O'Neil, 1949). 



Suspended sediment may affect the biota of this system via two pathways. 

 Turbidity due to suspended sediment decreases the light energy available to 

 photosynthetic organisms, and thus it reduces primary productivity. The mat- 

 forming species are unaffected because their photosynthetic tissues are almost 

 entirely above water. The second pathway involves siltation effects on benthic 

 flora and fauna. Because the quantity of suspended sediment is relatively low 



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