It is recognUed that in many cases the latter two assumptions, 

 especially the second, may be invalid. 



A medium or large spill (greater than 3,840 liters, or 24 barrels) 

 will require large numbers of men and equipment, and the resulting 

 traffic (boats, barges, marsh buggies, trucks, helicopters) will 

 increase the concentrations of suspended sediments and nutrients in 

 the area. Construction of dikes, dams, or retaining walls will add 

 to these concentrations and remove more vegetation and consumers. 

 Depending upon the soil moisture conditions, the vegetation may be 

 completely uprooted and destroyed in some areas. This results in an 

 immediate decrease in food and cover for the remaining consumers in 

 the area. The total area affected may or may not be small in compar- 

 ison to the remaining area of productive vegetation. The effects on 

 surviving animals, nitrogen fixation, and detritus production are 

 dependent upon this ratio of affected to remaining vegetation. The 

 amount of traffic and activity will be directly proportional to the 

 size of the spill and/or the size of the affected area. The tempo- 

 rary displacement of consumers by the noise and activity of cleanup 

 operations is of little importance. 



Although the total cleanup activities may trample and crush a con- 

 siderable amount of undisturbed vegetation in access and adjacent 

 zones, the most significant impacts of the entire spill-cleanup 

 sequence are the effects on waterflow regimes. Unlike the altera- 

 tions discussed above, the changes in waterflow regimes result in 

 long-term consequences. A variety of vehicles used during cleanup 

 (primarily marsh buggies in the marshes) have the ability to create 

 pathways and blockages which significantly alter water movements. 

 The depth and number of ruts created by marsh buggies is dependent 

 upon the number of vehicles and the degree to which they retrace 

 existing tracks. In areas that are submerged daily, the depressions 

 are less likely to significantly alter water movement patterns. 

 Hence, in the areas near the estuary, confinement of marsh buggy 

 traffic to a narrow corridor may be wise. However, in areas further 

 removed from the estuary, deep ruts resulting from retraced trails 

 would form a depression for the movement of water and, if deep 

 enough, may result in standing bodies of water after the tide has 

 receded. The orientation and depth of the depressions determine 

 whether they (1) remain for long periods of time and (2) increase or 

 decrease the frequency of inundation of a given area of land. Areas 

 dominated by saltgrass or shore grass may be replaced by stands of 

 smooth cordgrass when the frequency and/or duration of inundation 

 decreases. The total area affected is site specific and could range 

 from insignificant to highly significant when compared to the total 

 area of salt marsh. Consumers that depend upon smooth cordgrass and 

 its epiphytes for food and/or cover may ultimately increase or 

 decrease. 



The amount of detritus exported to the adjacent estuarine system is 

 directly proportional to the standing crop of smooth cordgrass. If 



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