disjunct borrow pits to build the ring levee. This work and the 

 auxiliary preparation of the wellsite interior removes vegetation 

 and associated insects, periwinkles, and meiofauna from a maximum of 

 1.4 ha or 3.5 acres. This removal represents a loss of food and 

 cover for all the remaining consumer groups - waterfowl, wading and 

 shorebirds, mammals, aquatic invertebrates, and fish. 



Short-term increases in suspended sediments and nutrients result 

 from construction activities. Longer term increases resulting from 

 erosion of the ring levee are of minor consequence since vegetation 

 usually develops in a year or less to control the erosion. Neither 

 the short-term nor the long-term erosion effects from the ring levee 

 have a large impact on the surrounding marsh unless conditions are 

 such that the turbidity spreads over a wide area. 



The ring levee may influence water flows by isolating/filling de- 

 pressions or blocking small drainages. The effects are usually 

 localized and insignificant when compared to (1) the remaining 

 unaffected marsh and (2) the effects of road construction. The 

 exterior borrow pits (depressions in land elevation, input 18), can 

 affect a larger area of marsh than the ring levee. The zone(s) 

 affected depends upon the placement pattern, depth, and surface area 

 of these pits. They may remain as isolated ponds of standing water 

 which collect runoff via intercepted drainage ditches, or these pits 

 could become interconnected due to drainage channels and/or consumer 

 use (compaction of pathways between ponds). The drying effect of 

 this increased drainage may or may not lead to vegetation changes in 

 adjacent lands. The total area affected is relatively small, and 

 the frequency of inundation is not affected. Hence, impacts on the 

 functioning of the ecosystem are insignificant. 



Replacement of marsh vegetation by bodies of standing water in 

 borrow pits results in changes in the biotic communities. The area 

 is converted from a salt marsh or tidal channel with frequent tidal 

 flux to a marsh isolated from tidal action, or to a deeper aquatic 

 system. Smooth cordgrass ( Spartina alterniflora ) and epiphytes may 

 die and be replaced by species such as Spartina patens and Eleocharis . 

 This would be indicative of a change of the impounded salt 

 marsh to brackish marsh. If the system were dominated by standing 

 water, the marsh plants and epiphytes would likely be replaced by 

 phytoplankton. While net algal primary production might increase 

 (Corliss and Trent, 1971), net production of organic material from 

 all sources would likely decrease (Darnell, 1976). 



With the shift in ecosystem type resulting from impounding or 

 digging pits, the consumers will change. Generally there is a 

 decrease in overall standing biomass of consumers when marshes are 

 converted to canals (Trent et al., 1972). In the case of an impounded 

 wellsite, it is expected that consumer abundance would greatly 

 decrease, owing to the use of the inside of the impoundment and pits 



189 



