is usually accomplished with manual labor. Site alterations are 

 restricted to vegetation trampling and small surface disturbances. 

 Cleanup of residual oil deposits too small to remove efficiently 

 with conventional collection techniques is accomplished by burning 

 the contaminated site. Producers, and consumers which do not 

 abandon the site, are removed. Fire accelerates biomass decomposi- 

 tion, thereby increasing the availability of soil nutrients. Removal 

 of standing plant materials and sediments soaked with oils lowers 

 the local land elevation (pathway 15) and could lead to new areas of 

 standing water. The storage of unavailable nutrients is decreased 

 slightly, but probably not enough to affect the ecosystem. Toxic 

 components of the spilled material are prevented from affecting 

 existing or future biotic elements when saturated substrates are 

 excavated. It is generally agreed among investigators that chemical 

 oil spill emulsifiers, dispersants, removers, etc. are '^ery toxic to 

 aquatic life. Not only are the chemical agents themselves toxic to 

 aquatic invertebrates and vertebrates, but synergistic reactions 

 occur which make a crude-oil/oil-spill-remover mixture much more 

 toxic than either component separately. 



Although cleanup activities may trample and crush extensive amounts 

 of uncontaminated vegetation, the most significant alterations of 

 the cleanup sequence are concerned with changes of the waterflow 

 regime. Movement of marsh buggies and earthwork equipment associ- 

 ated with constructing emergency containment levees or drainage 

 channels changes local land topographic features. Intramarsh circu- 

 lation patterns may be altered as a result of drainage blockage 

 (establishment of levees) or drainage enhancement (canal digging). 

 Basic characteristics of the marsh's hydrologic regime are altered - 

 average depth, duration of site submergence, and frequency of site 

 exposure to the atmosphere. The nature of such changes are site 

 specific, and areal miagnitude is a function of the spill size. 

 Plant alterations may result if the hydrologic regime is altered 

 such that wide areas or critical waterways are permanently affected. 

 Saltwater intrusion may result if the hydrologic regime is altered 

 such that wide areas or critical waterways are permanently affected. 

 Saltwater intrusion may be enhanced with diversion ditches or blocked 

 with containment levees or dams. Likewise, freshwater runoff may be 

 enhanced with ditching. 



Disturbance factors should be recognized as an important considera- 

 tion because they extend the project impacts beyond the boundaries 

 of the immediate site. 



Key attribute alterations 



The primary alteration is the complete or partial removal of biotic 

 components resulting from the effects of spilled oil and from several 

 aspects of the cleanup procedure. Consumer response varies by 

 species, size of the area affected, site characteristics, and result- 

 ant floristic changes. An oil spill has the potential to kill 



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