Perhaps the most commonly applied marsh restoration technique is the 

 physical removal of contaminated plants (i.e., cutting). In the author's 

 opinion, cutting as it is usually practiced can be extremely damaging to the 

 environment. Cutting is usually done with hand tools or hand-operated machines. 

 Although removal of the upper portions of marsh plants is in itself probably 

 not critical, the physical damage to root systems caused by the presence of 

 the cutting crews can be devastating. Without plants and their soil-binding 

 root systems, bank erosion can be accelerated with resulting land loss, turbid- 

 ity problems, and sedimentation effects. Cutting does have the beneficial 

 effect of removing the final amount of oil from the marsh environment, eliminating 

 concern of any possible sublethal long-term effects. In many cases, cutting 

 can be done without damage to the substrate. Mechanical weed-harvesting devices 

 are available on the market and can be used for cutting marsh fringes. Channel 

 and fringe areas (which are frequently the location of the largest portion 

 of contamination) normally have sufficient depth to permit the operation of 

 mechanical cutters. The larger cutters are capable of removing vegetation 

 up to several meters from the shoreline and of automatically collecting the 

 cut material . 



MANGROVES 



RELEVANT CHARACTERISTICS 



Mangroves are slow-growing shrubs or trees which grow in the more tropical 

 portions of the United States. Occurring primarily at intertidal and subtidal 

 levels, mangroves can be divided into two anatomically distinct types: 

 (1) red mangroves {Rhizophora mangle), which are characterized by red bark and 

 distinctive fork-like aerial prop roots, and which occur in lower intertidal 

 zones with open water exposures; and (2) black mangroves (Aviaennia nitida) , 

 which are characterized by pencil -like aerial "roots" and salt glands at the 

 base of each leaf, and which normally inhabit higher intertidal positions, 

 generally within a fringe of red mangroves. Mangrove forests are complex and 

 virtually inaccessible from directions other than seaward. 



Sediments in mangrove areas may be composed of oyster shell, fine 

 coral and organic silts, or almost pure organic debris. The specialized 

 root systems of mangroves have developed in response to continuous water 

 saturation and the anaerobic nature of these sediments. In addition to 

 providing a rich wildlife habitat, mangroves play an important role in 

 landbuilding and stabilization. 



Oil contamination of mangrove areas occurs in a fashion similar to that 

 in wetlands. The oil either floats or is blown into the aerial root system. 

 At high tide, the lower portion of the leaf canopy may be soaked with oil. 



Several mechanisms having an effect on the plants then begin to occur. 

 Acute toxicity takes place through direct penetration of oils into the plant 

 tissues. This is particularly true in the case of light distillate fuels. 

 Another mechanism involves mechanical clogging of air passages on the aerial 

 roots by heavier oils. A final mechanism includes mixing of oil with debris 

 and the eventual incorporation of these material in the substrate. Because 

 of the anaerobic nature of the sediments, oil incorporated in this way breaks 



109 



