Several authors have pointed out 

 that disturbance of substrate and ero- 

 sion during bulkhead construction leads 

 to turbidity and water quality degrada- 

 tion (Boberschmidt et al. 1976, Carstea 

 et al. 1975a, 1976, Environmental Qual- 

 ity Laboratory, Inc. 1977, Gantt 1975, 

 U.S. Army Engineer District, Baltimore 

 1975, Virginia Institute of Marine Science 

 1976). However, biological impacts from 

 turbidity and changes in water quality 

 have not been well documented. Con- 

 struction activities which cause the 

 greatest increases in turbidity are 

 dredging and filling, and pile driving 

 or jetting. Resuspension of bottom sed- 

 iments from these and other construc- 

 tion activities may release trapped nu- 

 trients, heavy metals, and other toxic 

 substances into the water. Suspended 

 sediments reduce light penetration 

 which may lead to a temporary decrease 

 in primary productivity. Suspended 

 materials also may interfere with respi- 

 ratory and feeding mechanisms of the 

 fishes, zooplankton, and benthic organ- 

 isms. 



Chronic effects. Bulkheading has 

 often been described as a relatively im- 

 permanent means of separating land 

 from water, especially in areas where 

 the shoreline is eroding (Coastal Plains 

 Center for Marine Development Service 

 1973, U.S. Army Corps of Engineers 

 1964, 1971b, Warnke 1973). Bulkheads, 

 like revetments, protect upland areas 

 directly behind the structure from the 

 eroding action of waves and currents. 

 However, they do not protect adjacent 

 beaches or the foreshore. 



A bulkhead often promotes erosion 

 of the foreshore (Bauer 1975, Bruun 

 and Manohar 1963, Coastal Plains Center 

 for Marine Development Service 1973, 

 King 1972, Massachusetts Coastal Zone 

 Management Proqram undated a, Pallet 

 and "Dobbie 1969, Schultz and Ashby 

 1967, Slaughter 1967, U.S. Army Corps 

 of Engineers undated). Erosion of the 

 foreshore is caused by an increase in 

 wave energy due to waves reflecting off 

 the face of the structure (Figure 21). 



Foreshore erosion is particularly 

 severe during storms. Damage inland 

 from hurricanes and storms often is in- 

 creased due to replacement of energy 



absorbing tidal marshes with impermeable 

 bulkheads (Gosselink et al. 1973, King 

 1972). A bulkhead restricts movement of 

 sand to and from beach and dune areas 

 (Georgia Department of Natural Resources 

 1975, Gifford 1977). This, coupled with 

 ongoing reflected wave energy from bulk- 

 heads, inhibits the recovery of sedi- 

 ments to storm eroded beaches. 



Bulkheads may also promote erosion 

 of adjacent beaches (Bel lis et al. 1975, 

 Carstea et al. 1975a, Gantt 1975, Georgia 

 Department of Natural Resources 1975, 

 Herbich and Schiller 1976, Pallet and 

 Dobbie 1969, U.S. Army Engineer District, 

 Baltimore 1975). Erosion of adjacent 

 beaches may be accelerated until a new 

 geohydraulic equilibrium is reached. 

 This erosion may result from alterations 

 in water circulation patterns or from 

 the structure intruding into the litto- 

 ral zone and obstructing littoral drift 

 (Bauer 1975, Carstea et al. 1975a, Gantt 

 1975, Georgia Department of Natural 

 Resources 1975). 



Bulkheads, like revetments, can af- 

 fect the plant and animal communities in 

 the upper foreshore and backshore zones. 

 Bulkheads, constructed in wetland areas, 

 can cause extensive damage to fish and 

 wildlife habitat. Construction and asso- 

 ciated backfilling destroy wetlands by 

 covering up narrow fringe marshes, by 

 covering up the waterfront edge, and by 

 altering water circulation in larger 

 shorefront marshes. Wetlands are highly 

 productive areas which filter upland 

 runoff and function as nutrient and sed- 

 iment traps. Destruction of shorefront 

 wetlands eliminates waterfowl feeding, 

 nesting, and resting habitats and de- 

 stroys the habitat for other birds, rep- 

 tiles, and small mammals (Boberschmidt 

 et al. 1976, Carstea et al. 1975a, 

 Herbich and Schiller 1976). 



The construction of a bulkhead 

 eliminates much of the intertidal zone. 

 If the structure is built below the mean 

 high waterline, it eliminates the tran- 

 sition zone between the intertidal and 

 adjacent subtidal areas. This region is 

 the most productive zone in estuaries 

 (Lindall 1973, Odum 1970, Stockley 

 1974). This transitional zone, replaced 

 with a vertical bulkhead, provides lit- 

 tle productive habitat. At most a wooden 



55 



