waterfowl and terrestrial species. Gantt 

 (1975) noted the destruction of fringe 

 marsh and shoreline when dredging oc- 

 curs, along with a reduction in species 

 diversity in the zone near shoreline; 

 nutrient cycle changes leading to lower 

 water quality; high oyster mortality in 

 the vicinity of the bulkhead; reduction 

 in invertebrate production; and preven- 

 tion of recolonization by scouring action 

 in front of the bulkhead. Wolcott (1977) 

 reported that bulkheads prevented the 

 ghost crab ( Ocypode quadrata ) from 

 reaching dune areas where they burrow 

 during cold weather. 



A bulkhead provides docking facili- 

 ties; however, it limits recreational ac- 

 tivities associated with a natural coast- 

 line (Carstea et al. 1975a). According 

 to Carstea et al. (1975a), even a small 

 bulkhead will cause erosion of sand and 

 shallow water on neighboring beaches. 

 Eliminating the littoral zone may reduce 

 productivity in an area and thus affect 

 fishing. They estimated that there was 

 generally little or no socioeconomic im- 

 pact of bulkhead construction in this 

 region. 



From a biological standpoint, bulk- 

 heads are generally not desirable struc- 

 tures in this region. Reduction in the 

 amount of marsh grass ( Spartina alter- 

 niflora , S. patens ) will result in a tang- 

 ible loss of the estuarine productivity. 

 Carstea et al. (1975a) estimated that a 

 150- ft (46-m) timber bulkhead, assum- 

 ing a width of 20 ft (6 m), would de- 

 stroy 3,000 ft2 (914 m 2 ) of habitat. 

 This would result in a loss of 1,230 lb 

 (558 kg) of detritus per year. This 

 amount of detritus could support ap- 

 proximately 9 lb (4 kg) of shellfish per 

 year at 125 lb (57 kg) of shellfish sup- 

 ported per acre per year (Carstea et 

 al. 1975a, cited by Isard, W. 1972. Eco- 

 logic-Economic Analysis for Regional De- 

 velopment . The Free Press, New York, 

 New York). 



It is possible to construct upland 

 bulkheads which preserve wetlands and 

 have a relatively minor effect on the 

 coastal ecosystem. Each proposed bulk- 

 head must be evaluated, based on its 

 potential for damage, in light of com- 

 munity existing at the proposed site. 



To afford maximum protection to the 

 coastal ecosystem each bulkhead should 

 be considered not as a single isolated 

 structure, but rather as an addition to 

 an ever-growing complex of shoreline 

 structures. 



A possible alternative to bulkhead 

 construction is the placement of riprap 

 or other types of revetments, but these 

 structures also have environmental con- 

 sequences. If mooring facilities are de- 

 sired, small piers may be substituted. 



CASE HISTORY - SANDBAG SILL 

 BREAKWATERS IN COASTAL REGION 

 6 - MIDDLE ATLANTIC 



Sandbag sills are being tested un- 

 der the auspices of the Virginia Insti- 

 tute of Marine Science as alternatives 

 to, or complements of, groins in the 

 Chesapeak Bay (Greer 1976). No quan- 

 titative biological studies were found 

 and only a minimum of other information 

 exists. However, since they are poten- 

 tially a viable alternative to groins as 

 shore protection devices, their use can 

 be expected to increase. 



Chesapeake Bay has a long history 

 of shoreline erosion, primarily resulting 

 from wind-generated wave action. Slow- 

 ly rising sea level also contributes to 

 this problem. Greer (1976) reports that 

 the 270 million cubic yards (249 million 

 cubic meters) of material were eroded 

 from Virginia's Chesapeake Bay shore- 

 line between 1850 and 1950. Bulkheads, 

 revetments, and groins have been used 

 in an attempt to retard or stop this 

 shoreline loss, but they are often un- 

 successful (Greer 1976). In addition, 

 navigation channels are clogged by 

 eroded sediment and valuable real estate 

 is being lost (Greer 1976, U.S. Army 

 Engineer District, Norfolk 1977a). The 

 constant and often severe erosion of the 

 shoreline prevents permanent vegetation 

 from becoming established. What already 

 is present is eventually washed away as 

 the shoreline recedes (U.S. Army Engi- 

 neer District, Norfolk undated b). The 

 result is a steady loss of shoreline wild- 

 life habitat and constant turbidity caus- 

 ed by soil being continually washed into 

 the waterway. 



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