metal uptake by plants and animals colonizing dredged material. Emphasis 

 should probably be placed on the "toxic metals" i.e., lead, mercury, cadmium, 

 and arsenic which are not needed by organisms, even in small amounts. Plants 

 and animals lack homeostatic defenses against these metals. See Gambrell et 

 al. (1978) for a discussion of the risks associated with various disposal 

 methods for contaminated dredged material. 



Laboratory and field tests were developed by the DMRP for predicting the 

 potential uptake of heavy metals and other contaminants (Lee et al. 1978, Wolf 

 et al. 1978). The laboratory test is not universally effective but will be 

 useful in many situations. The field test is very practical and inexpensive. 



Aquatic development . The development of aquatic habitat utilizing dredged 

 material offers much potential, but has not been studied and developed (Smith 

 1978). Possible habitats that could be developed include tidal flats, seagrass 

 beds, oyster beds, clam flats, and fish spawning areas. Wilson (1950) noted 

 that disposal of dredged material into shallow water could develop firm bottom 

 shoals that would permit setting of oysters or other mollusks. 



An example of a valuable aquatic habitat developed inadvertently is the 

 historic Eatons Neck Disposal Site in Long Island Sound. Dredged material and 

 building rubble are furnishing habitat for a valuable fishery for lobsters and 

 demersal fish (Valenti and Peters 1977). 



Many potential habitats could be developed by raising the elevation of 

 the bottom. However, sediment type is vitally important, because each the 

 shellfish or demersal fish species requires certain characteristics in the 

 substrate. 



Smith (1978) listed the following advantages to aquatic habitat develop- 

 ment: 



(a) High production -- e.g., an oyster reef constructed to a depth of 1 

 m (3 ft) in water that formerly was 2 m (6 ft) deep will be more productive 

 than the original bottom. 



(b) Potential for wide application -- many potential situations can be 

 envisioned in which aquatic habitat could be developed to replace communities 

 lost to dredging activities. Aquatic habitat can also be developed in combina- 

 tion with marsh habitat. 



(c) Complements other habitats -- a variety of habitats is preferred by 

 most ecologists, i.e., open water, flats reefs, and marshes. 



Lunz et al. (1978) discussed a number of uses of dredged material for 

 aquatic habitat development. These uses include chancing sediment type and 

 covering contaminated bottom sediments with a cleaner material. 



Smith (1978) stated that there is an inadequate understanding of tech- 

 niques for achieving aquatic habitat development. He believes this can be 

 overcome by careful site by site evaluation by local biologists and engineers. 



Another major problem is that of potential harmful effects from contami- 

 nants. Gambrell et al. (1S78) discussed limitations of aquatic disposal of 



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