(Thompson, 1973; Parr, Diener, and Lacy, 1978; Pearson and Riggs, 1981). The 

 sediments should be low in pollutants. Minimum damage to the beach animals 

 will occur when clean sand is placed on sandy substratum; the damage may be 

 great to the beach animals if fine, organic-rich sediments are used. The ver- 

 tical migration of infaunal animals may be inhibited when the particle size of 

 borrowed material differs from the original sediments (Maurer, et al., 1978). 



To minimize siltation and consequently the potential anoxic conditions 

 following beach nourishment, the percentage of fine sediment (less than 125 

 micrometers in size) should be kept to a minimum in the dredged material (Parr, 

 Diener, and Lacy, 1978). Silt, if present in the material, will be rapidly 

 moved offshore. It can be highly detrimental to corals and other beach and 

 offshore benthic invertebrates, and therefore should be avoided as much as 

 possible. Sedimentation can result in the reduction of species diversity. If 

 a key species is affected adversely, the entire animal community of the area 

 may be altered. 



d. Locating Dredge Machinery . Damage to coral reefs has been caused by 

 dragging of anchors or other equipment across a reef (Maragos, et al., 1977; 

 Spadoni, 1979; Courtenay, Hartig, and Loisel, 1980). Therefore, the locating 

 of all machinery should be done under the supervision of engineers-biologists 

 to insure that damage to the reef areas is avoided. The dredge should be 

 positioned within the designated borrow area and should not cross a live reef, 

 clam bed, or other valuable resources. Mooring cables and anchors for the 

 dredge should be in sand or another nonsensitive habitat to prevent unnecessary 

 destruction to live corals, shellfish beds, and associated fish habitat. 



e. Cutterhead Versus Suction Dredge . Cutterheads should not be used in 

 the vicinity of live coral reefs or other light sensitive resources (Courtenay, 

 et al., 1975) unless barriers are established to separate the dredge site from 

 the sensitive resource. Maragos, et al. (1977) suggested using a suction 

 dredge in the vicinity of live coral reefs to minimize suspension of sediments. 

 Some similar type system without a cutterhead would be environmentally desir- 

 able, provided the discharge area is diked or otherwise isolated from the 

 sensitive resource. 



f. Sedimentation and Turbidity . Monitoring sedimentation and turbidity 

 is important before, during, and after a project. Thorson (1964) showed that 

 a reduction of light in the water will prevent or postpone larval settlement. 

 High turbidities may affect larvae by delaying their final descent, subj ecting 

 them to increased predation. Sedimentation may change preferred bottom sub- 

 strate preventing colonization or smothering some species. 



g. Underwater Disposal . Nourishment material should be placed as close to 

 shore as possible to insure the least harm to the more stable, but less 

 resilient nearshore population. Thompson (1973) and Oliver and Slattery (1976) 

 suggested that organisms adapted to unstable bottom conditions tend to survive 

 perturbations better than those in a more stable environment. 



2 . Borrowing . 



The above recommendations also apply to borrowing operations. The selection 

 of the borrow sites should be given special consideration, based on benthic 

 surveys of several candidate sites to prevent unnecessary damage to benthic 



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