28 



tenuous given the long list of surrogate 

 measures. However, one must be 

 realistic about both expectations for 

 monitoring programs and practical 

 aspects of sampling and data return 

 rates. Also, this plan was developed to 

 provide the DAMOS managers at NED 

 with early warning measures for 

 potential problems with existing 

 management or monitoring practices. 

 It is foolhardy to think that all sources 

 of uncertainty can be eliminated from 

 a monitoring program. The best 

 approach is to admit its existence and 

 recognize that it must be dealt with 

 (Bernstein and Zalinski, 1986). Some 

 sources have even gone so far as to 

 argue that identifying the sources and 

 consequences of uncertainty are more 

 important than making predictions of 

 impacts (National Research Council, 

 1986). 



DAMOS program numerous traditional 

 benthic samples were taken. 

 Comparison of these results with 

 REMOTS® images showed that the 

 images could be used to identify the 

 successional status of the bottom 

 accurately. Because the REMOTS® 

 information is very cost effective and 

 provides rapid data return, sediment- 

 profile imaging has been the preferred 

 protocol. If detailed taxonomic data 

 are not needed to address a specific 

 null hypothesis, there is no reason to 

 spend the considerable time or 

 expense to collect that information. If 

 "ground-truth" benthic samples are 

 needed at any point to address a 

 specific management issue or null 

 hypothesis, they can be obtained to 

 provide taxonomic identifications, 

 population density measures, or 

 biomass estimates. 



The sources of uncertainty inherent 

 in the overall structure of the tiered 

 plan are related to the actual 

 utilization of the enhanced secondary 

 benthic production by demersal fish 

 and crustaceans. This only becomes 

 an important issue if bioaccumulation 

 by opportunistic benthic species really 

 is occurring. 



Another source of uncertainty is 

 related to what specific prey species 

 are participating in early succession 

 (Stage I seres). It usually is not 

 possible to make taxonomic 

 identifications from REMOTS® 

 photographs. The DAMOS program is 

 rather singular among current dredged 

 material disposal monitoring programs 

 by the infrequent use of traditional 

 benthic sampling in the routine 

 monitoring protocol. Early in the 



The uncertainty of relating tube 

 counts in REMOTS® photographs to 

 living polychaete counts also can be 

 resolved by "ground-truth" sampling. 

 However, our experience has shown 

 that the tubes of pioneering 

 polychaetes rapidly decompose and 

 disintegrate following death of a 

 worm. Foraging predators also will 

 ingest the tube as well as the worm, so 

 the standing stock of tubes closely 

 reflects the standing stock of 

 polychaetes. We note however, that 

 we have observed dense aggregations 

 of empty tubes of Stage II seres (e.g., 

 Ampelisca abdita) in REMOTS® 

 photographs, apparently related to 

 local bottom water hypoxia. This 

 condition is easily recognized from the 

 condition of the tubes. In the absence 

 of dissolved oxygen near the boundary 

 layer, the amphipods leave the bottom 



An Integrated, Tiered Approach to Monitoring and Management of Dredged Material Disposal Sites 



