27 



properties of sediments. 



To summarize the hierarchy of 

 surrogate measures that provide the 

 foundation for this particular tiered 

 plan: 



• Enumeration of polychaete tubes at 

 the sediment-water interface 



-> is a surrogate measure for: 



• Densities of opportunistic 

 colonizing polychaetes 



-» which is a surrogate measure 

 for: 



• The rate of benthic secondary 

 production of prey species 



-+ which is a surrogate measure 

 fon 



• Life history impacts and 

 population densities of 

 commercially important 

 demersal fishery species 



-> which is a surrogate measure 

 fon 



• An early warning signal that 

 impacts of disposal may 

 affect human health. 



It also should be noted that 

 the proposed monitoring 

 protocol (Figure 2), while 

 structured to recognize the 

 potential toxic effects of 

 sediment on colonizers through 

 reduced recruitment densities, 

 does not address questions of 

 bioaccumulation. The 



contaminant load of the tissues 

 of colonizers potentially may 

 be transferred to higher 

 trophic levels. This is 

 recognized as an important 

 shortcoming of the monitoring 

 protocol but, at this time, no 

 Standard Operating Procedure 

 (SOP) exists for analyzing and 

 evaluating contaminant 

 concentrations in pioneering 

 species. The reason for this is 

 that pioneering polychaetes 

 (e.g. spionids) have a very 

 small dry weight/individual. 

 Bioaccumulation studies 

 require between ca. 2-4 grams 

 dry weight of tissue for 

 analysis. The NED presently is 

 developing a field method for 

 efficiently concentrating 

 sufficient biomass for this 

 purpose, but the technique has 

 not yet been field tested. In 

 the past, a surrogate 

 equilibrium species (Nephtvs 

 incisa) has been used to check tissue 

 contaminant levels on a sporadic basis; 

 up to this point, invertebrate field 

 bioaccumulation studies have not been 

 applied routinely to disposal site 

 management. If it can be determined 

 that Stage I field bioaccumulation 

 studies are a technically feasible 

 option, then this particular monitoring 

 technique may be worked into the 

 tiered plan to address this specific 

 concern. 



4,1.2 Sources of Uncertainty 



One could look at the hierarchy of 

 surrogate measures above and 

 conclude that the foundation upon 

 which this tiered plan is structured is 



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



