44 



more details. 



Box 3.9 



"Toxic Response?" 



As emphasized in the previous 

 sections, these bioassay tests are for 

 acute responses (mortality) only and 

 will continue to be used until chronic 

 tests are available. The unstated null 

 hypothesis is: 



H : Mortalities of organisms in 

 sediment from the disposal 

 mound are not different from 

 references. 



Rejection of the null hypothesis will 

 place you in Box 3.17 in Tier 2; 

 acceptance will place you in Box 3.10 

 indicating no cause for alarm and will 

 lead to repeated periodic monitoring. 

 See the discussion in the previous 

 section under Box 2.8 for additional 

 explanation. 



Box 3.10 "Acceptable Response; No 



Immediate Action. Periodic 

 Monitoring" 



One can arrive at this box from 6 

 different routes (via boxes 3.5, 3.7, 3.9, 

 3.13, 3.20, or 3.21); all routes assume 

 the outcome of a predicted or possibly 

 unexpected but acceptable response. 

 Arrival in this box indicates there is no 

 cause to believe at this point that the 

 integrity of the cap has been 

 compromised. For the most part, 

 "periodic monitoring" means continue 

 to monitor on an annual basis during 

 the mid to late summer. If conditions 

 warrant high-resolution monitoring, 

 an additional REMOTS® survey could 

 be performed within 2-3 months 

 following the survey which initially 



led to this box. 



Underlying Assumptions : 

 Monitoring on an annual basis (as has 

 always been done under the DAMOS 

 program) assumes that seasonal 

 variability is not critical and will not 

 reveal any unknown impacts of 

 dredged material disposal. 



Box 3.11 "Stage 2 or 3 Community 



Develop After N+l Year(s)?" 



See the discussion in the previous 

 section under Box 2.4 for details and 

 assumptions associated with this step 

 of the monitoring protocol. The 

 unstated null hypothesis being tested 

 is: 



H : Stage 2 or 3 assemblages 

 (deposit-feeding taxa) are 

 present on the disposal mound 

 following one year from 

 cessation of disposal operations. 



Once again, data are collected with 

 REMOTS® technology; acceptance of 

 the null hypothesis would lead to Box 

 3.12. Rejection of the null hypothesis 

 would lead back to Box 3.6 to evaluate 

 the potential for physical effects as the 

 cause of the unexpected recolonization 

 response. 



Sources of Uncertainty : If the 

 mound has been capped with 

 predominantly sand, it is quite 

 possible that the successional 

 paradigm predicting an appearance of 

 infaunal deposit feeders will not be a 

 valid model. While the appearance of 

 a Stage II community could occur (a 

 dense assemblage of amphipods at the 

 sediment surface) on a sand 



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



