32 



these analytical techniques are 

 developed, however, we are resigned 

 at this point to having only an acute 

 mortality response of Stage I species as 

 a trigger to indicate our evaluation 

 protocols are faulty. 



Sources of Uncertainty: Even 

 though colonization is proceeding 

 normally, bioaccumulation still could 

 be occurring and never be detected. 

 However, if one has any level of 

 confidence in the initial permit 

 evaluation process, the possibility of 

 this occurrence would be low enough 

 to eliminate this possibility as a real 

 concern. 



Box 2.4 "Stage 2 or 3 Community 



Develop After N+l Years?" 



In the second year of monitoring, 

 under normal rates of successional 

 change, one expects the progressive 

 addition of Stage II and III taxa. This 

 commonly is accompanied by the 

 presence of less dense populations of 

 Stage I sere species in subsequent 

 years. This assumes that all disposal 

 has stopped and the successional 

 process is uninterrupted by further 

 disposal or other sources of 

 disturbance (e.g., bottom scour by a 

 hurricane). If the disposal mound is 

 disturbed, the successional status of 

 the mound may revert to a Stage I sere 

 and would trigger an evaluation of 

 causality in tiers 2 or 3. 



Stage II seres (tubicolous 

 amphipods) can occur as early as the 

 end of year one (3-6 months after 

 disposal operations have ceased). 

 Because the mound apex is usually 

 sandier than the rest of the mound, 



tubicolous amphipods may be 

 aggregated on the mound apex or 

 distributed in patches over other parts 

 of the deposit. The presence, timing, 

 and persistence of Stage II seres is less 

 predictable, and they may or may not 

 be an important faunal element in 

 subsequent years. 



Stage III assemblages also may 

 populate a disposal mound in the first 

 year as part of a secondary succession 

 (the process of reestablishment of 

 conditions similar to the original 

 community after a temporary 

 disturbance). Stage III species are 

 capable of immediately colonizing the 

 thin flanks of a disposal mound as 

 adults by burrowing upward through 

 the thin disposal overburden. The 

 appearance of species on parts of the 

 mound that are much thicker than 20- 

 30 cm requires larval recruitment or 

 recruitment of free swimming 

 polychaete epitokes (modes of 

 initiating primary succession). 

 Deposit-feeding taxa recruiting in this 

 way usually appear on disposal 

 mounds in the second to third years 

 (assuming no further disposal or major 

 physical disturbance takes place to 

 retrograde the succession). The 

 unstated null hypothesis being tested 



H„: Stage 2 or 3 assemblages 

 (deposit-feeding taxa) are 

 present on the disposal mound 

 one year from cessation of 

 disposal operations. 



Once again, data are collected with 

 REMOTS® technology; acceptance of 

 the null hypothesis would lead back to 

 Box 2.3 and provide verification that 



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



