54 



The 1987 REMOTS® surveys of MQR 

 and FVP indicated that both mounds had 

 recovered from the effects of Hurricane 

 Gloria and were resuming normal 

 recolonization (Figure 3-10). More 

 recently, a 1991 reconnaissance survey of 

 older capped mounds showed that benthic 

 recolonization at MQR had again regressed 

 since the 1987 sampling, even relative to 

 FVP. The median OSIs were significantly 

 lower than the three reference stations. 

 The June 1991 monitoring survey results 

 triggered a management response 

 according to the tiered approach (Germano 

 et al. 1994). An amphipod bioassay was 

 conducted to test the toxicity potential of 

 the MQR sediments. Percent survival 

 rates for amphipods exposed to MQR 

 sediments ranged from 10 to 45%, as 

 compared with control station survival 

 rates from 75 to 100% (Murray 1992). 



Sediment chemistry and coring results 

 have subsequently shown that capping 

 material at MQR contained organic 

 contaminants in relatively high 

 concentrations and could have contributed 

 to the slow recolonization following 

 disposal of the Black Rock/New Haven 

 Harbor sediments (Section 3.3.3). 

 However, the drastic drop in benthic 

 conditions as measured by REMOTS® 

 parameters in the 1991 survey was 

 probably caused by physical disturbance. 

 The combination of poor capping material 

 at MQR and potential episodes of physical 

 disturbance has forced management action. 

 Although a subsequent REMOTS® survey 

 in the summer of 1992 indicated improving 

 benthic conditions, amphipod bioassay and 

 sediment chemistry results were used to 



recommend recapping according to tiered 

 monitoring protocols (Germano et al. 

 1994). 



3.2.4 Bioaccumulation 



Although the REMOTS® surveys 

 provide a rapid evaluation of 

 recolonization and biological activities, 

 they cannot be used to measure 

 contaminant levels in sediments or 

 organisms. When used in a tiered 

 monitoring approach, the results of 

 REMOTS® analysis might trigger direct 

 investigations of sediment chemistry or 

 bioaccumulation (Germano et al. 1994). 

 For instance, if a survey indicated that a 

 previously healthy surface had areas 

 devoid of macrofauna, the first step would 

 be to look for evidence of physical 

 disturbance (erosion, trawling). If this 

 was not the case, one tiered approach 

 would be to collect vertical cores to look 

 for contaminant migration from the mound 

 and conduct bioassays on the sediments. 

 If contaminants and toxicity were found in 

 surface sediments, bioaccumulation studies 

 could help determine if surrounding 

 communities were affected. Because the 

 preponderance of biological and chemical 

 evidence has indicated that capped mounds 

 are recolonized quickly and have moderate 

 to low levels of contaminants in the 

 surface sediments, there were few 

 instances where bioaccumulation was 

 measured. 



At present, only one monitoring cruise 

 in August 1986 has been completed where 

 body burden concentrations have been 

 established for Nephtys incisa (Stage III 



Sediment Capping of Subaqueous Dredged Material Disposal Mounds 



