The rank order of these four mounds based on REMOTS® OSI 

 values was comparable to the species richness results from the 

 infaunal community analyses (Table 4-3) . The new CLIS reference 

 station, STNH-N mound, and FVP mound were essentially similar in 

 terms of mean OSI rank and species richness, showing no 

 statistically significant difference among these three areas for 

 these two parameters. However, MQR did stand out as having 

 significantly lower mean OSI and species richness values (Figure 

 4-3) . The combined results of the REMOTS® analysis, the benthic 

 infaunal community analyses, and the sediment chemistry analysis 

 all suggest that extremely stressed conditions still existed at the 

 MQR mound in July 1986. 



4.6 Body Burden Analysis 



A final objective of the 1986 field operations was to 

 assess the relationship between sediment contaminant levels and 

 bioaccumulation at the FVP, MQR, STNH-N, and CLIS-86 disposal 

 mounds. At the MQR and FVP mounds (both uncapped) , Cr and Cu 

 levels were elevated both in the sediment and in the collected 

 Nephtys . These results suggest some correlation between sediment 

 contaminant levels and bioaccumulation. However, at the STNH-N 

 mound the elevated concentrations of Cr, Cu, and Zn in Nephtys did 

 not correspond with elevated sediment concentrations of these three 

 metals. Concentrations in the sediment at this mound were 

 generally the same or lower than those in the sediment collected 

 at the reference station. Only Hg sediment concentrations were 

 elevated at STNH-N; however, this contaminant was not elevated in 

 Nephtys collected there. The sand cap at this mound could have 

 resulted in either dilution or isolation of contaminants in the 

 underlying disposed material to the extent that elevated 

 concentrations were not ' measured in the sediment grab samples 

 obtained. However, the observed elevated levels of Cr, Cu, and Zn 

 in the collected Nephtys imply that complete "biological isolation" 

 may not have been achieved. The polychaetes which were sampled may 

 possibly have been exposed to elevated contaminants in the 

 underlying sediment in the process of vertical migration and head- 

 down feeding. 



One possible explanation for the anomalous benthic 

 recolonization rates and different benthic community types 

 documented in the past at the MQR mound compared to all the other 

 CLIS mounds is bioaccumulation of inorganic metal contaminants. 

 However, Cr, Cu and Pb also showed significantly higher 

 concentrations in Nephtys collected at FVP, a mound which has 

 experienced relatively high rates of colonization by Stage III 

 infauna. Therefore, bioaccumulation of these three elements cannot 

 alone serve to explain the lack of infaunalization at MQR. It is 

 possible that metal contamination in combination with potential 

 hypoxia effects could have adversely affected the rate of 



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