16_ __ 



Both Stage I and Stage III infaunal successional stages were observed at the Bridgeport 

 Disposal Site. Stage I infauna were frequently observed in the same photograph as Stage III 

 head-down deposit feeders (as evidenced by feeding voids) (Figure 3-5). At three stations, 

 Stage I benthos were observed exclusively, and two of these stations were interpreted to be 

 ambient. The area, overall, was apparently occupied by Stage III infaunal benthos which 

 typically inhabit low disturbance regimes. 



3.2.5 Organism-Sediment Index 



The Organism-Sediment Index (OSI) values reflect both the apparent RPD depths and 

 the infaunal successional status of a REMOTS® photograph. OSI values can range from -10 

 (no apparent macrofaunal life and methane gas present) to 11 (deep apparent RPD, evidence of 

 mature macrofaunal assemblages, and no apparent methane). Based on other studies, SAIC 

 has determined that OSI values less than or equal to +6 are indicative of a "disturbed" benthic 

 environment (i.e., erosion, dredged material disposal, hypoxia, etc.; Rhoads and Germano 

 1986). OSI values ranged from +2 to +11 for all replicates with a mean value of +7 for all 

 stations. Among stations, there was no apparent pattern of OSI values. Those stations where 

 dredged material was observed displayed mean OSI values ranging from +3.3 to +10. Mean 

 OSI values for apparent ambient sediments ranged from +3.3 to +9.7. In comparison to 

 mean OSI indices measured in the MQR mound in 1992 (+3 to +7), the range of mean OSI 

 values observed in the Bridgeport Disposal Site fell within and slightly above those measured 

 in the MQR mound. These data suggest disturbances within the Bridgeport Disposal Site were 

 heterogeneous in their distribution. 



3.2.6 Apparent Relic Dredged Material 



Relic dredged material was detected in nine (B21, B28, B32, B33, B27, B29, B30, 

 B34, and B25) of the 13 stations occupied (Figure 3-6). Dredged material was recognized by 

 its coarse-grained, slightly reduced texture (Figure 3-7). Shell fragments were also observed. 

 Relic dredged material did not contrast sharply with ambient sediments in terms of sediment 

 color, reflectance, apparent RPD depth, or infaunal successional stage. Dredged material 

 layers ranged in thickness from 12 to 18 cm and frequently exceeded the camera prism 

 penetration depth. This indicates either that dredged material has remained in layers of this 

 thickness in the area surveyed or that relatively thin dredged material layers have been buried 

 with time by natural sedimentation. Two stations, B22 and B23, were characterized by 

 ambient sediment (Figure 3-6). Both possible relic dredged material and ambient sediment 

 were observed in some, but not all, of the replicate photos collected at the two westernmost 

 stations, B26 and B24. 



Reconnaissance Survey of the Historical Bridgeport Disposal Site, August 1992 



