occurred recently. 



The frequency distribution of the Redox Potential Discontinuity (RPD) values 

 was also right-skewed with approximately 73% of all photographs indicating values 

 less than 3.0 centimeters (Figure 3-13). Mean apparent RPD depths were greatest and 

 most distinct at stations 350W and 300W (Table 3-1) with some patchiness in the 

 distribution of grain size and RPD depth along the western half of the transect (e.g., 

 Station 150W; Figure 3-14). Apparent RPD depths decreased, becoming less clearly 

 defined toward the center of the mound where sediments were loosely consolidated 

 and poorly sorted. RPD depth was indeterminate at 50W and CTR. Mean RPD 

 depths gradually increased toward the eastern end of the transect to a maximum of 

 4.4 cm (300E). This was considerably less than RPD depths of 6.1 and 7.8 cm 

 (stations 350W and 300W, respectively), which suggested that the distribution of 

 dredged material extended beyond station 350E. 



The predominant successional stage at stations 350W to 200W and 250E to 

 350E was a Stage I surface taxa over a Stage III taxa (Figure 3-15 and Table 3-1). At 

 stations nearer the center of the mound, extensive reworking of the surface 

 sediments indicated the presence of Stage II taxa. Decreased camera penetrations, 

 resulting from increases in sediment grain size, prevented a conclusive 

 determination of successional stage at some stations (100W - 100E). Dense 

 assemblages of surface tubicolous taxa were observed in virtually all photographs 

 taken at stations 200E and eastward, with Stage II amphipods dispersed among 

 Stage I polychaete tubes (Figure 3-16). 



The broad range of OSI values (Figure 3-17) exhibited a symmetrical 

 distribution with OSI values increasing with distance from the mound center (Table 

 3-1). Median OSI values at stations 350W to 150W and 350E to 150E ranged from +6 

 to +11, whereas OSI values at stations nearer to the center (100W, 50E, and 100E) 

 ranged from +6 to +4. OSI values were indeterminate at stations CTR and 50W. 



Monitoring Cruise at the Cape Cod Canal Disposal Site and Springhill Beach Site 



