Reduced sediment patches were evident near the surface 

 at 60% of the NH-83 stations. The widespread appearance of 

 reduced sediment at the surface indicated the localized 

 redistribution of bottom sediments and dredged materials both 

 vertically and horizontally. As discussed in previous sections of 

 this report, vertical redistribution of material was most likely 

 due to the activity of large infaunal deposit-feeders. 



The frequency distribution for boundary roughness for 

 the August survey (Figure 3-77) indicated that small-scale 

 topographic relief had not changed significantly since the 

 September 1984 survey. Between September 1984 and August 1985, 

 the mean RPD depth for all stations at NH-83 had decreased 

 approximately 1 cm (3.76 to 2.86 cm). There was no obvious 

 spatial pattern in the distribution of the reduced RPD values 

 (Figure 3-78) . This decrease is potentially related to recent 

 biogenic disturbance of the bottom. 



As observed in 1984, a patchy spatial distribution of 

 Stage I and Stage III successional seres was evident (Figure 

 3-79) . Stage I successional seres were observed in 54% of the 

 replicates. Overall, Organism-Sediment Indices were lower than in 

 September, 1984 (Figure 3-77) , due in large part, to the shallower 

 RPD values. The wide range in the distribution of OSI values 

 (Figure 4-80) reflected the patchy mosaic of benthic conditions at 

 this time on the mound. 



3.3.8 Southeast CLIS (CLIS-SE) 



In August 1985, a REMOTS survey was conducted in the 

 southeast quadrant of the existing CLIS disposal site; one 

 REMOTS image was taken at each of 36 stations on a 6x6 

 orthogonal grid with stations regularly spaced at 200 meter 

 intervals. The purpose of this survey was to determine if any 

 dredged material was already present in this region and to 

 characterize baseline benthic conditions. 



No dredged material was evident in the CLIS-SE region. 

 The major modal grain size was >4 phi (silt-clay range) at all 

 stations, with a boundary roughness major mode (Figure 3-81) in 

 the 0.4 cm class interval. Relatively small, rounded mud clasts 

 were observed in six of the REMOTS images from this area. 

 These clasts may have been the result of epifaunal foraging 

 activity. Reduced patches of sediment were also evident in the 

 same number of images (17%) . This was the lowest abundance of 

 this near-surface reduced material of any survey grid, except for 

 MQR. As discussed above, this was apparently related to the low 

 abundance of Stage III infauna (see below) . In general, the 

 fine-grained sediments and low boundary roughness values indicate 

 that the CLIS-SE area is a low-kinetic area. 



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