± 0.81 cm.), while most values at CS-2 fell within the 4.0 cm class 

 interval (mean = 4.10 ± 0.68 cm.; Figure 3-45). The RPD values at 

 CS-2 were significantly greater than those at both CS-1 and the new 

 CLIS reference station (p < 0.05, Mann-Whitney U-test) . These deeper 

 RPD's may be attributed in part to greater sediment porosities 

 resulting from the increased grain-size associated with the sand cap 

 at CS-2. For both mounds however, the RPD values did not differ 

 significantly from those measured in August 1985 (p = 0.35 at CS-1; 

 p = 0.46 at CS-2). The mean RPD values at Center and 200M stations 

 at CS-1 were relatively deep (Figure 3-46) , which suggests that 

 bioturbation was actively occurring at stations located on the 

 thickest part of the disposal mound. All stations at CS-2 except 600N 

 had relatively deep mean apparent RPD depths. 



Half of the CS-1 stations had Stage III taxa present, 

 including station Center (Figures 3-47 and 3-48) . In August 1985, 

 stations 200N, 400W, 200NW, 200NE, and 200SE had only Stage I 

 assemblages present; the remaining 12 stations had either a Stage II 

 or III assemblage present. Because only one replicate per station was 

 analyzed in this survey, small-scale (i.e., within-station) patchiness 

 in the distribution of Stage III organisms was not assessed. The 

 apparent change in successional status is difficult to interpret 

 because Stage III organisms could have been missed. In the August 

 1985 survey (based on three replicates per station) , CS-2 had only 

 four stations dominated by a Stage I sere: 400W, 200E, 200SW, and 

 400S. Other stations consisted of a mixture of Stage I and Stage III 

 seres. In the present survey, seven stations appeared to be in a 

 Stage I condition: 200N, 200W, 400W, 600W, 200SW, 400S, and 600S 

 (Figure 3-48) . Station Center was populated by Stage III taxa and 

 shows evidence of deep bioturbation (Figure 3-47) . 



The major difference between the Organism-Sediment Index 

 frequency distributions for CS-1 and CS-2 is that CS-2 had more values 

 in the +10 and +11 class intervals and fewer values in the +5 and +6 

 class intervals (Figure 3-49) . The mean OSI value at CS-2 was very 

 high (9.24 ± 1.92), but not significantly different from CS-1 (p = 

 0.067) or the new CLIS reference station (p = 0.60, Mann-Whitney li- 

 test) . In addition, the OSI values at both mounds did not differ 

 significantly from those measured in August 1985. 



The mapped distribution of OSI values at CS-1 showed a 

 mixture of high and low values over the mound, with no clear spatial 

 trends relative to the mound center (Figure 3-50) . The spatial 

 distribution of OSI values at CS-2 showed that the benthic habitat 

 quality was uniformly high. Only station 200N and 400S had values of 

 +6, the threshold value for detecting disturbed habitats with this 

 parameter. These two stations apparently lag the rest of the 

 locations sampled on the mounds in terms of bioturbation depth and 

 successional status. The reason for this lag cannot be assessed from 

 the photographs. 



19 



