depression on the bottom. It is likely that this low reflectance 

 sediment was derived from macrofaunal burrow excavation activities. 



The frequency distribution of small-scale boundary roughness 

 (Figure 3-61) showed that most values fall within the 0.4 to 0.8 cm 

 classes, with a sample mean of 0.73 cm ± 0.29 cm. These values were 

 not significantly different from those measured in August 1985 (p = 

 0.68) . 



The frequency distribution of mean apparent RPD depths 

 showed major modes shared between the 3 and 4 cm class intervals 

 (Figure 3-61), with a sample mean of 3.15 cm ± 0.94 cm. These values 

 were significantly shallower than those measured in August 1985 (p < 

 0.05, Mann-Whitney U-test) . Low values were found at stations 200W, 

 400W, 200SW, 200E, 400E, and 600E (Figure 3-62). 



Stage III infaunal assemblages dominated the area, with 

 only stations Center, 200S, and 200SE being dominated by Stage I seres 

 (Figure 3-63) . The generally high successional status has remained 

 the same since the last survey in August 1985; stations 200S and 200SE 

 were dominated by a Stage I assemblage during this earlier survey 

 also. This apparent lack of colonization by Stage III taxa at these 

 two stations may reflect either natural variability in their 

 distribution or unfavorable physical/chemical sediment conditions 

 which are localized and not readily inferred from the REMOTS® 

 photographs . 



The Organism-Sediment Index values were predominately 

 greater than +7 (overall mean of +8.3), which means that the overall 

 area had a relatively high habitat quality as measured by this 

 parameter (Figure 3-61) . The 1986 OSI values were not significantly 

 different from those obtained in either the August 1985 survey or at 

 the new CLIS reference station. However, in comparison with the 

 August 1985 survey, fewer stations were encountered with a + 11 OSI 

 value. The mapped distribution of OSI values shows that values less 

 than +7 were clustered around the center of the mound (Figure 3-64) . 



In August 1986, SAIC made six measurements of dissolved 

 oxygen at this disposal point with a polarigraphic electrode (YSI) 

 at a height of 15 to 16 cm above the bottom (SAIC, 1987) . These 

 values were all within the hypoxic range (1.88, 1.90, 2.40, 1.84, 

 1.80, 1.76 mg/1) and indicated that oxygen stress may be occurring 

 in this region of the Sound during the summer. Future measurements 

 of dissolved oxygen are recommended to evaluate this potentially 

 important ecological factor. 



3.3.7 New Haven 74 (NH-7 4) Mound 



The major modal grain-size in this area remained unchanged 

 (> 4 phi) since the September 1984 REMOTS® survey. A diffuse surface 



22 



