In the present survey, only station Center was found to 

 have a major mode in the sand fraction (3-2 phi or fine sand) . The 

 upper 10 to 12 cm of the sand cap at this station appeared to remain 

 relatively free of mixing with mud (Figure 3-28) . This probably 

 resulted from the cap being thicker than the particle bioturbation 

 depth at this station, as well as from recently settled fines being 

 washed from the surface by bottom currents which are accelerated as 

 they flow up and over the mound apex. Although the silt-clay fraction 

 dominated at other stations (> 4 phi) , the upper few centimeters of 

 most stations contained a significant quantity of sand. In most 

 cases, the depth of disposed material was greater than the prism 

 penetration depth into the bottom (Figure 3-29) . The only stations 

 which did not show evidence of a surface sand fraction were 2 ON and 

 400N. 



The boundary roughness frequency distribution for July 1986 

 had a major mode at 0.8 cm (Figure 3-30). The boundary roughness 

 values were not significantly different than those measured in August 

 1985 (p = 0.63; Mann-Whitney U test) nor were they different from 

 those at the new CLIS reference station (p = 0.68). 



The frequency distribution of RPD values at this mound 

 (Figure 3-30) and the mapped values (Figure 3-31) showed no 

 significant difference from the new CLIS reference station (p = 0.53, 

 Mann-Whitney U-test) . They did not show any statistical difference 

 from those measured in August 1985 as well (p = 0.55). 



All stations except 200W showed the presence of head-down 

 feeders (Stage III successional seres) (Figures 3-32 and 3-33) . These 

 deposit-feeders are very efficient in particle bioturbation, and their 

 widespread distribution on the disposal mound (Figure 3-34) may 

 account for mixing of the original sand cap with the underlying mud 

 at stations away from the mound center. The STNH-N mound historically 

 has had a high successional status relative to other CLIS disposal 

 points. For example, seventy-nine percent of the station replicates 

 were in a Stage III condition in August 1985. 



The frequency distribution of OSI values (Figure 3-30) , and 

 their spatial distribution (Figure 3-35) showed relatively high 

 indices for all stations with the exception of station 200W. In past 

 REMOTS® monitoring in Long Island Sound, we have found that OSI values 

 greater than +6 represent benthic habitats that have not experienced 

 physical or chemical (e.g., low oxygen) disturbance in the recent 

 past. The July 1986 OSI values for mound stations (stations on 

 dredged material) were not significantly different from those measured 

 at the new CLIS reference station (sample mean = 9.5; p = 0.56, Mann- 

 Whitney U-test) nor were they significantly different from those 

 measured in August 1985 (p = 0.66). 



The STNH-N mound had the highest benthic habitat quality 

 relative to other CLIS disposal mounds and was indistinguishable in 

 its REMOTS® values from those measured at the new CLIS reference 



14 



