4.3 Benthic Habitat Quality at the CLIS Disposal Mounds and 

 the Mew Reference Station 



The REMOTS® surveys also were conducted to provide an 

 assessment of benthic recolonization and overall habitat conditions 

 at each disposal mound, as well as determine the suitability of the 

 new CLIS reference station. Summary statistics for the ten CLIS 

 disposal mounds, the new CLIS reference station and the GHOST-1 and 

 GHOST-2 sites surveyed in July 1986 (Table 4-1) showed that the new 

 CLIS reference station had a higher mean OSI value (9.55) than any 

 of the disposal mounds surveyed. Such a relatively high OSI value 

 would be expected in areas of the seafloor which was not been 

 affected by disturbance (e.g., dredged material disposal, erosion, 

 predator foraging, near-bottom hypoxia, etc.). Because it did not 

 appear to have been affected by dredged material disposal, the new 

 reference area should serve as an adequate representative of the 

 ambient seafloor and should therefore be a valid control station 

 for future monitoring at the disposal site. 



The rank-order position of the highest-ranked disposal 

 mound (STNH-N) , based on the average OSI values at the REMOTS® 

 stations having dredged material present (i.e., "mound" stations), 

 remained the same between August 1985 and July 1986 (Table 4-1) . 

 The OSI values at the STNH-N, FVP, NH-74, Norwalk, and CS-2 

 disposal mounds, as well as those at the GHOST-1 and GHOST-2 areas, 

 were not significantly different from the OSI values at the new 

 CLIS reference station for either the stations located on dredged 

 material of for stations on the edge or flanks of these mounds. 

 The OSI values for stations located on dredged material at the MQR, 

 NH-83, CLIS-86, STNH-S and CS-1 mounds were significantly lower 

 than those at the reference station. In addition, "edge and 

 ambient" stations at STNH-S also had significantly lower OSI values 

 than the reference station (Table 4-1) . 



The three disposal mounds that consistently have had low 

 mean OSI values (MQR, NH-83 and STNH-S) are located along the 

 southern border of the CLIS Disposal Site in approximately 65 feet 

 of water. In August 1986, SAIC measured dissolved oxygen from 

 Throgs Neck Bridge to the area off New Haven, including MQR station 

 Center, the old CLIS reference station, and a station in 126 feet 

 of water just north of Port Jefferson (SAIC, 1987). All of these 

 stations had hypoxic water (less than 3 mg/1 dissolved oxygen) ; in 

 fact, this hypoxic water extended all the way to Throgs Neck. 

 Extension of this hypoxic water eastward of the CLIS Disposal Site 

 remains undocumented. In addition, it is not known how far north 

 of the MQR mound this hypoxic water spread. In any event, it is 

 quite possible that this seasonal hypoxia, which had its greatest 

 effect in the deepest part of the Sound, contributed to the low OSI 

 values of the deeper mounds. Dissolved oxygen levels were also 

 measured over the WLIS Disposal Site in August 1986. Values fell 

 below 2 mg/1, and the mean OSI for the WLIS site (as measured in 

 August 1986) was low (5.8), (SAIC, 1987). 



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