^____ 47_ 



weathered dredged material (Figure 3-24 A and B). These dark sediments were detected at 

 all four stations sampled within the vicinity of the 2000W reference area. 



The presence of dredged material in stations sampled at 2000W appeared to alter the 

 characterization of the benthic environment, relative to SOUTH and SW-REF. The major 

 modal grain size at 2000W was consistently classified as >4 phi (silts and clays), and 

 replicate-average boundary roughness measurements ranged from 0.41 cm to 5.02 cm. 

 The sediments at SOUTH and SW-REF displayed more of a fine sand component with 

 many replicates classified as 4 to 3 phi major modal grain size. In addition, the boundary 

 roughness range was considerably narrower, relative to 2000W, with replicate-averaged 

 values from 0.46 cm to 1.75 cm (Appendix A, Table 3-4). The most common type of 

 surface roughness within all three reference areas appeared to be physical in nature. 



3.5.2 Benthic Community Assessment 



Overall, the mean RPD values at the 2000W stations seemed to be affected by the 

 presence of historic dredged material, with shallower depths relative to SOUTH and SW- 

 REF. The replicate-averaged RPD depths at 2000W ranged from 0.92 cm to 2.88 cm, 

 with low DO conditions detected in replicates of STA 1 and STA 4. In comparison, the 

 replicate-averaged RPD depths at SOUTH and SW-REF were deeper, ranging from 1.61 

 cm to 3.89 cm. However, low DO conditions were also discovered in one replicate of 

 STA 7 within reference area SOUTH. 



The successional stage stams of reference area 2000W appears to be adversely 

 affected as well. Four replicate photographs collected over 2000W were classified as azoic 

 or indeterminate. The remaining six replicates showed Stage I organisms in the surface 

 sediments with two of the six photographs displaying evidence of Stage III activity in the 

 subsurface layers. In addition to dark sulphidic sediments and a shallow RPD, methane 

 gas was detected in one replicate of STA 4 (Figure 3-24 A). As a result of the poor benthic 

 conditions at STA 1 and STA 4 within 2000W, median OSI values for the reference area 

 ranged from -2.0 to 5.0 (Appendix A, Table 3-4). 



Reference area SOUTH can be characterized as Stage I, with limited Stage III 

 activity detected at STA 7 and STA 8. Deep RPD depths served to elevate the median OSI 

 values to a range of 3.5 to 9.0 (Appendix A, Table 3-4). A thin layer of recently 

 deposited reduced sediment was detected in one replicate of STA 8, but had no adverse 

 impact on benthic conditions. At first, the gray, reduced clasts appear to be camera 

 artifacts, sediments carried from previous replicate locations and deposited by the 

 REMOTS® camera base frame or housing. However, closer examination of this recently 

 deposited material detected the presence of oxidized particles and Stage I pioneering 



Monitoring Cruise at the Western Long Island Sound Disposal Site, July 1996 



