42 



During the baseline survey, penetration depths of individual replicates over the five 

 sediment mounds (CLIS 87-88 complex, CLIS 89, CLIS 90, NORWALK, and SP) ranged 

 from 5.50 cm to 20.70 cm. The replicate-averaged mean penetration depths at the CLIS 

 87-88 mound complex ranged from 7.6 to 13.88 cm; CLIS 89 7.80 to 17.64 cm; CLIS 90 

 11.42 to 16.72 cm; NORWALK 9.83 to 17.35 cm; and SP 5.65 to 17.52 cm. The 

 penetration depths from individual replicates on the FVP mound ranged from 5.76 cm 

 (sediments with a surface layers of gravel and coarse sands over very fine sands) to 

 15.83 cm (sediments with a surface layer of coarse and medium sands over silt/clay 

 sediments). 



4.2.3 Mean Apparent Redox Potential Discontinuity (RPD) Depth 



Aerobic near-surface marine sediments typically have higher reflectance values 

 relative to underlying hypoxic or anoxic sediments. Surface sands washed free of mud also 

 have higher optical reflectance than underlying muddy sands. These differences in optical 

 reflectance are readily apparent in REMOTS® images; the oxidized surface sediment 

 contains particles coated with ferric hydroxide (an olive color associated with particles), 

 while reduced and muddy sediments below this oxygenated layer are darker, generally gray 

 to black. The boundary between the colored ferric hydroxide surface sediment and 

 underlying gray to black sediment is called the apparent redox potential discontinuity 

 (RPD). The replicate averaged RPD over the project area ranged from 1.10 cm to 

 3.06 cm during the baseline survey (Figure 4-15). The RPD values for the FVP mound 

 during the precap survey ranged from 1.09 cm to 2.72 cm. 



4.2.4 Infaunal Successional Stage 



The mapping of successional stages is based on the theory that organism-sediment 

 interactions follow a predictable sequence after a major seafloor perturbation such as the 

 disposal of dredged material (Rhoads and Germano 1990). All stations occupied during 

 the baseline REMOTS® survey showed evidence of Stage I pioneering polychaetes (Figure 

 4-16). Stage I on Stage III communities were present at CLIS-87 and CLIS-88, CLIS-90, 

 SP, and the east-southeast valley transect. Stage III taxa represent high-order successional 

 stages typically found in low disturbance regimes. Evidence of Stage II taxa was present at 

 CLIS-89, NORWALK, SP, and the east-southeast valley transect. Stage II organisms 

 represent a transitional stage to Stage III and are characterized by tubicolous amphipods 

 which can form extensive tube mats on the surface. 



All stations occupied over the FVP mound during the NHAV 93 precap survey 

 were characterized by presence of Stage I organisms. One replicate at FVP station 50W 

 showed signs of Stage III activity, and was designed as Stage I on III. These results 



Monitoring Surveys of the New Haven Capping Project, 1993-1994 



