14 



There was no dredged material detected at any of the three reference areas. Within CLIS, 

 all REMOTS® stations showed evidence of dredged material. The dredged material was 

 categorized as either relic or fresh dredged material based on sediment grain size, optical 

 reflectance, and sediment fabric (SAIC 1990c) (Figures 3-7 and 3-8). Most REMOTS® 

 stations within the disposal site contained fresh dredged material (Figure 3-9). Relic dredged 

 material occurred at the northernmost stations and in the south central area of the survey. 



The majority of REMOTS® stations in CLIS and the reference areas consisted of silt- 

 clay and very fine sand (>4 phi and 4-3 phi, Figure 3-10). Most of the disposal site stations 

 located near active disposal mounds exhibited finer grained sediment ( > 4 phi) than stations 

 away from recent deposition (4-3 phi, 3-2 phi). At the reference stations, most REMOTS® 

 photographs had a dominant grain size of 4-3 phi. The majority of small-scale surface 

 boundary roughness values at the disposal site stations were in the range of 0.0 to 1.6 cm, 

 while those at the reference stations were in the range of 0.4 to 1.2 cm. Boundary roughness 

 values (Figure 3-11) at the disposal site stations were not significantly different from those at 

 the reference stations (Mann-Whitney U-test, p=.841). 



Mean apparent redox potential discontinuity (RPD) depths ranged from 1.2 cm to 

 6.0 cm at CLIS and from 3.4 cm to 6.6 cm at the reference areas (Figure 3-12). The 

 frequency distribution of apparent RPD depths had a major mode at 5.0 cm for the reference 

 areas and at 3.0 cm for the disposal site (Figure 3-13). The disposal site RPD depths were 

 significantly shallower than those at the reference areas (Mann-Whitney U-test, p < .001). 

 RPD depths less than or equal to 3.0 cm occurred in 45 out of 65 disposal site station 

 locations. The deeper RPD values were around CS-90-1, CLIS-87, at the edges of the 

 survey grid, and in the reference areas. 



Stations with only Stage I organisms occurred at five locations: around disposal 

 mound CLIS-89, southwest of CS-90-1, southeast of CLIS-88, one station in reference area 

 CLIS-REF, and two stations in reference area 2500W. All other locations, both at the 

 disposal site and reference areas, had Stage III taxa in at least one replicate REMOTS® 

 photograph (Figure 3-14). Most of these stations had either a Stage III or Stage I on III taxa 

 (Figure 3-15). 



The multiparameter REMOTS® Organism-Sediment Index (OSI) is used to 

 characterize habitat dismrbance. The parameters used to calculate the OSI values are the 

 mean apparent RPD depth, the presence of methane or low dissolved oxygen, and the 

 successional stage (SAIC 1989). Based on the results of past REMOTS® surveys, OSI values 

 of < -1-6 are considered indicative of chronically stressed benthic habitats and/or habitats 

 which have experienced recent dismrbance (e.g., erosion, dredged material disposal, 

 hypoxia, demersal foraging, etc.; Rhoads and Germano 1986). 



Monitoring Cruise at the Central Long Island Sound Disposal Site, July 1990 



