epibionts. This phenomenon was most frequently encountered along 
the southern and western edge of the region. 
Areas with OSI values greater than +6 (hatched areas in 
Figure 3-19) represented the least "disturbed" benthic regions and 
included the majority of the disposal mounds. The remainder of the 
site exhibited relatively low OSI values (+6 or less). Toa large 
degree, these low OSI's reflect the shallow, or zero, RPD values. 
Given that the most stressed areas were located along the margins 
of the disposal site, this "disturbance" did not appear to be 
related to the disposal operations. The bimodal OSI distribution 
(Figure 3-13), with modes centered at values of 0 and +8, reflects 
the dichotomy in benthic conditions apparently arising from the 
patchy distribution of hypoxic conditions. 
August 1985 Survey 
A significant gradient in sediment properties was found 
to extend east to west across the southwest survey area (Figure 3- 
20). Five sedimentary facies (A through E) were recognized. 
Facies A consisted of a medium sand (2-1 phi) containing many 
mollusc shell fragments. This was surrounded by coarse sand (1-0 
phi), very course sand (0 to -1 phi), and granule (-1 to -2 phi) 
skeletal arenites (i.e., sands, Facies C). The surface of the 
sediment in Facies B consisted entirely of Zostera marina 
(eelgrass) detritus. Facies D was composed of a rippled shell-rich 
medium sand (possible evidence of deposited dredged material). 
This sand was apparently being transported westward over a mud 
bottom (>4 phi) identified as Facies E. From these facies 
relationships, one may construct kinetic gradients. Facies B was 
the lowest kinetic area, being a repository for low density organic 
detritus. The highest kinetic area was represented by the coarse 
sand to granule skeletal sands. The transgression of the medium 
sands of Facies D westward over the muds of Facies E indicated that 
this was the direction of net transport and that a strong kinetic 
gradient exists in this direction. Not surprisingly, the direction 
of this transport corresponds with the bathymetric gradient present 
in the area (see Figure 3-1). Overall, this area southwest of the 
disposal site appears to be dispersive. 
The small-scale boundary roughness frequency distribution 
shows that most of the values fell within the 0.4 to 0.8 cm modes 
(Figure 3-21). This relief reflects the presence of small sand 
ripples. The larger roughness values reflect the presence of blue 
mussel Mytilus edulis at the sediment surface, particularly in 
Facies E. 
Because of the shallow penetration depths of the camera 
prism due to coarse sediments and shell deposits over much of the 
area, values for RPD depth were only available for 8 of the 25 
stations (Figure 3-22). These stations were restricted to the 
20 
