Discrimination of mean apparent RPD depths was 

 particularly difficult in this March survey. Most photos showed 

 that the near-surface region of the sediment profile had a lower 

 optical reflectance than at depth (Figure 3-14) . Our experience 

 has shown that late winter to early spring sediment profiles have 

 this transient feature related to the recent sedimentation of 

 labile (reactive) planktonic detritus. The spring plankton bloom 

 takes place in this period with sedimentation of eaten or senescent 

 cells. The decay of this material on the bottom lowers the optical 

 reflectance of the near-surface layers of sediment. To avoid this 

 difficulty in the future, surveys should be scheduled for the 

 summer period. 



3.2.4 Infaunal Successional Stages 



The spatial distribution of infaunal successional seres 

 at the reference stations, as inferred from REMOTS® photos, showed 

 a high frequency of well-developed Stage III seres (Figure 3-15) . 

 Toward the center of the disposal site sampling grid, station 

 replicate photographs showed patchy mixtures within a station; some 

 pictures contained evidence of Stage III infauna while others 

 showed only Stage I seres. This type of patchiness is typical of 

 relatively thin-flank deposits where past disposal has resulted in 

 small spatial differences in mortality of Stage III residents. 

 Within-station patchiness also may be related to small-scale 

 differences in recruitment success of Stage III taxa. The cause of 

 this patchiness is due either to minimal impacts at localized 

 regions or to sufficient time for infaunal recovery coupled with a 

 lack of recent disturbance. 



Stations located at the center of the disposal site and 

 north and west of the center apparently are dominated by Stage I 

 seres. Notable exceptions are Station 21, located on relict 

 dredged material, and Station 8, located on the ambient bottom. 



3.2.5 Organism-Sediment Indices 



Past mapping experience has shown that OSI values less 

 than +6 indicate bottom disturbance by either chemical or physical 

 means. Only those stations with mean OSI values < +6 were 

 contoured and include stations 14, 18, 19, 20, 25, 26, 11, and 34 

 (Figure 3-16) . With the exception of Station 11, all of these 

 stations were located on dredged material. The first six stations 

 were located around the center of the disposal site. The three 

 reference areas all had uniformly high OSI values, typical of 

 undisturbed bottoms. 



The OSI frequency distribution for the disposal site 

 shows a distinctly bimodal distribution with a mode at +5 and 

 another at +11 (Figure 3-17) . Some disposal site stations were 

 located on dredged material (+5 values) while others were located 

 on the ambient bottom (+11 values) . The reference areas (combined) 



