36 



The eastern half of the 1988 REMOTS® survey (centered at CLIS-86) overlapped the 

 western half of the 1990 REMOTS® survey area. In 1988, Stage I taxa were identified at the 

 CLIS-86 (Center) station, and 400 m to the east. The remaining 1988 stations exhibited 

 Stage III taxa. By 1990, the REMOTS® station at the CLIS-86 mound was recolonized by 

 Stage III taxa. During the 1989/1990 disposal season, dredged material was again released at 

 the station 400 m east of CLIS-86, resulting in the continuation of Stage I taxa at this station. 



The objective of the CTD/DO sampling was to assess near-bottom dissolved oxygen 

 concentrations in relation to benthic habitat conditions at and near the site. The dissolved 

 oxygen concentrations in the bottom waters, 3.4 to 6.3 mgl"' , were all within the aerobic 

 DO range (Table 4-1). In addition, the 1990 REMOTS® analysis suggested that a relatively 

 healthy and stable benthic habitat persisted within the three reference areas and that infaunal 

 recolonization of the recently deposited dredged material was proceeding at on-site stations. 

 In conjunction with near-bottom DO concentrations, the 1990 REMOTS® analysis indicated 

 that no recent or significant stress relating to near-bottom hypoxic conditions has occurred at 

 CLIS. 



Table 4-1 



Ecologically Important Dissolved Oxygen Ranges as Determined 



from Permanently Stratified Low-Oxygen Marine Basins 



(from Rhoads and Morse 1971) 



Dissolved Oxygen Range (mg'l"^ ) Fades 



>3.0 Aerobic 



3.0 to 0.41 Hypoxic* 



0.4 to 0.14 Dysaerobic 



<0.14 Anaerobic 



*The hypoxic facies has been added to the Rhoads and Morse (1971) basin model by Dr. 

 Barbara Welsh, University of Connecticut, to include responses of high metabolic rate 

 demersal or benthic megafauna. 



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



