67_ 



The sediments of WLIS G were subjected to hypoxic conditions during the summer 

 of 1995 and allowed to recover over the fall and winter months. This one-year-old 

 sediment deposit now supports a stable Stage I infaimal population over the center of the 

 mound with progression to Stage III on the mound periphery. The solid successional stage 

 status and moderate to deep RPD depths indicate this sediment deposit is continuing to 

 recover despite the reduction of bottom water DO concentrations during the summer 

 months. The G moimd should display a mature benthic assemblage over its entire surface 

 m fumre monitoring efforts. In order to verify this prediction, an additional REMOTS® 

 sediment-profile photography survey should be conducted over WLIS G during the 1998 

 monitoring cruise. 



Although found to be recovering as expected in the initial benthic commimity 

 assessment survey in 1990, the southern flank of the historic WLIS D moimd displayed 

 signs of benthic habitat degradation during subsequent survey operations. Two stations 

 over WLIS D, 200 m and 300 m south of the moimd center, were revisited in July 1996 to 

 document improvement in the benthic environment. The results of the 1996 survey show 

 dramatic improvement in benthic conditions at D300S while OSI values for 200S remain 

 quite low. 



The variability between replicates, as well as the strong signs of benthic recovery 

 detected over the eastern and southern G mound REMOTS® stations, suggest the problem 

 area is localized between the Stations D200S and D300S. The progression in habitat 

 quality docimiented at D300S during the July 1996 survey is most likely due to the 

 construction of WLIS G approximately 60 m to the northeast. The development of a wide 

 apron around the G moimd provided 10 cm to 20 cm of new sediment to overlay the 

 historic dredged material composing the southern flank of the D mound. 



A final solution to the localized problem between D200S and D300S that would 

 facilitate the improvement of benthic conditions, as well as complement a recommended 

 management plan for the disposal site, is the development of a new disposal mound 

 southwest of the G mound center. The new sediment would overlie the southern flank of 

 the D mound, covering any existing problems in the subsurface sediment layers. In 

 addition, the new material would assist in closing the supplemental lateral containment cell 

 described above while promoting benthic conditions comparable to those of the WLIS 

 reference areas. 



The DAMOS Program uses reference areas to provide a baseline against which 

 results from the dredged material mounds are compared. However, the lack of ambient 

 western Long Island Sound sediments within some of the previously selected reference 

 areas has complicated this process. Benthic conditions at reference area 2000W, as 

 detected at ST A 1 and ST A 4, appear to be highly dismrbed due to the presence of dark. 



Monitoring Cruise at the Western Long Island Sound Disposal Site, July 1996 



