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physical characteristics or contaminant concentrations on the plateau away from the center 

 apex of the mound, most likely due to the widely distributed CDM disposal locations. Total 

 organic carbon concentrations of >5% were all located in the inner zone cores, but there was 

 no similar pattern to the measured organic contaminants. 



• Evaluate Benthic Conditions and decolonization 



Sediment profile images continued to show the widespread presence of improvement 

 material (gray Gardiner's clay) that was serving to cover and stabilize the mound surface. 

 The presence of this non-marine, glacially-derived plastic clay continued to slow somewhat 

 the normal rate of recolonization. 



The successional stage of the Seawolf Mound during the 1998 survey did show signs 

 of advancement since 1997, with a combination of Stage n, Stage HI, and Stage II on IE 

 seres. Stage HI feeding voids were visible in areas of gray clay, suggesting some biological 

 breakdown near the sediment surface. Patchy sulfidic sediments were observed in sediment- 

 profile photographs collected over the apex and plateau of the mound. Some sulfidic 

 sediment was also seen on the apron of the mound and was similar to sediments seen in 

 some of the replicates from the NEREF reference area. The sulfidic sediments may have 

 acted to decrease sediment dissolved oxygen levels and hinder recolonization rates at some 

 stations of the Seawolf Mound in 1998. 



The surface sediments of the Seawolf Mound showed evidence of current winnowing 

 within the top 3 cm, manifested by the presence of disturbed amphipod mats, armoring by 

 shell hash, and sand-over-mud topography, consistent with 1997 results, results from surveys 

 over the past two decades, and predictions from physical oceanographic measurements 

 conducted in a separate study (Waddell et al. 2001). 



5.3 Recommendations 



• Continue to monitor the benthic recolonization on the surface of the mound to provide 

 long-term response to glacial clays in the estuarine environment. 



• Future surveys at NLDS could optimally be scheduled after benthic recruitment has 

 begun (early June) but before mid-August when tube mats appear to senesce. 



Monitoring Cruise at the New London Disposal Site, Seawolf Mound 1995 - 1998 



