56 



A ring of dark, anoxic silts and clay surrounding a large, partially collapsed 

 macrofaunal burrow surrounded by a chaotic fabric of oxidized and reduced sediments 

 could also suggest a biological origin. The excavator or inhabitant of this burrow may 

 have used this chamber to stockpile organic debris (food, waste material, etc.) which is 

 now in the process of autolysis and decay. The aerobic microbes that expedite the 

 decomposition and breakdown of organic material may be exhausting the limited supply of 

 oxygen within the surrounding sediments causing the development of a pocket of anoxia. 



The isolated namre of this dismrbance and the presence of mixed layers of sediment 

 within the photograph fails to provide strong evidence that would support one specific 

 cause. As a result, a more detailed investigation of the area surrounding STA 9 is 

 recommended. Additional REMOTS® photographs should be collected in close proximity 

 to 41° 08.100' N, 72° 50.112' W (NAD 27) during the 1997 monitoring activity in an 

 attempt to better characterize these sediments. 



Another instance of disturbance within a CLIS reference area was detected in July 

 1994 as several REMOTS® photographs obtained from 2500W found evidence of heavy 

 trawling activity (Morris and Tufts 1997). The action of a trawl net and chain sweep 

 across the bottom had scoured the oxidized surface sediment layer and displaced all surface 

 and shallow-dwelling organisms (Figure 4-5 A). The resulting high boundary roughness 

 values and chaotic surficial sediment layers made many of the replicate photographs invalid 

 for comparison with the CLIS project mound data for the 1994 survey. However, the area 

 recovered from the disturbance as expected and was utilized for comparisons with the 

 disposal mound photographs in 1995 and 1996 (Figure 4-5B). The same outcome is 

 predicted for the limited benthic dismrbance detected at CLIS-REF in July 1996. 



4.4 Disposal Site Management, Mound Stabilization, and Consolidation 



The results of the bathymetric surveying activity performed at CLIS in 1994, 1995, 

 and 1996 have indicated that the dredged material management strategy adopted in 1984 

 has been successful. For the past twelve years, disposal activity at CLIS has been 

 controlled to achieve the construction of artificial containment cells on a relatively flat 

 bottom. The ring of mounds formed by smaller disposal projects from 1984 through 1992 

 continues to maintain its integrity and support the central dredged material deposit. 



The development of the CLIS 95 mound in close proximity to the NHAV 74 mound 

 represents the continuation of the successful management strategy demonstrated with the 

 construction of the NHAV 93 mound (Morris et al. 1996). Deposition of additional 



Monitoring Cruise at the Central Long Island Sourid Disposal Site, July 1996 



