the natural heterogeneity of the region and compared well with the 

 concentrations found at the Reference station. Concentrations of 

 PCB's and DDT's were below detection limits, as was arsenic. 



3 . 5 Benthic Community 



The sediment collected at each station in the CLIS-SE 

 area for benthic community analysis was also visually described as 

 soft silty clay with a 2-3 cm oxidized layer at the surface with 

 worm tubes and some shell hash present. The community sampled in 

 August (Table 3-3) was dominated by deposit feeders including 

 Mediomastus ambiseta , Nephtys incisa, Paraonis gracilis, and 

 oligochaete species. The other numerically dominant species 

 included the bivalves Nucula annulata and Yoldia limatula as well 

 as the nemertine worm, Tubulanus pellucidus . All the samples taken 

 at CLIS-SE had similar total number of species and individuals. 

 The largest difference occurred with the dominant species Nucula . 

 The relatively high densities of Nephtys in the samples were due 

 to the recent settlement of young. 



The benthic community at the CLIS Reference station was 

 similar to that at CLIS-SE except for low numbers of^ the 

 polychaetes Cossura, Mediomastus , Spio , and Tharyx . The higher 

 water content of the sediment at this deeper station may have 

 accounted for this difference in population characteristics. 



3.6 In-situ Observations 



Present at all mounds visited during the CLIS survey were 

 megafaunal assemblages characteristic of that region of Long Island 

 Sound. All species seemed to exhibit normal foraging and motile 

 behavior. The surface sediments at FVP appeared weathered with a 

 thin layer of coarse sand material overlying loosely cohesive clay- 

 muds. 



The faunal component at the FVP mound still appeared to 

 be in a state of recolonization. No major evidence of mature or 

 equilibrium infaunal successional seres (i.e., large surface worm 

 tube features, fecal casts) was observed during survey dives. The 

 distribution of the megafaunal component (Crustacea and finfish) 

 was very patchy and possibly reflected predation on newly settled 

 patches of prey (i.e. , Mulinia or similar rapid colonizer species) . 



The Black Rock material at the FVP mound was utilized by 

 motile epibenthos, such as shelter-seeking, burrowing taxa like C. 

 irroratus, and other important prey and juveniles of commercially 

 important species. The sediment at CS-1 was cohesive and stable, 

 except for some evidence of eroding clay clumps. The material at 

 CS-2 remained stable and cohesive. The sand cap at STNH-N 

 appeared intact with homogeneous coverage. The material at STNH- 

 S was compacted with no evidence of any major erosional events. 



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