3.3.5 Mill-Quinnipiac River (MQR) Mound 



In the present survey, the major modal grain-size continued 

 to be > 4 phi (silt-clay) for all stations. As in the August 1985 

 survey, the near-surface sediment at most stations consisted of a 

 subordinate mode falling within the 3-2 to 2-1 phi size classes (fine 

 to medium sand) . Disposed material was present at all stations except 

 600S (Figure 3-51) . The thickness of dredged material exceeded the 

 penetration of the camera prism at all stations except station 600W. 

 Methanogenic sediments were detected at station 20 ON (two out of three 

 replicates) and in one replicate at station 200E (Figure 3-52) . 

 Methane was detected previously at station Center and 200N in the 

 post-hurricane survey of October 1985. 



The small-scale boundary roughness freguency distribution 

 (Figure 3-53) showed a major mode at the 0.4 cm class interval (sample 

 mean = 0.7 cm) . Surface boundary roughness did not changed 

 significantly from values measured in August 1985 nor were they 

 significantly different than those measured at the new CLIS reference 

 station. 



The mean apparent RPD depth freguency distribution showed 

 a major mode at the 3.0 cm class interval (Figure 3-53). Mean RPD 

 depths at MQR were significantly shallower than those measured at 

 both the new CLIS reference station (p < 0.001, Mann-Whitney U-test) 

 and the MQR mound in August 1985 (p < 0.001) . The mapped distribution 

 of mean apparent RPD depths (Figure 3-54) showed no clear spatial 

 pattern; the transect segment from Center to 600E consists of 

 uniformly low values, and two replicates of station 600N had very thin 

 RPD depths, possibly associated with local surface disturbance. 



Thirty-one percent of the REMOTS® photographs from MQR 

 showed the presence of well-developed subsurface feeding voids 

 (Figures 3-55 and 3-56) . This indicates that Stage III head-down 

 feeders have successfully populated the MQR disposal mound for the 

 first time since our initial survey in January 1983. However, it is 

 not clear if this colonization was primarily the result of larval 

 recruitment or immigration of adults. It is possible that turbulence 

 associated with the passage of Hurricane Gloria in September 1985 may 

 have caused the passive redistribution of benthic invertebrates. The 

 August and October 1985 REMOTS® survey showed Stage III seres at only 

 two stations in each survey. Future REMOTS® surveys at the MQR mound 

 will be important for documenting the progressive colonization of the 

 area by Stage III taxa. 



The freguency distribution of Organism-Sediment Indices for 

 the MQR disposal mound had a major mode at the +5 class interval 

 (Figure 3-53) . These values were significantly less than the new CLIS 

 reference station (Mann-Whitney U test; p < 0.001) and from those 

 measured in the August 1985 survey (p = 0.004). In fact, the mean OSI 

 value for the MQR mound was the lowest of any of the 11 disposal 

 mounds surveyed in 1986 (5.58 ± 2.59). This largely reflects the 



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