area and MQR results from the June 1991 survey. All but one MQR station in the 1991 

 survey consisted of a >4 phi grain size major mode. 



In addition to the 1991 MQR stations consisting of overall finer grain sizes, a higher 

 percentage of the 1991 stations contained numerous mudclasts. The presence of mudclasts is 

 indicative of surface sediment disturbance (presumably by physical bottom scour or faunal 

 activity). Other evidence of surface disturbance included erosional features such as scours 

 and rip-ups (Appendix). Mud clasts documented at stations both in 1991 and 1992 were 

 primarily oxidized, but some reduced mudclasts were present during both surveys (Appendix; 

 Wiley and Charles 1994). 



All of the REMOTS® replicates penetrated relic dredged material; only two replicates 

 at 195W and one replicate at 195N penetrated below the dredged material layer. Average 

 thicknesses of relic dredged material were no different between the 1991 and 1992 surveys. 

 No material was described as "fresh" dredged material in the 1992 photographs. In contrast, 

 more than half (18 out of 37) of the 1991 replicate photographs were described as containing 

 "fresh" dredged material, although no fresh dredged material has been disposed at MQR 

 since 1983. The presence of material which appears fresh is strongly indicative of recent 

 disturbance. 



3.1.2 Boundary Roughness 



Boundary roughness is the vertical distance (parallel to the film border) between the 

 highest and lowest points of the sediment- water interface. The presumed origin of this small- 

 scale topographical feature is recorded so that inferences can be made as to surface character. 

 Two types of boundary roughness are usually present: biological and physical. Biological 

 disturbance causes boundary roughness primarily through macrofaunal activity. Physical 

 disturbance can be caused by anything from waves or currents to anthropogenic effects like 

 bottom trawls. 



Replicate-averaged boundary roughness values from the 1992 survey ranged from 

 0.34 to 0.96 cm. Boundary roughness values were within those measured at the CLIS 

 reference replicate stations in 1991 (0.21 to 1.9). Averaged values measured at MQR in 

 June 1991 were considerably larger and ranged from 0.35 to 2.43 cm. Individual replicates 

 in 1991 reached a maximum boundary roughness of 4.81 cm (Figure 3-1). 



The presumed cause of boundary roughness is documented during analysis of 

 REMOTS® photographs. The three categories described during REMOTS® analysis are 

 biological, physical, and indeterminate. A mature and undisturbed benthic environment will 

 be dominated by biological disturbance, as evidenced by the majority of stations (86%) at the 

 CLIS reference area classified as biological roughness type. In the 1992 MQR survey, 

 approximately half of the replicates were classified as biological and half as physical, in 



Recolonization of the Mill-Quinnipiac River Disposal Mound (MQR): Results of a REMOTS® Survey, August 1992 



