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bearing strength of the sediment. If the weight of the camera prism is held constant, the 

 change in penetration depth over a surveyed site will reflect changes in geotechnical 

 properties of the bottom. In this sense, the camera prism acts as a static-load penetrometer. 

 The depth of penetration of the optical prism into the bottom can be a useful parameter, 

 because dredged and capped materials often will have different shear strengths and bearing 

 capacities. 



Small-scale surface boundary roughness is the amount of surface relief at the 

 sediment-water interface, and is calculated by measuring the vertical distance between the 

 high and low points of the interface in each sediment-profile photograph. Boundary 

 roughness can be categorized as biological, physical, or indeterminate. Biological 

 disturbances, typically the result of macrofaunal activity, usually result in only a small 

 increase is boundary roughness (<1 cm). A mature and undisturbed benthic environment 

 tends to have biological boundary roughness. Physical disturbances can be anthropogenic in 

 origin (for example, by bottom trawling or dredged material disposal) or attributed to natural 

 processes such as wave and current motion. 



The Apparent Redox Potential Discontinuity (RPD) depth is the boundary between 

 oxygenated sediment and the underlying hypoxic or anoxic sediment. The RPD depth is a 

 sensitive indicator of the biological mixing depth, infaunal successional status, and within- 

 station patchiness (Revelas et al. 1987). The RPD is determined by measuring the thickness 

 of the high reflectance sediment layer at the sediment-water interface formed by light- 

 colored oxygenated or oxidized sediment. 



Successional stage mapping is based upon the hypothesis that organism-sediment 

 interactions follow a predictable successional sequence after a major seafloor disturbance 

 (Rhoads and Germano 1986). A disturbance can be any type of event that induces seafloor 

 erosion, changes seafloor chemistry, or causes major reorganization of the resident benthos. 

 These perturbations can be natural events (i.e., strong currents or a passing storm) or 

 anthropogenic events (i.e., dredged material disposal or power plant effluent). 



Pioneering assemblages (Stage I) usually consist of dense aggregations of near- 

 surface living, tube-dwelling polychaetes. These organisms begin to populate a sediment 

 deposit within days of a benthic disturbance, as they readily exploit the competition-free 

 space. Due to their limited interaction with the sediment, these organisms are usually 

 associated with a shallow RPD. 



In more stable environments Stage I assemblages are replaced by infaunal deposit 

 feeders or larger tube dwellers (Stage II). Typical Stage II organisms in Long Island Sound 

 include shallow-dwelling bivalves and tubicolous amphipods. In general, tubicolous 



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



