Infaunal Influences on Sedimentology of Shelf-Slope Boundary: ABSTRACT

Abstract

Although the benthic infauna of the inner continental shelf and continental slope have been studied in some detail, the infauna of the shelf-slope break have received scant attention. The shelf-slope break marks the transition from the highly variable and physically controlled environment of the shelf to the more stable biologically controlled environment of the deep slope and basins. A slight change in depth across the shelf-slope break can cause a drastic change in the composition of the infauna. Since sediment grain size at the shelf-slope break can range from silt-clay to sand and is commonly coarser than the sediment shoreward on the adjacent shelf, infaunal composition of a particular assemblage can range from predominantly suspension feeders to predominantly deposi feeders. The density and biomass of these assemblages, which in some areas may be greater than on the adjacent shelf or slope, appear to be related mostly to current patterns and degree of sediment heterogeneity whereas salinity and temperature variations are minimal and play only a minor role. In those areas such as the shelf-slope break off New England, infaunal densities are relatively large and these infauna may be a significant factor in regulating sediment structure through carbonate and feces deposition as well as through bioturbation. In addition, the removal of organic material from the pelagic realm and the reworking of deposited organic material by the organisms make the infauna at the shelf-slope break an important mechanism for enhancing the transport or organic material to the ocean basin. End_of_Article - Last_Page 902------------