Enhanced deposition to pits: A local food source for benthos

作者：Patricia Lynn Yager, Arthur R. M. Nowell, Peter A. Jumars · 发表于：Journal of Marine Research · 年份：1993 · DOI：10.1357/0022240933223819 · 被引用次数：114 · 研究领域：Coastal and Marine Dynamics、Aeolian processes and effects、Coastal wetland ecosystem dynamics

Particle deposition experiments using mimics of biogenous negative relief (“pits”) and low-excess-density particles in a small annular flume indicate a significantly enhanced deposition rate (number of particles per time) compared to smooth, flat patches of the same diameter. This study included flow visualizations as well as observations of particle residence times, particle concentrations in the pits, and particle fluxes to the pits from the main flow. Experimental conditions of particle concentration, shear velocity, and particle settling velocity mimicked the dynamic characteristics (low excess density and large size) of organic-rich floes and flow conditions in the subtidal and deep sea where biogenous pits are common features. Results suggest that pits provide benthic organisms an important capture mechanism for such floes. Flow visualizations concur qualitatively with previously reported results for twodimensional cavity flow, with unique features due to the conical shape of the pits. When the Rouse number (settling velocity/shear velocity) was much less than 1, pit deposition rate increased with increasing pit aspect ratio (AR = depth/diameter; ranging from 0.25 to 2) and always exceeded deposition to a flat patch of comparable diameter. For the single aspect ratio tested (AR = 0.5) under conditions of increasing turbulence, deposition to the pit increased under transitional flow, but then decreased to near zero when conditions reached fully rough flow. Relative enhan...