| Popis: |
Marine sedimentary infauna alter acoustic properties of sediments by creating voids and air bubbles, manipulating grain and shell distributions, moving interstitial fluid and creating surface roughness elements. Our prior results from ONR support suggest that conceptual models of organism modifications of solute flux are grossly inaccurate in both diffusion-dominated and advectively permeable environments. The porewater transients detected by our pressure transducers represent several cm of water pressure in many cases and result in advective flows. The strong, pulsed flows imposed by organisms are radically different from the current models of irrigation-mediated transport or surface-driven porewater advection, a result with significant implications for bacterial transformations and particle movements. Our research addresses fundamental questions in benthic biological oceanography with significant relevance to naval operations: what factors affect infaunal activity patterns and movements and how do these processes affect sediment acoustic properties? Our research has three thrusts: (1) the development of new technologies to measure, in real-time, organism movements and the effects of these movements on the pressures, voids, fluid flows and surface roughness elements of nearshore sediments; (2) the experimental determination of the ecological and geochemical factors, including organism density, resource availability, and the concentration of metabolites in porewater that affect rates of organism movement; and (3) the evaluation of the ecological and geochemical consequences of these interactions. These results will allow us to link the behaviors and dynamics of macrofauna to ecosystem-level processes in coastal habitats and to the predictability of acoustic properties of operational importance to the Navy. |
