Abstract

Biological resuspension of sediments from the seafloor occurs when fish and other marine creatures search for food and shelter. In high-energy habitats, waves and currents dominate the resuspension of sediments, however, studies suggest that biological resuspension is the dominant process in areas below the wave action including the deep sea and in low energy zones such as lagoons and other sheltered basins. Biological resuspension is a highly punctuated process both in time and space, generating high concentration sediment plumes that quickly sink and disperse. It is therefore not surprising that despite its potentially large impact, no quantitative data exists regarding its extent and ecological impact in the ocean. To resolve the difficulty in monitoring and quantifying these short-live resuspension events, we develop a model named the footprint model that converts field measurements of horizontal sediment fluxes, into estimates of long-term average fluxes of biological resuspension. Measurements of the horizontal fluxes of the suspended sediments by off-the-shelf instruments serve as an input to the footprint model, which are then analyzed by the algebraic equations of the model. Given a horizontal velocity profile, the model quantifies the sedimentation of heavy particles as a function of their size, initial distribution and advection. Flow measurements are then used to include the effect of dispersion by the turbulent flow. The document provides a detailed description of the model derivation and proposes techniques that can be used for validation of the model results.