## Discussion  
### Inferences from Optical Properties  
The vertical profiles of the attenuation and backscattering coefficients were fit reasonably well by Rouse profiles, and the estimated settling velocities increased with increasing shear stresses, as expected. The magnitudes of the estimated settling velocities are within ranges expected for flocs and for the fine sands typical of the seabed at the MVCO site. The \(\sim\)0.1 mm s\({}^{-1}\) estimated settling velocities during the calm period were small, and they indicate material that behaved as slowly sinking washload that is evenly distributed throughout the boundary layer. The \(\sim\)0.4 mm s\({}^{-1}\) estimated settling velocities during the spring tides are in the range of typical floc-settling velocities, and the \(\sim\)1 mm s\({}^{-1}\) estimated settling velocities during the passage of Maria are typical of flocs (e.g., [48]). The \(\sim\)4 mm s\({}^{-1}\) observed during the passage of Ophelia are larger than typical floc-settling velocities, but they are representative of very fine sand (\(D\) = -80 \(\upmu\)m; [49]) or densely packed aggregates [21]. Interestingly, boundary shear stresses during passage of Maria were similar to boundary shear stresses during the spring-tide period, yet the estimated settling velocities were more than two times larger during Maria. Residual plots of the Rouse fits indicate that the profiles had smaller gradients (lower settling velocities) during spring tides than the profiles near the bed during passage of Maria. In addition, Sauter diameters were smaller during passage of Maria, as were the spectral exponents of attenuation. Particle size was inverted during the spring tides, with larger particles farther above bottom. The spectral exponent of backscattering was lower during the spring tides than during passage of Maria, and it decreased with height above bottom. Despite the similar stresses during these two periods, these observations suggest different particle dynamics. The larger Sauter diameters, inverted particle size, and smaller values of \(\gamma_{\mathit{Tbp}}\) are consistent with the hypothesis that flocs dominated the suspension during the spring tides. The flocs were fragile, and they were disrupted near the bed, but they were able to reform higher in the boundary layer. The breakage of flocs near the bed decreased bulk estimated settling velocities from the profiles by transferring mass near the bed from faster-sinking large flocs (\(\sim\)1 mm s\({}^{-1}\)) into slower-sinking smaller flocs or single grains. Overall, however, the extensive packaging of small particles into large flocs during spring tides was associated with small values of \(\gamma_{\mathit{Tbp}}\)[15]. During the passage of Maria, we hypothesize that higher bottom shear stresses associated with the larger swell caused resuspension of fine sand typical of the site (\(D\) = \(\sim\)125 \(\upmu\)m; [50]) and caused a greater degree of floc breakup. Resuspension of sand caused larger gradients in optical properties near the bed. Resuspended sand also can account for the broadened peak in the particle size distributions. Greater floc breakup can account for smaller values of \(\gamma_{cp}\) during passage of Maria, because particle mass was transferred out of large flocs that were not sensed by the AC-9 into smaller flocs or single grains that were [15]. It can also account for large values of \(\gamma_{bbp}\)[15]. During passage of Ophelia, when stress was highest, particle sizes were smallest. This result suggests that floc breakup was more extensive during Ophelia (e.g., [26]). The finer mode in the LISST size distributions was similar to the fine sands at the site (\(D\) = \(\sim\)125 \(\upmu\)m), and the presence of this sand, with typical settling velocities of 8 mm s\({}^{-1}\)[51], steepened the near-bed profiles of the optical properties. The appearance of the coarser mode at the upper limit of the LISST size range, however, is not consistent with greater floc breakup.