Linking feeding activity and sediment reworking in the deposit-feeding bivalve Abra ovata with image analysis, laser telemetry, and luminophore tracers

The quantitative relationship between activity (as detected by the comparison of grey levels in successive images using automated software) and sediment reworking in the deposit-feeding bivalve Abra ovata was investigated based on simultaneous and continuous measurements using laser telemetry, luminophore tracers, and image analysis. Total activity included both feeding (siphoning) and shell and/or foot activity. Sediment reworking was assessed through the measurements of surface sediment handling and vertical sediment mixing during 2 separate experiments. Surface sediment handling correlated positively with surface feeding activity. Shell and/or foot activity induced oscillatory movements of the superficial sediment layer but did not account for true vertical sediment mixing. Conversely, feeding activity induced intense vertical sediment mixing. Quantitative changes in feeding activity and vertical sediment mixing based on a biodiffusion model were positively correlated. These results underscore the importance of considering both the nature and intensity of infaunal activity when parameterizing models of sediment reworking.