Aggregate studies in the benthic boundary layer at a continental margin

A new instrument for aggregate size determinations in the benthic boundary layer is described. It takes video pictures from the horizontal aggregate flux at 10 to 100 cm above sea floor. For retrieving water samples at the depth of the video pictures, the system can be integrated into an existing bottom water sampler, the BIOPROBE system or work as an independent camera/sampling module in free fall lander systems at a maximum depth of 6000 m. A computer-based image analysis system is used to convert video film material to quantitative particle size and morphology data. Deployments in the Greenland Sea continental margin down to 2800 m gave encouraging results. An analysis of horizontal aggregate flow at 60 cm above sea floor is presented. The aggregate size distribution was different due to varying particle characteristics of the water and boundary layer flow conditions.