An attempt to evaluate the sampling efficiency of the Smith-Mclntyre grab

Abstract

Sampling efficiency of the Smith-McIntyre grab was evaluated by comparing the sampling data with those from the Scripps-type Box Corer (Spade Corer) at 3 sampling stations from two different depth zones (100m and 200m) around the shelf edge of the Wakasa Bay, the Sea of Japan. At two shallower sandy stations (100m) the efficiency appeared to be highly dependent on the sediment volume collected up to the volume of 7 liter or more, where the maximum level (almost 100%) was obtained. Sampling too much volume of sediment beyond 10 liter or more rather tends to lower the efficiency. Whithin the range of the moderate sediment volume the actual efficiency level was somewhat higher than that theoretically supposed to be. Brief discussion was focused on this point. At the deeper mud station (200m), the efficiency was extremely low in terms of the number of individuals: the level hardly exceeds 40%. The reason why such an inadequate sampling would be made at the deeper station is not clear at present since the sediment volume collected does not seem to affect the efficiency here, in sharp contrast to the cases at the shallower stations.