Observations on the biting profiles of three 0.1 m2bottom-samplers

Abstract

Observations were made on the mode of biting of three widely used bottom samplers: the Petersen, van Veen, and Smith & Mcintyre grabs. Air-to-ground trials were conducted with the 0.1 m₂ models on hard and soft substrata. Examination of grab bites revealed that the Petersen and van Veen grabs dig deeper along the edges of the bite. The van Veen grab gave the most rectangular cuts in both types of substrata. The performance of the Smith & McIntyre sampler is considerably affected by the consistency of the substratum, with the sampler digging deeper in the middle of the sampling area in soft substratum and cutting less deeply but more rectangularly in firmer sediments. While the bite patterns of the first two grabs are relatively similar in both soft and hard substratum, the Smith & McIntyre bite pattern differs considerably. In the first two, biting profiles seem to be a reflection of their particular closing mechanisms, while the Smith & McIntyre bite pattern is further affected hy the substratum consistency.