To test the efficiency of the 0-2 m2 Van Veen grab in sampling macrofaunal benthos, comparative hauls were made with a large-volume deep-penetrating corer, the Reineck 0·06 m2 box sampler. The size, abundance and biomass of the animals caught were compared. The tests were made off the Netherlands coast in relatively fine sands, where the grab penetrated to only 5-6 cm. Depth levels of the species were observed from the undisturbed samples. Numerical densities obtained from the grab samples equalled those from the box samples only in the species living exclusively in the top 5 cm of the sediment. The grab especially underestimated the large worms Nephtys and Lanice. Where such species predominate the fauna biomass estimates by means of the Van Veen grab can be far from correct. |
