The Nansen closing method with vertical plankton nets

Abstract

Several methods have been devised for sampling plankton in the different water layers in the ocean, but for many years vertically hauled nets closed by a method devised by Nansen (1915) have fulfilled this purpose. Recently, however, an investigation by Barnes (1949) cast doubt on the validity of this method for quantitative work, and as in his paper he specifically referred to nets of the type used on the ‘Discovery’ Expeditions, the present observations were conducted to determine whether Barnes's findings were of general application to the method.