Sampling and filtration efficiency of two commonly used plankton nets. A comparative study of the Nansen and the Unesco WP 2 net

The paper presents the results from a study in which two commonly used plankton nets, the Nansen net and the WP 2 net, were compared. The study was performed at six stations in the Baltic Sea and the samples were collected during seasons of both high and low particle abundance. The comparison included both qualitative and quantitative filtration capacity of the nets under different environmental conditions. Different mesh sizes were also tested. The results show that the Nansen net has an efficiency of 50-70% compared to the WP 2 net under favourable conditions. When conditions are unfavourable, i.e. during periods of high particle abundance or during long hauls, the efficiency may be as low as 25-30%.