Multinet - Multiple Plankton Sampler

The MultiNet is a multiple net plankton sampling system for horizontal, oblique and vertical collections in successive water layers that allows a cuantitative sampling of plankton. The advantage of this method is the hability of taking plankton samples at different stratus of the water collumn whith a selected mesh size for each bag that is attached to the instrument (Table 1). It allows having a sample of all the water column or at the stratus that we think it will be of more interest (e.g up and down the termocline or at the maximum of chlorophyl). There are different models that variates in the size of the apertures and the number of bags that are attached to de stainless steel frame.

Table 1: Size of plankton organism that would lead to different methods of collection or different mesh sizes.




0,02-0,2 μm



0,2-2 μm



2-20 μm


Phytoplankton, protozooplankton

20-200 μm


Phytoplankton, protozooplankton

200 μm-2 mm



2-20 mm



20 mm-200 cm




How it works?

In its initial position the MultiNet is brought to water with all net bags closed and the water flowing freely through the frame. The instrument can be lowered to the greatest desired depth. There the first net bag is opened by push-button control from a the Deck Command Unit. At the end of the horizontal collection the first net bag is closed by a second command. The second net is opened simultaneously. This procedure is repeated for the remaining net bags and the Deck Command Unit indicates the number of the currently active net bag. The net bags are opened and closed by means of levers which are triggered by a battery powered Motor Unit. The commands for actuation of the net bags are given via single or multi-conductor cable between the Underwater Unit and the included Deck Command Unit. An integrated Pressure Sensor allows continuous supervision of the current operating depth. Two Electronic Flow Meters with automatic angle compensation are mounted to the Underwater Unit: one inside the frame for the determination of the amount of water passing through the open nets, one outside the opening for the determination of clogging effects.