Method and device for plankton separation

A method for separating plankton comprising:

• placing a plankton sample comprising water, zooplankton and phytoplankton in a separating device, the separating device comprising a darkened chamber having an outer perimeter surrounding a central axis and a first inner width, a darkened transitional area extending from the darkened chamber along the central axis having a second inner width that is smaller than the first inner width, and a transparent collection container extending from the darkened transitional area along the central axis for allowing entrance of light therein, the transparent collection container being of sufficient length to reinforce migration of plankton for separation, and extending beyond a point that makes about a 48° angle to the central axis while extending to nearest location of maximum outer perimeter dimension of the darkened chamber, and extending away beyond a point that makes about a 20°±2° angle to the central axis while extending to the nearest location of the maximum outer perimeter dimension;
• introducing light to the separation device to initiate phototactic movement of the zooplankton to the transparent collection container;
• and
• collecting separated zooplankton and/or phytoplankton samples from the separation device.