Collecting phytoplankton is fun and easy to do, as long as you have a good plankton net. These nets are made with very high quality mesh with uniformly sized holes so that you can match the net to the type of organism that you wish to collect.
Plankton (including both phyto- and zooplankton) may be classified by size in the following scheme:
So, if you are interested in finding dinoflagellates and diatoms, you would use a mesh size that has holes just larger than your target: so, about 50 µm wide.
Because phytoplankton are usually found in dilute concentrations, it helps to sample a large volume of water. The easiest way to do this is to drag the net behind a boat for a few minutes. If you don't have access to a boat, it is just as easy to walk back and forth along a dock, it will simply take you a little longer to sample the same volume of water. Generally, the cod end of your plankton net will take on a golden-brown or greenish tint when you have sampled a sufficient volume of water.
© 2001 Caren E. Braby