Text and illustrations below are excerpts from an article, entitled:  
 A Toolbox for Working With Living Invertebrates by Charlie Drewes [See Toolbox contents >]

to be published in Proceedings of the Association for Biology Laboratory Education (ABLE), vol. 26, 2004

 

II. Pour-Person Plankton Net

 

Purpose of tool:

 

This tool provides a quick, inexpensive, and simplistic alternative to a plankton net.  It is especially useful in situations where there is not enough space or distance to maneuver a plankton net.  The tool effectively collects and concentrates zooplankton.  To use this net in the field, water is collected from a dock or shoreline in a pail-sized container.  The net is held by one person while another pours the water sample(s) through the net. The sieved materials are then back-flushed into a collection container.  Alternatively, the net may be hand-held vertically and guided through pond water (or aquarium water in the lab) using figure-eight motions.  Then, the concentrated plankton are back-flushed into a storage container.

 

Required materials:

 

Scissors

Netting material (Recommend: heavy chiffon fabric or light-weight nylon. Both are available at most fabric stores or in the craft section of large discount department stores for less than $2/square yard.)

Super glue
Wooden embroidery hoops with screw tightening mechanism (Suggested size: 6 in diameter hoops. Cost is about 50 cents per hoop set.)

 

Assembly and use of this tool:

 

  1. Cut out a square of material.  The size of the square should be about 2-3 inches greater than the diameter of the hoop (Fig. 4).

 

  1. Separate inner and outer hoops; clamp the square of material loosely in the center.

 

  1. Using circular motions of your fingers, press down very gently in the center of the clamped material (Fig. 5).  The idea is to create a 1-2 inch-deep pocket in the material, while keeping the material loosely clamped around the entire circumference of the hoop.

 

  1. Next, tighten the screw clamp and use scissors to trim edges of the material (Fig. 5).

 

  1. Apply a small amount of super glue all around the hoop circumference where the inner and hoops meet. This will permanently secure the netting to both hoops (Figs. 5 & 6).

 

[Total cost of one assembled net is less than $1. Estimated assembly time is about 15 min/unit.]

 

 

Figure 4. Top view of embroidery hoop and fabric square.

 

 

 

Figure 5. Clamped fabric with shallow pocket and trimmed edges.

 

Collection Procedure

 

The following are suggestions for field use of the Pour-Person Plankton net: (a) small to medium-sized pail, (b) pour-person plankton net, and (c) wide mouth, unbreakable collection jars with tight lid (about 500-1000 ml capacity). A two-person team is also suggested.

 

  1. Use a small bucket to gather a water sample from the edge of a lake, pond, or stream.  Collecting samples from a dock may also work if the water surface is within reach. Avoid collecting from areas where the water samples have a significant amounts of suspended algae or macrophytes.  These will clog the net. Avoid falling in the water!

 

  1. While one person holds the hoop level over the water, a second person slowly pours the water through the net.  The net acts to filter the zooplankton out of the water sample. Make sure the water does not overflow the edges of the net, or zooplankton may be lost.

 

  1. Now, obtain a few cups of clear water. Turn the net over. While centering the net over an empty wide-mouth collection jar, slowly and carefully pour the small volume of water through the net and into the jar. This back-flushing procedure will dislodge plankton which collected on the net and these now will be concentrated in the collection jar.  If the plankton yield is small, obtain another pail-full of water and repeat the filtration and back-flushing sequence.

 

  1. Do not allow the plankton sample to heat up and do not keep the plankton sealed in the collection container for more than an hour (preferably less).

 

  1. In the lab, place the sample in a large, transparent, labeled container where zooplankton may be easily viewed and withdrawn with a pipet. Dilute the sample with spring water, if needed, to prevent overcrowding. Gentle aeration of samples is strongly recommended to avoid mass die-off. Use spring water to replace water lost by evaporation. Feed plankton tiny amounts of powdered Spirulina algae (Recommend: Algae Feast Aquatic Eco-Systems, Inc., Catalog #SP1; 1.2 lbs/$24; www.aquaticeco.com).  Do not overfeed.

 

 

 

Figure 6. Photograph of completed pour-person plankton net