Setting Up and Deploying the Plastic Plant Pot Experiment

This post provides detailed instructions about how to set out the plastic plant pot experiments that are at the heart of work that students do in CSI-Maine. It provides a list of materials and tells you what to do with them.  If any of this is confusing or seems to leave something, please tell us by leaving a reply using the link at the top of the post, right below the title.

The Big Picture

Usually, the experiment will consist of 36 plastic plant pots — set out with 4 pots per grouping. Each grouping is located within a 1 m2 area (quadrat). Typically the investigation looks at 3 different tide levels, deploying 3 quadrats (and the pots each quadrat) at each tide level. The overall layout of the experiment looks something like this, but more spread out and less all-in-a-line and neat.

List of Materials

  • Clam seed — each about 12mm in length.  (x12 per plant pot)
  • Waxed paper packets (x1 per plant pot; 5-inch x 5-inch) — to place 12 clam seed in for each pot
  • Stapler
  • Small cooler to keep clams in while traveling.  Use ice packs or something else that is dry to keep the clams cool. Do not use water and ice since that will make a mess of the waxed paper packets (see below).
  • 6-inch plant pots x 6-inch deep (minimum; 12 pots per tidal zone)
  • Plastic mesh netting at ¼-inch aperture
    • 18-inch x 18-inch pieces (half the # of plant pots)
    • 30-inch x 6-inch strips (half the # of plant pots)
  • 1-meter² quadrat (at least one — it is useful to have enough to set out all the quadrates for a single tide level — usually 3)
  • Trowels
  • Large rubberbands (Size = 107, which is 7” x 5/8” see: (x1 per plant pot))
  • Wooden stakes (several feet long) to pound into the mud to mark the position of each quadrat (4 for each quadrat, 12 for each tidal zone, assuming 3 quadrats per zone)
  • Mud flat and tidal zones available for seeding
    • E.g. low, medium, high tidal zone

Example List of Materials for a 36 Plant Pot Project with 12 Clams Per Pot

  • Clam seed (x12 per plant pot; 432 clams total)
  • Wax paper packets (x36)
  • 6-inch plant pots (x36)
  • Plastic mesh netting at ¼-inch aperture
    • 18-inch x 18-inch squares (x18)
    • 30-inch x 6-inch strips (x18)
  • 1-meter² quadrat (x1 minimum)
  • Trowels
  • Large rubberband (x36)
  • Mud flat with 3 tidal zones available for seeding
    • Low (x12 plant pots)
    • Medium (x12 plant pots)
    • High (x12 plant pots)
  • Nice to have: A long, water and salt proof tape measure (preferably at least 100 meters).  Used to record spacing between quadrats at each tide level.
  • Nice to have:  A GPS device for recording a known point (e.g. right edge) for each set of quadrats at each tide level in the experiment.


Before Start of Class

(Students might do this work the day before …)

  • Cut plastic mesh netting into 18-inch x 18-inch pieces (x half the # of plant pots).  This will not go over the pots until each pot receives enough sediment to nearly fill it, followed by planting the seed clams in each pot.
  • Cut plastic mesh netting into 30-inch x 6-inch strips (x half the # of plant pots)
  • Fasten netting strips to the top of half the # of plant pots with a large rubberband before going to the study site

This photo at the top of this post shows a 6-inch plant pot with a strip of netting encircling its periphery.  This strip of netting will help retain (corral) clams so that they will remain in the 6-inch diameter area of the pot, but this will not deter predators.

In the Classroom, Before Heading onto the Flats

  • Count out 12 seed clams per plant pot
  • Place each set of 12 clams into wax paper packets.  Keep clams cool and moist to ensure they survive. Details of making the packets:
    • Fold in sides of paper packet twice
    • Fold down top of paper packet
    • Staple shut (making sure not to staple any of the clams)
  • Place each packet into the cooler.  I usually put them in small plastic bags (snack size), with 4 packets per bag (enough for one quadrat).  How many to put together depends on the number of students that will be working at the same time.  More students = more bags.

Out on the Flats

  • Gather materials and travel to the mud flat
  • Locate and mark the ends of the transect for the first tidal zone. (Or, with a large class, mark each zone and do them all at the same time.)  Set out the quadrats do show students where to work. (It is nice to be able to set out all the quadrats for each tide level — usually 3)
  • For the four pots in each quadrat, fill each plant pot with sediment from the mud flat, leaving 1/4 ito 1/2 inch of space below the top edge.
    • Two of these pots should have the mesh strip collar already in place
    • Two should be plain pots — no mesh attached
  • Place the clam seed from a waxed paper packet into each pot, spreading them across the pot.
  • Using soft, very wet mud from the surface of the clam flat, cover the clams in each pot with a thin layer of soft mud, pressing them down gently so that they will not be washed away as the tide comes back in.
  • Wrap one of the 18 inch square pieces of net over the two pots in each quadrat that do not have a collar.  Make sure that the net is stretched evenly across the top and wrapped down to the bottom of the pot.  Then secure the net with a rubber band around the top edge. This is easier of two students work together, one holding the pot and net and one stretching and placing the rubber band.
  • Using the quadrat, the four pots into the corners of the quadrat, leaving a small part of the plant pot lip extended above the sediment surface, following these instructions:
    • Place the 2 plant pots with the net collars (not fully covered with a net) across from each other along the diagonal of the quadrant. Place them into the sediment so that just the top of the pot is visible and so that the netting will stick up out of the flat about an inch. We are aiming for an arrangement in each quadrat that looks like this:
Layout of Plant Pots
  • Place the 2 plant pots where the seed clams are fully covered with netting on the other diagonal, as illustrated above.  Place them into the sediment so that just the top of the pot and netting is visible as illustrated below.
Plant pot covered with netting

Repeat this procedure for each quadrat in the experiment.  It is a good idea to keep notes about the locations … of the quadrats.  GPS coordinates are nice.

After the students complete work on each quadrat, drive wooden stakes into the mud to mark the boundaries of the quadrat. I place a stake at the center of each side of the rectangle rather than in the corners.  I am sure that marking the corners would work too.  Just be sure to make notes about what you did.  Finding the plots after 6-7 months of tides and storms washing of them can be difficult if you do not have good notes.

1 thought on “Setting Up and Deploying the Plastic Plant Pot Experiment

  1. mschauff

    Thanks for these details, and the photos. I will pass the link to the WeatherBlur team at MMSA, in case any coastal teachers are interested. A very do-able experiment.


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