Wetland Health Evaluation Program (WHEP)

Macroinvertebrate sampling protocols

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Taken from:  "A Citizen's Guide to Biological Assessment of Wetlands, The Macroinvertebrate Index of Biological Integrity", Dr. Judy Helgen, MPCA 2000.

When to Sample:
Macroinvertebrates should be sampled during the month of June, or at the latest, early July.  Monitoring occurs during this time of year for two primary reasons. 
           1.  To ensure that the macroinvertebrates are a size that is easy to identify. 
           2.  To ensure that the majority 
of the macroinvertebrates collected matured in the site
                sampled.  If it is later in the season, there is a greater chance that the macroinvertebrates
                may have flown in from another nearby wetland.

Where to Sample:
Samples should be collected in the shallow, near-shore area not deeper than 3 feet (1 meter).  The same general area should be used for the bottletrap placement and the dipnet sampling.  If there is a cattail fringe (or other emergent vegetation), sample in the area between the cattails and the shore.  If there is no water between the emergent vegetation and the shore, then sample within the cattails and to the outer edge of the cattails towards the open water.  If there is no emergent vegetation, sample very near shore in water up to 3 feet deep.  Refer to diagrams.  DN=Dipnet sampling location   BT=Bottletrap placement

Little vegetation.

Dense vegetation.

Spread along about 60 ft of shoreline.

Setting Bottletraps
1.  Use 6 bottletraps per site.  Set the traps out in 3 pairs, the mebers of each pair about 3-6 ft. apart.
     Spread the 3 pairs along the shore, with pairs roughly 20ft. apart.  You will combine the data
     from all 6 traps for metrics.
2.  Put at least 2 of the traps in very shallow water near shore, the others in shallow water not deeper
     than about 2-3 ft.    
3.  Set the traps 2 nights before collecting them.  Be aware of rain events prior to bottle placement and
     after.  Wetland water levels can fluctuate quickly.
4.  Fill traps with water with no air bubles (tip trap under water so bubbles escape).
5.  Press funnel into trap opening so it snaps in tightly.  Again, remove air bubbles.
6.  Lower bottle on dowel, orient bottle horizontally in water.
7.  Put bottletraps about one hand length under the water.

Collecting Bottletraps
1.  Collect each pair of bottletraps each into one jar (3 jars total for 3 paris of BTs), unlees the sample
     occupies more than 1/4 volume of the jar.  If so, use a second jar.
2.  Raise trap up the dowel, remove the funnel, pour the trap contents through your sieve.
3.  Dislodge any critters stuck to the inside walls of the bottle.  What's on the outside of the bottle
     is not part of the sample.
4.  Collect the second trap of the pair, and pour contents into sieve.
5.  Backflush the contents of the sieve into your sample jar with 95% alcohol.
If you have alot of leeches or other ogranisms in your traps, you may need to use more jars
              to preserve the sample.
         b.  If you have fish, tadpoles or salamanders you should note these on your field data sheet and
              leave them at the site.  Note approximate numbers.
6.  Label properly.  Put pencil or India ink label inside the jars.  Label outside for convenience.  See further labeling information below.

Collecting a Dipnet (DN) Sample
You collect one dipnet sample per site.  Each DN sample consists of two dipnetting efforts.  Dipnet in the near-shore shallow areas in water up to one meter deep.  "Sample close to edge and in the veg."  Use a 12 x 16" wood framed 1/2" hardware cloth screen over a tray (or 2 Coleman cooler trays) of water.  The tray(s) of water should sit within a larger kitty litter pan or dishpan.  This can float on the wetland.

     1.  Put water in your collecting pans that sit underneath your hardwary cloth screen.
     2.  Place the framed hardware closth screen over the water so its edges don't hang over the edge of
          the pans.  This way the critters go down into the water in the pans.
     3.  Hold the long-handled dip net vertically, one hand near net, one hand up handle. 
     4.  Using stron strokes, sweep the net through the water towards you about 3-5 times.
     5.  Be sure to sample right into the vegetation near shore.
6.  Evert all of the net contents onto the hardware cloth screen.  Get everything out of the net.
     7.  Spread the vegetation, loosen it.  Do this periodically for up to 10 minutes.  This allows the
          critters to get down into the water in the pans.
     8.  After 10 minutes, remove the vegetation and do the second dipnetting effort.

     1.  Move to a different shallow area.
     2.  Repeat the steps described in 1-7 above.
     3.  After spreading out the vegetation for 10 minutes, remove it, and pour the water from the
          collecting pans through your sieve.  Be sure to dislodge the leeches and snails which might
          attach to the pan.
    4.   Backflush the sieve contents into your sample jar with 95% alcohol.  Be sure to get any critters
          which attach to the sieve walls.  Use two jars if critters and debris occupy more than 1/4 of the
          jar volume.

Sample Labeling
1.  Record sample code on field data sheet, especially if different from site name.
2.  Use pencil or truly permanent India ink on 100% cotton cardstock or index card.
3.  Indicate Site Name, Sample Code, Date, County, Collector's name, if DN or BT sample.  Indicate
     if there is more than one jar--jar #1 of 2, jar #2 of 2.
4.  Place label INSIDE jar.  This is the only label you trust.
5.  For convenience, label also on the outside of the jar.
6.  Remember alcohol is falmmable.  Keep lids tight.  Store away from flame or heat.