Sampling the bugs (macroinvertebrates) that live in a stream provides valuable insights into the health of the stream.This is a great activity that children to adults can take part in!
To collect the samples you will need a surber sampler. This instructable provides you with a way to make your own.
A surber sampler collects macroinvertebrates from riffles in shallow streams. Flowing water carries the invertebrates into the collecting net as the stream bottom is disturbed. Samplers of different sizes can accommodate different conditions (e.g. larger samplers can be used in deeper areas, smaller samplers sometimes work better in shallow streams with low velocity). The sampler may also be used for qualitative sampling by dragging the sampler across a pond bottom.
Materials you'll need:
- 32 by 82 cm silkscreen mesh with a 500 micron openings
- 2 inch bias tape x 100 cm and 1 inch wide bias tape
- ¼ inch by 100 cm coated steel rod
- 5/16 redirod connector
Step 1: Making the Frame
Bend the rod into a rectangle 33 cm wide and 15 cm deep, joining at the mid point along the top side. Cut the rod so the two top edge pieces match.
Drill a ¼ inch hole through the mid point of the redirod connector. Weld the 5/16 bolt on to the end of the 40 cm rebar to create a removable handle.
Step 2: Sewing the Net
Cut the silk screen into a strip 32 cm wide by 56 cm long then cut two side panels 16 x 21 cm.
Sew the two side panels onto the longer strip, forming a box 15 cm x 33cm x 20 cm with an open top.
Step 3: Putting the Screen and the Frame Together
Cover the seams with 1 inch bias tape and sew in place.
Sew an edge of the 2 inch bias tape around the open end of the box.
Fold the bias tape around the ¼ rod frame and sew back onto the screen. This will require sliding the screen along the rod as you get to the corners.
Hand sew the final section to close the screen.
Step 4: Using a Surber Sampler
Select a riffle in the stream as your sample area. Set the surber with the net upright, water flowing into the net. Work the base of the net into the stream bottom.
Hold the surber in place while turning over and hand-rubbing all the stones upstream of the frame to dislodge any organisms that may be clinging to them. Sometimes insect larvae and pupae cling very tightly. Make sure everything gets caught in the sampler net.
Stir the remaining gravel and sand with your hands or sticks to a depth of 5 to 10 cm. This will dislodge bottom-dwelling organisms.
Hand-pick snails and other “heavier” organisms that are not picked up by the current.
Once the sample is taken, invert the net into a sample container and rinse down the net.
You are now ready to collect and identify the organisms you have found!