At the Stream:

Digital Thermometer:  Use of a digital thermometer to record air and water temperature will be demonstrated and monitored by staff.  Temperatures will be taken in both Fahrenheit and Celsius. 

Surber Bottom Sampler:

Description:  Use of a Surber sampler gives researchers a quantitative method to study stream macroinvertebrates.  The 12” x 12” horizontal frame is the collection area and serves as the experimental control, which allows the researcher to estimate the number of macroinvertebrates in the riffle beyond the collection frame.  The 24” long net attached to a vertical frame catches macroinvertebrates from the collection area.

Placement for Collection:  Riffles are an ideal place to study stream macroinvertebrates due to the shallow, rapidly flowing water.  Rocks on the stream bed covered in algae and debris provide food and protection for aquatic insects.  Staff will place the Surber sampler in the riffle in a random place.  The Surber sampler’s horizontal frame, which defines a boundary for the collection area, is placed under the water, on the stream bed.  The net is placed downstream from the collection area to allow the current to push the sample into the net.

Collection Procedure:  Collect from within the defined collection area of the horizontal frame only.  Rinse all material within the frame and then place the material outside the collection area so someone else doesn’t rinse it again.  Rinse material such as rocks, plants, dead leaves, and sticks.  To rinse, lightly rub the surface and swish the object in the water to dislodge the invertebrates.   Rinse and swish the material within the collection area directly in front of the net, while holding the object underneath the water so the current will force the invertebrates directly into the net.  Do not dislodge rocks imbedded in the stream bed, which will contaminate or pollute the sample with organic debris and mud.

Collection Behavior:  Each student will be provided a pair of rubber boots.  Only two or three students will enter the water to take the collection at one time.  It is important students do not step directly in front (upstream) of the Surber sampler collection frame.  This will contaminate the sample by adding organisms from outside the defined area and by kicking up organic material and debris from outside the collection area.  Students should walk and stand downstream from the Surber sampler frame at all times.

Collection Procedure Part II:  Rinsing the Surber Net:  The Surber bottom sampler containing the stream macroinvertebrate sample is brought onto the bank by staff.  The net is turned inside-out over a white pan.  Students use water bottles to rinse invertebrates clinging to the net into the white pan for examination.  The macroinvertebrate sample will be examined in the Education Center laboratory. 

Lab Equipment Skills:

Data sheet:  First, it is important to completely fill out the information requested, such as school name, date, student name, water temperature, etc. Students need to be encouraged to tally invertebrates as they capture and identify them.     

Identification sheets & keys:  Familiarize students with Stream Insects & Crustaceans and the student Datasheet before you visit.

Pipette (eye dropper):  Squeeze bulb, aim tip over invertebrate, place tip underwater, release bulb slowly to capture invertebrate with a small amount of water.  To release invertebrate in Petri dish, squeeze bulb to expel invertebrate and water.  (Many students squeeze the air out of the bulb under the water, which pushes away the invertebrate.)

Forceps (tweezers):  To use, gently grasp invertebrate between tips. Use to catch invertebrates that are too big to be picked up by the pipette.

Petri dish and divided tray:  Students will organize invertebrates by species within the divided tray, placing the same type of invertebrate together.  This will make identification easier, as well as recording the correct quantity on the data sheet. 

Hand lens (magnifying glass):  The white button on the side turns the light on. The light source should be aimed on invertebrate.  Focus on the invertebrate by moving the lens closer to or farther from it.

Two-way viewer:  Remove the conical cover, place the invertebrate in the dish covered in a small droplet of water to restrict movement.  Replace the cover.  Look through the eye piece below the dish or down the cover eye piece to see the invertebrate close-up.