Biodiversity Field Sampling
There are endless numbers of accepted methods for examining the biotic components of an ecosystem. For the purposes of the 4empowerment projects, field sampling techniques have been narrowed down to the kick net method.
Using the kick net method of collecting aquatic samples with the protocol below helps insure that all project participants are utilizing identical methods for collecting biodiversity data so that each group's regional results can be compared.
USING THE KICK NET
Kick nets are smaller nets that are typically attached to a pole or handle.
Nets of this type are generally used along the more confined edges or on the
bottom of water bodies. Kick nets are typically pushed through the water or
placed upright on the bottom where the sediments upstream from the net can be
disturbed, allowing disturbed organisms to flow into the net.
Determining which kick net method to use:
There are two methods for using the kick net which depend on the type of watershed you monitor.
For standing water, the lentic method is used. This involves placing the net on the bottom and pushing or jumping it (with a light bumping of the bottom) over a specified distance.
For flowing water in which a current will carry organisms into the net on its own, the lotic method is used. This involves moving the net very slowly through the substrate while kicking up or fluffing the area in front of the net.
Using the net to disturb the bottom (in the lentic situation) is more appropriate for soft bottoms since everything goes right into the net. Any type of hard bottom will make the net skip across the substrate without disturbing intervening soft areas. In this case, you are better off kicking and rubbing the large rocks (the lotic situation). In general, if you are having a hard time determining which method to use, the lotic kicking method (as opposed to the lentic jumping method) is probably your best bet.
Safety
You know your site better than anyone so use your best judgment. If you deem it unsafe to participate in biodiversity monitoring due to the depths of the river or slopes of the bank, you can always seek out a shallow, accessible site regardless of whether or not that area is different from where you are conducting water quality monitoring. The important thing to stress is consistency in procedure and location.
Kicking the Net in Lotic Situations For flowing water in which a current will carry organisms into the net on its own
Sampling with the kick net requires at least two people, preferably three: one to hold the net, one to disturb (kick) the substrate, and one, if possible, to act as a timekeeper.
Lotic Procedure: One kick for 3 minutes.
- Do not wade through the area to be sampled. To do so would disturb the
habitat and dislodge many organisms before collection. Start downstream
from the area to be sampled and move upstream during collection.
- One person should hold the net firmly against the bottom of the stream,
just downstream from the area to be sampled.
- The second person should stand just upstream of the net, no more than
12-18 inches away from its opening. Distance from the net depends on the
velocity of the stream. In a slower current, stand closer to the net to
make sure the organisms dislodged during the kick do not settle before
they reach the net.
- Once the kicker is ready to begin, the timekeeper should note the time.
The kick should last for three minutes. It is OK to rest during the kick;
just keep track of the total time spent kicking. The goal is to get a
100 critter count from your sample, which will represent your community.
- Kick up the substrate in front of the net, making sure that the plume
of the sediment and debris is moving through the net. Large rocks should
be held underwater and rubbed by hand to dislodge any organisms. Both the
kicker and the net holder should move slowly upstream across the riffle
during the kick, making sure the same ground is not covered twice. How long
you move the net is up to you. We suggest 1 meter to be consistent with
the
Correction Factor Determination Form, Biodiversity Step 2. If the edge
of the riffle is reached before the time is up, continue back across the
stream. When the three minutes are up, lift the net out of the water. If
there is a lot of sediment in the net, rinse the contents by dipping the
net up and down in the stream several times, keeping the opening above the
water surface. Then take it to the shoreline, being careful not to lose
any of the contents.
- Fill a pan with water for cleaning the rocks and debris from the net.
Remove any large rocks from the net, rinse them in the pan to remove the
organisms, and then replace the rocks in the stream. Turn the net inside
out over the pan and use water from the stream to rinse from the outside
of the net. Be sure to get all of the debris from the corners of the net
into the pan. For ease in sorting, you may need to strain excess water
out of the pan at this point. Too much water in the pan makes it difficult
to find and capture the organisms.
- Normally, identification will take place in the field to reduce handling
of specimens and to use their natural color as an aid. However, if conditions
do not allow further field study, cover the pan and take the sample indoors
for identification. Once identification is complete, the sample should
be preserved as detailed below.
- For a good representation of the benthic community in the stream, you
need a sample of around 100 organisms for identification. After you have
obtained a number around 100, you may begin picking organisms out of the
debris in the pan. Fill the sorting tray (ice cube tray) with water and
sort similar bugs into compartments for identification. Use the Macroinvertebrate
Key to help with the grouping.
- Keep an approximate running count and stop picking when you have reached
100. You may not get EXACTLY 100 organisms from one kick. This is only
a suggested standard to ensure you have a good representative sample.
Examples of acceptable values for a good sample size are 79, 88 or 93.
However, if your sample is very sparse (less than 70 to 75), you might
want to do another kick. Note this on your data sheet. Count and group
the organisms from this second kick, and if the new total is not up to
100, do NOT try again. Simply identify all the organisms you have.
- If you are concerned that collecting 100 critters would jeopardize your benthic community, again: use your best judgment. This is a determination that is best left to you based on your knowledge of your particular ecosystem.
Jumping the Net in Lentic Situations For standing water that requires a slight jumping of the kick net on the river bottom
Jumping the kicknet over the substrate requires only one person to jump the net and one person to act as a timekeeper.
Lentic Procedure: Use Species Area Curve to determine replicate number.
- After locating a suitable, safe sample area, the collection team
should prepare their equipment and discuss the collection procedures.
The net "trip" line should be measured (.5 to 1 meter) and attached to
the student's leg or ankle. An easy way to do this is to measure out how
long the line will be (1 meter is what your example uses) and tie a rope
to the student's ankle and then attach the rope with a clothespin to the
net. This way, when the rope comes off of the net, the student will know
when he/she has reached the determined length of the kick.
- The student should then wade into the water at the shore to the appropriate
depth (knee to thigh high). Facing upstream, the net should be placed
directly in front of the students shoe touching the substrate.
- The student should then slowly bounce the net along the substrate until
the trip line is tight. This should take approximately 20 to 30 seconds.
Be careful not to bury the net into the substrate or to lift the net too
high off of the bottom. A happy medium must exist between the two extremes.
Bouncing the net one to two inches high seems to work best. This will
allow the students to collect the proper epi-benthic sample.
- When the line becomes tight, the sample episode is complete. The net
should immediately be lifted up and out of the water. The student may
then wade back to the shore or hand the net to another member of the team
for labeling and collection purposes.
- The process should be repeated as many times as deemed necessary by the
Species Area Curve for proper statistical analysis. Five is the typical
maximum number for Species
Area Curve replicates. The reasoning behind this is out of a concern
for over collecting in the ecosystem.
- For multiple samples, do not sample the exact same area. The next sample should begin slightly upstream, just ahead of the previous collection in "like" conditions.
