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Field guide to macroinvertebrates – this needs to have information about your location. Check with your teacher, local college or university for recommendations.
Kick net or dip net.
Large white tray – the white color is important, as it is easier to see the organisms.
Sample jars.
Magnifying glass or field microscope.
Pencil and notebook.
Warning Hazard
The equipment used is safe for all ages. However, sampling takes place in and near water where the danger of drowning is always present. Make sure there is sufficient responsible supervision to ensure safety. Younger children require more care but young adults should operate a buddy system to keep watch on each other
Method.
There are two main methods for sampling macroinvertebrates in water. In shallow water the kick net method is often preferred especially faster flowing streams with stone or gravel bottoms. The dip net is essential in deeper water.
Kick Net Sampling.
1.Start by selecting a suitable sampling site and identify an area comparable to the size of the net. If the net is a meter wide then the sample area should be one square meter. 1.The bottom edge of the kick net must be placed firmly on the streambed. It is important to avoid water going under or over the net as this can result in poor sampling.
2.Use the toe or heel of a boot to dislodge the top layer of stones and gravel on the streambed.
3.Be very careful not to disturb the sample site before the net is in place otherwise it is possible to lose macroinvertebrates.
4.Macroinvertebrates on large stones or wood can be dislodged by hand or small brush.
5.Scoop the net forward when lifting it out of the water. This helps prevent the loss of organisms.
6.Carry the net to the bank (unless you are very experienced do not view it in the water as you are likely to lose the sample or not see some organisms) 1.Make sure the trays contain stream water before emptying the contents from the net.
2.Some of the macroinvertebrates are very small so take your time to ensure everything is out of the net.
Dip Net Sampling
1.Select a suitable sampling area. Often this can be from the bank, a bridge or boat. If the water is very deep you may need to use a drag net.
2.Drag the net along the bottom and lift vertically to prevent loss of organisms.
3.As with the kick net method view the sample in a white tray filled with water from the sampling site. Identifying Macroinvertebrates.
Use your field guide to start identifying the organisms present. Record what you see in your notebook. Use a pencil rather than pen. If the paper gets wet (you are near water) then it will still be possible to read your notes.
Don’t forget to record where samples were taken, date, time of day, weather conditions, characteristics of the water (depth, speed of flow, color/turbidity of the water etc). This type of information can help build a picture over time and can help future researchers. Using this type of sampling you can only really produce a list of organism present not their numbers. However, do make notes about the relative abundance. This will often tie in with the time of year.
Take a picture. The development of digital cameras are great for showing the sample area and can make your report more interesting. A picture really is worth a thousand words.
Background Information
Species composition will vary with location and time of year. The following are examples of what might be found.
Species in areas with good water composition.
Mayfly larvae Caddisfly larvae Stonefly larvae Snails Planaria
Species where the water quality is fair
(Note: these will also be found where there is good water quality) Crayfish Beetles Dragonfly Cranefly larvae Damselfly Clam or mussel.
Species where the water quality is poor
Midge fly larvae Blackfly larvae Leeches Aquatic worms Lung snails
Experiment Ideas.
Compare streams with different flow rates or streams and ponds.
Compare streams in different locations or the same stream at various places along its course.
Study one location of a period of time.
Your aim should be to try and identify reasons why there may be differences. Is it time of year, pollution, environmental factors? Consider measuring water temperature, speed of flow, pH, phosphates, electrical conductivity, dissolved oxygen.
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