Aquatic Insect flashcards

182 Pages·2012·13.5 MB·English

by  Natalie Carroll

4-H-1018
Bioindicators of Water Quality
Authors: Julie Speelman and Natalie Carroll
Photographer (unless otherwise noted): Julie Speelman
Design and Layout: Linda Hines
Aquatic insects can be used as bioindicators
of water quality. These bioindicator cards show
larval stages of aquatic insects that may be found in
Indiana waterways and a corresponding tolerance score.
The tolerance score represents the insect’s sensitivity to
pollution and is used to estimate water quality. Insects
with a tolerance score value of 0 are intolerant to
pollution, while insects with a tolerance score of 10 are
very tolerant of pollution.
More complete instructions and data sheets are
available at:
www.four-h.purdue.edu/natural_resources/
(select “Resources for Teachers” and “Bioindicators”)
Instructions:
• Take samples from all stream habitats along a Materials Needed:
200-foot section. dip net
• Collect insects for 45 minutes. Captured insects should plastic bowl
be placed in container with stream water. or dishpan
• Sort the insects that look the same into different egg carton
compartments.
• Use the bioindicator cards to identify the insects. a stream to sample
• Record the number of insects from each insect
family you identify on the data sheet.
• Complete the calculations and determine the stream water quality rating.
Assessing the water quality for your site:
1. Determine the Family Tolerance Score by multiplying the number of insects in
each family by the tolerance value given for that family.
2. Determine the Order Totals by summing the number of insects and Family
Tolerance Scores for each order.
3. Determine the Grand Total by summing the Order Totals (number of insects and
Tolerance)
4. Determine the Biotic Index by dividing the Total tolerance score by the
Total number of insects.
5. Estimate the stream water quality rating and degree of organic pollution from
the Biotic Index table.
Biotic Index Water Quality Rating Degree of Organic Pollution
0.00-3.75 Excellent Organic Pollution Unlikely
3.76-4.25 Very Good Slight Organic Pollution Possible
4.26-5.00 Good Some Organic Pollution Probable
5.01-5.75 Fair Fairly Substantial Pollution Likely
5.76-6.50 Fairly Poor Substantial Pollution Likely
6.51-7.25 Poor Very Substantial Pollution Likely
7.26-10.0 Very Poor Severe Organic Pollution Likely
Ephemeroptera
Mayflies

Isonychiidae
Common name: Brush-Legged Mayfly
Occurrence: 16 species in North America
Size: 8-17 mm
Habitat: Riffle areas of streams and rivers on leaves and
sticks
Feeding group: Collectors/filterers
Tolerance score: 2 (low)

Polymitarcyidae
Common name: Pale Burrowering Mayfly
Occurrence: 7 species in North America
Size: 12-35 mm
Habitat: Silt- and clay-bottomed rivers, lakes, and
streams
Feeding group: Collectors/gatherers/filterers
Tolerance score: 2 (low)