Diversity Worksheet – pp.99-102 Field Manual
Name_____________________________Date______Period_____
Part I - PTI – Pollution Tolerance Index
In the field you conducted a macroinvertebrate study to determine the health of the stream. After 3
samples using a kick seine you have collected and identified several species. Now you must run a few
tests to draw your conclusions. Below is a list of the species collected:
# specimens
Common Name
5
13
10
6
2
5
106
7
15
Mayflies
Caddisflies
Crayfish
Damselflies
Lunged Snail
Midges
Sowbugs
Worms
Stoneflies
Group (I,
II, III)
Abundance Code
(R, C, D)
Order (or Class)
`
1. Fill in the GROUP (I, II, III) and order (or class in some cases) for each species in the table
above.
2. Identify the macroinvertebrates (to order) in your sample. Record the number of
organisms below and then assign each organism an abundance code:
R (rare) = 1-9 organisms; C (common) = 10-99 organisms; or D (dominant) = 100 or more organisms
Example: _ 20_ ( C )_ Water Penny Larvae
3. Calculate the water quality rating using the scale below. Show all #s.
Based on the species collected, what do you hypothesize the water quality
rating will be (Good, Fair, Poor)?
To calculate the index value, add the number of letters (not numbers of macros) found in the
three groups on the other side and multiply by the indicated weighing factor.
________________________________________________________________________
Group I – Sensitive
(# of R’s) x 5.0 = _______________
(# of C’s) x 5.6 = _______________
(# of D’s) x 5.3 = _______________
Sum of Index Value for Group I = _______________
________________________________________________________________________
Group II – Somewhat Sensitive
(# of R’s) x 3.2 = _______________
(# of C’s) x 3.4 = _______________
(# of D’s) x 3.0 = _______________
Sum of Index Value for Group II = _______________
________________________________________________________________________
Group III – Tolerant
(# of R’s) x 1.2 = _______________
(# of C’s) x 1.1 = _______________
(# of D’s) x 1.0 = _______________
Sum of Index Value for Group III = _______________
________________________________________________________________________
To calculate the water quality score for the stream site, add
together the index values for each pollution tolerance group.
The sum of these values equals the water quality score.
Water Quality Score = ____________________
Compare this score to the following number ranges to determine the quality of your stream site:
Circle the Rating you Calculate
Good > 40
Fair
20 – 40
Poor < 20
Note: The tolerance groupings (Group I, II, III) and the water quality rating categories were
developed for streams in the Mid-Atlantic states.
Part II – Sequential Comparison Index
Complete the SCI for the following scenario:
A
BBBB
AAA
C
BBB
1
2
3
4
5
1. Total # Runs = ________
2. Total # Individuals = ________
3. SCI = _______
4. SCI Value (Fill in the category) (1 point each)
4 (____________) 0.9-1.0
3 (____________) 0.6-0.89
2 (____________) 0.3-0.59
1 (____________) 0.0-0.29
Conclusions:
5. What is the SCI Value (from table above)?
6. What would you say about the relative
abundance of organisms in this sample?
7. What is the Diversity Index for the sample above?
Show equation & work.
DD
6
Part III – EPT Richness
Biological diversity can be quantified in many different ways. The two main factors taken into
account when measuring diversity are richness and evenness. Richness is a measure of the
number of different kinds of organisms present in a particular area. For example, species
richness is the number of different species present. However, diversity depends not only on
richness, but also on evenness. Evenness compares the similarity of the population size of each
of the species present.
EPT Richness
1. Choose 3*3 m sample and collect specimens using a kick net or D net
2. Sample 3 times.
3. Pick through and count the # of taxa representing the three orders: Ephemeroptera, Plecoptera,
& Trichoptera.
4. Divide total # of EPT individuals by the total # of chironomid individuals = EPT/midge ratio. A
healthy system >.75
EPT Richness
4 (Excellent)
>15 families
3 (Good)
12-15 families
2 (Fair)
8-12 families
1 (Good)
<8 families
Scenario:
In the field you collect the following organisms:
3 Mayfly Families = 16 species
4 Stonefly Families = 12 species
2 Caddisfly families = 5 species
11 Midges
Determine the EPT Richness for this particular area.