Module 4 Stream Invertebrate Survey Interpretation
ALEXANDER CREEK | Survey ID: 74
A) Abundance and density
ABUNDANCE: 137 / NUMBER OF SAMPLES: (1 *.09) = DENSITY: 1,522.22
B) PREDOMINANT TAXON
Mayfly Larva
C) WATER QUALITY ASSESSMENTS
POLLUTION TOLERANT INDEX
Good
Acceptable
Marginal
Poor
greater than 22
22 - 17
16 - 11
less than 11
3 x (# of category 1) = 12
2 x (# of category 2) = 0
(# of category 3) = 4
= 16
EPT INDEX
Good
Acceptable
Marginal
Poor
greater than 8
5 - 8
2 - 5
0 - 1
Total number of EPT taxa from Column C = 14
EPT TO TOTAL RATIO
Good
Acceptable
Marginal
Poor
0.75 - 1.00
0.50 - 0.75
0.25 - 0.50
0 - 0.25
# of EPT
121 / total
137 =
0.88
D) DIVERSITY ASSESSMENT
TOTAL NUMBER OF TAXA: 20
PREDOMINANT TAXON RATIO
Good
Acceptable
Marginal
Poor
0 - 0.40
0.40 - 0.60
0.60 - 0.80
0.80 - 1.0
PREDOMINANT TAXON RATIO: Predominant Taxa 59 / 137 = 0.4307
SITE ASSESMENT RATING
Good
Acceptable
Marginal
Poor
4
3
2
1
Pollution Tolerance Index: 2
EPT Index: 4
EPT to Total Ratio: 4
Predominant Taxon Ratio: 3
Total: 3.25
| POLLUTION TOLERANT INDEX | |||
|---|---|---|---|
| Good | Acceptable | Marginal | Poor |
| greater than 22 | 22 - 17 | 16 - 11 | less than 11 |
3 x (# of category 1) = 12
2 x (# of category 2) = 0
(# of category 3) = 4
= 16
2 x (# of category 2) = 0
(# of category 3) = 4
= 16
| EPT INDEX | |||
|---|---|---|---|
| Good | Acceptable | Marginal | Poor |
| greater than 8 | 5 - 8 | 2 - 5 | 0 - 1 |
| EPT TO TOTAL RATIO | |||
|---|---|---|---|
| Good | Acceptable | Marginal | Poor |
| 0.75 - 1.00 | 0.50 - 0.75 | 0.25 - 0.50 | 0 - 0.25 |
# of EPT
121 / total
137 =
0.88
| PREDOMINANT TAXON RATIO | |||
|---|---|---|---|
| Good | Acceptable | Marginal | Poor |
| 0 - 0.40 | 0.40 - 0.60 | 0.60 - 0.80 | 0.80 - 1.0 |
| SITE ASSESMENT RATING | |||
|---|---|---|---|
| Good | Acceptable | Marginal | Poor |
| 4 | 3 | 2 | 1 |
Pollution Tolerance Index: 2
EPT Index: 4
EPT to Total Ratio: 4
Predominant Taxon Ratio: 3
Total: 3.25
EPT Index: 4
EPT to Total Ratio: 4
Predominant Taxon Ratio: 3
Total: 3.25
Field Data as Collected
Polution Tolerance |
Number Counted | Number of Taxa | Common Name |
| Category 1 - Polution Intolerant | 22 | 4 | Caddisfly |
| Dobsonfly | |||
| Gilled Snail | |||
| 59 | 6 | Mayfly | |
| 1 | 1 | Riffle Beetle | |
| 40 | 4 | Stonefly | |
| Water Penny | |||
| Sub Total: | 122 | 15 | 4 |
| Category 2 - Somewhat Pollution Tolerant | Alderfly larva | ||
| Aquatic Beetle | |||
| Aquatic Sowbug | |||
| Clam, Mussel | |||
| Cranefly Larva | |||
| Crayfish | |||
| Damselfy Larva | |||
| Dragonfly Larva | |||
| Fishfly Larva | |||
| Scud | |||
| Watersnipe Larva | |||
| Sub Total: | 0 | 0 | 0 |
| Category 3 - Pollution Tolerant | Aquatic Worm | ||
| 1 | 1 | Blackfly Larva | |
| Leech | |||
| 9 | 2 | Midge Larva (chironomid) | |
| 3 | 1 | Planarian | |
| Pouch Snail | |||
| Truebug Adult | |||
| 2 | 1 | Water Mite | |
| Sub Total: | 15 | 5 | 4 |
| Total: | 137 | 20 | 8 |