Module 4 Stream Invertebrate Survey Interpretation
ALEXANDER CREEK | Survey ID: 73
A) Abundance and density
ABUNDANCE: 994 / NUMBER OF SAMPLES: (3 *.09) = DENSITY: 3,681.48
B) PREDOMINANT TAXON
Stonefly 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) = 2
(# of category 3) = 4
= 18
EPT INDEX
Good
Acceptable
Marginal
Poor
greater than 8
5 - 8
2 - 5
0 - 1
Total number of EPT taxa from Column C = 16
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
857 / total
994 =
0.86
D) DIVERSITY ASSESSMENT
TOTAL NUMBER OF TAXA: 24
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 321 / 994 = 0.3229
SITE ASSESMENT RATING
Good
Acceptable
Marginal
Poor
4
3
2
1
Pollution Tolerance Index: 3
EPT Index: 4
EPT to Total Ratio: 4
Predominant Taxon Ratio: 4
Total: 3.75
| 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) = 2
(# of category 3) = 4
= 18
2 x (# of category 2) = 2
(# of category 3) = 4
= 18
| 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
857 / total
994 =
0.86
| 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: 3
EPT Index: 4
EPT to Total Ratio: 4
Predominant Taxon Ratio: 4
Total: 3.75
EPT Index: 4
EPT to Total Ratio: 4
Predominant Taxon Ratio: 4
Total: 3.75
Field Data as Collected
Polution Tolerance |
Number Counted | Number of Taxa | Common Name |
| Category 1 - Polution Intolerant | 274 | 5 | Caddisfly |
| Dobsonfly | |||
| Gilled Snail | |||
| 262 | 6 | Mayfly | |
| 2 | 1 | Riffle Beetle | |
| 321 | 5 | Stonefly | |
| Water Penny | |||
| Sub Total: | 859 | 17 | 4 |
| Category 2 - Somewhat Pollution Tolerant | Alderfly larva | ||
| 3 | 1 | Aquatic Beetle | |
| Aquatic Sowbug | |||
| Clam, Mussel | |||
| Cranefly Larva | |||
| Crayfish | |||
| Damselfy Larva | |||
| Dragonfly Larva | |||
| Fishfly Larva | |||
| Scud | |||
| Watersnipe Larva | |||
| Sub Total: | 3 | 1 | 1 |
| Category 3 - Pollution Tolerant | 20 | 1 | Aquatic Worm |
| Blackfly Larva | |||
| Leech | |||
| 66 | 2 | Midge Larva (chironomid) | |
| 25 | 1 | Planarian | |
| Pouch Snail | |||
| Truebug Adult | |||
| 21 | 2 | Water Mite | |
| Sub Total: | 132 | 6 | 4 |
| Total: | 994 | 24 | 9 |