Module 4 Stream Invertebrate Survey Interpretation
Little Toquaht River, May 20, 2022 | Survey ID: 252
A) ABUNDANCE AND DENSITY
ABUNDANCE total number of organisms from Column B: 24
DENSITY invertebrate density per square meter
# of 30cm x 30cm samples: 3
(total # counted 24) / (# of 30cm x 30cm samples x.09m2 3 / (Area: 0.27)) : 88.89
DENSITY invertebrate density per square meter
# of 30cm x 30cm samples: 3
(total # counted 24) / (# of 30cm x 30cm samples x.09m2 3 / (Area: 0.27)) : 88.89
B) PREDOMINANT TAXON: Mayfly, (17)
C) WATER QUALITY ASSESSMENTS
| POLLUTION TOLERANT INDEX | |||
| Good | Acceptable | Marginal | Poor |
| greater than 22 | 22 - 17 | 17 -11 | less than 11 |
3 x (# of category 1) = 3
2 x (# of category 2) = 0
(# of category 3) = 0
Pollution Tolerant Index = 3
2 x (# of category 2) = 0
(# of category 3) = 0
Pollution Tolerant Index = 3
| EPT INDEX | |||
| Good | Acceptable | Marginal | Poor |
| greater than 8 | 5 - 8 | 2 - 5 | 0 - 2 |
Total number of EPT taxa from Column C = 2
| 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 20 / total 24 = 0.83
D) DIVERSITY ASSESSMENT
Total Number of Taxa: 2
| 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:
17 / 24 = 0.7083
17 / 24 = 0.7083
| SITE ASSESMENT RATING | |||
| Good | Acceptable | Marginal | Poor |
| 4 | 3 | 2 | 1 |
| Pollution Tolerance Index: | 1 |
| EPT Index: | 2 |
| EPT to Total Ratio: | 4 |
| Predominant Taxon Ratio: | 2 |
| Total: | 2.25 |
Field Data as Collected
Polution Tolerance |
Number Counted | Number of Taxa | Common Name |
| Category 1 - Polution Intolerant | 0 | 0 | Caddisfly |
| 0 | 0 | Dobsonfly | |
| 0 | 0 | Gilled Snail | |
| 17 | 2 | Mayfly | |
| 0 | 0 | Riffle Beetle | |
| 3 | 0 | Stonefly | |
| 0 | 0 | Water Penny | |
| Sub Total: | 20 | 2 | |
| Category 2 - Somewhat Pollution Tolerant | 0 | 0 | Alderfly larva |
| 0 | 0 | Aquatic Beetle | |
| 0 | 0 | Aquatic Sowbug | |
| 0 | 0 | Clam, Mussel | |
| 0 | 0 | Cranefly Larva | |
| 0 | 0 | Crayfish | |
| 0 | 0 | Damselfy Larva | |
| 0 | 0 | Dragonfly Larva | |
| 0 | 0 | Fishfly Larva | |
| 0 | 0 | Scud | |
| 0 | 0 | Watersnipe Larva | |
| Sub Total: | 0 | 0 | |
| Category 3 - Pollution Tolerant | 0 | 0 | Aquatic Worm |
| 2 | 0 | Blackfly Larva | |
| 0 | 0 | Leech | |
| 0 | 0 | Midge Larva (chironomid) | |
| 0 | 0 | Planarian | |
| 0 | 0 | Pouch Snail | |
| 0 | 0 | Truebug Adult | |
| 2 | 0 | Water Mite | |
| Sub Total: | 4 | 0 |