Module 4 Stream Invertebrate Survey Interpretation
Hoy Creek, Sep 23, 2017 | Survey ID: 190
A) ABUNDANCE AND DENSITY
ABUNDANCE total number of organisms from Column B: 381
DENSITY invertebrate density per square meter
# of 30cm x 30cm samples: 2
(total # counted 381) / (# of 30cm x 30cm samples x.09m2 2 / (Area: 0.18)) : 2,116.67
B) PREDOMINANT TAXON: Caddisfly, (123)
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) = 9
2 x (# of category 2) = 8
(# of category 3) = 5
Pollution Tolerant Index = 22
EPT INDEX
Good Acceptable Marginal Poor
greater than 8 5 - 8 2 - 5 0 - 2
Total number of EPT taxa from Column C = 10
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 305 / total 381 = 0.80
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:
123 / 381 = 0.3228
SITE ASSESMENT RATING
Good Acceptable Marginal Poor
4 3 2 1
Pollution Tolerance Index: 4
EPT Index: 4
EPT to Total Ratio: 4
Predominant Taxon Ratio: 4
Total: 4

Field Data as Collected
Polution Tolerance
Number Counted
Number of Taxa
Common Name
Category 1 - Polution Intolerant 123 3 Caddisfly
Dobsonfly
Gilled Snail
101 2 Mayfly
Riffle Beetle
81 5 Stonefly
Water Penny
Sub Total: 305 10
Category 2 - Somewhat Pollution Tolerant Alderfly larva
1 1 Aquatic Beetle
1 1 Aquatic Sowbug
3 1 Clam, Mussel
Cranefly Larva
Crayfish
Damselfy Larva
Dragonfly Larva
Fishfly Larva
7 1 Scud
Watersnipe Larva
Sub Total: 12 4
Category 3 - Pollution Tolerant 33 2 Aquatic Worm
Blackfly Larva
10 1 Leech
4 1 Midge Larva (chironomid)
Planarian
Pouch Snail
1 1 Truebug Adult
16 1 Water Mite
Sub Total: 64 6