Module 4 Stream Invertebrate Survey Interpretation
Brandt Creek, Nov 03, 2001 | Survey ID: 3
A) ABUNDANCE AND DENSITY
ABUNDANCE total number of organisms from Column B: 171
DENSITY invertebrate density per square meter
# of 30cm x 30cm samples: 3
(total # counted 171) / (# of 30cm x 30cm samples x.09m2 3 / (Area: 0.27)) : 633.33
B) PREDOMINANT TAXON: Aquatic Worm, (100)
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) = 4
(# of category 3) = 5
Pollution Tolerant Index = 12
EPT INDEX
Good Acceptable Marginal Poor
greater than 8 5 - 8 2 - 5 0 - 2
Total number of EPT taxa from Column C = 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 6 / total 171 = 0.04
D) DIVERSITY ASSESSMENT
Total Number of Taxa: 12
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:
100 / 171 = 0.5848
SITE ASSESMENT RATING
Good Acceptable Marginal Poor
4 3 2 1
Pollution Tolerance Index: 2
EPT Index: 1
EPT to Total Ratio: 1
Predominant Taxon Ratio: 3
Total: 1.75

Field Data as Collected
Polution Tolerance
Number Counted
Number of Taxa
Common Name
Category 1 - Polution Intolerant Caddisfly
Dobsonfly
Gilled Snail
6 1 Mayfly
Riffle Beetle
Stonefly
Water Penny
Sub Total: 6 1
Category 2 - Somewhat Pollution Tolerant Alderfly larva
1 1 Aquatic Beetle
Aquatic Sowbug
Clam, Mussel
Cranefly Larva
Crayfish
Damselfy Larva
Dragonfly Larva
Fishfly Larva
2 1 Scud
Watersnipe Larva
Sub Total: 3 2
Category 3 - Pollution Tolerant 100 2 Aquatic Worm
Blackfly Larva
Leech
3 2 Midge Larva (chironomid)
Planarian
8 3 Pouch Snail
1 1 Truebug Adult
50 1 Water Mite
Sub Total: 162 9