Module 4 Stream Invertebrate Survey Interpretation
Coquitlam River, Sep 21, 2017 | Survey ID: 189
A) ABUNDANCE AND DENSITY
ABUNDANCE total number of organisms from Column B: 114
DENSITY invertebrate density per square meter
# of 30cm x 30cm samples: 1
(total # counted 114) / (# of 30cm x 30cm samples x.09m2 1 / (Area: 0.09)) : 1,266.67
B) PREDOMINANT TAXON: Mayfly, (29)
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) = 6
(# of category 3) = 5
Pollution Tolerant Index = 20
EPT INDEX
Good Acceptable Marginal Poor
greater than 8 5 - 8 2 - 5 0 - 2
Total number of EPT taxa from Column C = 7
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 36 / total 114 = 0.32
D) DIVERSITY ASSESSMENT
Total Number of Taxa: 17
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:
29 / 114 = 0.2544
SITE ASSESMENT RATING
Good Acceptable Marginal Poor
4 3 2 1
Pollution Tolerance Index: 3
EPT Index: 3
EPT to Total Ratio: 2
Predominant Taxon Ratio: 4
Total: 3

Field Data as Collected
Polution Tolerance
Number Counted
Number of Taxa
Common Name
Category 1 - Polution Intolerant 6 1 Caddisfly
Dobsonfly
Gilled Snail
29 5 Mayfly
Riffle Beetle
1 1 Stonefly
Water Penny
Sub Total: 36 7
Category 2 - Somewhat Pollution Tolerant Alderfly larva
1 1 Aquatic Beetle
3 1 Aquatic Sowbug
Clam, Mussel
Cranefly Larva
Crayfish
Damselfy Larva
Dragonfly Larva
Fishfly Larva
19 1 Scud
Watersnipe Larva
Sub Total: 23 3
Category 3 - Pollution Tolerant 25 3 Aquatic Worm
15 1 Blackfly Larva
Leech
2 1 Midge Larva (chironomid)
4 1 Planarian
Pouch Snail
Truebug Adult
9 1 Water Mite
Sub Total: 55 7