Module 4 Stream Invertebrate Survey Interpretation
Mackay Creek, Jul 08, 2018 | Survey ID: 205
A) ABUNDANCE AND DENSITY
ABUNDANCE total number of organisms from Column B: 185
DENSITY invertebrate density per square meter
# of 30cm x 30cm samples: 1
(total # counted 185) / (# of 30cm x 30cm samples x.09m2 1 / (Area: 0.09)) : 2,055.56
B) PREDOMINANT TAXON: Mayfly, (159)
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) = 12
2 x (# of category 2) = 2
(# of category 3) = 3
Pollution Tolerant Index = 17
EPT INDEX
Good Acceptable Marginal Poor
greater than 8 5 - 8 2 - 5 0 - 2
Total number of EPT taxa from Column C = 4
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 165 / total 185 = 0.89
D) DIVERSITY ASSESSMENT
Total Number of Taxa: 9
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:
159 / 185 = 0.8595
SITE ASSESMENT RATING
Good Acceptable Marginal Poor
4 3 2 1
Pollution Tolerance Index: 3
EPT Index: 2
EPT to Total Ratio: 4
Predominant Taxon Ratio: 1
Total: 2.5

Field Data as Collected
Polution Tolerance
Number Counted
Number of Taxa
Common Name
Category 1 - Polution Intolerant 3 1 Caddisfly
Dobsonfly
Gilled Snail
159 2 Mayfly
1 1 Riffle Beetle
3 1 Stonefly
Water Penny
Sub Total: 166 5
Category 2 - Somewhat Pollution Tolerant Alderfly larva
Aquatic Beetle
Aquatic Sowbug
Clam, Mussel
Cranefly Larva
Crayfish
Damselfy Larva
Dragonfly Larva
Fishfly Larva
Scud
1 1 Watersnipe Larva
Sub Total: 1 1
Category 3 - Pollution Tolerant 2 1 Aquatic Worm
Blackfly Larva
Leech
3 1 Midge Larva (chironomid)
Planarian
Pouch Snail
Truebug Adult
13 1 Water Mite
Sub Total: 18 3