Module 4 Stream Invertebrate Survey Interpretation
Mackay Creek, Oct 03, 2007 | Survey ID: 153
A) ABUNDANCE AND DENSITY
ABUNDANCE total number of organisms from Column B: 589
DENSITY invertebrate density per square meter
# of 30cm x 30cm samples: 3
(total # counted 589) / (# of 30cm x 30cm samples x.09m2 3 / (Area: 0.27)) : 2,181.48
B) PREDOMINANT TAXON: Mayfly, (347)
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) = 8
(# of category 3) = 4
Pollution Tolerant Index = 24
EPT INDEX
Good Acceptable Marginal Poor
greater than 8 5 - 8 2 - 5 0 - 2
Total number of EPT taxa from Column C = 12
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 488 / total 589 = 0.83
D) DIVERSITY ASSESSMENT
Total Number of Taxa: 26
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:
347 / 589 = 0.5891
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: 3
Total: 3.75

Field Data as Collected
Polution Tolerance
Number Counted
Number of Taxa
Common Name
Category 1 - Polution Intolerant 10 4 Caddisfly
Dobsonfly
Gilled Snail
347 3 Mayfly
1 1 Riffle Beetle
131 5 Stonefly
Water Penny
Sub Total: 489 13
Category 2 - Somewhat Pollution Tolerant Alderfly larva
Aquatic Beetle
1 1 Aquatic Sowbug
Clam, Mussel
4 2 Cranefly Larva
Crayfish
Damselfy Larva
Dragonfly Larva
Fishfly Larva
1 1 Scud
1 1 Watersnipe Larva
Sub Total: 7 5
Category 3 - Pollution Tolerant 25 3 Aquatic Worm
1 1 Blackfly Larva
Leech
3 2 Midge Larva (chironomid)
Planarian
Pouch Snail
Truebug Adult
64 2 Water Mite
Sub Total: 93 8