Module 4 Stream Invertebrate Survey Interpretation
Spanish Bank Creek, Jul 23, 2005 | Survey ID: 163
A) ABUNDANCE AND DENSITY
ABUNDANCE total number of organisms from Column B: 574
DENSITY invertebrate density per square meter
# of 30cm x 30cm samples: 3
(total # counted 574) / (# of 30cm x 30cm samples x.09m2 3 / (Area: 0.27)) : 2,125.93
B) PREDOMINANT TAXON: Blackfly Larva, (269)
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) = 4
Pollution Tolerant Index = 18
EPT INDEX
Good Acceptable Marginal Poor
greater than 8 5 - 8 2 - 5 0 - 2
Total number of EPT taxa from Column C = 9
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 218 / total 574 = 0.38
D) DIVERSITY ASSESSMENT
Total Number of Taxa: 15
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:
269 / 574 = 0.4686
SITE ASSESMENT RATING
Good Acceptable Marginal Poor
4 3 2 1
Pollution Tolerance Index: 3
EPT Index: 4
EPT to Total Ratio: 2
Predominant Taxon Ratio: 3
Total: 3

Field Data as Collected
Polution Tolerance
Number Counted
Number of Taxa
Common Name
Category 1 - Polution Intolerant 28 3 Caddisfly
Dobsonfly
Gilled Snail
168 4 Mayfly
1 1 Riffle Beetle
22 2 Stonefly
Water Penny
Sub Total: 219 10
Category 2 - Somewhat Pollution Tolerant Alderfly larva
Aquatic Beetle
Aquatic Sowbug
Clam, Mussel
Cranefly Larva
Crayfish
Damselfy Larva
Dragonfly Larva
Fishfly Larva
Scud
18 1 Watersnipe Larva
Sub Total: 18 1
Category 3 - Pollution Tolerant 51 1 Aquatic Worm
269 1 Blackfly Larva
Leech
2 1 Midge Larva (chironomid)
15 1 Planarian
Pouch Snail
Truebug Adult
Water Mite
Sub Total: 337 4
Category 1 - Polution Intolerant Caddisfly
Dobsonfly
Gilled Snail
210 3 Mayfly
Riffle Beetle
1 1 Stonefly
Water Penny
Sub Total: 219 10
Category 2 - Somewhat Pollution Tolerant Alderfly larva
Aquatic Beetle
Aquatic Sowbug
Clam, Mussel
Cranefly Larva
Crayfish
Damselfy Larva
Dragonfly Larva
Fishfly Larva
41 3 Scud
Watersnipe Larva
Sub Total: 18 1
Category 3 - Pollution Tolerant 323 4 Aquatic Worm
Blackfly Larva
8 1 Leech
152 4 Midge Larva (chironomid)
1 1 Planarian
1 1 Pouch Snail
Truebug Adult
Water Mite
Sub Total: 337 4