th
20
Annual Student
GREEN Congress
“Counting Critters”
Workshop
What are Benthic
Macroinvertebrates?
Benthic
Macro
= bottom dwelling
= large enough to see with the naked eye
Invertebrate
= without a backbone (could be a clam, a worm, a
crab, or an insect, for example)
Often refer to them as “stream bugs”
Big Diversity of Benthic
Macroinvertebrates
Stonefly
Leech
Black fly larva
Mayfly
Caddisfly
Gilled snail
Cranefly
Crawdad
Midge
Dragonfly
Mosquito
Why Do We Monitor
Stream Bugs?
Chemical WQ data offers good, but limited
information.


Only a “snapshot” view of conditions
Doesn’t measure “biology”
Biological
Assessment
 Use
living organisms to tell us something
about the environment
Why Use “stream bugs” in
Bioassessment of Streams

Abundant

Diverse

Sedentary
Plus, They Have the Same Habitat
Needs as Salmon
 Clean,
cold, oxygenated water
 Connected migration paths
 Habitat features for spawning and
rearing
 Dependable stream flows
Stream Bugs
Tell A Story

No “good” or “bad” bugs

Presence or absence can be indicators of
good or poor stream health.

Diversity (not total number of bugs) = Healthier
sample
How Do They Tell The Story?
“Benthic

Index of Biological Integrity”
B.I.B.I.
10
“metrics” indicating stream health
10 Metrics










Mayfly
larva
Taxa richness
# mayfly taxa (Ephemeroptera)
# stonefly taxa (Plecoptera)
Stonefly
# caddisfly taxa (Trichoptera)
larva
# long-lived taxa
# intolerant taxa
Caddisfly
% tolerant taxa
larva
% predators
# clinger taxa
Caddisfly
% dominance (3 taxa)
case
Taxa Richness
Stonefly
Leech
Black fly larva
Mayfly
Caddisfly
Gilled snail
Cranefly
Crawdad
Midge
Dragonfly
Mosquito
% Dominance (3 taxa)
Tolerant species
Intolerant species
bloodworm
Ephemeroptera
Plecoptera
leech
Plecoptera
netspinner caddisfly
Trichoptera
Number of Intolerant Taxa
lepidostomatidae caddisfly
Dobsonfly larva
Gilled snail
Water penny
Riffle beetle
ephemerellidae mayfly nymph
capniidae stonefly nymph
% Tolerant Taxa
black fly larva
leech
Midge larva
bloodworm
baetidae mayflies
netspinner caddisfly
Number of Clinger Taxa
Water penny
Mayfly nymph
Stonefly nymph
Alderfly
Caddisfly larvae –
Caddisfly
Riffle beetle larva
Number of Long-Lived Taxa
Pteronarcys
stonefly
Dragonfly nymph
Dragonfly
nymph
Alderfly larva
Gilled snail
Number of Mayfly Taxa
(Ephemeroptera)
Number of Caddisfly Taxa
(Trichoptera)
Number of Stonefly Taxa
(Plecoptera)
% Predators taxa
Great diving beetle
Rhycophila
caddisfly
Stonefly larva
Dragonfly
larva
water beetle
Computing the B.I.B.I.
 Example:
Taxa Richness
0-20 taxa = low (1)
21-40 taxa = moderate (3)
40+ taxa = high (5)
Computing the B.I.B.I.










Taxa richness
# mayfly taxa (Ephemeroptera)
# stonefly taxa (Plecoptera)
# caddisfly taxa (Trichoptera)
# long-lived taxa
# intolerant taxa
% tolerant taxa
% predators
# clinger taxa
% dominance (3 taxa)
1
1
1
1
1
1
1
1
1
1
3
3
3
3
3
3
3
3
3
3
5
5
5
5
5
5
5
5
5
5
Computing the B.I.B.I.











Taxa richness
3
# mayfly taxa (Ephemeroptera) 5
# stonefly taxa (Plecoptera)
3
# caddisfly taxa (Trichoptera)
1
# long-lived taxa
1
# intolerant taxa
3
% tolerant taxa
1
% predators
3
# clinger taxa
5
% dominance (3 taxa)
5
TOTAL:
30
Final B.I.B.I. Scores*
Caddisfly
10 – 16 = Very Poor
 18 - 26 = Poor
 28 – 36 = Fair
 38 – 44 = Good
 46 - 50 = Excellent

Stonefly
*10 Metric B-IBI Score used by Mindy Allen
When in the Field….
Observe: land use, canopy cover…etc.