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Biomonitoring
the study of biological organisms and their responses to environmental conditions; can be fish, algae or insect communities
Benthic macroinvertebrates Benthic = Live on or in bottom
substrate Macro = Large enough to be seen
with unaided eye Invertebrate = Animal without a
backbone
Why study macroinvertebrates? Affected by the physical, chemical
and biological conditions of stream Can’t escape pollution - show the
effects of short and long-term pollution events
Can show the cumulative impacts of pollution
May show the impacts of habitat loss
Why study macroinvertebrates? Critical part of the stream’s food
web Relatively easy to sample and
identify (easier than algae) Have greater diversity in stream
than fish - sport fishing, stocking of fish and exotic species have altered fish community
IDENTIFICATION
Key identification features Overall body shape (NOT SIZE) Case made of sticks, leaves, stone Legs Presence and location of gills Presence and location of cerci (“tails”) Head capsule, unusual appendages Movement (crawl; swim side-to-side, up-
down)
Body shape
Case
Legs and prolegs
Caddis removed from case
Prolegs on midge
Gills
Mayfly (Speckle-Winged Quill, Callibaetis)
Cerci (tails)
Baetis has center tail that is ½ length of outer tails
Head capsule
Stoneflies (Plecoptera) Sensitive
Nymphs: Two distinct "tails" called cerci, which are actually
sensory feelers Usual movement = crawl; swim side-side Insect nymphs with three pair of jointed legs,
each with paired claws. Two pair of wing pads (developing wings) present
on thorax. No gills along abdomen Length up to 3 inches
Stonefly nymph (Golden stone)
Stoneflies (Plecoptera) Sensitive
Feeding types: Predator Shredder Omnivore
Adults: resemble nymphs, but possess a long pair of wings
folded down the length of the body.
Eaten by a variety of fish species
Stonefly adult (Little Yellow Stone)
Mayflies (Ephemeroptera) Sensitive
Nymphs: Three tails, occasionally two Gills usually visible on abdomen Typical movement = crawl, swim (up-
down) Small - Total length < 1 inch
Mayfly nymph (Pale Evening Dun)
Head is widest part of body
Mayfly nymph (Small Yellow May)
Nymph with only two tails
Head is widest part of body
Mayflies (Ephemeroptera) Sensitive
Feeding Types: Collector-Gatherers Scrapers
Adults: Resemble nymphs with two pair of long, lacy wings
folded upright Adults usually have only two tails (cerci)
Food for fish and predatory macroinvertebrates
Mayfly adult
Mayfly adult (Hexagenia)
Caddisflies (Tricoptera) Sensitive
Larvae: Soft “worm-like”bodies Head contains a hard covering Larvae are known for their construction of
hollow cases that they either carry with them or attach to rocks built from twigs or bark, small stones, or rolled leaves used for protection and pupation
Anal hooks usually present Large - Length up to 2 inches
Caddisfly larvae w/ caseOctober caddis
“Free-living” CaddisflySpotted sedge
Branched gills on abdomen
Caddisflies (Tricoptera) Sensitive
Feeding Types: Predators Grazers Collector-Gatherers
Adults: “Moth-like”; usually nocturnal Wings fold into “tent” on back
Eaten by fish and by some macroinvert predators
Collector-FilterersScrapersShredders
Caddisfly adult (October caddis)
Water Pennies (Coleoptera)Sensitive
Circular-shaped Attach firmly to
rocks Sensitive – need
high oxygen and fast flowing water
MegalopteraSensitive
Dobsonfly/ hellgrammites (Corydalidae) Large mandibles 2 short “tails” Predator
Alderfly (Sialidae) Long, single “tail” Predator
OdonataWide range
Damselfly 3 fan-shaped
caudal gills
Dragonfly Robust body Well-developed
“jaws”
Crayfish (Decapoda)Wide Range
4 pairs of walking legs
Large pair of pinchers
Up to 6 inches
Scuds (Amphipoda)Wide Range
“Shrimp-like” 14 feet Prefer muddy
substrate with rooted vegetation
Cranefly (Diptera)Wide Range
Worm-like Head capsule,
usually retracted into “accordion-like” body
Shredders
Midge Larvae (Diptera)Tolerant
Pear-shaped body, with swollen base where they attach
Filter feeders
Snails (Gastropoda)Tolerant
Cylindrical shell May be right or
left handed
OthersTolerant
Worms (Oligochaeta) Segmented
bodies
Leeches (Hirundinea) Suckers at both
ends
Identification
Green Rock Worm (Tricoptera)
No case Predator Found in
riffles
Only first thoracic segment has hard shell
Pair of anal hooks
Riffle Beetle (Coleoptera) Hard shelled, tube-
shaped larvae Found in riffles No tails or anal hooks
Gills concealed in chamber at rear of abdomen
Midge Larvae (Diptera) Head
capsule No jointed
legs Variety of
colors Prolegs on
1st thoracic and last abdominal segments
ProlegsProlegs
Data Analysis Data collection is key Level of ID determines level of analysis Score (5) vs. interpretation (“POOR”) Use the same data analysis tool for
comparing data Local-scale tool most accurate
Requires time High quality “reference” sites
Pollution Tolerance Index National-level tool ID to Order 3 groups
Pollution Sensitive (3 pts) Wide Range (2 pts) Pollution Tolerant (1 pt)
Data limited since # organisms not considered
Example PTI calculation
Organism # PTI
Midge (Diptera) 11 1
Scud (Amphipoda) 57 2
Periwinkle (Tricoptera) 3 3
Snails (Gastropoda) 14 1
Waterboatman 5 1
PTI = (1x3)+(1x2)+(3x1) = 8 (POOR)
Hilsenhof Biotic Index (HBI) Considers organic pollution ID to Family or lower 10-point scale where:
0 = most sensitive 10 = most tolerant
# organisms is considered Sometimes included as 1 metric in a
multi-metric analysis, such as IBI
Hilsenhof Biotic Index (HBI)
HBI = (Taxa count) (HBI score)(Total count)
Rating:
0 - 2 2 - 4 4 - 7 7 - 10
CleanSlightly
EnrichedEnriched Polluted
Example HBI calculation
Organism # HBI
Midge (Diptera) 11 8
Scud (Amphipoda) 57 4
Periwinkle (Tricoptera) 3 4
Snails (Gastropoda) 14 7
Waterboatman 5 8
HBI = (11x8)+(57x4)+(3x4)+(14x7)+(5x8)90
HBI = 5.18 (POOR/Enriched)
Biometrics
“Biometric” - a measure of some characteristic of the biological community
Taxa Richness and Composition EPT
Tolerance and Intolerance HBI
Feeding Ecology % or abundance of functional feeding groups
Population Attributes dominance
Family-level metrics Taxa Richness (# diff taxa identified) Mayfly Taxa Stonefly Taxa Caddisfly Taxa % Diptera HBI
Multi-metric indices Include several (usually 5-10)
metrics Combined, they measure various
aspects of stream health Examples:
Index of Biological Integrity (IBI) State of Oregon Multi-metric Index