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