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Benthic Macroinvertebrate Ecology & Identification

Susan F. CushmanHobart & William Smith Colleges

Geneva, [email protected]

315-‐781-‐3599

mailto:[email protected]

http://fli.hws.edu/

Outline

I. Reason to study, definition, identifying characteristics

II. Sampling protocolIII. Identification of major groupsIV. Tier 2 analysisV. Stream habitat for macroinvertebratesVI. Aquatic food webs

Outline



Why Macroinvertebrates?

• Provide an integrated picture of stream chemistry (water quality), physical habitat, and environmental change

• Easy to collect and identify to determine potential impact

• Inexpensive equipment• Assessment models are easy to understand• Great activity to get kids involved with!

Definition

A macroinvertebrate is the term used for invertebrate fauna that can be captured by a 500-‐ m net or sieve.

This includes arthropods (insects, mites, scuds and crayfish), molluscs (snails, limpets, mussels and clams), annelids (segmented worms), nematodes(roundworms), and platyhelminthes (flatworms).

(Hauer and Resh, 1996. Methods in Stream Ecology, Academic Press, San Diego, CA.)

Presenter

Many Ecologists use net sizes 125-250micrometers due to early life stages being much smaller than 500, and therefore would pass through the net.

BMI Lifecycles

• Larval aquatic forms– Spend most of their juvenile life underwater

• Live multiple years in water

Incomplete Metamorphosis Complete Metamorphosis

Basic Anatomy

Outline



Macroinvertebrate Protocol

• Take one benthic sample per visit– Disturb debris along diagonal transect for 5 mins– Place contents of net in pan for inspection

D-‐net sampling

Outline



Major Group Analysis

Major Group: EphemeropteraCommon name: Mayflies

Tier 2 – Major Group

Presenter

Elongate body with 6 legs, distinct head, thorax and abdomen; 2 or 3 tails on abdomen Feathery gills on dorsal side of abdominal segments Wing pads present attached from thorax, may cover part of abdomen

Major Group: PlecopteraCommon name: Stoneflies


Presenter

Insect with 3 body parts – head, thorax, abdomen, 6 legs originating from thorax, distinct head Wing pads present on thorax, may have filamentous gills at the intersection of legs and thorax, but NEVER on abdomen Two tails

Major Group: TrichopteraCommon name: Caddisflies


Presenter

Insect larvae with 6 legs originating from thorax, distinct head, pigmented “exoskeleton” (sclerites) on all or some thorax segments May have feathery gills on the ventral side of abdominal segments Last abdominal segment has 2 hooked claws May be freeliving or emerge from a case

Major Group: Diptera -‐ ChironomidaeCommon name: Midges


Presenter

Soft bodied segmented worms

Major Group: ColeopteraCommon name: Beetles


Presenter

Both larval and adult stages present in stream samples Larval forms are elongated and may look like caddisflies – but have exoskeleton on all thoracic and abdominal segments whereas caddis only have hardened exoskeleton on thorax

Major Group: OligochaetaCommon name: Aquatic worms


Presenter

Soft bodied segmented worms

Biotic Index Analysis

Tier 2 – Biotic Index

Net spinning Caddisflies

Non -‐ Net spinning Caddisflies

7 10

Tier Two – Biotic Index

Major Group: MegalopteraCommon name: Dobsonfly

http://www.cals.ncsu.edu/course/ent525/water/aquatic/images/14.jpg


Major Group: ColeopteraMinor Group: ElmidaeCommon name: Riffle Beetle


Major Group: ColeopteraMinor Group: PsephenidaeCommon name: Water Penny Beetle


Major Group: ColeopteraCommon name: Other…


Major Group: DipteraMinor Group: TipulidaeCommon name: Crane Fly


Major Group: GastropodaCommon name: Gilled Snail

Major Group: GastropodaCommon name: Lunged Snail


Major Group: AmphipodaCommon name: Scud


Major Group: MegalopteraCommon name: Alderfly


Major Group: OdonataCommon name: Damselfy

Dragonfly


Major Group: DipteraMinor Group: SimuliidaeCommon name: Black Fly


Major Group: IsopodaCommon name: Sow Bug

Outline


II. Sampling protocolIII. Identification of major groupsIV. Tier 2 analysis -‐ PMAV. Stream habitat for macroinvertebratesVI. Aquatic food webs

PMA

PMA

41

03

28

19

06

03

00

100

100

100

100

100

100

100

41%

0%

28%

19%

6%

3%

3%

Outline



Hierarchical classification of stream habitats

Habitat is made more complex by: Organic matter• Large woody debris• Rootwads• Leaf packs/debris jamsChannel morphology• Geologic formations• Forces of erosion (undercutting)• Slope of the stream• Pools, riffles, runs, glides

Landscape influences• Slope of the land adjacent to stream• Landuse near the stream• Low extent of upstream environmental impacts

Habitat Complexity

Large woody debris

-‐Non-‐living logs that are found near, hangingover, or in the stream channel

Rootwads

-‐Living trees that line the streambank, whichprovide streambank stability and habitat forfish and macroinvertebrates

Undercut and eroded banks

Undercut banks are stabilized by roots and provide habitat for fish and macroinvertebrates, while eroded banks have exposed, bare soil that are susceptible to future erosion from storm events and will release sediment into the stream channel.

Pool/Riffle System-Depth-Sediment size-Flow rate

BMI HabitatPreferred habitat varies• Lithophilous taxa: stony

substrates– Ex. Water penny

(Psephenidae)• Sammophilous taxa:

sandy substrate– Ex. Tube-‐building

caddisflies(hydropsychidae)

• Burrowing taxa:– Ex. Amelytidae mayflies

• Xylophilous taxa: wood dwelling – Ex. Some beetle larvae

• Phytophilous taxa: aquatic plants– Ex. Rhyacophila caddisflies

(free-‐living)

Outline



Invertebrate consumers

Feeding Role• Shredders

• Suspension– Filter– Collector

• Deposit – Gatherer

• Grazer

• Predator

Food Resources, Examples• Non-‐woody CPOM, leaves, fungi, microbiota

– Trichoptera, plecoptera, crustacea• FPOM, bacteria, sloghed periphyton

– Net spinning trich, simuliidae (diptera), ephemeroptera

• FPOM, bacteria– Ephemeroptera, chironomidae (diptera)

• Periphyton, diatoms, biofilms– Many ephem, trich; some diptera,

coleoptera• Animal prey

– Odonata, megaloptera, some Plec, Trich, Dip, Colep

Vertebrate inhabitants of stream ecosystems

Leopard Frog

Green Frog

No. Water snake

Box Turtle

No. two linedsalamander

BlacknoseDace

CreekChub

Rosyside Dace

White Sucker

GreenSunfish

BluegillSunfish

Stream fish: minnows, sunfish, suckers, sculpins

Mottled Sculpin