1 benthic macroinvertebrates identification. 2 backswimmer
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Benthic Benthic MacroinvertebratesMacroinvertebrates
IdentificationIdentification
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BackswimmerBackswimmer
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Caddisfly LarvaCaddisfly Larva
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Crane FlyCrane Fly
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CrayfishCrayfish
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DamselflyDamselfly
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DamselflyDamselfly
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DragonflyDragonfly
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HellgrammiteHellgrammite
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MayflyMayfly
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MayflyMayfly
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StoneflyStonefly
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Water BoatmanWater Boatman
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Water PennyWater Penny
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Water StriderWater Strider
benthic macroinvertebrates- animals without a backbone, visible to the unaided eye, living in or on the stream bottom
•one of the best indicators of stream health
•present throughout the year
•population reflects environmental changes
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Examples:
insects, snails, clams, mussels, crustaceans, worms, and leeches
Large proportion in a stream are insects.
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Insects go through metamorphosis (life changes) from egg to adult.
Due to these life cycles, the size and abundance of insects present in a stream will vary with the season.
Insects have a rigid exoskeleton that must be replaced in order for them to grow.
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complete metamorphosis- 4 stages
(88% of all insects)
egg- female insect lays eggs
larva- hatch from egg, usually worm-like shape, do not look like adult
pupa- inside a cocoon, larva develops adult shape (4 days to months)
adult- emerges from cocoon
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egg
larva
pupa
adult
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incomplete metamorphosis - 3 stages
(12% of all insects)
egg- female lays eggs
nymph- looks like small adult, usually without wings, molt exoskeleton 4-8 times
adult- insect stops molting when adult size is reached and now have grown wings
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eggnymph
adult
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Complete metamorphosis orders(species)
• Tricoptera (caddis flies)
• Megaloptera (dobsonflies, fish flies, alderflies)
• Coleoptera (beetles)
• Diptera (true flies)
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Incomplete metamorphosis orders(species)
• Ephemeroptera (mayflies)
• Plecoptera (stone flies)
• Odonata (dragonflies, damselflies)
• Hemiptera (true bugs)
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Seasonal Cycle
• Summer -eggs hatch
• Fall/Winter
-nymphs and larva feed and grow
• Late Spring/Early Winter-adults emerge
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Stream Communities and Feeding Groups
•Shredders-macroinvertebrates with chewing mouth parts
-feed on decaying organic matter processes into finer particles
-aquatic sowbugs, a few caddisfly larvae, some cranefly larvae, scuds, and most stonefly nymphs
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•Grazers / scrapers
-feed on algae
-most caddisfly larvae and water pennies
-changes in habitat result in an increase of grazers with a decrease of shredders
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•Collectors
-feed on fine organic particles
-blackfly larvae, most caddisfly larvae, mayfly nymphs, midge larvae, riffle beetles, and riffle beetle larvae
-collectors are found in all stream regions, but are dominant in the lower regions of a stream system
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•Predators
-feed on prey
-alderfly larvae, backswimmers, most beetles and beetle larvae, damselfly nymphs, dobsonfly larvae (hellgrammites), dragonfly nymphs, fishfly larvae, some stonefly nymphs, and some cranefly larvae
-predators are found in all stream regions (wherever prey is found)