Transcript Benthic Macroinvertebrates

Benthic Macroinvertebrates
Identification
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Backswimmer
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Caddisfly Larva
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Crane Fly
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Crayfish
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Damselfly
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Damselfly
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Dragonfly
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Hellgrammite
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Mayfly
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Mayfly
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Stonefly
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Water Boatman
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Water Penny
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Water Strider
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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
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 wormlike 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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egg
nymph
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)
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