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Benthic Macroinvertebrates

Benthic Macroinvertebrates. Identification. Backswimmer. Caddisfly Larva. Crane Fly. Crayfish. Damselfly. Damselfly. Dragonfly. Hellgrammite. Mayfly. Mayfly. Stonefly. Water Boatman. Water Penny. Water Strider.

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Benthic Macroinvertebrates

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  1. Benthic Macroinvertebrates Identification

  2. Backswimmer

  3. Caddisfly Larva

  4. Crane Fly

  5. Crayfish

  6. Damselfly

  7. Damselfly

  8. Dragonfly

  9. Hellgrammite

  10. Mayfly

  11. Mayfly

  12. Stonefly

  13. Water Boatman

  14. Water Penny

  15. Water Strider

  16. 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

  17. Examples: insects, snails, clams, mussels, crustaceans, worms, and leeches Large proportion in a stream are insects.

  18. 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.

  19. 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

  20. egg larva pupa adult

  21. 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

  22. egg nymph adult

  23. Complete metamorphosis orders(species) • Tricoptera (caddis flies) • Megaloptera (dobsonflies, fish flies, alderflies) • Coleoptera (beetles) • Diptera (true flies)

  24. Incomplete metamorphosis orders(species) • Ephemeroptera (mayflies) • Plecoptera (stone flies) • Odonata (dragonflies, damselflies) • Hemiptera (true bugs)

  25. Seasonal Cycle • Summer • -eggs hatch • Fall/Winter • -nymphs and larva feed and grow • Late Spring/Early Winter • -adults emerge 7

  26. 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

  27. 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

  28. 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

  29. 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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