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Benthic Macroinvertebrates

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Presentation on theme: "Benthic Macroinvertebrates"— Presentation transcript:

1 Benthic Macroinvertebrates

2 Benthic Macroinvertebrates
Benthic – bottom-dwelling Macro – can be seen with the unaided eye Invertebrates – without a backbone or spinal column Examples: clams, snails, worms, crustaceans, insects

3 Question How do we know whether a stream is “healthy” or polluted?

4 Qualitative Sampling (finding as many as you can)
D net Kick the stream bed vigorously upstream Collect in different habitats Sand, silt, gravel, mud, rub large stones, overhanging banks, under overhanging brush, etc.

5 Benthic Macroinvertebrates as Indicators of Water Quality
Every species has a range of conditions in which it can survive “Tolerant” species - can survive in a wide range of conditions “Intolerant” species - are sensitive to pollution A large number of intolerant species indicates unpolluted water

6 Examples - Snails Gilled Snail (right-handed) – pollution intolerant
Lunged or Pouch Snail (left-handed) – pollution tolerant

7 Examples - Crustaceans
Scuds (Amphipods) Crayfish

8 Aquatic Worms Tubifex Worms Aquatic Earthworm

9 Examples – Insects Life Cycles

10 Examples – Insects Life Cycles

11 Insects – Mayflies Nymphs 1-2 years, Adults 1-2 days

12 Insects – Stoneflies Nymphs 1-4 years, Adults a few weeks

13 Insects – Caddisflies Use silk to make nets and cases Adults 1-2 weeks, Complete life cycle 1 year

14 Insects – Dobsonflies Larvae: a few years, Adults: 7 days
Adult Female – can bite! Up to 5” long Larva: “Hellgrammite” Adult Male

15 Insects – Craneflies Look like large mosquitoes, but do not bite

16 Insects – Blackflies Complete Life Cycle: 6-15 weeks
Larvae attach to rocks and catch food with “fans” Females feed on blood

17 Some Larva known as “blood worms”
Insects – Midges Larvae are “C” shaped, includes biting midges or “no-see-ums” Complete Life Cycle: Can be 2-3 weeks Some Larva known as “blood worms”

18 Insects – Dragonflies Predators of mosquitoes Larvae 1-4 years, Adults a few months

19 Insects – Damselflies Complete Life Cycle: 1-2 years

20 Using an Identification Key


22 Question Which of these is the most reliable indicator of whether a stream is “healthy” or polluted? Water color and cloudiness Chemical tests Litter and trash Benthic macroinvertebrates

23 Importance for Recreation

24 The Adams Fly: Invented in 1922 by guide Leonard Halladay for Judge Charles B. Adams, Mayfield Twp.

25 Benthic Macroinvertebrates

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