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
EGG
LARVA
ADULT
PUPA

10. Examples – Insects Life Cycles
EGG
NYMPHS
ADULT

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