1. Benthic Macroinvertebrate and Pollution Tolerance

2. Questions from reading
Describe the environment in which you would find organisms from Group 1.
Describe the environment in which you would find organisms from Group 4.
2. What organism is considered to be the canary of clean water and why?
3. What factors in a relatively polluted environment may actually support pollution-tolerant organisms?
4. In what portion of the stream do most benthic macroinvertebrates live?

3. What is benthic?
Means bottom dweller

4. Benthic Macroinverts and Water Quality
Used as indicators of water quality
Separated into four groups
We count the number of species per group
Most pollution tolerant group is weighted heavily (multiply by a larger number)
Least tolerant weighted most lightly (multiply by a smaller number)
The greater the number the more polluted the river

5. Pollution tolerant organisms like clean water as well as intolerant organisms, but tolerant organisms can also survive in polluted places while those others can’t.
Example: You will find leeches and other worms (group 4) in clean water as well as polluted but stoneflies (group 1) are only found in clean water.

6. Group I: Pollution Intolerant
Need high levels of D.O.
Cannot survive in habitats affected by nutrient pollution
Mostly shredders or predators
Live in clean, cold stream. Found in riffles, why?
Canary of clean water: stonefly
Dobsonfly, alderfly and snipefly

7. Group II: Moderately Intolerant
More tolerant of nutrient enrichment and drops in D.O.
As algae increase, scrapers increase (water pennies and mayflies)
Greatest number of organisms, most diverse.

8. Group III: Fairly Tolerant
Organisms can accept low levels of D.O.
Mostly scavengers and collectors
Includes sow bugs, scuds, and right handed snail (gilled).

9. Group IV: Pollution Tolerant
Very tolerant of low D.O. and severe nutrient pollution.
Most have special adaptations for breathing oxygen at surface
left handed snail: breathes air from a pouch
Bloodworms (midge larva) have hemoglobin type blood to help them move oxygen through their body