Part 2: Biotic Indicators Fresh Water Studies: Water Quality & Living Organisms

Part 2:

Biotic Indicators

Fresh Water Studies: Water Quality & Living Organisms

How do abiotic factors affect freshwater organisms?How do abiotic factors affect freshwater organisms?

How do abiotic factors affect freshwater organisms?

Temperature



Optimal Temperature Range

Organism Temp(°C)

Trout 5-20

Smallmouth Bass 5-28

Caddisfly larvae 10-25

Mosquito larvae 10-25

Carp 10-25

Catfish 20-25

Temperature



Dissolved Oxygen



Dissolved Oxygen

Minimum DO Requirements

Organism DO (mg/l)

Trout 6.5

Smallmouth Bass 6.5

Caddisfly larvae 4.0

Carp 2.0

Catfish 2.5

Mosquito larvae 1.0



pH



pH

Effects of pH on aquatic life

pH___________Effect__________________

4.0-4.5 All fish, most frogs, insects absent

5.0-5.5 Bacteria die. Detritus accumulates, locking up essential

nutrients.

6.5-8.2 Optimal for most organisms

11.0-11.5 Rapidly lethal to all species of fish



Total Dissolved Solids (TDS)



Total Dissolved Solids (TDS)

Natural TDS come from rocks and soil from the watershed that drains into the stream, river, pond or lake. Changes in TDS can indicate a problem. If salts are high, dehydration occurs. Solids cause a laxative effect. Dissolved minerals can affect the pH, raising or lowering depending on the ions present. Range: 50-250 mg/l



Turbidity



Turbidity

High turbidity decreases sunlight which decreases the rate of photosynthesis. Water that is highly turbid will warm faster, decreasing the dissolved oxygen available for respiration of all organisms.

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Includes

• Insects

• Crustaceans

• Mollusks

• Sensitive to Changes

• Cannot easily escape changes

• Collected very easily

What do macroinvertebrates do?

Job Example

• Predators dragonfly, damselfly, beetles

• Filter feeders mussels, fly larvae, midge larvae

• Scrapers snails, mayfly larvae

• Collectors worms, planarians

• Shredders amphipods, caddisfly larvae

Group A: Very sensitive to Environmental Stresses

Stoneflies Mayflies Caddisflies Dobsonflies Water penny

Group B: Somewhat sensitive to Environmental Stresses

Dragonflies Craneflies Damselflies Crayfish Scuds

Group C: Tolerant to Environmental Stresses

Midges Leeches Snails Pouch Snails Blackfly larva

Conclusion:

• Freshwater organisms-the Biotic part of the Freshwater environment- have “Limits” or “Optimal ranges” in water quality where they prefer to live.

• The quality of water can be determined by what and how many organisms are living in that environment.

• Macroinvertebrates are used to evaluate the quality and history of the water environment.

Image credits-Used with permission

1-17 R.B. Elder18-25 Norbert Hamm26-32 Norbert Hamm

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Part 2: Biotic Indicators Fresh Water Studies: Water Quality & Living Organisms