EXPERIMENT VII - What is in the Source Water

Freshwater biomes include lakes, ponds, wetlands, and rivers. Most aquatic organisms live near the surface where nutrients and oxygen are plentiful. Different types of communities of organisms dwell successfully in bodies of freshwater, depending on temperature, humidity, and amount of light. Some freshwater invertebrates are protists, green algae, and monerans (bacteria and blue-green algae). Other invertebrates, such as mayflies, stoneflies, snails, riffle beetles, crayfish, and caddisflies, may also be abundant.

Bioassessment is a technique used to monitor water quality. This type of testing is a supplement to chemical testing. Usually different species are found in differing proportions and can be used as indicators of water quality. Some tolerant species 2-72 can survive drastic changes in conditions. Other intolerant species are affected even by small amounts of pollution. Populations change when water quality changes.

Material Needed:

  • Jars
  • Sample of “pond water”
  • Sample of “stream water”
  • Medicine dropper (per group)
  • Microscope (per group)
  • Slides with cover slips
  • Kick nets or D-ring nets
  • Distilled water
  • Jars and labels
  • Rice
  • Wallpaper paste


  1. Go over the different zones in a pond that support life.
  2. Prepare microscope slides of pond and stream water using medicine droppers and cover slips.
  3. If testing five-day-old pond water samples, add a few rice grains to each jar to feed organisms.
  4. Compare and contrast the results for different samples and determine water quality.

In this experiment you will observe pond and stream water samples for microorganisms and macro invertebrates present in those aquatic ecosystems. Categorize and compare the types of microorganisms in pond samples and stream samples. You can then determine which ponds have a more sophisticated ecosystem and a more abundant source of life. More importantly, have some fun with this experiment and don't be afraid to feed the amoebas!

These are Common Freshwater Organisms

Fish Organism

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