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Then let’s discuss aquatic macroinvertebrates. I observed more variety and greater numbers of insect larvae in the warmer sections of the river. Of course, I know that insect distributions are affected by more than just the water temperature. The river’s sediment and the rate the water is flowing are other important factors. Now I realize the thermal runoff adds bicarbonates to the river which increases plant growth on the bottom of the stream. This means there is more food available and more surfaces for bottom-dwelling creatures to attach themselves.

In streams affected by thermal pollution, the respiration and growth rates of certain species of macroinvertebrates sometimes change, as well as their feeding rates and reproduction patterns. This dovetails with observations made here in Yellowstone. The macroinvertebrates in the thermally influenced waters of the park vary more in shape and size than their counterparts in cooler water—and some even experience changes in life behavior.

What do you mean?

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Cast of characters - Maya Crowbes, Dr. A Beadle, Gray Fischer, Viola DeRama
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Q: How are macroinvertebrates in streams affected by thermal pollution?

GLOSSARY: respiration—the physical and chemical processes by which an organism takes in and uses oxygen and emits carbon dioxide

dovetail(s)—to fit or coincide with

counterpart(s)— a person or thing that closely resembles another