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Most stream insects have an annual turnover—once a species hatches, the entire population disappears from the water in a short period of time and doesn’t grow back until the following year. However, in thermally influenced areas, some of these stream insects are actually producing two times a year! For example, a certain caddisfly, which emerges from cold water streams in March or April, is also hatching from the Firehole River in November!

Oh, wonderful.

Doc, our Firehole investigation started when Viola DeRama expressed concern about the EPT species in Obsidian Creek. How do the Firehole EPT critters fare?

I observed that many mayflies seemed to prefer the cooler areas of the river, while caddisflies were thriving in the warmer, bicarbonate enriched zones. Naturally, there was considerable variation within these groups. I didn’t see certain types of caddisflies at all in the warmer waters, while several of the smaller-sized species of caddisflies were only found there.

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Cast of characters - Maya Crowbes, Dr. A Beadle, Gray Fischer, Viola DeRama
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Q: Can stream insects reproduce in thermally influenced areas?

QUIZ 3 of 4: Questions 21-30 (12KB pdf)