STEVE INSKEEP, HOST:
Now let's meet a scientist who gets to work in a national park. The park service is 100 years old. So we're reporting this year on its employees. The many parks are destinations for millions of tourists. They are also places where researchers can get a clear view of our environment. That is the job this scientist has been doing alongside NPR's Nathan Rott in the Great Smoky Mountains National Park.
NATHAN ROTT, BYLINE: All right, put on your waders and foam-soled boots. And let's go wade out into a shallow shaded creek. Now, before we get too deep let's introduce our guide.
BECKY NICHOLS: My name is Becky Nichols. I've been in the park now for almost 20 years.
ROTT: Wading knee-deep into creeks and streams like this all around Great Smoky Mountains National Park.
NICHOLS: So this ripple right here should be a good one.
ROTT: Nichols unrolls a rectangular net like a poster, shoving two wooden poles on other side into the creek bed, submerging the bottom of the net.
NICHOLS: So if I get that down in there, then maybe you could hold that.
NICHOLS: And I'll disturb the substrate.
ROTT: Which is a real fancy way of saying she's kicking rocks upstream. This is called kick netting, #science.
NICHOLS: All right, let's see if we caught anything.
ROTT: We walk the net to the shore and look at the collected goop at bottom.
Like the stuff you'd pull out of a gutter, right?
NICHOLS: (Laughter) Yeah.
ROTT: And in that goop, bugs. Nichols is an entomologist. She studies insects.
NICHOLS: There's a nice one.
ROTT: Yeah, what's that?
NICHOLS: That's a stone fly.
ROTT: A big old guy.
NICHOLS: Isn't he pretty?
ROTT: If I showed that to a lot of people, I don't know if pretty would be the first word that came to their mouth.
She pulls out caddisflies, mayflies, crawfish and puts them in a white dish. She'll take these insects to a lab, count them, categorize them and add them to a list of more than a thousand different tiny aquatic insect species found here in the park that tell a much bigger picture. They're the proverbial canary in the coal mine. By documenting the variety and number of them in the same stream over decades...
NICHOLS: The insects can tell us about the stream health.
ROTT: And how or if it's being affected by issues like pollution, acidification, invasive species or climate change.
NICHOLS: Everything we see here is an indicator of good water quality.
ROTT: This is a healthy stream. Nichols says that's the case for most of the waterways here in Great Smoky Mountains National Park. That's not to say that all of the waterways here are healthy. There are non-native fish, pollution, acid rain caused by bad air quality.
But by and large, things are pretty good, which is one of the main reasons that streams in other largely undisturbed ecosystems in national parks like the Great Smokys (ph) are so important for researchers and scientists.
NICHOLS: It can serve as a baseline, perhaps, for other areas.
ROTT: This is where you want to be.
NICHOLS: Yeah, the best example of what a stream should be.
ROTT: By having that example, that baseline, a biologist or a state or a mining company tasked with restoring a stream has a target to aim for, a target that's as close to normal as it can be. Nathan Rott, NPR News, Great Smoky Mountains National Park. Transcript provided by NPR, Copyright NPR.