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Aquatic Macroinvertebrate Monitoring

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[Sound of running water, the feeling of being outside next to a stream] Kelly Reeve: Stacy Stumpf sometimes devotes nine hours a day to gathering insect larvae from streams. And the water can be cold. Stacy Stumpf: You warm up on the hike in, but once you get down there, it’s like a refrigerator. KR: Stacy is an aquatic ecologist with the National Park Service, and today he and his crew are canvassing a mountain stream in Bandelier National Park in New Mexico. Their goal is to collect as many species of aquatic macroinvertebrates in the stream as possible. These aquatic macroinvertebrates, which are mostly insect larvae attached to the cobbles and debris in the stream, so to ferret them out of their hiding places, the crew uses a three-pronged scraper to dig through the stream bottom. Any aquatic macroinvertebrates that they set free will float into the big net just downstream. And after they do this at five riffles, Stacy hoists the net and gets ready to use it to take samples from every type of habitat along the entire length of the reach. SS: ...so riffles, pools, leaf packs, algal mats, woody debris, any place that there might be a bug, we sample. [Sound of walking through water... Male voice: ...cobbles, fast and shallow... Sound of wet net being lifted out of the water, water dripping back into stream] KR: When he’s done sampling, his net is full of wet leaves and sticks. He places handfuls of them in a sieve and then washes them off that he can pick out those aquatic macroinvertebrates. [Sound of water being poured through the sieve, sieve shaken back and forth rapidly, more water being poured] SS: So we’re just trying to wash the leaves [sniffles] and all the sediments so that these guys get knocked loose. And then that makes it easier to pick it, because you can see [chuckle]... KR: [chuckle] So cool ! SS: ...thousands of leaves. So... KR: The aquatic macroinvertebrates in the sieve look like translucent worms crawling through the autumn leaves and dark brown debris. Some are as thin as pine needles and maybe an inch long, but they come in all sizes. And sometimes they just leave cases made up of small stones or sticks. [Male voice: Whoa ! Female voice: ...wow... Male voice: ...look at him!... Female voice: ...beautiful... Male voice: ...wow... ] KR: Stacy places the aquatic macroinvertebrates he’s picked into a jar of alcohol. And then, later, entomologists will identify the species of each bug. [Female voice: Look at all those stone flies... ] KR: Stacy and his crew will be collecting aquatic macroinvertebrates at the same site, year after year, to track changes to the communities. This is their forth year and they’re doing the same sampling at 12 other sites in national parks on the Southern Colorado Plateau. SS: To pick up long-term datasets on particular vital signs within the park is, I think, a rather unique idea. You know, in our eyes, we hope 100 years down the line people are still collecting this data in a similar manner, and they can compare it to what we did, that’s pretty cutting edge and there should be a lot of information that can be gained from that kind of data. KR: They’re monitoring aquatic macroinvertebrates because they are a good vital sign of the health of the streams. SS: They’re something that’s easily measurable and found in all streams on the Plateau where there's water. And so a lot of insect organisms lay their eggs in the streams. The streams provide the beginning life stages for these organisms. They’re found in nearly every freshwater ecosystem so they’re a really good thing to track. KR: And they’re also an essential link in the stream food web. They eat pieces of overhanging plants that fall into the streams, and they also eat the algae and bacteria that grow in the water. They’re the primary food for most fish. And they are sensitive to changes in the water flow and pollution. SS: Like in the Mancos last year, there was a fire upstream on a mulching company’s property and they dumped a bunch of sediments and organic material into the stream. So we have three years of data from that season that shows what the community was like, and then we got in right after that to collect samples to see how that might have affected it. So when things like that happen, we can get out into the field, hopefully, in enough time to see how the communities reacted, and then use that dataset against our long-term dataset to see how it differs. KR: Besides just collecting macroinvertebrates, the crew also evaluates the available habitats in the stream. The habitat data helps them understand how the stream itself is changing through time. So, at transects across the stream, the crew will measure the stream’s velocity, its depth, the plants on the banks, and how much canopy there is. [Sound of running water... Male voice: What's your depth ? Female voice: ...point zero, six, I'm on a rock... KR: And how many do you do? How many transects? Just the one? SS: Eleven. KR: Oh!] KR: And then, finally, two crew members will walk the length of the stream picking up 400 pebbles and calling out their diameters to the person recording the data on shore. [Sound of running water and walking through water Female voice: ... seven... Male voice: ...thirty-five... Female voice: ...thirty- two... ] KR: So you do a lot of work [laughs] at each reach. SS: Yes ! Yeah, it takes about nine hours to complete. KR: Fieldwork on these streams is not always so uneventful. SS: [Laughs] We got caught in a flash flood in Coyote Gulch, that ended up being the beginning of a death march, through the desert, in the dark. I think we got up on the rim probably around 8:30, and it was 12:30, 1 o’clock when we got back to our cars [laughs]. We had wandered so far out of the way before we realized where we were, and we forgot to take a GPS point of where we parked the truck, so that was our downfall. We were all guessing for a good couple hours where we were. When you're lost, and it's dark, and you're wet, and you have no dry clothes, in your head, you’re thinking, well, if we have to sleep out here it’s going to be a really, really long night. So... [laughs]. KR: For Stacy, aquatic macroinvertebrate sampling also has other benefits. KR: Do you have a favorite site? SS: Oh, it changes from year to year [laughs]. I really like working on [pause] in Glen Canyon on the Escalante. Those streams cut through some of the most beautiful and scenic canyons in the Southwest. Plus they’re not as hard to get into, like Grand Canyon [laughs]. There’s more reward with little effort [laughs] compared to Grand Canyon. KR: But ultimately, Stacy says that helping national parks protect their streams and rivers is really the most satisfying part of the job. SS: We’re providing the parks with information that they would otherwise not have. And, you go to a lot of parks, and they’re so understaffed that if there is data that’s collected in the park, it's in spreadsheets on someone’s computer, or in a filing cabinet somewhere, and no one can do anything with it. So we have a program in place across the Park Service now, where we can actively collect data, analyze it and provide useful information to the parks. KR: Without that data, national parks might not know if the health of their streams is declining. But, with the long-term monitoring data, they can spot problems and then try to fix them. The goal is to keep the limited water in the Southwest clean and healthy for all the life in the national parks. [Sound of a babbling stream... ]

Description

Aquatic macroinvertebrate assemblages are monitored annually along 1–3 reaches of selected streams in five parks in the Southern Colorado Plateau Network (SCPN). In this podcast, recorded in October 2010, SCPN aquatic ecologist Stacy Stumpf explains why monitoring aquatic invertebrates helps parks to protect streams.