Cataract Canyon Crystal Waters

By: Kate Savage

No matter how magnificent they are, the rivers of the West are more or less made out of mud. Those Grand Canyon walls? Petrified mud. And the grounding base of life in this place is made up of wriggling mud-bugs.

By ‘mud-bugs’ I mean the larval form of aquatic insects: mayflies, caddisflies, stoneflies, dragonflies and damselflies. They’re the ones mimicked in fly-fishing lures, the ones we think of as gliding gracefully through the air, rays of river sun through transparent wings. But their flying life is merely one last hoorah for them. In fact, some of those fliers don’t even have functional mouthparts, since they’ll only live long enough to mate and lay eggs.

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Source: Wikimedia Commons

For the vast majority of their lives they crawl along the river bottom, grappling the underbellies of stones. Out of our sight and out of our minds. But present for the fish, who depend on them, hunting them out from underneath their rock shelters.

And so when whole groups of aquatic insects mysteriously disappeared downstream of the Glen Canyon Dam, ecologists took note. As flying adults, these insects are food for birds, bats, and spiders. In their larval form, they feed endangered and threatened fish, including the largest remaining population of endangered humpback chub. (As a note: the humpback chub is a delightful fish that appears to have been given a head too small for its body. Another thing I’ve learned: no matter how much you respect this fish, it’s not a good nickname for your friends or lovers.)

If the mud-bugs go, the chub will likely follow. The very foundation of an ecosystem has been kicked out from underneath it. What can be done?

Searching for survival downstream from the dam

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Source: Wikimedia Commons

As long as the decision-makers are humans instead of chub, it’s unlikely that mud-bugs will be chosen over energy production. The dam will likely stay. So we could just give up, says Jack Schmidt, with the US Geological Survey: “We could just walk away from this place as a society, and say well we put all these dams here, we’re not even going to try to have a healthy natural environment.”

But Schmidt and the other scientists with the USGS are clever and good-hearted, and went searching for another option. Their question: even if we keep the dams, are there ways to manage them to support aquatic insect populations?

At this point they ran into another problem: to understand how different dam behavior affected mud-bugs, they needed huge numbers of samples taken in an extremely remote area, reachable only through river trips. While some of us might think it’s a wise investment to fund armies of rafting entomologists, once again, we’re likely not the ones making these decisions.

So in order to even gather the data to figure out clever solutions, the USGS had to figure out new clever solutions.

They wound up with river guides. A number of river guides became Citizen Scientists, meaning they were trained in the basics of taking scientific samples of insect populations, labelling them well, and getting them back to the USGS. They did this more than 2,500 times in the Colorado River downstream of Glen Canyon Dam.

Data was also collected by youth groups going through the river with Grand Canyon Youth. (Carol Fitzinger, an ecologist with USGS, notes that the program also gave kids a deep interaction with ecosystem science, leaving them with a sense of awareness of place that will stick with them. I dare you to watch the video and not cry.)

And armed with all that rich data, the USGS scientists went to work. And they found hope.

Hope to end hydropeaking

What’s important is what happens at the water’s edge.

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Most of the insects that have disappeared in this area are the ones who lay their eggs at the edge of a river, just underwater. For six million years or so, the Colorado River was a perfect place for this strategy, which species like the mayfly have been honing for 100 million years or so.

Plunking a dam into this canyon changed all of that. The water coming out of the dam is cold now, and it’s been cleared of all the sediment it dumped into the reservoir. It doesn’t follow the yearly flood patterns. All of these things issues are obstacles for native species.

But there’s one obstacle bigger than all the rest, when it comes to the mud-bugs. It’s called ‘hydropeaking,’ and it’s happens because of our fluctuating energy needs. During peak energy use hours, the dams will release huge amounts of water, which tapers off during slower times. It’s a kind of artificial tide, and no organisms have had time to adapt to it.

A female caddisfly experiences the whole thing like this: she hatches out of their larval form, winged and out of the water, without a mouth and with only a week or two left to live (which, to be fair, seems an eternity compared to hours or day an adult mayfly’s got). She does her business, mating mid-air, and then hurries to the river’s edge. She lays hundreds of eggs, cementing them in a gelatinous mass just under the surface of the water.

And then she dies, having done her duty. But within minutes or hours of that egg-laying, the dam tapers off energy production and the river level plummets. The egg sac is now hung out to dry, and drying means dying. And that’s curtains for the next generation of caddisflies.

But the awful consequences of this one practice points to the possibility of change. The scientists are showing: even if the dam stays, even just going several days without hydropeaking (perhaps during the weekend, when energy demands are milder) could give bugs — and therefore chubs — a fighting chance.

This upcoming river season this Glen Canyon Dam focused project will be expanded to the entire basin and similar studies will begin in Dinosaur National Monument. New guides, including those with Holiday River Expeditions will join in this new round of citizen scientists; this time with a greater focus on getting some baseline information to understand the differences between the canyons across this great plateau.  Who knows, other endangered fish in the upper drainage, like the Razorback Sucker could benefit in the near future.  With a whole new team of ecosystem keepers, we could be seeing a literal shifting tide for Flaming Gorge Dam as well.

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This is reasonable. This is doable. So here’s a thank you note to the scientists who dug through the data to find some hope, and to the rafters and guides who got them that data. In Jack Schmidt’s words: “I tell ya, none of the science that we’ve done down here in Grand Canyon could ever have been conducted without the full support of the guides who make it possible for us to work here.” Hopefully we can create the same citizen science culture in the Upper Basin in Dinosaur National Monument, and see a truly inter-connected, and nuanced web of ecosystems spanning a watershed. 

Kate-Corgi-shotWritten by Kate Savage, desert wanderer, river lover and freelance writer.  Check out Holiday’s River Currents blog for more of Kate’s writing soon!

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