Perennial Water Sources
Utah is home to over 800 rock glaciers. These masses of ice covered with rock debris are key to perennial streams and alpine biodiversity, but they are poorly understood. We talk with Scott Hotaling, Assistant Professor in the Department of Watershed Sciences at Utah State University, who is studying the rare stonefly in order to gain understanding of how alpine streams are faring as glaciers recede under a warming and drying climate.
Meet the Scientist: Scott Hotaling
Scott Hotaling is an Assistant Professor in the Department of Watershed Sciences at Utah State University. His lab studies how mountain ecosystems are being impacted by climate change including the downstream effects of receding snow and ice on water resources and biodiversity. Of particular interest to Scott and his group are rock glaciers—large masses of ice in western mountains that appear to be uniquely resilient to climate warming due to their insulating debris cover. There are approximately 800 rock glaciers in Utah including many in the Moab area. To learn more about the lab’s work, visit our YouTube channel: https://www.youtube.com/@mountainfutures.
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Interview Excerpt - Rock Glaciers
Today we are talking with Scott Hotaling, assistant professor in the Department of Watershed Sciences at Utah State University. Scott studies the rare stonefly in order to understand how alpine streams are changing as the climate warms and glaciers recede.
Science Moab: Why study the rare stonefly and what does it have to do with climate change and the melting glaciers?
Hotaling: There’s a practical reason and there’s a basic science reason. The practical reason is the National Forest as a federal entity has mandates for biodiversity protection and species get on their radar as being of conservation concern and then they need to have more information about them. This is a collaborative project with the Manti La Sal National Forest and this species is one of the species of conservation concern on their end. The basic research component is that headwaters are changing very rapidly around the world. I often like to tell people, especially in places like Moab, we all literally live downstream. And so what happens in our headwaters genuinely affects what happens in people’s lives, irrigation, gardens, what comes out of your tap, understanding how headwaters are changing and how various species or communities that live there might be affected by climate change is a very important broad scale goal.
And so these species like galfinia cristata, which is the stonefly that we’re talking about, they’re indicators. If it’s lived in these headwaters for a long time and something is now changing with snowpack or how the streams are flowing, whether or not they’re actually flowing year round is really critical, then that’s going to impact the stonefly, which is in turn going to tell us something about how these habitats are changing.
Science Moab: Does the stonefly necessarily need to be in a stream that is part of a receding glacier?
Hotaling: I would argue that the La Sals have a glaciated present, not just past. So the La Sals are full of these things called rock glaciers. Rock glaciers are masses of debris-covered ice that are flowing downhill. they’re perennial, they stick around year to year, and they are critical to water resource availability, especially in the La Sal mountains. These rock glaciers provide a perennial water source that allows species to live there. Most stoneflies, especially those in the mountains, are not going to live in a stream that dries out. So a rise in the intermittency of mountain streams is perhaps one of the biggest risks to biodiversity in these places, including for this stonefly.
Science Moab: you’re saying that underneath a lot of these debris flows there is perennial ice?
Hotaling: Yes, there is a lot of perennial ice. We know that because these features move, that they’re actually actively shifting downhill and deforming centimeters per year, every year. And we can tell that from satellite imagery and other work that we’ve done in the La Sals and other places. There are about 800 rock glaciers in Utah as a state. There are thousands of rock glaciers in the Western U. S. A big part of my work is doing some basic research in these places to understand more about a species like Galifinia cristata and raising awareness of what is present in Utah’s mountains and what might happen to it in the future. One of the main reasons we care about rock glaciers is that they aren’t losing ice at the same rate as surface ice glaciers because they’re insulated with a debris cover that actively buffers them against ambient warming and solar radiation. These rock glaciers are going to be increasingly critical for mountain watersheds in the future, but in Southern Utah, in places like the LaSals, we’re already to that future where all that’s left are rock glaciers. so it’s really critical to understand how they’re changing and what their relationship is to various aquatic biodiversity and terrestrial biodiversity.
Science Moab: How do you see this research influencing policy and/or decision making in the future?
Hotaling: Knowing the trajectory of these headwaters, and especially learning about the trajectory of these headwater ice masses, like rock glaciers, paired with declining trends in snowpack, starts to paint a picture of how, and the rate at which these headwater environments are changing. This circles back to what we need to do about it and the timeline of when we need to take whatever action, whether it’s water conservation or if there’s only three streams that this stonefly still persists in that still flow perennially, I would love to see some fencing and blocking off around them such that humans and particularly livestock can’t access them or there’s more protection for the watershed. It’s hard to make the case for conservation action, blocking off entire, entire areas when all you have is a hammer and you want to block off all the LaSals because of that. But if you have a scalpel and you can say, this basin is critically important for these reasons. Then you can make a management decision that’s much more palatable for people. It will give more fodder for the managers in that region to decide what’s best for the ecosystems that we’re studying.
