Recovery plan developed for rare stonefly populations

Two of the smallest creatures in Glacier National Park are getting king-sized attention as a new U.S. Fish and Wildlife Service recovery plan proposes spending $735,000 to help struggling meltwater lednian and western glacier stonefly populations.

Neither species larger than a fingernail, the meltwater lednian stonefly was discovered in the Many Glacier area in 1952 while the western glacier stonefly was first identified in five locations inside Glacier National Park in 1971. Both species begin life as eggs, hatch into aquatic nymphs and later mature into winged adults, surviving briefly on land before reproducing and dying.

Cold water (usually between 50 and 56 degrees Fahrenheit) streams at high altitude resulting from glacial and annual snowmelt are essential to the flies’ survival.

With rising temperatures and receding glaciers ravaging their habitat, both species were listed as “threatened” by the U.S. Fish and Wildlife Service in 2019. They were among the first species to gain Endangered Species Act protections as a sole result of climate change after a landmark November 2019 decision to furnish federal protections on the obscure aquatic bugs.

The U.S. Fish and Wildlife Service’s new recovery plan, released Jan. 18, proposes a three-pronged approach over the next 20 years to protect the two species that some may simply dismiss as being insignificant.

“Anything in the natural world holds some sort of value,” said U.S. Fish and Wildlife Service biologist Jim Boyd, the lead researcher on the project. “There is a biological value to this species as part of the food chain. They are also a sentinel — a canary in the coal mine, so to speak. When anything happens to these stoneflies, it is our first indicator of effects from climate change to the environment where they live. We can’t afford to look at them as ‘just flies.’”

While researchers suspect the insects are vital to their alpine environments, they are still figuring out exactly how the two stonefly species fit into the ecosystem.

“These are prey items for birds such as the American Dipper as well as predatory aquatic insects. They are at the bottom of the food chain, for sure, but they are still important,” Boyd said. “We still don’t really know a whole lot about how they fit into their ecosystem, but we are learning. They just happen to live in very small and remote areas where it is hard to study them.”

Calling the habitats of these two species of stonefly “small and remote” may be a gross understatement.

The meltwater lednian stonefly is only known to occupy roughly 35 miles of area spread across 113 streams in and around the immediate area of Glacier National Park while the western glacier stonefly lives along just 13.2 miles of 24 streams from Glacier National Park to Grand Teton National park in Wyoming. A few are also found in the Wind River Range of Wyoming and in the Absaroka/Beartooth Mountains along the Montana-Wyoming border as well as southern Alberta, Canada. The areas are mainly under National Park Service and U.S. Forest Service control, while a small portion is on Confederated Salish and Kootenai Tribes land or Canadian soil.

WHILE THE meltwater lednian and western glacier stoneflies are estimated to have populations in the millions and tens of thousands respectively, both face a dire threat from the rapidly receding glaciers and snowfields that provide the water for their homes.

“It really all comes back to the threats on the landscape and climate change. As soon as one of these streams goes dry, every insect in that stream is dead. There is huge potential out there for these streams to start drying up and, even though we have a lot of these insects right now, we are losing them in large numbers at a time,” Boyd said. “All it takes for these insects is one really low snow year and they could disappear from an area that goes dry. The trend we are seeing right now is that all of the alpine water, no matter the source, is declining fairly rapidly. A good chunk of it is going to be gone as soon as by the end of this decade. With the way things are trending, over the next 100 years we could be in a position to see these species disappear from the landscape altogether.”

According to Boyd, the meltwater lednian stonefly is facing a greater than 80% loss of its habitat over the next two decades alone.

Unfortunately for scientists, there are no easy answers.

“As many of these meltwater sources begin to disappear, streamflows are expected to become intermittent and water temperatures warmer. Therefore, decisive action to address climate change is the most important recovery action for both species, a daunting task that will require global action,” the recovery plan states. “The most important recovery action is decisive action to address the effects of global climate change, which is driven primarily by increasing atmospheric concentrations of greenhouse gasses. Without action to effectively address climate change, which melts glaciers and snowfields that feed [the insects’] habitats, the recovery of both species will be extremely challenging. Addressing the increasing air temperatures associated with climate change will require global action. Given this daunting task, in this recovery plan we focus on actions within the United States.”

The plan sets forth a range of habitat requirements for recovery, including the two species' need for cold, flowing water and more than 3,000 acres of glaciers and snowfields. One prong of the plan looks at identifying suitable locations for possible translocation of the flies, but there is no guarantee any area found wouldn’t soon be facing the same challenges.

The second part of the recovery action plan focuses on increasing public awareness of the effects of climate change on alpine biodiversity in the hopes of curtailing greenhouse gas emissions, though the document laments that any effort on that front might already be too late.

“Currently, average global surface air temperatures are expected to rise by the end of the century. Thus, at this time, average global air temperature through the end of the century will likely not be conducive to glacier preservation or growth across the range of either species under any modeled emissions scenarios.”

The final part of the recovery plan involves finding ways to artificially propagate both species to keep them alive.

While the plan, which is non-regulatory and acts more as a set of guidelines, is optimistic that the status of both species could be improved in approximately 20 years with full implementation of all actions, it is quick to point out that timeline could take much longer if decisive action is not taken to curtail the effects of global climate change.

Reporter Jeremy Weber can be reached at jweber@dailyinterlake.com.