Glacier Park Stonefly Threatened by Climate Change

Wildlife advocates seeking protections for rare aquatic insect dependent on melting glaciers

By Tristan Scott
The western glacier stonefly, Zapada glacier. Courtesy Joe Giersch

Wildlife advocates say one of Glacier National Park’s most obscure species is on the brink of extinction, and has become a veritable canary in the coal mine of a rare mountain ecosystem threatened by climate change.

While the western glacier stonefly doesn’t loom as large as some of North America’s charismatic megafauna, which often capture attention in discussions about a warming world – polar bears, grizzlies, wolverines – the tiny aquatic insect has been grabbing headlines due to its dependence on high-alpine, glacier-fed melt-water streams in Glacier Park, making it the new poster-bug of global warming.

The western glacier stonefly, or Zapada glacier, lives exclusively in cold-water streams fed by Glacier Park’s melting glaciers and snowfields, and a recent study by government researchers in the park links the insect’s survival directly to the fast-declining glaciers.

On April 15, wildlife advocates with the Center for Biological Diversity asked a judge to force federal officials to decide if a rare aquatic insect that’s found only in Montana’s Glacier National Park should be protected under the Endangered Species Act.

“Protection can’t come soon enough for this stonefly,” said Tierra Curry, a senior scientist at the Center for Biological Diversity. “Glacier National Park will have no glaciers in 15 years if we don’t take action to curb climate change. The plight of the glacier stonefly is a wakeup call that unless the United States takes major action to reduce our greenhouse gas emissions, this special insect and more than one-third of all plants and animals on Earth could go extinct by 2050.”

Western glacier stoneflies were first identified by scientists in 1963. They live in five streams fed by cold water from glaciers in northwest Montana, on the east side of the Continental Divide.

Those glaciers are predicted to vanish by 2030 – in part because of warmer temperatures due to climate change – and researchers say the stoneflies also could disappear.

In the lawsuit, the Center for Biological Diversity said the U.S. Fish and Wildlife Service failed to follow through on a 2011 finding that protections might be needed for the insects. Although the FWS determined that Endangered Species Act protections might be warranted for the stonefly, the agency still hasn’t issued a decision on the petition.

The group has asked U.S. District Judge Emmet Sullivan in Washington, D.C., to declare the agency violated federal law by not issuing a final determination on whether the species should be listed as threatened or endangered.

Joe Giersch, a U.S. Geological Survey scientist based in Glacier National Park, recently led a study linking the insect’s survival to the fast-declining glaciers, and continues to research their distribution in Glacier’s high-alpine terrain.

In the study, Giersch and researchers with Bucknell University and the University of Montana used data spanning from 1960 to 2012 to illustrate habitat range contractions of the western glacier stonefly associated with glacial recession.

Giersch said Glacier is home to numerous cold-water dependent aquatic species that are at risk of extinction due to the loss of permanent snow and ice, and under the specter of a warming climate, the biodiversity of not just those species, but aquatic alpine species worldwide, is threatened.

Still, he said, their habitat warrants further species, and the concern should not be focused on a single species because the threat is representative of an entire, unique ecosystem.

“More research is urgently needed to assess the extent to which climate change threatens the persistence of [the western glacier stonefly] and other endemic mountaintop invertebrates and communities in GNP and worldwide,” Giersch said.

“We have been working with the Fish and Wildlife Service to do more work on the species, which we will be doing this summer to get a better idea of the distribution of the stonefly in Glacier National Park,” he added.

Since 1900 the mean annual temperature in Glacier National Park has increased by about 2.5 degrees Fahrenheit – nearly two times the global mean temperature increase. Of the estimated 150 glaciers in the park in 1850, only 25 remain, and they continue to shrink.

Clint Muhlfeld, an aquatic ecologist with the USGS, said the stonefly’s contracting habitat means action to mitigate the effects of climate change on the species is imperative.

“Survival of these species will require dispersal to suitable habitats via upstream range shifts or migration to other streams. However, there is nowhere to go for these species – it’s squeeze play at the top of the Continent,” Muhlfeld said. “Dispersal to other suitable sites that may be tens to hundreds of kilometers from [the stonefly’s] current range is highly improbable, so assisted migration may be the only management option to prevent extirpation and extinction.”

According to the Center for Biological Diversity, stoneflies are excellent indicators of the health of their freshwater habitats. Extremely sensitive to changes in water quality, they are among the first organisms to disappear from degraded rivers and streams.

Despite their importance, these insects are one of the most imperiled groups of animals in North America: More than 40 percent of all stoneflies are vulnerable to extinction because they are especially sensitive to pollution, according to the center, which petitioned for the stonefly with the Xerces Society for Invertebrate Conservation.

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