Feds Say Glacier Stoneflies Threatened by Climate Change

Wildlife agency says greater protections needed for obscure alpine insects dependent on glacial streams

By Tristan Scott
Meltwater Lednian Stonefly larva. Courtesy USGS

U.S. wildlife officials have determined that greater protections are needed for two rare alpine insects found high in the glacial-fed streams of Glacier National Park, attributing its decision to climate change and the species’ diminishing cold aquatic habitat.

The U.S. Fish and Wildlife Service on Oct. 3 proposed adding the western glacier stonefly, or Zapada glacier, and the meltwater lednian stonefly, or Lednia tumana, to the government’s list of threatened species under the Endangered Species Act.

The stoneflies live in streams fed by cold water from glaciers in Northwest Montana, but as those glaciers are predicted to largely disappear by 2030, in part due to climate change, researchers say the stoneflies also could vanish as well.

Joe Giersch, an aquatic entomologist with U.S. Geologic Survey who conducted much of the field research the federal agency relied on to base its decision, said he considers the stoneflies “charismatic microfauna.” While they don’t loom as large as some of North America’s species of concern during discussions about a warming world — polar bears, grizzlies, wolverines — the implications to the tiny aquatic insect are no less significant due to its dependence on high-alpine melt-water streams in Glacier Park, making them the new poster-bugs of global warming.

They also play a critical role in the ecosystem as a whole, Giersch said, and their migratory retreat toward colder, higher-elevation streams serves as an indicator of the broader repercussions of habitat loss.

Stoneflies are excellent indicators of the health of their freshwater habitats, Giersch said; extremely sensitive to changes in water quality, they are among the first organisms to disappear from degraded rivers and streams. They also play a significant role in many aquatic ecosystems, decomposing leaves and other organic material and forming the base of the food chain.

“They are kind of a canary in a coal mine. They serve as a real indicator of the health of the ecosystem,” Giersch said. “We talk about glaciers as being the water towers of the continent, the source of not just cold water but also permanent water, and the effects of their loss will be felt not just by people but the ecosystem as a whole.”

It’s uncertain what measures management agencies could take to preserve the insects, but Giersch has identified translocation, as well as raising stoneflies in laboratories and seeding different streams with them, as the most likely tool.

Clint Muhlfeld, a research ecologist at the USGS Northern Rockies Science Center in Glacier Park, said the proposed listing of the stoneflies as threatened is significant, and could mark the beginning of a cascade of species being listed with climate change as the most significant threat.

“These species are the only other species that I’m aware of that may be listed under the ESA due to climate change impacts, other than the polar bear,” he said. “They are the polar bears of Glacier National Park.”

“Also, more importantly, there will be winners and some losers as impending climate change and glacier loss unfolds,” he continued. “But these species are indicative of an entire ecosystem under threat due to climate warming.”

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.

He said the stoneflies’ contracting habitat means action to mitigate the effects of climate change on the species is imperative.

“It is definitely unprecedented for the Fish and Wildlife Service to be taking such an interest in species like these, which for the most part don’t have a whole lot of visible, direct economic or ecological value,” Giersch said. “But this is a powerful indication of the threats that climate change pose to the biodiversity of the entire Crown of the Continent ecosystem.”

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