UM Bio Station Researchers Unlock Mystery of Subterranean Stoneflies

by the University of Montana

FLBS intern Grant Marshall samples stonefly specimens from the alluvial aquifer beneath the Nyack floodplain outside of Glacier National Park. Aquifer stoneflies spend most of their one- to two-year lives in the nymph stage in subterranean aquifers.

FLATHEAD LAKE – In a new study published in the scientific journal Ecology, researchers from the University of Montana’s Flathead Lake Biological Station may have unlocked a mystery surrounding unique aquatic insects in the Flathead watershed.

“There’s a surprising adaptation of stoneflies in alluvial aquifers that allows them to use low-oxygen or oxygen-free environments,” said FLBS researcher Rachel Malison, lead author on the study. “These aquifers are hotspots of biodiversity, and this study highlights the vital role gravel-bed river floodplains play on the landscape.”

River floodplains are among the most biodiverse landscapes on earth. They provide an important habitat for aquatic and terrestrial organisms, and their aquifers (i.e., shallow groundwater beneath and adjacent to the river) are key components of complex ecosystems worldwide. The Nyack floodplain of the Middle Fork Flathead River outside Glacier National Park, for instance, sustains everything from microbes to grizzly bears and is home to over half of the 100-plus species of stoneflies known in the state of Montana.

But there’s a unique mystery at work within these river floodplains. Out of sight and under the surface, alluvial aquifers are composed of unconsolidated materials and offer limited sources of carbon for sustaining organisms and food webs. Alluvial aquifers also can contain extreme environmental conditions and an abundance of methane gas, which is typically produced in freshwater ecosystems within anoxic (zero-oxygen) or hypoxic (significantly low-oxygen) environments.

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Read the study in Ecology here: