Researchers from Oregon State University say ecological data gathered during a recent low-flow experiment in the Grand Canyon is a key step toward understanding Colorado River ecosystems as the amount of water in the river continues to decline.
Dave Lytle, professor of integrative biology, and Ph.D. students Angelika Kurthen and Jared Freedman teamed with scientists from the United States Geological Survey during the March 2021 project to examine the quantity and diversity of invertebrates in the river. Monitoring aquatic invertebrates is an important tool for keeping track of stream health.
“The Colorado River and its dams are important to cities throughout the Southwest, and as a result of that management the river experiences some pretty unusual flows,” Lytle said. “We’re experimenting with ways to change river flows to make them more compatible with productive ecosystems.”
Between the U.S. and Mexico, 40 million people depend on water from the Colorado. The snowmelt-fed river has seen its flows drop by 20% over the last 100 years as runoff efficiency – the percentage of precipitation that ends up in the river – has declined as summers have become hotter and drier, cooking the soil.
“We saw really large areas of vegetation and invasive species like New Zealand mud snails and quagga mussels, which are there in high numbers at the expense of native invertebrates,” said Lytle.
As the climate continues to warm and the amount of water available for humans continues to drop, low flows such as the one during this year’s experiment may become the new normal, he added.
“That presents challenges but also opportunities for research,” he said. “One question we’re asking is whether there could be ecological benefits, at least at certain important times of year, to low flows."
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