CORVALLIS, Ore., Oct. 13 (UPI) -- Frequent and severe drought has pushed some desert ecosystems into catastrophic change from which many species won't recover, a U.S. scientist says.
Oregon State University zoologist David Lytle said he worries climate change, over-pumping of aquifers for urban water use and land management practices may permanently affect which species can survive, a university release said Thursday.
"Populations that have persisted for hundreds or thousands of years are now dying out," David Lytle said. "Springs that used to be permanent are drying up. Streams that used to be perennial are now intermittent. And species that used to rise and fall in their populations are now disappearing."
Lytle examined the effect of complete water loss on aquatic insect communities in a formerly perennial desert stream in Arizona's French Joe Canyon before and after severe droughts in the early 2000s.
The stream completely dried up in several years, creating a rapid "regime shift" in which some species went extinct locally and others took their place.
The ecosystem dynamics are different now and show no sign of returning to their former state, Lytle said.
"Before 2004, this area was like a beautiful oasis, with lots of vegetation, birds and rare species," Lytle said. "The spring has lost a number of key insect species, has a lot less water, and now has very different characteristics."