March 26, 2008

Global Warming Poses Threat to Lake Tahoe

Lake Tahoe's ecosystem could be in danger of being altered by global warming, according to a study conducted by researchers at University of California, Davis.

The Tahoe Environmental Research team sought to answer crucial questions about the lake's temperature, algae concentration and clarity. Until now, the only measurement of Lake Tahoe's status had been available to the public was the Secchi depth, an annual clarity report.

Researchers hope to determine if lowered global greenhouse-gas emissions would significantly slow the lake's decline or possibly prevent it.

The team said warmer lake temperatures would shun many cold-water fish while inviting more invasive species like carp, large-mouth bass and bluegill.

"What we expect is that deep mixing of Lake Tahoe's water layers will become less frequent, even nonexistent, depleting the bottom waters of oxygen," said Geoffrey Schladow, director of the Tahoe Environmental Research Center at U.S. Davis.

Schladow joined Associate Director John Reuter and postdoctoral researcher Goloka Sahoo to present their findings at Incline Village at a conference focusing on global warming and deep-water lakes last week. They voiced concerns that the lake may be in danger of becoming murky within the coming decade.

The circulation of the lake waters acts to circulate nutrients from the bottom of the lake to the top where algae is grown while Oxygen from the surface can spread throughout the lake to support aquatic life.

"A permanently stratified Lake Tahoe becomes just like any other lake or pond," Schladow said. "It is no longer this unique, effervescent jewel, the finest example of nature's grandeur."

The study found that if greenhouse-gases continue at their current rate, lake mixing could become less frequent and possibly stop as early as 2019.

"While we expected that the lake would mix less in the future, learning that we may be only a decade or two from the complete shutdown of deep mixing was very surprising." Schladow said.

"If mixing shuts down, then no new oxygen gets to the bottom of the lake, and creatures that need it, such as lake trout, will have a large part of their range excluded," Schladow said.


On the Net:

State of the Lake ReportState of the Lake Report

Tahoe Environmental Research Center