[Water_news] 1. DWR'S CALIFORNIA WATER NEWS - Top Item for 10/6/08

Department of Water Resources

California Water News

A daily compilation for DWR personnel of significant news articles and comment

 

October 6, 2008

 

1.  Top Items -

 

 

Tahoe mussel worries on rise

Reno Gazette Journal – 10/6/08

By Jeff Delong, staff writer

 

Discovery of invasive mussels in a set of high-elevation Colorado lakes is diminishing confidence that Lake Tahoe could be immune from invasion.

Quagga and zebra mussel larvae were discovered at Lake Granby this summer and have now been found in two other reservoirs connected to the lake, said Steve Chilton, aquatic invasive species coordinator for the U.S. Fish and Wildlife Service.

 

"Granby was probably at less risk than we are. If they can establish themselves at that lake, they can certainly do so at Lake Tahoe," Chilton said.

Zebra and quagga mussels are close cousins native to Eurasia, believed to have been introduced to the United States through the ballast of oceangoing ships. They were first discovered in the Great Lakes in the late 1980s and have since proliferated widely in that region.

 

Their westward migration reached Nevada in January 2007, when quagga mussels were found in Lake Mead. They have since spread, probably as stowaways aboard pleasure boats, to several other bodies of water in Southern Nevada and Southern California, while zebra mussels were recently discovered in a Northern California reservoir only 250 miles from Lake Tahoe.

 

Both types of mussels can cause widespread problems, wreaking havoc on ecosystems, clogging water intakes, damaging boats and littering beaches with sharp and stinking shells.

 

The potential threat to Tahoe has prompted emergency action to inspect boats launching into the lake to ensure they are not infested, with one boat attempting to launch at the lake in August found with quagga mussels attached to its stern.

 

Scientists at the University of Nevada, Reno are attempting to determine whether mussels could flourish at Tahoe, with work focusing on the question of whether the lake's waters have sufficient calcium levels for them to grow their shells.

 

Preliminary results suggest that while the water is generally low in calcium, there are hot spots with higher levels. That's particularly true where another invader, the asian clam, is already living in Tahoe's waters.

 

The concern, experts said, is that the clams could boost calcium levels to the point they could make establishment of quagga or zebra mussels at Tahoe possible.

Lake Granby, which also has asian clams, was thought to have insufficient calcium and be too cold for mussels but the discovery of juveniles there suggests that's not the case, Chilton said. Tahoe is warmer than Granby.

 

"They haven't found any adults yet, but I think that's just a matter of time. There are adults there somewhere," Chilton said. "Invasives adapt themselves very quickly to whatever environment they are in."

 

Others agreed the Colorado discovery could be bad news for Tahoe.

"It underlies the fact some of these invasives can occur in systems where you may not think they could occur," said Sudeep Chandra, a UNR researcher now studying the mussel threat.

 

"It's just another piece of the puzzle that suggests there is a risk," agreed Ted Thayer, who is heading up the Tahoe Regional Planning Agency's mussel program.

"Lake Granby is just another piece of evidence they could survive and reproduce here," Thayer said.

http://news.rgj.com/apps/pbcs.dll/article?AID=/20081006/NEWS16/810060338/1047/TT

 

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