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Scientists battle alien invaders at Lake Tahoe

Page Last Updated: Tuesday August 18, 2009 12:00am PDT

Jack Bowe- News 4

Dr. Sudeep Chandra is a University of Nevada, Reno limnologist. He studies the environment and ecology of fresh water lakes, and right now he is really concerned about one of the biggest threats ever to the aquatic life of Tahoe: an alien invasion "The greatest challenge right now to the near shore ecology is in the introduction of invasive species, and these are species that are not typically found in the lake and that are brought in from other eco systems and that will cause change within the area. They can change things like clarity, that's a big concern up here. They can change the bio diversity and things like that," Chandra said.

Chief on the danger list for Tahoe scientists is the invasive mussel. Although no mussels are believed to be in the lake yet, the fear is that what happened in Lake Mead will happen in Lake Tahoe. Lake Mead has over three trillion mussels taking up residence in that reservoir.

Chandra says if those mussels were to hitch a ride into Tahoe on a boat, they could probably survive. UNR scientists have put the mussels in water collected from Tahoe, and they've found that 86 percent of them survive, and they might have the capability to reproduce.

Although mussels are topping the threat list, they are not the scientists' only concern. Even non-native sport fish like blue gill are considered a threat.

"With the intentional or human induced introduction you almost shock the system, and you can cause all sorts of other ecological changes, clarity loss or changes in native bio diversity that are unpredictable. You don't know which way don't they're going to shift," Chandra said.

Not all the invasions into the Tahoe Basin's ecology come by way of water. Some show up as innocent weeds, poised to take over the vegetation of an entire system.

"We were alarmed because we knew that prior experience in other locations showed that it will move in and take over and not retard erosion," Sue Donaldson of the UNR Cooperative Extension said.

These weeds pose a big threat to lake clarity. Experts say their best attack against the knapweed is a tiny, living creature.

"It's a little weevil that lays it eggs on the plant and when the larvae hatch they eat the seeds of the plant," Donaldson said.

In the water and on land, it's a constant battle between UNR scientists and the alien invaders.

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