SOUTH LAKE TAHOE — When UC Davis researchers Katie Webb and Brant Allan bubbled to the surface in scuba gear on Tuesday, they were greeted by two boatloads of news cameras and reporters.
Such is the iconic status of the lake that even the fingernail-sized Asian clams scooped from the bottom by Webb and Allan get that sort of attention.
UCD’s Tahoe Environmental Research Center is helping to lead an $810,000 project to eradicate 5.5 acres of the invasive clams along the mouth of Emerald Bay by smothering them with rubber mats.
Geoffrey Schladow, the center’s director, will be the first to admit there are plenty of lakes worse off than Tahoe receiving much less attention and a fraction of the funding.
That makes UCD’s efforts at understanding and preserving the lake’s ecosystem all the more important, he said.
“We have almost a responsibility to try these things and get that information out,” he said. “People have always looked at Tahoe first of all as an example of a lake where, because of human influence, the clarity has been going down — but it’s also now becoming an example of where that can be reversed.
“If we can do it at Tahoe, there is hope for all these other thousands and tens of thousands of lakes. If, with all this attention, Tahoe can’t be improved, then what’s the point of dealing with a lake in Anywhere, USA?”
Research done on the lake has pointed the way f0r projects in other lakes. The rubber mats, first used successfully by UCD researchers in 2010, are being used to kill Asian clams at Lake George in New York.
UCD is also responsible for a major shift in thinking about lake clarity, which researchers have been tracking at Tahoe since the early 1960s.
“The conventional wisdom on what was controlling clarity was nutrients that were causing algae to grow,” Schladow said. “We were able to show, very convincingly, that probably the major cause of clarity decline were actually very fine particles that tend to scatter the light.
“Nutrients are still important, but the sudden realization that it’s these fine particles and that the places they are coming from are these urbanized areas around the lake — suddenly, this meant the whole focus of restoration was shifted to urban areas.”
Because of that, Schladow said, some of the many agencies and nonprofit organizations that seek to safeguard Tahoe are working to devise ways to control urban runoff.
University of Colorado researchers have built on that research at Grand Lake, near Rocky Mountain National Park, which also has seen its own decline in clarity.
The Asian clams, which may have first arrived on a boat or from a dumped aquarium, deposit concentrated nutrients into the water, allowing algae to thrive.
“That first year when we found them, we had these sort of filamentous strings of algae washing up on the beach. Those bays were bright green. People realized that if that started to spread to here or to the north shore, it would affect the whole economy.
“Right now, we’re talking something like 100 acres that needs treating. If funds are available, 15 or 20 acres a year could be treated. If it was 10,000 acres, with 120 miles of shoreline, it just couldn’t be done.”
UCD research at the lake dates back to 1958. The Tahoe Center for Environmental Sciences, built in Incline Village, Nevada, in a partnership with Sierra Nevada College, opened in 2006.
UCD’s center, which operates on an annual budget of about $2 million, most of that from state and federal grants, includes about 15 affiliated faculty and staff researchers. Another half-dozen or so UCD faculty perform research with the center, and, at any given time, about 10 graduate students are toiling on Tahoe research.
The center attracts visiting researchers from around the world, most recently from Spain and Brazil. With a partner closer to home, UC Berkeley, UCD researchers plan to release onto the lake 64 small plastic drums carrying cell phones — “the mother of all family plans,” Schladow jokes — that will be used to study the lake’s currents.
That information could be vital to responding to, say, a busted sewer pipe dumping waste into the lake or figuring out where a colony of clams might turn up next.
UCD also operates two educational centers, at its historic fish hatchery location, the Tahoe City Field Station, and at the Long Foundation Education Center at Incline Village. The latter, with its 3-D theater, now attracts about 13,000 visitors per year — making it one of UCD’s most-visited facilities.
The center has expanded its annual clarity report in recent years. Its “State of the Lake” report is an attempt to improve public understanding of the larger Tahoe ecosystem.
Allison Gamble, a post-doctoral researcher, is co-principal investigator on the clam project. Among other things, she hopes to learn how the mats are killing the clams, she said. Suffocation, stress, lack of food or suppressing egg production — and “all of the above” — are possibilities.
“It’s an isolated population,” she said. “Can we take the science that we did on a small scale and apply it to management and actually get close to extirpating this population?
“If you look at the story of invasive species control, it is not, like, the most happy story. If we can extirpate or even suppress (the number of clams) down so that they don’t rebound for like 10 years in an isolated portion in this lake, I think it would be a huge scientific achievement.”
— Reach Cory Golden at firstname.lastname@example.org or 530-747-8046.