Friday, September 19, 2014
YOLO COUNTY NEWS
99 CENTS

UCD readies effort to repel Tahoe’s clam invasion

UC Davis research engineer Bill Sluis paints a red X Tuesday on rubber mats that will be used to suffocate invasive Asian clams on the bottom of Lake Tahoe's Emerald Bay. The X will guide divers to where the flap can be found in the mat. Sue Cockrell/Enterprise photo

By
From page A1 | October 17, 2012 |

Call them unwelcome mats.

UC Davis staff and students on Tuesday worked at Bainer Hall to prepare 5 acres of rubber barriers meant to suffocate thumbnail-sized Asian clams invading Lake Tahoe.

Starting next week, excavators on a barge will lower 200 of the mats into the water near the mouth of Emerald Bay.

UCD’s Tahoe Environmental Research Center scientists first pioneered the use of the mats in 2010, killing all of the clams over 1 acre.

This new project will cost about $810,000. It is believed to be the largest of its type to have been attempted.

Other areas of the lake are now home to more clams: 6,000 to 7,000 per square yard in some places, compared to about 50 per square yard where the mats are being deployed.

Emerald Bay is viewed as a special case and a unique opportunity, however.

“This is Emerald Bay — it’s probably one of the most photographed spots in the country. It’s a state park,” said Geoff Schladow, the research center’s director. “And it’s an isolated population, so in a way it’s an experiment to see, ‘Can we hit these satellite populations and control them there?’ ”

Asian clams — which may have arrived on a boat or even a dumped aquarium — first turned up in large numbers about four years ago.

Though it’s too soon to know what their effect on other species will be, the clams have the potential to produce large algae blooms along the shore — clouds of green that can not only make Tahoe’s crystal waters less pleasing to the eye but in need of more filtering for drinking.

Plus, sharp, broken clam shells can make for one unhappy day at the beach.

“(The clams) filter out what’s in the water, algae, detritus and things like that. They concentrate it in their bodies, they consume a small amount of it, and then they excrete highly concentrated nutrients,” Schladow said.

“So what you have in the vicinity of these clam beds are locations of very high nutrients. Algae, which typically in Tahoe exist in small numbers, because the nutrient level is low, suddenly can flourish because of these high concentrations. It’s like an all-you-can-eat restaurant for them.”

The decision to try mats came in response to the question of how to control the invaders in a place where chemicals aren’t allowed and the water level can’t be lowered like a manmade reservoir. The idea has since been copied at Lake George in New York, which is battling an Asian clam problem of its own.

The mats are made of the same 1/16-inch-thick material used to line backyard ponds. They cut off oxygen to the clams, which burrow into the top few inches of silt.

Once the location of the furthest reaches of the glacier that carved out Emerald Bay, the uneven, sometimes rocky lakebed at the bay’s mouth presents a greater challenge than the flat areas where the researchers first tried out the mats.

Because oxygenated water flows through the silt to the clams, UCD is adding a second prong to its attack.

Before spreading out the rubber mats, divers unroll sheets made up of strands from aspen trees. The researchers believe the decomposing material will use up more oxygen, perhaps killing off clams more quickly.

Instruments in six locations will allow researchers to monitor nutrient levels under the mats. In another 48 spots, divers will be able to take samples from under the mat with a syringe.

The puzzle of how to modify the mats so they could be deployed and held in place fell to UCD research engineers Bill Sluis and Daret Kehlet.

Their lab is home to everything from the student concrete canoe building team to research looking at how rainfall moves pesticide down a sloped concrete surface. They’ve also built buoys that record meteorological data on the lake.

With their student workers, the engineers are unrolling the 100-foot-long, 10-foot-wide mats, then attaching grommets along each side. Divers later will use those when they zip-tie the mats to 10 miles of steel rebar, the weight of which will prevent the current from flipping the mats.

Each mat is riveted to two-inch plumbing pipe, which in turn holds a steel pipe strong enough not to buckle when the 300-pound rubber mats are hoisted over the water.

Sluis and Kehlet devised a system in which the ropes are attached by caps on the pipes. Once the rolled mat settles on the lake bottom, air will be shot through a hose into the pipe, popping the caps off. Then, divers can move in safely.

Readying the mats will take four to five weeks, their installation at the lake three or four. The work will be done on weekdays to interfere less with boating traffic heading into the bay, which can reach 1,000 boats a day during summer.

Schladow said the clams have invaded only “a couple of hundred acres” out of 191,588 square miles of lake.

Still, wiping them out would be all but impossible.

The researchers hope they’ll be able to kill off 99 percent of the clams under the mats, and eventually be able to hand off a refined process to about 40 public and private organizations who safeguard the lake. The Lahontan Regional Water Quality Control Board, U.S. Fish and Wildlife Service and U.S. Forest Service Pacific Southwest Research Station are funding the project.

Asked by a television reporter on Tuesday whether eating Asian clams might be one way to get rid of them, Schladow said they’re reputed to be less than tasty.

Plus, he added, “We need an invasion of linguine first.”

— Online: http://terc.ucdavis.edu

— Reach Cory Golden at cgolden@davisenterprise.net or 530-747-8046.

Comments

comments

Cory Golden

Cory Golden

The Enterprise's higher-education and congressional reporter. http://about.me/cory_golden
  • Recent Posts

  • Enter your email address to subscribe to this newspaper and receive notifications of new articles by email.

  • .

    News

    UC to create $250 million venture capital fund

    By San Francisco Chronicle | From Page: A1

     
    School district may redevelop downtown site

    By Jeff Hudson | From Page: A1

    Grant means new push for moving tracks out of town

    By Dave Ryan | From Page: A1 | Gallery

     
    Some say council needs to reconsider MRAP

    By Dave Ryan | From Page: A1

    Man faces arson charge in huge California wildfire

    By The Associated Press | From Page: A2

     
    DUI suspected in crash

    By Lauren Keene | From Page: A2

     
    Master Gardeners share their wisdom at free workshops

    By Enterprise staff | From Page: A2

    Scots vote to stay in UK

    By The Associated Press | From Page: A2

     
    France strikes Islamic State group’s depot in Iraq

    By The Associated Press | From Page: A2

    Project Linus seeks donations

    By Enterprise staff | From Page: A3

     
    Rabid bat found at Holmes Junior High

    By Enterprise staff | From Page: A3

    Students invited to apply for Blue & White grants

    By Enterprise staff | From Page: A3

     
    Halloween costume sale benefits preschool

    By Enterprise staff | From Page: A3

    Telling tales, on ‘Davisville’

    By Enterprise staff | From Page: A3

     
    Volunteers sought to make veggie bags

    By Enterprise staff | From Page: A3

    Storyteller will draw on music, dance

    By Enterprise staff | From Page: A3

     
    Woodland Healthcare offering flu shots

    By Enterprise staff | From Page: A3

     
    Putah Creek Bike Path to close temporarily

    By Enterprise staff | From Page: A3

    Little Free Libraries open at Montgomery

    By Anne Ternus-Bellamy | From Page: A3

     
    Nonprofits can get DCN’s help

    By Enterprise staff | From Page: A4

    Register to vote by Oct. 20

    By Enterprise staff | From Page: A4

     
    Free workout class set at library

    By Special to The Enterprise | From Page: A4

     
    Explorit: Lots of ways to be a volunteer

    By Lisa Justice | From Page: A4 | Gallery

    Sierra Club remembers longtime walker

    By Special to The Enterprise | From Page: A4

     
    DHS Classes of 1954 and 1955 will hold 60th reunion

    By Enterprise staff | From Page: A4

    Davis maps available at Chamber office

    By Enterprise staff | From Page: A5

     
    Need a new best friend?

    By Enterprise staff | From Page: A5 | Gallery

    Reception benefits endangered gorillas

    By Special to The Enterprise | From Page: A5

     
    Downtown history tour planned in October

    By Enterprise staff | From Page: A7

    Davis hosts its own climate change rally

    By Special to The Enterprise | From Page: A8

     
    Sutter Farmers Market offers local goods

    By Enterprise staff | From Page: A8 | Gallery

    Wolk applauds approval of stronger rules for olive oil

    By Special to The Enterprise | From Page: A8

     
    Qigong classes available for heart health

    By Enterprise staff | From Page: A9

    .

    Forum

    Sick of being the bad guy

    By Creators Syndicate | From Page: B5

     
    Project has safety risks

    By Letters to the Editor | From Page: A6

    Learn more about Paso Fino

    By Letters to the Editor | From Page: A6

     
    Educate homeless with dogs

    By Letters to the Editor | From Page: A6, 1 Comment

    Cheers and Jeers: Not the end of the rainbow

    By Our View | From Page: A6

     
    Tom Meyer cartoon

    By Debbie Davis | From Page: A6

    Return to previous plan

    By Letters to the Editor | From Page: A6

     
    Save the ‘pine cone place’

    By Letters to the Editor | From Page: A6

    Affirm our community values

    By Letters to the Editor | From Page: A6

     
    .

    Sports

    Devils hope the light bulb turns on at Edison

    By Enterprise staff | From Page: B1

     
    River Cats and Giants sign two-year deal

    By Enterprise staff | From Page: B1

    Blue Devil volleyballers hold off Herd

    By Spencer Ault | From Page: B1 | Gallery

     
    Aggies’ new energy could be scary for Big West

    By Bruce Gallaudet | From Page: B1

    No rest for the weary: Aggie TE Martindale busy on and off the field

    By Bruce Gallaudet | From Page: B1 | Gallery

     
    Mustangs are no match for DHS boys in water polo

    By Enterprise staff | From Page: B2

    Take Zona and Bama this week

    By Bob Dunning | From Page: B2

     
    A’s slide continues as Rangers sweep

    By The Associated Press | From Page: B8

    .

    Features

    Name Droppers: Awards keep coming for UC Davis retiree

    By Enterprise staff | From Page: A7

     
    .

    Business

    Redesigned 2015 Escalade remains breed all its own

    By Ann M. Job | From Page: B3 | Gallery

     
    .

    Obituaries

    Carol L. Walsh

    By Special to The Enterprise | From Page: A4

     
    .

    Comics

    Comics: Friday, September 19, 2014

    By Creator | From Page: A10

     
    .

    Real Estate Review

    Featured Listing

    By Zack Snow | From Page: RER1

    Professional Services Directory

    By Zack Snow | From Page: RER2

    Taylor Morrison

    By Zack Snow | From Page: RER3

    Malek Baroody

    By Zack Snow | From Page: RER4

    Norcal Land

    By Zack Snow | From Page: RER5

    Robin Garland

    By Zack Snow | From Page: RER6

    Karen Waggoner

    By Zack Snow | From Page: RER7

    Dana Hawkins

    By Zack Snow | From Page: RER7

    Martha Bernauer

    By Zack Snow | From Page: RER8

    Joe Kaplan

    By Zack Snow | From Page: RER8

    Lynne Wegner

    By Zack Snow | From Page: RER8

    Remax

    By Zack Snow | From Page: RER9

    Melrina A Maggiora

    By Zack Snow | From Page: RER10

    Wells Fargo Home Mortgage

    By Zack Snow | From Page: RER11

    Julie Leonard

    By Zack Snow | From Page: RER11

    Coldwell Banker

    By Zack Snow | From Page: RER12

    Kim Eichorn

    By Zack Snow | From Page: RER14

    Lyon Real Estate

    By Zack Snow | From Page: RER15

    Jamie Madison & Associates

    By Zack Snow | From Page: RER16

    Marcelo Campos

    By Zack Snow | From Page: RER16

    Julie Partain

    By Zack Snow | From Page: RER16

    Bob Bockwinkel

    By Zack Snow | From Page: RER17

    Juan Ramirez

    By Zack Snow | From Page: RER17

    Kim Merrel Lamb

    By Zack Snow | From Page: RER17

    Chris Snow

    By Zack Snow | From Page: RER18

    James Hanna

    By Zack Snow | From Page: RER18

    Raul Zamora

    By Zack Snow | From Page: RER19

    Susan von Geldern

    By Zack Snow | From Page: RER19

    Travis Credit Union

    By Zack Snow | From Page: RER20

    Karen Waggoner

    By Zack Snow | From Page: RER21

    Jamie Madison

    By Zack Snow | From Page: RER21

    Tracy Harris

    By Zack Snow | From Page: RER22

    Lisa Haass

    By Zack Snow | From Page: RER22

    First Street Real Estate

    By Zack Snow | From Page: RER24