Weed warriors target invasive aquatic elodea

By Joseph Robertia
Special to the Tribune

Photo courtesy of the Kenai National Wildlife Refuge  The invasive elodea plant reproduces asexually, thrives in cold water and spreads rapidly. The Kenai Peninsula Cooperative Weed Management Area is spearheading efforts to remove the plant before it reaches a critical mass, such as seen here in a lake in the Lower 48.

Photo courtesy of the Kenai National Wildlife Refuge
The invasive elodea plant reproduces asexually, thrives in cold water and spreads rapidly. The Kenai Peninsula Cooperative Weed Management Area is spearheading efforts to remove the plant before it reaches a critical mass, such as seen here in a lake in the Lower 48.

A scourge threatening the ecological health of waterways in the Nikiski area — and possibly beyond, if it isn’t stopped — sounds like something out of a science fiction movie:
The invasive submersed aquatic plant elodea was first found on the Kenai Peninsula in September 2012 in Stormy Lake. Left unchecked the plant can spread exponentially, as only a tiny fragment of elodea — attached to a float plane or boat propeller or trailer — is all it takes to start a new colony. It can not only survive freezing temperatures, but the hybrid species of the invasive plant seems to actually be thriving in Alaska’s cooler waters.
Yet it seems so innocuous. Elodea is a common aquarium plant and specimen in school biological supply kits. But if left unimpeded in ecosystems where it does not occur naturally, elodea can and will entirely suffocate a water body, growing in a thick carpet from shoreline to shoreline and from the lake bed to the surface.
Ecologically, the choking mass would ruin spawning areas for salmon, trout and grayling, as well as migration areas for waterfowl. An infiltration also poses safety hazards, as a lake full of elodea would limit people’s ability to swim, float-plane rudders could be snagged and boats wouldn’t be able to navigate due to clogged propellers.
Efforts are being made to curtail the infestation, with a meeting held last week in Soldotna, hosted by Kenai Peninsula Cooperative Weed Management Area partners, to discuss the continuing efforts to stop the spread of elodea, proposed methods to eradicate it from currently infested water bodies, and to inform the public about the dangers of this seemingly innocuous plant.
Brianne Blackburn, a natural resource specialist with the Alaska Department of Natural Resources, gave an update on the state’s response to elodea.
The Division of Agriculture issued an emergency action quarantine for five species of aquatic plants March 5, she said. It prohibits the importation, sale and intentional transport of elodea, as well as Brazilian waterweed, hydrilla and Eurasian watermilfoil.
Blackburn said that an aggressive outreach campaign is ongoing to inform the public about elodea, the dangers of it thriving and what can be done to keep it from spreading. Outreach also is occurring to other state and local agencies to ensure their operations don’t accidentally spread elodea, such as when fire crews take water from local lakes to combat a blaze.
“We wouldn’t want them to take water from an impacted lake and introduce elodea to another,” she said.
Libby Bella, with the U.S. Fish and Wildlife Service, provided information on the 2013 lake survey conducted by the service, the Alaska Department of Fish and Game, Kenai National Wildlife Refuge and Friends of Alaska Refuges volunteers. They surveyed 68 lakes with multiple collection points in each lake.
“After the surveys, we now know where elodea occurs and the extent of the infestation,” Bella said. On the peninsula, elodea was found in Stormy, Daniels and Beck lakes.
“The plan is to treat these lakes this summer, evaluate the success and process this information as a model for other areas, since re-infestation is likely unless other areas are brought under control,” she added, referring to Anchorage, Cordova and Fairbanks, where elodea has also been identified in several lakes, ponds, sloughs and rivers.
Lars Anderson, an aquatic invasive species expert from California, where the battle against elodea has been ongoing for years, spoke about the options available for combating the invasive plant, based on trial and error with various mechanical and chemical methods his home state has attempted over the years. A successful plan is one that includes species not yet found, he said, since only focusing on waters where elodea is known to exist can mean, when a new infiltration is discovered, starting all over again with the bureaucratic process of drafting action plans, filing permits, seeking funds, etc.
Anderson added that any plans being drafted to combat elodea, or other aquatic invasives, need to be done openly to the public, with their opinions and input sought, so they understand exactly what and why the stakeholders are taking the actions they are pursuing.
“So far, you’re doing a great job of that here,” he said.
Trish Wurtz, invasive plant program coordinator with the U.S. Forest Service, spoke about attempts to use suction dredging to remove elodea from the Chena Slough in Fairbanks, a waterway that, “Used to be a world-class grayling fishery, but not anymore,” since the 2002 introduction of the invasive plant.
The dredge essentially vacuumed the plants from the water but it did not work well in areas less than three 3 feet deep, so pitchforks were used in the shallow areas. Also, the removed elodea was very heavy once bagged, and the overall work was so physically taxing that those dredging didn’t exceed four hours of work at a time.
“Elodea removal is extremely difficult with mechanical methods,” Wurtz concluded.
Andrew Skibo, an aquatic researcher from the SePRO Corporation, spoke about the safety of using his company’s product Sonar, which has fluridone as the active ingredient, as a chemical means of eradication.
“It is absorbed through the roots and shoots of the plants and then translocates to the shoot tissues,” he said.
It can be administered in pellet or liquid forms, and at the dosage intended to treat Kenai Peninsula lakes — not more than 8 parts per billion — the product comes without swimming, fishing or potable water restrictions from the state or Environmental Protection Agency.
Skibo said the product poses negligible risk to the safety to the safety of the environment and wildlife — such as invertebrates, fish, birds and mammals. Sonar degrades in the hydrosoil in roughly 90 days and from aquatic environments in around nine months, and in lab tests of the herbicide administered as high as 5,000 parts per billion, there was no effect on salmonoid fry and fingerlings, which, he added, “Really speaks to the safety of this product.”
A second herbicide, diquat, will also be used selectively, as it is not as selective in killing only elodea species and will cause some die-off of native plants, as well.
John Morton, a supervisory biologist at the refuge and a leading proponent of the local fight against elodea, presented on the permitting process and plan to use Sonar in the three local lakes starting this summer.
Stormy and Beck will require whole-lake treatments, and Daniels will be a partial-lake treatment, he said.
Stormy Lake, at 295 acres, will require liquid and pellet treatment at a total cost of $329,000, with treatment slated to begin July 1. Beck Lake, at 198 acres, will also require both types of treatments at a cost of $117,000 with treatment scheduled for June 1. Daniels Lake, with elodea confined to five main areas, will only require pelleted treatment, at a cost of $172,000, scheduled to begin in June, as well.
“We think we nipped Daniels in the bud. We’re confident, from surveys, that it is only at those five sites, which is only about 50 acres of the 650 acre lake,” Morton said.
The local treatments will take place four times over three years, and the Stormy Lake boat launch will likely be closed for a second summer this season. Nets that permit fish passage will also be maintained at the outlets of Beck and Daniels to prevent elodea from entering Bishop’s Creek.
In addition, the public outreach campaign to inform people of what elodea looks like and the dangers it presents will continue, in the hope of curbing its spread and isolating it in any lakes or ponds outside of those surveyed on refuge land.
“It’s been a lot of work,” Morton said, “but we’ve fast-tracked this thing and we’re ready to treat.”
For more information or to report a sighting, visit plants.alaska.gov/invasives/edolea.htm or call 877-INVASIV (468-2748).
Joseph Robertia writes for the Redoubt Reporter in Kenai.

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Posted by on May 6th, 2014 and filed under Headline News. You can follow any responses to this entry through the RSS 2.0. Both comments and pings are currently closed.

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