Alaska gets tough on invasive plants, quarantines 5 species

Devin Kelly
Flowering Canadian Waterweed, or Elodea canadensis, is seen growing in a shallow ditch. The plants have partly become encrusted in lime That’s why the leaves’ surface look somewhat covered.
Canadian Waterweed, Elodea canadensis, with enlarged cross section of a single whorl. In this instance, the leaves are relatively long and narrow, four times longer than wide.
Photo by Christian Fischer

The state Department of Natural Resources on Tuesday established a quarantine for five invasive aquatic plant species, the first measure of its kind and the latest in an aggressive effort to contain invasive plant infestations in Alaska's rivers and lakes.

The five species, all of which have historically been found in the aquarium trade, are as follows:

• Canadian waterweed (Elodea canadensis)

• Western nuttallii (Elodea nuttallii)

• Brazilian waterweed (Egeria densa)

• Hydrilla (Hydrilla verticillata)

• Eurasian watermilfoil (Myriophyllum spicatum)

Two of the five, Canadian waterweed and western nuttalli, have been identified in Alaska waters. Also referred to as elodea, the plants are currently the focus of an aggressive containment effort, with ecologists warning the plant could threaten fish as well as boating, float plane and commercial and sport fishing enterprises. Since 2009, the fast-growing freshwater plants, which thrive in colder temperatures, have been found in Fairbanks, the Kenai Peninsula and in Anchorage, prompting a host of regional responses.

The other three species listed in the quarantine were selected because all are known as high-risk invasive aquatic plant species in other places, said Brianne Blackburn, natural resources specialist with the Department of Natural Resources' Division of Agriculture. Hydrilla, for example, is a federally-recognized noxious species that has threatened regions like the Sacramento-San Joaquin Delta waterway in California.

The quarantine stipulates that "it is prohibited to import, transport, buy, sell, offer for sale, or distribute plants or plant parts of the regulated species within the state of Alaska. It is further prohibited to intentionally transplant wild plants and/or plant parts of these species within the state of Alaska."

Blackburn noted that the state has rarely established quarantines for invasive plant species. In past cases, such quarantines have generally related to the agricultural community, and diseases affecting crops like tomatoes or potatoes.

"This is kind of a first," Blackburn said. "It definitely signals the priority that the (Department of Natural Resources) is trying to place on freshwater aquatic invasive plants."

Officials are in the process of reviewing the department's regulations for noxious weeds, and will eventually be adding the five species to the list, Blackburn said. She said the quarantine is an interim measure until those changes formally take effect.

In January 2013, the Department of Natural Resources took charge of managing the state's freshwater aquatic invasive plants, specifically for the two elodea species. The slender plant with whorled leaves is popular in the aquarium industry and as a specimen in school biology classes, which was likely how it made its way into Alaskan waters.

Each of the main affected regions -- Fairbanks, Anchorage and the Kenai -- has developed a technical advisory group to look at sites with elodea infestations and decide the best way to move forward. On the Kenai Peninsula, a decision has already been made to move forward with an herbicide treatment at some lakes in the region.

As those containment efforts progress, the state's Division of Agriculture formally recommended the quarantine to keep the problem from spreading any further, Blackburn said.

"If we're putting resources toward managing something, we don't want to be allowing more issues to arise," Blackburn said.

From here, inspections staff with the Department of Natural Resources will be next making contact with school districts and businesses to explain the quarantine, and offer instructions for properly disposing of the plant, Blackburn said.

Blackburn said officials also plan to help develop alternatives to the invasive plant species in both classroom and business settings. For schools, that may take the form of providing access to a native alternative to elodea for use in biology classes, Blackburn said.

In working with the aquarium industry, the state hopes to eventually come up with a list of warm-water species that do well in fish tanks, but would not survive in the harsher Alaskan climate.

"There are lots of other alternatives," Blackburn said.