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Brazilian elodea (Egeria densa) is an attractive, robust plant
well-suited to aquarium life.
Up until 1996 it was commonly sold in Washington
pet stores under the name "anacharis." It was also sold in plant nurseries as
an "oxygen" plant. Because of its invasive properties that allow it take over in
waterbodies where it is introduced, it is no longer being sold in Washington.
Unfortunately Brazilian elodea grows very well in Washington lakes when thoughtless people dispose of aquarium contents in our lakes or when boaters carry it from an infested lake into an uninfested waterbody. Because Brazilian elodea is from South America and was originally imported disease and insect free for the aquarium trade, it has few natural predators to keep its growth in check. When introduced to a lake, it soon forms dense mats that choke out our native aquatic plants. These mats are unsightly, interfere with swimming, boating, fishing, and water skiing and provide poor habitat for fish. Brazilian elodea has been introduced into many lakes in western Washington (follow this link to see which lakes it is found in). Because the lakes are not close together, we believe that most infestations are the result of people dumping aquariums into the lake.
Once introduced, Brazilian elodea reproduces by the spread of plant fragments. Because all the Brazilian elodea plants in the United States are male, no seeds are produced. Branches sprout from "double nodes" located at about eight inch intervals along the stems. If a Brazilian elodea fragment does not have a "double node", it can not grow into a new plant.
In lakes where Brazilian elodea is established, it may outcompete Eurasian watermilfoil (milfoil). Harvesting tends to spread the plant around and some aquatic herbicides do not effectively control its growth. Stocking sterile (triploid) grass carp does show promise as a control technique because Brazilian elodea is highly palatable and older grass carp will eat it in preference to other plants. However, stocking grass carp is not an option in Washington lakes with anadromous fish runs (salmon or steelhead) or in lakes that provide important waterfowl habitat.
Lake residents face big bills for control costs when Brazilian elodea becomes established. Lake Limerick residents in Mason County spend up to $25,000 each year to control this plant. Other lake residents spend similar amounts of money to control Brazilian elodea in their lakes. California has allocated two million dollars in 2000 to manage the problems with Brazilian elodea in the Sacramento-Delta area.
Luckily, there is a good alternative aquarium plant that can be substituted for Brazilian elodea. Canadian elodea or American waterweed (Elodea canadensis) looks very similar to Brazilian elodea and is commonly found in most Washington Lakes. Because it is a native species, American waterweed does not create the same kind of serious problems as Brazilian elodea, although it has been known to become weedy in nutrient-rich waters.
Brazilian elodea and its relatives hydrilla and American waterweed look very similar. Here are some ways to tell these three plants apart:
Follow this Link for More Technical Information About Brazilian Elodea
Problems with this page, contact Kathy Hamel at kham461@ecy.wa.gov
Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html.
