Hydrilla in Lake Eufaula


Alabama Park Rangers said they're alarmed over the discovery of about 60 acres of hydrilla rapidly growing in Lake Eufaula.

Hydrilla is an aquatic plant that grows between one to three inches daily.

Conservation officials are planning to use an EPA approved herbicide to try to kill the plant.

No one knows how the hydrilla was introduced into the lake.

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Hydrilla Verticillata

Hydrilla verticillata is a submersed plant. It can grow to the surface and form dense mats. It may be found in many types of water bodies. Hydrilla once was cultured and sold as an aquarium plant.

Hydrilla Habit

  • Perennial

  • Requires a wet habitat

  • Forms dense stands of very long stems (25 ft.) in the water

  • Reproduces mainly by regrowth of stem fragments; also reproduces by growth of axillary buds (turions) and subterranean tubers; tubers can remain viable for more than four years

Hydrilla Habitat

  • Can grow in almost any freshwater: springs, lakes, marshes, ditches, rivers, tidal zones

  • Can grow in only a few inches of water, or in water more than 20 feet deep

  • Can grow in low nutrient to high nutrient conditions

  • Can grow in 7 percent salinity of seawater

  • Can grow in 1 percent of full sunlight, so it can start growing before other plants do

Hydrilla Origin and Spread

  • There is only one species of Hydrilla in the world.

  • Hydrilla verticillata’s dioecious type (plants having female flowers only) originates from southern India. Hydrilla's monoecious type (plants having male and female flowers on the same plant) is probably from Korea.

  • Hydrilla occurs in Europe, Asia, Australia and the Pacific, Africa, South America and North America.

  • Hydrilla is present from Florida to Connecticut and west to California and Washington. Its dioecious form is mainly in the southern U.S.; north of South Carolina hydrilla is mainly monoecious.

  • Hydrilla verticillata was probably brought to the Tampa and Miami, Florida areas as an aquarium plant in the late 1950s; by the 1970s, it was established throughout Florida.

  • Hydrilla spreads to new waters mainly as fragments on boats and trailers.

Hydrilla Problems/Effects

  • Hydrilla fills the lake or river that it infests, "topping out" at the surface. Hydrilla can grow an inch a day. When hydrilla invades, ecologically-important native submersed plants are shaded out by hydrilla's thick mats, or are simply outcompeted, and eliminated.

  • Hydrilla greatly slows water flow and clogs irrigation and flood-control canals.

  • Hydrilla seriously interferes with boating, both recreational and commercial, and prevents swimming and fishing; major infestations limit sportfish weight and size.

  • Dense Hydrilla infestations can alter water chemistry and oxygen levels.

Hydrilla Control

  • in some cases, lake drawdowns may help manage Hydrilla by letting the exposed plants die and decompose.

  • The action of mechanical harvestors and chopping machines remove Hydrilla from the water and transport it to disposal on shore; chopping machines, unfortunately, fragment the Hydrilla plants and may actually increase the plant's distribution.

  • Fish and insects have been introduced to control Hydrilla. The Chinese grass carp, an herbivorous biological control fish, has a preference for Hydrilla; other biological control work has been done for this species, including tuber-feeding weevils and leaf-eating flies.

  • Registered aquatic herbicides provide temporary control of Hydrilla.

Source: http://plants.ifas.ufl.edu/seagrant/hydver2.html (Center for Aquatic and Invasive Plants, University of Florida and Sea Grant)