Mean Weeds in Our Waterways: The Horrible Hydrilla!

Hydrilla (Hydrilla verticillata) is one mean weed that is found in nearly all of Florida’s freshwater ecosystems. It is an invasive exotic that was introduced to Florida in the early 1950s. It was originally imported for use in aquariums but then became established in Florida’s inland water systems after Hydrilla plants were discarded into canals in Tampa and Miami.

Now, Hydrilla occupies more than 140,000 acres of public lakes and rivers in Florida. It has a very aggressive growth rate, growing more than an inch per day; stems can grow up to 35 feet in length! It is usually seen drifting in the upper 2 feet of freshwater ecosystems and can produce a dense canopy near the water’s surface. It shades out our native aquatic plants, reduces oxygen levels, and degrades water quality. It can also block waterways and limit boat traffic, recreation, flood control, and native wildlife. The Florida Fish and Wildlife Conservation Commission (FWC) is designated by the Florida Legislature as the lead agency responsible for managing invasive plants such as Hydrilla in Florida’s public waterways. Progress has been made using physical removal (hand-pulling), mechanical harvesting, biological control (using species such as grass carp (Ctenopharyngodon idella) and aquatic weevil (Bagous affinis)), and herbicides such as Fluridone.

To prevent the spread of Hydrilla please clean all boats and trailers, live wells, and diving gear of plant material before entering or leaving a waterbody!


Photos: Hydrilla found in the Hillsborough River, Tampa
Source: Le’a Dawes