Considered among the “world’s worst” aquatic weeds, a northern hydrilla subspecies (lithuanica) hinders recreational activities by forming dense canopies. If unchecked, it has the potential to displace native species, and host a bacterium that produces a neuro toxin implicated in bald eagle and waterfowl deaths. Unfortunately, new research shows it is invading new waterbodies in the Northeastern U.S. very quickly.

“The spread and establishment of yet another hydrilla subspecies in the United States is alarming,” says Jeremiah Foley, an assistant agricultural scientist with the Connecticut Agricultural Experiment Station, and lead author for the study. “Especially alarming is the negative impacts that this invasive aquatic weed can have on native aquatic and non-aquatic plant and animal species, and how quickly it’s spreading.”

Until 2022, this subspecies had remained undocumented outside the Connecticut River.  However, by the end of 2023, researchers had documented its presence in five additional Connecticut waterbodies and one in Massachusetts. With only one exception, the newly infested sites were discovered close to or at boat-launch ramps. Several newly infested waterbodies also serve as hosts for angling tournaments.

Thus, assessing angling tournament impacts on spreading invasive species like Hydrilla verticillata from one waterbody to another should be considered for future research, recommends Foley. “Management efforts should prioritize early detection and prevention strategies, such as increased monitoring at boat-launch ramps and enhanced education for boaters to mitigate the spread of this invasive species.”

More information is available in the online article, “Northern hydrilla (Hydrilla verticillata ssp. lithuanica): discovery and establishment outside the Connecticut River,” published in Invasive Plant Science and Management, vol. 17, issue 1, by Cambridge University Press. Invasive Plant Science and Management is the official publication of the Weed Science Society of America.

About Invasive Plant Science and Management

Invasive Plant Science and Management is a journal of the Weed Science Society of America, a nonprofit scientific society focused on weeds and their impact on the environment. The publication presents peer-reviewed original research related to all aspects of weed science, including the biology, ecology, physiology, management and control of weeds. To learn more, visit www.wssa.net.

This entry was posted in Featured Articles, Press Release.