One of 'World's Worst' Weeds Invading US Northeast

One of the "world's worst" aquatic weeds is spreading across waters in the U.S. Northeast, a new study has found.

The weed, which is subspecies of the hydrilla plant, grows in thick surface mats that greatly affect native wildlife. It can prevent sunlight from entering the water and lead to decreased oxygen levels, giving off a neuro toxin that is highly dangerous if ingested in high quantities. This toxin has previously been linked to the deaths of bald eagles and waterfowls, the study says, and the lack of oxygen in the water can also kill fish.

Hydrilla has long been a problem in water bodies across the U.S. The plant is actually native to Southeast Asia, making it an invasive species to the U.S. It was first found in Florida's Crystal River system in the 1960s, through the aquarium trade, according to the Chesapeake Bay program. From there the plant continued to spread, and in the 1980s, large infestations were found in the Potomac River in Washington, D.C.

And now, researchers from the Connecticut Agricultural Experiment Station have found that it is presenting a very real threat to water bodies in the Northeast and spreading very quickly.

"The spread and establishment of yet another hydrilla subspecies in the United States is alarming," Jeremiah Foley, an assistant agricultural scientist with the Connecticut Agricultural Experiment Station and lead author for the study, said in a statement. "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."

This particular hydrilla species was previously undetected in the Connecticut River until 2022. But by the end of last year, scientists found it in five waterbodies spread throughout Connecticut and even one in Massachusetts, the study reported.

The plant was mostly detected near boat-launch ramps, in bodies of water that are popular for fishing and angling competitions, the researchers reported. This suggests that these recreational activities are playing a part in helping the species spread.

More research into this will be needed to help prevent the spread, the researchers noted.

"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," Foley said.

The study, "Northern hydrilla (Hydrilla verticillata ssp. lithuanica): discovery and establishment outside the Connecticut River," is published in the journal Invasive Plant Science and Management.

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