Invasive plant species could have negative impact on Coventry Lake


In this photo, Coventry Lake is pictured in Storrs, Connecticut. Invasive hydrilla found in the lake could reduce the area’s recreational value for boaters and other residents, UConn professor Don Les said. (Ashley Maher/The Daily Campus)

Invasive hydrilla found in Coventry Lake on Sept. 23 could reduce the area’s recreational value for boaters and other residents, said Don Les, professor of UConn’s Aquatic Plant Biology class that identified the species.

Les, who is also director of UConn’s herbarium, said a mislabeled specimen in the university’s collection first alerted him to hydrilla’s presence in Mystic, Connecticut in 1989. Since then, the invasive species has spread throughout the state’s waterways on the underside of recreational boats, limiting their use because of its aggressive growth.

“It looks like astroturf on the surface, you can’t image how thick this stuff can get,” Les said. “The whole lake could eventually have every recreational aspect of it ruined.”

In order to curb the spread of hydrilla and other aquatic invasives, boaters in all areas need to thoroughly clean and dry the bottom of their crafts whenever they leave the water.

“Doing this inspection is really something that every boater should be doing for their own good because if the lake gets messed up, they’re not going to be able to use it anymore,” he said. “We’re not trying to blow this out of proportion, we’ve seen this happen before.”

Ursula King, an ecology and evolutionary biology doctoral student in Les’ lab, said the three-inch hydrilla fragment she found during their biannual class trip to Coventry Lake would be enough to disrupt an ecosystem itself.

“Small fragments of the plant can break off and generate new roots,” King said. “They have the potential to grow into a full plant and further propagate.”

While all invasive species benefit from an absence of natural predators, hydrilla’s ability to grow in dense monocultures allows it alter the chemistry of an aquatic ecosystem, boxing out native competitors.

“When you have aquatic invasives that cover a water body, then that minimizes light that may reach into deeper parts of the water,” said Donna Ellis, senior extension educator for UConn’s Department of Plant Science.

This can lead to changes in oxygen levels, acidity and other elements of a lake system that native species aren’t prepared to adapt to, Les said.

“These plants live at the edge of their existence, they’re in there, but they’re in there very, very tentatively,” he said. “If you change anything in there, especially light, they go quickly.”

Reclaiming these delicate ecosystems can be expensive, though, because hydrilla winters beneath the surface of a lake’s sediment and is becoming resistant to herbicides, King said. According to the Journal of Agriculture and Applied Economics, the state of Florida, where hydrilla was first identified as an invasive species in the 1950s, spends nearly $32 million per year controlling invasive plant species in recreational waterways.

Hydrilla in particular demands continuous maintenance, she said. Just four years after the invasive species was identified in Orange Lake, Florida, it had covered more than 90 percent of the lake’s surface.

“The problem with hydrilla is if it’s not detected at an early stage, it’s virtually impossible to eradicate it,” King said.

While Les’ class didn’t find hydrilla in Coventry Lake during its unofficial survey two years ago, he said, that doesn’t mean it hadn’t taken root. The population may simply have been too small at the time to be detected.

The Connecticut Department of Energy and Environmental Protection said in a press release Sept. 25 that it is initiating further investigation into hydrilla’s presence in the lake. The agency will also station boating division staff in the area to encourage responsible boating practices to prevent further contamination.

Kimberly Armstrong is a staff writer for The Daily Campus. She can be reached via email at

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