Noxious, fast-growing hydrilla invasive discovered at Twin Lakes

SALISBURY — A fast-growing invasive aquatic plant species known as Hydrilla verticillata has hitch hiked its way to East Twin Lake. The noxious weed was discovered on June 29 near the public boat launch at O’Hara’s Landing Marina, prompting swift action by lake officials to target and eradicate the noxious weed before it multiplies and chokes the watershed.

“Hydrilla is a very bad plant,” TLA board member Russ Conklin told attendees at the TLA’s annual meeting held at Camp Isola Bella on Saturday, Aug. 5. Fragments of the federally identified noxious weed are easily transported by boats, boat trailers and fishing gear and can easily sprout new roots.

Since its discovery at East Twin two weeks ago, several hundred pounds of hydrilla have been yanked from the lake’s waters by the TLA’s lake management contractor.

Once hydrilla, also commonly called water thyme, establishes itself in a body of water, it crowds out native vegetation, harms fisheries, sickens wildfowl, impedes recreation and reduces property values, according to the Connecticut Agricultural Experiment Station (CAES).

In other words, it stomps out life from the bottom up.

A ‘concern’ for Lake Wononscopomuc

Meanwhile the discovery of hydrilla in a nearby lake has Bill Littauer, president of the Lake Wononscopomuc Association, on high alert.

“We haven’t found any hydrilla in Wononscopomuc yet, but it is a concern if it has been found in Twin Lakes,” said Littauer, who noted that the association has a boat watch at the Town Grove. “We will have to warn them to be on the watch for weeds as well as Zebra Mussels.”

The Grove staff monitors boat launchings between April and Labor Day, and the lake association pays for a guard the remainder of the time the launch site is open, Littauer explained.

There is no formal monitoring of boats entering and exiting the launch at O’Hara’s Landing on East Twin, although lake officials advised those who use the lake to carefully inspect and clean their watercraft and equipment before and after each outing.

Harvesting it by hand

The discovery of hydrilla in the waters of East Twin was made by TLA’s lake management consulting contractor, George Knoecklein of NEAR (North End Aquatic Research, LLC). The limnologist reported that during a June 29 water quality visit, a “suspicious aquatic plant” was found in the vicinity of the marina that resembled hydrilla, whose origin is Asia.

Samples were immediately turned over to Greg Bugbee, associate scientist with the (CAES) in New Haven, who had them genetically identified at the University of Wisconsin-Whitewater as the Connecticut River strain of hydrilla, said Conklin.

Since then, Knoecklein has been doing extensive surveys of the area and has hand removed more than 200 pounds of hydrilla from East Twin. The limnologist is also documenting the locations where the specimen is found, according to TLA officials.

“The temptation is going to be to pull it out, but please don’t,” Conklin implored lake property owners at the TLA meeting, explaining that hydrilla is not easily identified.

“If you think it’s there, tell us and we can call in people who are trained to identify it. You might not get it all, and then three weeks later, it has resprouted.”

TLA president Grant Bogle stressed the importance of allowing experts to pinpoint the exact locations of the plant, so that treatment can be targeted to those areas. “We need to have trained scientists keep track of where they confirm that it has been found.”

While the overdue treatment of milfoil at Twin Lakes is scheduled to take place on Aug. 14, the state Department of Energy and Environmental Protection (DEEP) has not approved chemical treatment of hydrilla this year due to the proximity to native aquatic plants in the vicinity of the marina. “The DEEP is not allowing us to treat for this weed this year,” said TLA president Grant Bogle.

Conklin noted that the TLA’s limnologist has found “one escapee” from the marina area heading north on East Twin, “so we are not done with it. It’s likely out there and it’s likely that we will find it over the next few years, but it can be contained.”

Dealing with a ‘robust’ variant

Conklin said genetic testing of the hydrilla pulled from the area of the marina confirmed that it is the Connecticut River variant. “It’s a robust variant,” identified by serrated leaves with a spiny vein down the center, he explained.

The invasive plant, which lives up to 30 feet below the surface, can grow up to a foot a day, making it one of the world’s most invasive plants, according to Cornell University’s Cooperative Extension. It is also found on the USDA’s federal noxious weed list.

Once hydrilla becomes established in a new area, its long, stringy vines thicken into heavy mats, blocking out sunlight to native vegetation and affecting the ecosystem’s oxygen flow, altering native species’ habitat.

The variety of hydrilla plant originally from Asia presented with bulb-shaped tuber, or bulb,  as part of its root system. The Connecticut River species does not have that tuber as part of its genetic makeup. But the rest of the plant is the same.

“One of the things to keep in mind is that the tuber has not been in the Connecticut River variety, and that’s a good thing because the tubers have a long life and it would make it harder to deal with,” Conklin said.

TLA officials said the lake association will be collaborating with CAES’ Bugbee, who is an expert on invasive aquatic plants, as well as officials from the state Department of Energy and Environmental Protection (DEEP), to work towards finding and eradicating the invasive species.

“We are going to have to do surveys on that marina on a regular basis,” said Conklin.

State task force formed in 2018

Following reports of hydrilla occurring in the southern portion of the Connecticut River, a task force led by the CAES Invasive Aquatic Plant Program was formed in 2018 to perform a preliminary survey from central Vermont/New Hampshire to Long Island Sound.

“No hydrilla was found north of southern Massachusetts; however, from the Connecticut border south, hydrilla became common,” CAES had reported at the time.  Portions of the river and its coves were choked with the weed. The densest beds occurred on shallow shoals and in protected coves.

“Finding such dense stands of hydrilla in a northern state is alarming and could be the result of warning climate,” according to Bugbee, who warned that Connecticut River hydrilla is “far more robust than that seen elsewhere in the state.”

During the TLA annual meeting, the membership unanimously approved a spending request to allow the board to engage with contractors to manage all lake quality and treatment matters and spend up to $80,000 of funds, including $5,000 for hydrilla eradication, from its general fund through June 2024 and up to $30,000 of earmarked funds to support weed harvesting and skimmer operation on West Twin.

TLA officials said in addition to initiating periodic surveys of the marina, future action will include a permit update from DEEP to allow for hydrilla treatment.

Key features of hydrilla:

Plants are submersed.

Stems are slender, branched and up to 25 feet long.

Leaves are whorled approximately 0.7 inches long. Whorls often have five leaves, and leaf margins are visibly toothed.

Flowers: female flowers have three translucent petals that have reddish streaks; male flowers have three petals and can be white to red in color.

Fruits/seeds: small tubers (key feature) can be found in the sediment, turions form along the stem.

Reproduction: Fragmentation, turions, tubers and seeds.

(Note: The Connecticut River variant, which was found in Twin Lakes, is genetically distinct and has no observed tubers)

—Source: Twin Lakes Association