On a sunny September morning on the Connecticut River, Gregory Bugbee nudged his skiff into Selden Cove in Hadlyme, Connecticut, and it happened again. He got stuck.

Two years ago, the cove was a magnet for anglers, a clear pond from which Selden Creek runs south through sunken meadows of wild rice and drowned oaks to join the river at the bottom of Selden Neck.

Now you can’t sink a hook in the cove. It can be difficult even to push a boat through. It is choked from its sandy bottom to the water’s surface by an acre-sized mat of a ferocious aquatic weed called hydrilla.

Hydrilla is a notoriously troublesome, invasive weed, particularly in the southern U.S., where it has clogged ponds and blocked rivers for years.

But what scientists have found in Selden Cove and everywhere else along the 200 miles of the Connecticut River and its tributaries below Springfield is something different: A previously undiscovered, genetically unique and exceptionally robust strain of hydrilla that so far has not been found anywhere else in the world.

The newly discovered Connecticut River strain has proven just as troubling as its southern relations, but is new enough to be something of a mystery. It was unknown two decades ago and has spread so explosively since that there is concern it could threaten the half century of environmental progress that has made the river a $1 billion-plus a year contributor to the state economy.

Marina owners have had to pay to have channels cleared. Kayakers can’t paddle through it, swimmers won’t swim in it and fishermen have given up on choice spots in coves and creeks. It has choked the shallow Mattabesset River in Middletown enough to slow the flow rate, threatening to turn it into a giant mosquito breeding ground. Owners of million dollar waterfront homes look out over mats of weed and tax collectors are worrying about property values.

Beyond aesthetics and recreation, there is reason to worry about the weed’s effect on the river ecosystem, not the least of which is its potential to threaten the big birds such as bald eagles and osprey that have repopulated the river. Similar, although genetically distinct, southern hydrilla harbors an algae-like cyanobacteria that produces a neurotoxin that gets into the food chain and kills birds. The new strain is being studied to learn whether it attracts the same bacteria.

Scientists like Bugbee, who is directing state efforts against hydrilla, are trying to figure out how to control Connecticut River hydrilla, the impact of which has been captured in a stunning video by the Connecticut Resource Conservation and Development Program, or CT RC&D.

Invading the CT River- The Spread of Hydrilla from Emily DeLuca on Vimeo.

There is fear it will crowd out long established plants and animals, sending an unpredictable ripple across the river ecosystem — just one of the new strain of hydrilla plants produces 191 tips that grow an inch a day. As important is finding a means of control — herbicide is one solution — that doesn’t hurt the river’s long term health.

“It is nothing like we’ve seen, from a standpoint of rapid movement and coverage on a scale like this,” said Bugbee, an aquatic plant expert with the Connecticut Agricultural Experiment Station and the principal investigator with the state’s invasive aquatic plant program.

“There is a lot to learn. It is a big issue.”

SOME HISTORY

To get out of Selden Cove, Bugbee had to pole his boat a ways and stop to unspool yards of vine-like Connecticut River hydrilla from his outboard to reach a clear channel.

The cove is one of the places he and his colleagues have spent two years studying, using their two small boats and satellite location technology to map the weed’s spread. They found it everywhere, from the lower reaches of the river — it apparently cannot survive salt — to a spot about a mile north of the state border, near the Six Flags amusement park in Agawam, Massachusetts, where, curiously, it stopped.

“Agawam is its northern point,” he said. “And in many years, it hasn’t moved farther north, which is very strange.”

In 1995, during the last comprehensive inventory of river plants in Connecticut, hydrilla wasn’t even mentioned. Bugbee said he first learned of what would become the new genetic strain in 2016, from a report by a group of volunteer scientists and river enthusiasts.

“They get together in one area and they try to identify every organism that they can – from plants to insects to whatever,” Bugbee said. “It’s called a bio blitz. This was being done in the Glastonbury area, in the area of Keeney Cove. And they couldn’t identify a plant. So it came to us. And we initially couldn’t positively identify it.

“It looked like hydrilla to some extent, but it had characteristics that were slightly different. It was more robust than any hydrilla we had seen in Connecticut. We had seen hydrilla before in some lakes and reservoirs and streams, particularly in the western part of the state. This was just different.”

One difference was the number of leaves. Hydrilla known to that point had five leaves growing in a whorl from a stem. What was growing in Keeney Cove had as many as 11 leaves.

Bugbee and his colleagues consulted scientists elsewhere, who couldn’t explain it either. So they sequenced the new plant’s DNA and ran it against a database of the world’s known plants. There was no match, just “close relatives” found in Ireland, Latvia and Asia.

“So we had to decide, ‘What is it?’ ” Bugbee said. “It is hydrilla, but it is distinct enough to be called a separate strain. Not a separate species, but a separate strain, or if you want to use the scientific term a separate clade.”

A clade is the group of all descendants of a common ancestor. The new Connecticut River weed was named clade c, making it distinct from the two other clades found in the U.S., clades a and b.

WHAT IS KNOWN

No one knows for sure where the new hydrilla came from, other than somewhere else. Scientists suspect the culprit was the aquarium trade: Someone dumped a fish tank into the river and an ornamental aquatic plant, probably from East Asia, took root and essentially took charge.

During their two year river survey, Bugbee said he and his colleagues raked up discarded aquaria. While filming the survey work, scientists recorded a father and son dumping a tank.

The new hydrilla apparently does not spread, as do the southern varieties, by producing potato-like tubers, which is a good thing in terms of controlling the weed. Tubers from southern plants can persist buried a foot deep in sediment for a decade — meaning that even if the roots and top growth are killed it grows back.

“From a managing it perspective, not having tubers could be a huge advantage and we are pretty confident that it does not. Which is extremely rare. No hydrilla has ever been known not to have it. So it is very strange,” Bugbee said.

On the other hand, by not producing tubers, he said the new hydrilla can direct energy to the upper portion of the plant, the part experts believe the new hydrilla uses to propagate by “fragmentation.”

Leaves, stems and little buds called turions break off from the plants, drift south on the current or north on the tide and grow into new plants. That makes efforts to control the plant by pulling it out, raking it up and chopping it off counterproductive. Fragments float away and root themselves.

The new hydrilla has not been found in deep parts of the river, but is confined to depths of up to 10 feet or so in the coves and creeks and along the river banks. Travel up and down river isn’t being impeded, but swimming, picnicking, paddling and fishing along the shore is.

In the fall, the new hydrilla disappears. It fragments, collects in large floating mats and drift away, spreading bits and pieces that it is believed will form the next year’s crop.

“If you come (to Selden Cove) in September, October, you will notice just huge mats sort of floating,” Bugbee said. “Everything just breaks up and floats away. It’s called auto fragmentation.”

The new strain is stronger and grows more densely than the southern varieties. A reason may be its ability to flourish in both high and low light levels. It already is crowding out native species such as eel grass, and, by extension, anything that depends on eel grass. It creates a toxic environment that favors itself — by blocking sunlight to other plants and reducing the level of oxygen in the water.

It was thought to be confined to the Connecticut River, but recently was found in East Twin Lake in Salisbury and Amos Lake in Preston, getting there, probably, by fragments carried on boat trailers.

“We’re finding it only near the boat ramps, so far, “ Bugbee said. “Anglers in particular love to fish in the river and they also like to fish in lakes.”

AN UNDERAPPRECIATED PLACE

There are tens of millions of dollars of boats in marinas along the river and tens of millions of dollars more on the water any weekend. It is an underappreciated place of spectacular visits. Granite ledges rise from the water in places, separated by hundred-acre swamps where eagles and osprey nest in piles of twigs stacked atop dead trees.

Stunning waterfront homes with private docks have appeared along the lower river.

The Connecticut Marine Trades Association believes the river is worth more than a $1 billion a year commercially. An study by the Connecticut Center for Economic Analysis at UConn estimates the lower river’s cultural, recreational, aesthetic and real estate values contribute hundreds of millions of dollars more.

Joseph Standart owns the three-century old Selden homestead in Lyme and has one of the million dollar views over Selden Cove and across the river to Chester.

“We used to see tons of fishermen in the cove all summer,” Standart said. “Then a year or two ago, the hydrilla just exploded. It looked like you could walk across the cove. It was that solid. This year, we’ve seen maybe one or two fishermen.”

Just north, in Whalebone Cove, Diana Fiske was part of a group of neighbors who set out in kayaks each summer to pull up another invasive weed, water chestnut. Not any longer.

“We have found by the second week of August the hydrilla hampers our effort to take up the other invasives,” she said. “Anything off the main channel can’t be paddled by the middle of August. We had a lot of success controlling the water chestnut. But the hydrilla is a whole new animal.”

On the other side of the river, at Chester Boat Basin, owner Robert Petzold said that by midsummer he now has to clear channels for his customers.

“Normally what happens, by the middle of August I have to hire a contractor to come in and cut this hydrilla or remediate this hydrilla from the basin so the boats can travel in and out,” he said.

“It’s hard to describe how dense it is. It is like you haven’t cut your grass in three weeks, and it’s wet and you try to push the lawn mower through it and it just stalls.”

Up river, Portland Boat Works has experimented with anchoring mats to the river bottom in the spring and removing them each fall in an effort to prevent hydrilla growth.

“The question is,” Petzold said, “are the boaters just going to get tired of it and go somewhere else, into salt water that doesn’t have it?”

REMEDIATION

There is a chance, however remote, of a natural process occurring — perhaps something involving an insect, fish or plant disease — that would control the new hydrilla. Or that scientists are able to introduce a biologic control — again, an insect or hydrilla specific plant disease. But Bugbee said the first alternative would be fortuitous and the second needs a lot more study.

“Those studies essentially have not even begun,” he said.

There are fish, he said, that love to eat hydrilla. After invasive milfoil took over Candlewood Lake, 10,000 sterilized grass carp were introduced and, in short order, consumed nearly every piece of vegetation. Bass fishermen, who complained of too many weeds, are complaining of too few.

Voracious, vegetarian fish could have more unpredictable and undesirable consequences in a complex system like the river. Native river plants filter nutrients and create habitat for fish like the menhaden, which mature in the river and are often called the most important fish in the sea. And there is nothing to keep plant-eating fish from swimming upstream to Vermont and New Hampshire, where there is no hydrilla and they are unneeded.

To attack the hydrilla problem, Connecticut has created the Office of Aquatic Invasive Species. It is part of the Connecticut Agricultural Experiment Station and Bugbee leads it.

This summer, the U.S. Army Corps of Engineers joined with the new office and the 15 towns making up the Lower Connecticut River Valley Council of Governments in a study of whether hydrilla can be controlled by an herbicide.

As a first step, the corps has begun introducing a fluorescent dye at Keeney Cove in Glastonbury, Chapman Pond in East Haddam, Chester Boat Works in Chester and Selden Cove in Hadlyme. If additional testing were needed, the corps said it would be done in Deep River, the Mattabesset River in Middletown and at Portland Boat Works in Portland.

The corps said it is using a dye that is proven safe and it is being used to chart river current and tidal flow. It is preliminary, the corps said to a plan to treat selected sites with herbicide next summer.

“We don’t have another option, or a large scale option,” Bugbee said. “We don’t think harvesting is going to be effective. We’ve shown that benthic barriers (mats anchored to the river bottom) can work, but it is usually too labor intensive to work on a large area.

“There is always a hope that somebody can come up with some sort of biocontrol. Insect, fish or something that eats it. Maybe a hydrilla specific disease. That could potentially work. But right now there is nothing there.”

Jeanne Davies, the recently retired executive director of CT RC&D and creator of the video that attracted attention to the hydrilla problem, said the river has always been a unifying force in Connecticut and she hopes eradicating hydrilla can reinforce that sense.

“There is a whole thing about the Connecticut River,” she said. “It divides and unites Connecticut. Nobody particularly owns it, but it is a unifying aspect of Connecticut. It creates two cultures in Connecticut, from the west side to the east side. But yet it also unifies Connecticut.

“And I have always looked at this hydrilla issue as a unifying element of the Connecticut River. Because if everybody works together toward a solution on the river it becomes a unifier for Connecticut.”

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