Will painting the Connecticut River help keep it alive?
The Connecticut River is facing a crisis: An aggressive invasive plant that grows in thick underwater mats is spreading rapidly.
It smothers native plants, changes the chemical balance of the water and increases its temperature. It traps boaters and slows the river’s flow, increasing the risk of flooding and providing an ideal breeding ground for mosquitoes. And it’s on the move: The plant, a new species of hydrilla, was discovered this year in several other water bodies in Connecticut.
“The rate of increase is really skyrocketing,” said Jeremiah Foley, a scientist at the Connecticut Agricultural Experiment Station, as he navigated a small research boat through one of the river’s tributaries near East Haddam, Connecticut, northeast of New Haven sent. .
Government scientists are rushing to control the hydrilla before it spreads even further in the Connecticut River, the longest river in New England and which flows through four states.
They fight back with an unlikely weapon: red tracer dye.
The dye will not damage the hydrilla. Instead, it is intended as a test for herbicides that scientists plan to put into the river next year. They will track how quickly it disappears in specific areas to decide how much herbicide to use.
Their goal is to find a sweet spot: enough herbicide to kill the hydrilla, but not enough to damage native plants.
“We use that dye as a surrogate to inform us that we should use as little herbicide as possible,” says Benjamin Sperry, a research biologist at the US Army Engineer Research and Development Center who specializes in aquatic plants.
The scientists, many of whom work with the Army Corps of Engineers, sometimes begin applying the dye before dawn. It spreads quickly in the water and disappears with the naked eye. But it leaves behind fluorescent trails that appear when scientists shine sensors into the water.
At the same time, scientists are studying this new species of hydrilla – considered genetically different of other varieties found in the US – to understand their growth patterns.
“We have to figure out how to kill it,” said Dr. Foley. “But we also have to figure out how it grows.”
Hydrilla, many species of which originate in Asia, first appeared in the American South decades ago before spreading through much of the country.
This outbreak was first identified in 2016. Since then, hydrilla has been found throughout the river, in Connecticut and into Massachusettsalong an area extending at least 70 miles.
“It’s further north than it’s ever been before,” said Dr. Foley, his hand on the tiller as he navigated the boat through the river. Around him, the tops of hydrilla plants broke through the surface of the shallow water, almost like debris strips on the sides of a highway. “And it is more robust than ever.”
Scientists have fought hydrilla in other states for decades. And in New York, California, North Carolina And Indianaherbicides have slowed its growth.
But the plant is a tough opponent.
It has no natural predators in the region and can change the pH balance or oxygen level of a river, which can disrupt the growth of native plants and animals.
In Connecticut, there is no longer any hope of eradication, said Dr. Foley. Instead, by killing the hydrilla with herbicide and educating boaters, scientists hope to defeat the pest year after year.
Very few aquatic herbicides are approved by the Environmental Protection Agency. Those that are largely broken down or broken down into non-toxic molecules, says Rob Richardson, an aquatic weed expert at North Carolina State University and a national expert on hydrilla, although there are still risks.
Researchers see the dye as a crucial step in using the chemicals safely and finding the right recipe.
“It’s basically like baking a cake,” said Dr. Foley. Using too much herbicide can “burn it all.” But if you use too little, the invasive plants can be left charred but alive.
Even environmental groups favor controlled chemical use: “They know this problem is necessary and that it can’t be solved any other way,” said Rhea Drozdenko, an advocate with the Connecticut River Conservancy.
But herbicides, no matter how powerful, are only a short-term solution to control hydrilla. Water sports enthusiasts must also be vigilant.
The contamination almost certainly started when someone dumped a personal aquarium, scientists said.
And people still spread it — unknowingly or carelessly — as they move their boats between waterways without properly cleaning, draining and drying them.
“This is ground zero,” Dr. Foley said as he pushed his boat off a dock and raked away the hydrilla from his engine as the fog rose around him.
As he steered through the water, he repeatedly turned off the power to pull off the plants by hand.
Some boaters and fishermen say the government waited far too long to tackle the outbreak, which is affecting many marinas, including the Chester Boat Basinabout half an hour from the mouth of the river.
Steven Leonti, the marina’s manager, said hydrilla can be dangerous and can hold up a powerboat that is difficult to maneuver in tight spaces.
But kayakers have it worse. At low tide, “you’re literally trying to push yourself through the grass,” he said. “It is so bad.”
It can also be expensive: The marina recently spent more than $20,000 to rake mats of hydrilla from the water and throw them into dumpsters, Mr. Leonti said.
He felt like he had no choice but to do it manually. Without government permission, he said he feared using an herbicide himself and risking a fine.
“What should we do about it? Nothing?” he said. “It’s killing our river.”