By Julia Carlin
THE BOSTON GLOBE
In the shadow of the Longfellow Bridge sits the lower basin of the Charles River — the most stagnant part of the river, which sees a steady stream of nutrient pollution from Route 28 runoff. It’s perhaps the dirtiest stretch of “that dirty water.”
But a few yards from the seawall a 700-square-foot floating oasis bobs on the water exploding with lush green plants and blooming native flowers.
A year after its creation, researchers from Northeastern University and the Charles River Conservancy said they are seeing impressive plant growth on the wetland, which was launched in June 2020. The floating wetland project aims to reduce harmful algal blooms in the Charles by creating a small habitat that will reduce nutrient pollution, enhance sedimentation, and strengthen missing a link of the river’s food chain by increasing the zooplankton population.
The researchers envision people eventually jumping off the docks of the Esplanade and splashing around in the river. The wetland, researchers said, will add momentum to conservation efforts by raising public awareness.
“That vision is what moves me and motivates me,” said Max Rome, a PhD candidate at Northeastern University and leader of wetland research for the conservancy.
Rome and his colleagues are still in the process of assessing exactly what their findings mean and whether the abundant plant growth is indicative of a healthier river.
But even if the research is inconclusive, Rome hopes the wetland will succeed in “shock[ing] people out of their complacency.” He wants people to see it and think ‘What if we could swim in the river…’ and wonder why the river isn’t more biodiverse.
Laura Jasinski, the conservancy’s executive director, said regardless of the experiment’s outcome, the wetland has been vital for raising public awareness and is helping battle the “dirty water stigma.”
The conservancy has engaged students at Cambridge Public Schools to conduct wetland experiments and been presentat events such as the Cambridge Arts Festival in an effort to bolster public education and interest in the river.
Jasinski hopes to expand the wetland project in the future once the researchers can identify where in the river the wetland will be most effective. She envisions a kayaking path that would navigate through different wetlands and offer a beautiful and peaceful respite from the noisy, busy city.
“We want people to engage with the river and build an emotional and recreational connection so they will think about how they can care for it,” said Jasinski. “Fun, memory-generating experiences with natural resources are helpful when you’re trying to change people’s behaviors.”
Notably, despite the extreme heat and heavy rainfall, there has not been an algal bloom yet this year, said Rome.
Algal blooms, which thrive in warm and polluted water, are the biggest obstacle when it comes to restoring open-water swimming, said Rome. The blooms can produce toxins that turn the water murky, are harmful to humans and wildlife and indicate that the ecology of the river is off balance.
Zooplankton eat algae, naturally preventing algal blooms and helping restore balance to the river. But because the river has a man-made seawall rather than a natural shoreline lush with plants, there are fewer places for zooplankton to hide from predators. The floating wetland will provide a habit for zooplankton to proliferate. Then, Rome said, they will eat the algae.
On Wednesday morning, Rome took a kayak and paddled out to the wetland to gather water samples containing zooplankton, which he does three times a week.
As there is “no going back to before humans intervened,” Rome said, the wetland could provide a semblance of ecological restoration. The river used to be surrounded by wetlands and was home to salmon and trout, he said.
“There’s no way to go all the way back, but we can create a biodiverse and ecologically rich habitat,” said Rome, who views biodiversity as innately good for the environment and those living in it.
As a kid, Rome said, he often playedalong the Charles. He remembers the awe and thrill of seeing dragonflies dart through the grass on the shore and watching alewife swimming below the water’s surface.
“I think it really enriches your life experience to have a river that’s not just nontoxic, but is actually filled with aquatic life and is rising and healthy,” said Rome.
Being in nature, he said, “is a very life-affirming part of living in a city.”
