Education / Environment

Bronx River is classroom for seaweed scientists

Kristina Siriotis

Environmental Program apprentice Alissa Hickson, 17, checking the lines of the seaweed farm she helps maintain with Rocking the Boat staff.

Rocking the Boat goes underwater to reduce pollution

On one of the last warm days of the year, a group of budding scientists cruised down the Bronx River in a speedboat with an ecological mission in mind. Their destination? The seaweed farm just off the shores of the peninsula.

The team – Sam Marquand, Rocking the Boat’s environmental program director, and five high schoolers —was on its way to introduce its newest members to a favorite field of study: nutrient bio-extraction. The process allows them to study what the seaweed absorbs, and look for traces of nitrogen, phosphorous and carbon – a sure sign that the water is being polluted by sewage. On a small scale here in the Bronx River, the seaweed also works to remove contaminants from the water because the aquatic plant is a natural filter-feeder.

Sadly, the seaweed has a seemingly endless buffet in the coastal waters off Hunts Point. Using it to clean the river of the nitrogen that builds up as a result of industrial dumping has its limitations, Marquand said, but it is a promising first step.

The impurities in the Bronx River come from a variety of sources, such as lawn fertilizer, poor septic and sewage infrastructure and water treatment plants. Hunts Point’s own water treatment plant, around the corner from the seaweed farm, is a key contributor, along with natural events like hurricanes, which can multiply the amount of pollutants in the water by stirring up sediment.

For the team at Rocking the Boat, the process begins by bringing small seaweed bundles, about the size of an orange, out to a site off Hunts Point’s southern tip and growing the seaweed on lines anchored with buoys. After three weeks the seaweed has grown to nearly 10 times its size and it is ready to be harvested, weighed and dried on a rooftop. The group then sends samples of the dried seaweed to labs for testing.

Analysis of the seaweed tissue has shown that nitrogen-15 is present, an indicator of human waste in the water.

The seaweed experiment off the Hunts Point peninsula has Dr. Charles Yarish to thank. A professor of ecology and evolutionary biology at the University of Connecticut, he helped establish the seaweed farm here, which is now manned solely by Marquand and his students. Yarish is passionate about the potential seaweed and other native species, such as shellfish, have to clean coastal waters. He depends on others to employ this process, however, and applauds organizations such as Rocking the Boat for being committed to the idea.

“They want to do the work, care about the environment, and care about education,” said Yarish. Continued support and funding depends on informing the public about the degradation of coastal waters, he says.

Marquand and his 11 apprentices have been cultivating the native red seaweed in the under-water farm since May, as it is a summer crop that thrives in temperatures above 60 degrees. The farm consists of carefully constructed lines made of rope that sprawl out horizontally and vertically, and are supported by neon buoys. “We basically built the entire thing from scratch,” says Alissa Hickson, 17, a seasoned seaweed apprentice at Rocking the Boat.

Abram Johnson, another apprentice at the organization, explained that the farm is a learning experience, as well as a necessary cleaning task. “I love that environmental projects make people aware of the wildlife that they wouldn’t expect to see in the Bronx,” said Johnson, who has also monitored eels in the Bronx River.

In addition to filtering the water, seaweed farms bolster the eco-system by bringing more fish, especially juvenile fish, to the area. And the seaweed can then be farmed and sold as a culinary product to the food industry. Some shellfish farmers Yarish has worked with have switched to seaweed farming because of the demand and profitability.

“There are absolutely no disadvantages to the process. It’s a win-win,” says Yarish.

Although some preliminary tests have shown that levels of harmful by-products, such as heavy metals, were below Food and Drug Administration maximum levels, many more tests would have to be preformed before any seaweed from the Bronx River can be sold for consumption and revenue.

Marquand explains that New York City’s combined sewer and water systems are the root of the problem, and can’t be fixed with seaweed alone. “We can’t rip up all of New York and start over,” he acknowledges. Change will have to come from a combination of environmental solutions, all over time.

In the meantime, Rocking the Boat’s seaweed farmers will soon be bringing out the last line of the season, before the red seaweed season ends. Over the winter, the organization might give more thought to other underwater undertakings: shellfish, also filter-feeders, or kelp, a winter crop that can filter when it’s too cold for the red seaweed to grow. In the meantime, the work, they say, is a great excuse for a boat ride on the Bronx River.

“Access to the river is possible again,” said Marquand. “We take that access to the next logical step, by encouraging young people from the community protect their river and their natural resources.”

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