Professor of biology Aaren Freeman, PhD (second from left), is a marine evolutionary ecologist.

Biology professor Aaren Freeman, PhD (second from left), is known for his efforts to bring oyster beds back to Oyster Bay, Long Island. Now he’s also pioneering a new way to fertilize the town’s golf courses—with kelp. It’s a great example of Adelphi's commitment to sustainability.

Adelphi professor of biology Aaren Freeman, PhD, is making the ocean and bays around Long Island cleaner. And he’s using the sea’s natural water-cleaning tools—sugar kelp and oysters—to do it.

Dr. Freeman helped launch a program that uses sugar kelp to fertilize golf courses in Oyster Bay, New York, 10 miles from Adelphi’s campus in Garden City. He showed the town how to grow crops of sugar kelp, an alga native to the local waters, in its harbor. The alga, which is nutrient dense and packed with minerals and vitamins that golf course grass needs to stay green, is harvested, dried, ground up and sprinkled on the fairways. It’s an organic soil amendment that’s far preferable to the industrially made fertilizers normally used to keep golf courses green.

Dr. Freeman’s idea isn’t exactly new. Dr. Freeman revived an ancient idea: Various kelps have been used by farmers around the world as fertilizer for thousands of years.

Kelp removes nitrogen pollution from the water

Dr. Freeman’s kelp solution packs a one-two punch of water-cleaning power. Industrial fertilizers used on lawns, parks and golf courses get into the waters around Long Island. They degrade water quality by causing nitrogen rates to soar, leading to harmful algal blooms and a decrease in oxygen that fish and other aquatic life need to breath. Substituting sugar kelp for industrial fertilizers reduces that harmful nitrogen runoff.

Kelp also soaks up nitrogen from the water as it grows, so it cleans the water just by existing. “Normally, the kelp would rot in the water and the nitrogen would go back into the marine ecosystem,” Dr. Freeman said. “By taking it out of the water and putting it on the golf course, we close the nitrogen loop.”

If the kelp works on the golf course, the town plans to use it in its parks as well.

Dr. Freeman said that the project in Oyster Bay is a trial to demonstrate the viability of kelp as a substitute for industrial fertilizers, and that using the alga on golf courses alone won’t solve the water pollution problem. “I want to emphasize this is not a silver bullet,” he said. “It’s just one arrow in the quiver to use against excess nitrogen.”

The nitrogen degrading the water around Long Island comes from septic tanks and rainwater runoff, he said, so a lot more needs to be done. “Right now, they’re harvesting 200 pounds of kelp a year,” he said. “If we want to really have a big impact, we would need to be harvesting tens of thousands of pounds a year.”

There’s a kelp movement growing, though. “When I started doing this four years ago, there were maybe three people on Long Island familiar with growing kelp,” Dr. Freeman said. “Now there are at least 20 entities growing it.” The towns of Hempstead and Oyster Bay are among them, and oyster farmers are growing kelp in the winter, their off-season. And a nonprofit, Lazy Point Farms, is giving grants and training to aspiring sugar kelp farmers. “I’m very pleased that it’s become a self-perpetuating program,” Dr. Freeman said.

Restoring the oyster beds of Oyster Bay

Like kelp, oysters are natural water cleaners, with a single adult oyster able to filter up to 50 gallons of water a day, removing excess nitrogen. But oyster populations have crashed around Oyster Bay due to a decline in water quality, overharvesting and climate change. “There were once more than 200,000 acres of oyster beds in the New York area,” Dr. Freeman explained. “Now there’s around 200 acres. They’ve been almost completely extirpated.”

Restoring those oyster beds would go a long way to cleaning up the water. So Dr. Freeman and visiting assistant professor of environmental studies Ryan Wallace, PhD, are working on a program to rebuild the beds in Oyster Bay. Armed with a $64,000 grant from the National Fish and Wildlife Foundation Long Island Sound Futures Fund, they’re looking for the best spots to rebuild oyster reefs. Cornell Cooperative Extension is involved with the project, too, along with a half-dozen other entities. “We have a whole team pulling this together,” Dr. Freeman said. “It’s really cool.”

To figure out where to reestablish reefs, the team is monitoring currents and water quality characteristics like pH, salinity and temperature so they can develop a model to predict where oysters will come. Once oysters establish themselves, they build their own reef and populate an area. Dr. Freeman is looking for the spots with just the right conditions. He and his team are also putting out some test oysters to see if they thrive in an area. “We put oyster shells out in the water in little mesh bags and let them sit there a month,” he said. “Then we collect them and look for baby oysters on the shells.”

They’ve been doing this for five years, and they haven’t found many baby oysters in their bags. “Most of the sites, we get no oysters settling whatsoever,” Dr. Freeman said. In the three spots where the baby oysters did show up in the test bags, they’re putting out more oyster shells and attempting to rebuild reefs. The next step of the study? Monitoring the reefs to see if the oysters make it. “I don’t have any solid data yet on survival rates, because we’re going to come back in a year and see if the oysters we put out are still alive.” They plan to do their first survey of the newly rebuilt and seeded beds in August, and then follow up with another check-in next summer.

Dr. Freeman and Dr. Wallace hope to expand oyster reefs and correct the oyster population decline. “Our goal is to bring back oysters as a food source and to remove excess nitrogen from the coastal ecosystem,” Dr. Freeman said. “We could feed people and clean up the water.”

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