Looking for more sustainable ways to protect waterways and protect themselves from climate risks, more communities are turning to the humble oyster to strengthen their coastlines. Seaside cities throughout California use oysters to dampen storm surges and purify water, and now, New York City is taking advantage of the strategy as well.

New York City was once one of the largest exporters of oysters in the world, but water quality issues and overharvesting decimated populations. The city has spent many years restoring New York Harbor, and most recently, the water quality was deemed high enough to introduce the next step in the water purification process: the addition of 11.2 million juvenile oysters.

Added to a sector of the Hudson River near Lower Manhattan, the bivalves work to clean the water, balance the food chain, and, if they grow big enough, dissipate wave energy to protect the city’s shorelines.

The oysters are a part of the Hudson River Park’s estuarine sanctuary, an area which supports 85 species of fish. The improved water quality means that researchers have even spotted native oysters popping up as well.

The oysters were provided by the Billion Oyster Project, a nonprofit which aims to use oysters as nature’s most powerful habitat restoration tool. The $1.5 million project was put together by the New York State Department of Environmental Conservation, the Hudson River Park Trust, and engineering firm Moffatt and Nichol.

The impact of the oysters will be monitored by researchers at the River Project. River Project also runs a small aquarium to educate the public about New York’s abundant marine life. Although native oyster populations are rebounding in New York City, River Project notes that it will likely be many decades before the water is clean enough to actually eat the shelled delicacy.