The Biggest Threat to Long Island Sound—And How to Fix It

C+S 2020 students are blogging about topics that interest them for Applications in Climate and Society, a core spring class.

Nitrogen overload, hypoxia, eutrophication: all of these words sound like they can be found in a science textbook but sadly, they can be found in the real world as well. They tell the disturbing story about what is happening to the waters off Long Island, New York as well as other places around the world. 

The waters surrounding Long Island have been heavily impacted by nitrogen overload, hypoxia, and eutrophication in recent decades. Several factors contribute to this. Nutrient loading, specifically from fertilizers that are spread on lawns and other places of flora, is one of the main drivers. Besides being extremely high in nitrogen concentrations, fertilizers are mostly petroleum-based. Along with fertilizer runoff, Long Island has a major problem with aging septic systems. These systems simply do not have the capability to remove or filter out nitrogen, which means a massive influx of nitrogen ends up leaching into Long Island Sound to the north of the island and Great South Bay off the southern coast.

The waters surrounding Long Island are filled with extremely productive ecosystems. This estuary serves as a feeding, breeding and nursery area for countless species such as oysters, Atlantic blue crabs, flounder, and ocean sunfish. Around 4 million people also live along the estuary. According to a 2015 research paper, the economic value of the Long Island Sound is estimated to range from $17 to $37 billion every year. This makes it a vital part of the local economies in Long Island as well as parts of Connecticut.  The ecosystems within the surrounding waters of Long Island are now severely stressed due to nitrogen overload, hypoxia, eutrophication, and may be near or in the process of collapse. The collapse of these ecosystems and contamination of this watershed would mean the loss of fisheries and biodiversity as well as have disastrous health effects for humans, plants and animals that all depend on it.

Bioextraction—that is, using natural filters—is a newer idea to deal with these issues, and New York has started using it. In the case of New York, oysters are among the bioextractors of choice because they are highly efficient at filtering the water column and removing nitrogen from it. Research funded by Sea Grant has shown that an adult oyster can filter 50 gallons of water a day and store around a third of a gram of nitrogen in its shell. This is a significant amount in relation to how small an oyster is. Fishermen along with local non-governmental organizations have begun farming shellfish to help reduce the amount of nitrogen in the waters of Long Island. Oysters reefs not only filter the water column but also serve as great places for biodiversity to flourish as these organic reefs attract other forms of sea life to the area.  Along with water filtration and an addition to biodiversity, oysters are great natural storm barriers. Billion Oyster Project researchers found that creating oyster reefs in New York Harbor can help reduce storm damage from large waves and flash flooding during hurricane season as well as  heavy rain events that can happen anytime of year. These reefs can also help slow coastal degradation.

The use of oysters as bioextractors has shown promise in the waters surrounding Long Island and can serve as a guide in other areas around the world. For example, oyster reefs have also been implemented as a solution in the Chesapeake Bay and the Gulf of Mexico, both areas with high amounts of nitrogen in the water column.