This graphic describes how the Hare Lab measures wild spat-on-shell oysters.

Courtesy of Matt Hare

This graphic describes how the Hare Lab measures wild spat-on-shell oysters.

March 26, 2018

New Data on Remnant Oyster Population Could Help Restore the Hudson River

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The Hudson River is infamous for being one of the most polluted rivers in America, but its waters have a lot more to them than meets the eye. Estuaries like the Hudson are some of the most biodiverse ecosystems in the world, where one can find marine, brackish and freshwater species intermingling in a relatively small area. In the Hudson River, oysters served as the foundation for this rich environment until around 1900, when a combination of overfishing and pollution locally decimated the stocks.

Oysters begin their life cycle as small, mobile larvae. As they mature, they seek out a surface to settle on and develop their recognizable shells. They have a tendency to cement down on previously established oyster beds and eventually form large reefs in brackish environments. These reefs create habitat for a variety of species within estuaries, as well as provide direct social and economic benefits for the communities around them. Oyster reefs are also capable of reducing the impact of storm surges and other natural disasters. As filter feeders, oysters have also been studied extensively for their ability to filter some water pollutants and regulate phytoplankton populations in bodies of water which are over nutrified.

Given the numerous ecosystem services oysters perform, many groups, including New York State and the City of New York have taken part in efforts to restore oyster populations in the Hudson to their historic levels. Notable undertakings, such as the Billion Oyster Project and NY Baykeepers, have led the charge in engaging the community in seeding hatchery-bred oysters into the Hudson.

In the past, hatchery-bred oysters were the most feasible source of spat, or young oysters, for restoration projects. However, a new report from the Hare Lab in Cornell’s Department of Natural Resources suggests a new source of healthy oysters: a wild Hudson River species located near the Tappan Zee Bridge in the New York City metropolitan area. Discovered during unrelated research by Prof. Matthew Hare, natural resources, and his team, this new find is proof that a wild population of Hudson oysters has survived the degradation of the river and are stable enough to reproduce regularly.

The significance of a stable wild oyster population ultimately boils down to genetics. All oysters sourced from a hatchery are subject to the conditions inside the hatchery. These conditions can sometimes create genetic bottleneck events, favoring certain genetic groups over others.

After such an event, the genetic diversity of hatchery oyster populations are severely reduced. With lower genetic diversity, there is a lower chance that a given population will be able to thrive. With the discovery of a stable, wild Hudson River oyster population, Hare hopes that future projects can implement their genetics to increase chances of future successful populations.

Hare elaborated on the genetic differences between hatchery and wild populations. Hare discussed why local species are better suited than hatchery species for restoring oyster populations.

“It comes down to climate change and a population’s adaptive capacity during environmental change,” Hare said.