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Eelgrass

Restoring Eelgrass in Shinnecock Bay

Eelgrass is an underwater plant that grows in saltwater environments like estuaries and forms beds or meadows. Eelgrass is a critical habitat for fish and shellfish, and generates oxygen, absorbs nutrients, binds sediment, and is a buffer against storms. Like all plants, eelgrass needs light to grow and thrive. With degrading water quality and the presence of harmful algae blooms in western Shinnecock Bay, eelgrass was in a state of decline. 

 

Restoring eelgrass to western Shinnecock Bay is part of ShiRP’s multi-faceted approach. We hypothesized that as the large influx of shellfish took hold in the bay, filtration rates would increase, creating better conditions for eelgrass to grow and reproduce. Our approach was not to create new beds of eelgrass randomly, but rather, to expand existing eelgrass beds where evidence shows that the plant is already growing and surviving. 

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Shinnecock Bay: Eelgrass Restoration Since 2013 

In 2012 and 2013, we used a transplanting technique where eelgrass shoots were woven into burlap discs and buried in a grid within sandy habitats. Though this method can yield some success, it is extremely time-intensive and therefore limited in total capacity and number of shoots that can be planted. Adult shoots can also be stressed by this method.

 

From 2014 through 2019, we used the Buoy-Deployed Seeding System (BUDS; Pickerell et al. 2005), in which reproductive eelgrass shoots with near-mature seeds are collected and grouped into mesh bags held in the water column by buoys. As the seeds mature and release, they fall through the mesh, and with the right circumstances, colonize the surrounding bare sediment. This activity was done in June/July, when seeds were mature and would naturally reproduce. 

ShiRP involved the public in our eelgrass restoration efforts by holding an annual event where members of the public would help prepare and deploy eelgrass seeds into the bay.

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Hand broadcasting eelgrass seeds

In the fall of 2019, we experimented with hand broadcasting eelgrass seeds in a selected area in Shinnecock Bay.  This method, done in late fall, can lead to higher seedling success because there are less consumers present once temperatures drop. Since then, from 2020-2022, we hand broadcasted seeds as our primary restoration technique, especially due to COVID-19 and the cancellation of our annual community outreach event where the public assists us with building and deploying BuDS units.

The evolution of our eelgrass restoration approaches demonstrates the value and importance of an adaptive management strategy, where information gathered in the field and in the peer-reviewed literature, can inform and improve project methodologies. 

The Results...

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187,000

reproductive donor shoots collected

9.35 million

seeds distributed into plots covering more than 12 acres 

87 acres

of new eelgrass established in Western Shinnecock Bay

Monitoring

What are we monitoring?

  • New eelgass growth via visual surveys obtained by divers 

  • Net gains of eelgrass over time via ariel imagery and machine learning 

  • Light levels within the bay

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Eelgrass Monitoring

We began focusing on filter feeding bivalves, particularly hard clams, and noticed experimentally that more clams could clear the water faster, promoting seagrass growth. The regrowth of hundreds of thousands of square meters of seagrass beds in the past few years is a testament to the improving water quality and ecosystem health in Shinnecock Bay."

-​ Dr. Christopher Gobler

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