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The Science of Oysters

With each “dip,” the scientists documented the type of sediment and the size and presence of live oysters (if there were any). Some oysters remained on the boat for disease sampling; others were thrown back, depending on their age.

By: Kathryn E. Arion

“That’s some nasty mud right there.” While out on the Nanticoke River in early October, I had the chance to witness first-hand the current condition of the river’s oyster population. The day began with meeting the research group at a harbor in Bivalve, Maryland, a town name that gives a nod to the influence of these shellfish since colonization.

Oysters are an essential part of the Chesapeake Bay ecosystem since they naturally filter the water. An adult oyster can filter 50 gallons of water a day; at their prime, the entire population filtered the entire bay in just one week! These creatures also provide habitat for other animals like blue crabs and rockfish, species also vital to the Bay.

The Chesapeake Bay once had the largest population of oysters east of the Mississippi River. Today, in rivers like the Nanticoke, where the river bottom once boasted a carpet of oyster reefs lies black, slimy mud.

On this day, Benjamin Parks, Sr. and his son, Benjamin “Benny” Parks, Jr. took our group, including Conservancy staff and University of Maryland Research Assistant Adriane Michaelis, out on their charter boat to check out the situation. Several days a week every fall, Michaelis and some colleagues collect oyster samples from Chesapeake Bay tributaries to test for diseases like Dermo and MSX, two parasites that can kill oysters and spread quickly throughout a population. Using mapping technologies, the researchers can pinpoint areas in the rivers harboring oyster shells, and hopefully living oysters, to collect for sampling. This scientific approach is what the Conservancy’s work is based upon, and I was excited to see what we would find.

We set off to each mapped point, dropping a patent tong to retrieve samples from the bottom of the river. Once used to harvest millions of oysters from the Bay and its tributaries, this tool is only allowed for scientific purposes due to their destructive effect on the river bottom and resident oyster populations. With each “dip,” the scientists documented the type of sediment and the size and presence of live oysters (if there were any). Some oysters remained on the boat for disease sampling; others were thrown back, depending on their age.

After six hours and 81 dips, fewer than 100 living oysters were found. More than 75% of the sediment samples were straight mud. Several times throughout the day, Parks Jr. muttered, “SSDD: Same stuff, different dip.”

The sampling reveals what Parks already knows, that oyster populations throughout the Chesapeake Bay and its tributaries have been decimated due to disease and overharvesting. However, The Nature Conservancy, along with other groups like the Oyster Recovery Partnership (ORP) and the Maryland Department of Natural Resources (DNR), are convening like never before in order to turn things around for these creatures. This includes breeding and returning oysters to various tributaries of the Chesapeake Bay, where the baby oysters (or “spat”) are placed onto reefs built from recycled shells and other materials. Just like the hundreds of millions of oysters that have already been planted by the Conservancy and partners around the world, the spat will have the opportunity to grow into a healthy, thriving reef.

“By leveraging policies set forth by the State of Maryland, sound science, years of experience in restoring oyster reefs, and the right partners we have an amazing opportunity to improve the health of the Chesapeake Bay,” said Mark Bryer, Chesapeake Bay program director for The Nature Conservancy. “Once restored, the oyster reefs benefit crab and rockfish as well as filter the waters of the Chesapeake Bay. It’s a project that improves the Bay’s health while also supporting local economies and the unique Chesapeake Bay culture we all enjoy.”

Sidebar: Chesapeake Bay

Learn more about our work in the Chesapeake Bay

For decades, The Conservancy has been working with agricultural interests, landowners, and policy makers to protect over 160,000 acres within the Chesapeake Bay watershed. Over the past ten years we have expanded that land-based work to include oyster reef restoration and other underwater habitat protection. By working with partners and throughout the watershed, The Conservancy is achieving lasting results for the Chesapeake Bay at an important scale.

Sidebar: Harris Creek

Learn more about our restoration plans in Harris Creek

The Nature Conservancy, Oyster Recovery Partnership, Maryland’s Department of Natural Resources, and other partners are working on the largest oyster restoration project ever attempted in the Chesapeake Bay. Together, we plan to restore more than 350 acres of healthy oyster reefs to Harris Creek rebuilding habitat for iconic crabs and rockfish while filtering the bay waters. This project also offers a path forward for additional oyster reef restoration helping the bay but also the people that depend upon its health for food, tourism, and the culture we all enjoy.

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