January 23, 2026 — As a fisheries and aquaculture specialist at the Barnstable County Cooperative Extension, Abigail Archer spends a lot of time trying to help the public connect the dots between shellfish, nitrogen, and healthy estuaries. This relationship starts when nitrogen travels through freshwater streams and runoff into our marine environment.
“Oysters are kind of like sheep grazing out in a field. And so, you know, the sheep are not standing in a field absorbing the nutrients from the grass. They’re actually munching on the grass and then eating that and then getting the nutrients in the grass,” she explained.
“And so it’s the same thing for the oysters. So the nitrogen that’s coming through our groundwater is then fertilizing basically the algae, the phytoplankton that’s in the water. And then the oysters are filter feeders. And so they’re they’re kind of grazing on all of that yummy algae.”
And this is how things are supposed to work. But as Abigail’s colleague and fellow fisheries and aquaculture specialist Josh Reitsma explained to me, in many places, the system has gotten out of balance.
“So nitrogen in and of itself is a good thing. We all need it. It’s an essential element for all of us, including oysters, or quahogs for that matter. But the challenge is, in the marine environment when too much nitrogen is entering the system, it overloads the system,” Josh said.