Aquaculture and Oysters

cape oyster catch

AQUACULTURE AND OYSTERS

Barnstable Clean Water Coalition

The numbers are sobering. Every day, nitrogen equal to sixty-five 50-pound bags of fertilizer flows into the 1,251-acre Three Bays Estuary. Excess nitrogen leaching from septic systems, road runoff from lawn fertilizers, detergents from washing cars and doing laundry, as well as other metals and hydrocarbons pour into an overwhelmed marine environment. Nitrogen levels far exceed critical levels established by the Massachusetts Estuary Project (MEP.)

It’s our responsibility to protect these waters that represent our collective heritage.

Nationwide, oysters have been used for years to mitigate water quality problems in impaired environments including Chesapeake Bay, Long Island and Boston Harbor. A single adult oyster can filter up to 50 gallons of impure water every day, and that’s why these bivalves are called nature’s perfect purifiers. Oyster gardens create habitats that attract small bottom-dwelling organisms like grass shrimp and worms that in turn support populations of crabs, fish and other important species.
Three Bays has been growing oysters since 2008 when it teamed with the Town of Barnstable’s Natural Resources Program to purchase 600,000 oyster seeds and grew them at the entrance to Prince’s Cove. The oysters absolutely thrived in their new environment. The oysters grew so well that they were able to be planted after only one season of growth.

Our aquaculture program has been growing every year since. In spring 2016, we planted over 200,000 oyster seeds in 400 huge plastic floating bags in Middle Cove in North Bay where excess nitrogen has significantly threatened water quality. That’s the good news. Nitrogen, however, from the worst-ever algae bloom of Rust Tide in early August 2016 heavily impacted our restoration efforts. The Rust Tide was caused by a common saltwater organism or zooplankton called a dinoflagellate (Cochlodinium polykrikoides) that turns salt water a murky red, and depleted oxygen from the water column where the oysters were incubating in suspended bags. Tens of thousands of them were killed.

Despite the algae bloom of last summer, Barnstable Clean Water Coalition remains committed to a vigorous aquaculture program and its vital role in restoring our impaired waters.

Please click on the links below to read current studies on aquaculture and how it can be used as a tool to remove nitrogen from our embayment:

  1. Comparative Analysis of Modeled Nitrogen Removal by Shellfish Farms pdf icon
  2. Denitrification & Nutrient Assimilation on a Restored Oyster Reef 2013 pdf icon
  3. Nitrogen Bulletin 2014 Shellfish Nitrogen Removal pdf icon

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