Placing shell baskets in the Basin.
Test plot: Placing shell baskets in the Basin. © Theresa Chesnut/TNC

Stories in Maine

Science on the Half Shell

Learning how to grow shellfish populations in the Basin.

On a hot summer day, two scientists donned heavy scuba gear and slipped below the ocean’s surface in a protected cove on Maine’s midcoast. Surrounded by support boats and a team of sweltering colleagues, these divers weren’t exploring a reef, they were building one. This was the beginning of a project to test oyster and blue mussel reef restoration techniques in the waters just off the Basin Preserve in Phippsburg.

Oyster reefs and shellfish beds provide critical habitat for fish, crabs, shrimp, and other near-shore creatures. They also improve water quality as shellfish filter-feed on phytoplankton and tiny pieces of debris, removing excess nutrients and suspended particles. The cleaner, clearer water then allows for species such as eelgrass to thrive, further improving the health and productivity of the area. Reefs also help stabilize sediments and provide natural shoreline protection as storms become more frequent and powerful. And they’re tasty!

Launched by The Nature Conservancy in Maine in partnership with local, state and private agencies and organizations, the project involves setting on the seabed special one-foot by one-foot tiles resembling cement sand castles that are designed to reproduce the ideal surface for young shellfish to attach and grow. As part of the test, some of the tiles have been “seeded” with very young oysters called spat, along with small discarded mussels from a nearby aquaculture operation. Additionally, other methods, including setting oyster spat on recycled oyster shells, are being tested in the same grid area.

Over the next two years, scientists will monitor the different species and methods to compare their effectiveness at establishing solid reefs. The results of the effort will help determine the potential growth rates, ideal habitat conditions, costs, and scalability of building oyster and blue mussel beds and reefs in Maine.

The Conservancy is receiving support and guidance from the Town of Phippsburg, Maine Sea Grant, Casco Bay Estuary Partnership, the University of New England Marine Science Program, and the Department of Environmental Protection Marine Program.