‘Oyster Castle’ Project Planned for Mordecai Island

Jun 28, 2017
Photo by: Ryan Morrill

More than 15 years ago, members of the Little Egg Harbor Yacht Cub in Beach Haven formed the Mordecai Land Trust in an attempt to curb erosion that had been eating away at Mordecai Island, located in the bay just west of the docks. The claw-shaped island currently covers 41 acres, although at one time it covered more than 70 acres.

According to the land trust, the island protects Beach Haven’s western edge from storms and at the same time serves as a wonderful ecosystem that is a habitat for a variety of species of wildlife that includes migrating birds, shore birds and a number of threatened species.

While there have been dredging projects along with geotube placement and grass plantings for short-term fixes, the trust has been hoping to establish a breakwater project to reduce the wave energy on the island’s west end as a permanent solution.

“That’s the area that takes a pounding during storms,” said Jim Dugan, an engineer and land trust board member. “The western shore of Mordecai Island has been eroding at an unsustainable rate due to wave action from winds and the New Jersey Intracoastal Waterway boat traffic.”

Dugan said that when the trust first was formed, the breakwater project was going to involve rock jetty-type structures.

“Then there was the possibility of wooden slats,” he said. “Now it’s back to the jetties, and it is still in the feasibility study phase with the Army Corps of Engineers.”

Dugan said the land trust’s board recently approved an interim project to pilot a small breakwater demonstration installation.

“It would be a living shoreline, and one of the guiding principles of living shorelines is strengthening the communication between the estuary and shoreline,” he said. “This becomes critical when a breakwater is required to attenuate wave forces, as in the case of Mordecai Island. It cannot sever natural processes between the riparian, intertidal and aquatic areas. It enables tidal exchange, promotes sediment transport and supports plant and shellfish habitat.”

One possibility is oyster castles, in which the land trust would be working with ReClam the Bay.

“Constructing an on-site prototype with oyster castles offers the greatest opportunity to evaluate the structural geometry of the breakwater to fulfill its wave attenuating and habitat creating possibilities,” he said.

Dugan said each castle is 12 inches by 12 inches by 8 inches, weighs 30 pounds and is made of concrete, crushed shell, limestone and silica. They are shipped 72 per pallet, and each can be easily handled and stacked by volunteers

“Several oyster castles have been operating successfully in New Jersey, Delaware, Maryland, South Carolina, Florida and Virginia,” said Dugan. “Different arrays of oyster castles will be constructed to address stability, wave attenuation and habitat creation. Plot plans for each will vary from about 3 to 4 feet wide by 5 to 8 feet long. The arrays will be spaced and staggered to allow tidal exchange.”

Dugan said the structures would be erected in July and  monitored weekly throughout the summer months into November.

“The perimeter of the facility will be clearly marked with posts,” he said. “Photos and reports will be prepared noting the performance, structure stability and health of the shellfish and flora. Photos and reports will occur through the ensuing months as weather and boating conditions allow.”

— Eric Englund


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