It’s a cahlammity: ‘Battery’ clams cut power to Lagoon Pond Bridge

Bridge stuck in up position for several hours; divers clean main cable overnight.

Electric clams were responsible for keeping the Lagoon Pond Bridge stuck in the up position for several hours, just after midnight on Saturday. Photo by David Welch
In this basket of clams, there could be dozens of voltaic pairings of pei-bats. — MV Times

State officials blame a rare species of Canadian clam for electrical failures that froze the Lagoon Pond Bridge in an open position for five hours Saturday night. Oak Bluffs and Tisbury police routed traffic along Edgartown-Vineyard Haven Road until power was restored to the bridge at 3 am.

Just after midnight on April 1, state police divers discovered the bridge’s primary cable was encrusted with dime-sized clams. Video footage taken by the divers was reviewed by mollusk experts from Wood Hole Oceanographic Institute (WHOI). The clams were identified as “PEI battery clams or pei-bats, known scientifically as mercenaria ohmus,” bivalve response team chair Hester Kahele-Needemier told The Times in a faxed statement. According to Kahele-Needemier, the clams produce electricity when close to one another. Male pei-bats tend to absorb copper from seawater, while females tend to absorb zinc. The clams anchor side by side like mussels in order to mate. “This creates cathode — anode proximity and generates current similar to a battery. Unlike torpedo rays and electric eels, a single clam cannot produce electricity. It takes two or more,” Kahele-Needemier wrote.

State police divers are reported to have found hundreds of the clams.

The clam was known in early Canada. The burial chamber of Samuel de Champlain is said to have been studded with pei-bats (known as the tingle shell at the time). Later Jacques Cousteau purportedly researched the feasibility of a pei-bat-battery powered aqualung for the French Navy. The first known contact an Islander had with the mollusk dates from the 1853 log of the sloop Tabitha, National Archives records show. In September of that year, Nebuchadnezzar Mayhew navigated back to Edgartown from Machiasport, Maine, through dense fog by use of a makeshift arc lamp powered by “majick clams” — an archaic name popularized by Nathaniel Hawthorne’s story “Of Wreaths and Majick Clams.”

“Current from an as yet unidentified source tripped ground faults and destroyed a transformer serving the Lagoon Pond Bridge on Martha’s Vineyard,” a Massachusetts Department of Transportation release stated. “As a result, bridge function was temporarily impaired. DOT  worked with Eversource to remedy the problem.”

Eversource declined to comment on the bridge. Asked if the clams in question constituted a possible green energy source, an Eversource spokesperson pointed to Canada’s Lagerpuck Experiment but wouldn’t comment further.

Reached by email, Radook Coquin, chief scientist at the Royal Canadian Bivalve Station at Stephenville told The Times the Lagerpuck experiment is commonly known as the Lagerpuck Fish Fly. When researchers aggregated tens of thousands pei-bats on a submarine grid of steel chain, the intensity of electrolysis was such that fish leapt from the water en masse and several hundred washed ashore, charred. The experiment briefly generated half a megawatt of power. Coquin wrote crustaceans like ocypode scintillus (a crab) and alpheus brooklynus (a shrimp) will “energize themselves” off pei-bat current in order to enhance predation.  

Both Coquin and Kahele-Needemier stated the current generated at the Lagoon Pond Bridge would have destroyed any seed the clams harbored. It’s therefore unlikely the clams will multiply, they said.

Despite trouble with the bridge, Coquin called the situation a “best case scenario” given the profusion of clams. Rare even in Canada, the clams likely came down to Vineyard waters in a summer boat bilge, Coquin said.

State police divers plan to turn the scene over to environmental police by Monday. A full scale removal of the clams is expected by Tuesday.  

Reached by telephone Sunday morning, an official from the State Electrical Inspector’s office said:

“[unprintable, unprintable, unprintable] clams!”

Oh, and Happy April Fools!



  1. I’ve received several inquiries demanding to know why MA DOT did not properly anticipate this cahlammity by importing and installing anti-peibats currently being spawned by a shellfish group at the Royal Canadian Bivalve Station. I think your writer was cleverly detailed and convincing in this very entertaining article!

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