A tiny, prized shellfish behind a $7 billion global seafood industry has just crossed a new ecological threshold: scientists have confirmed that Manila clams have established themselves along the northwestern Atlantic coastline, making New England the last region in the entire Northern Hemisphere to lose its Manila-clam-free status.
The Discovery
A team of biologists led by the University of Massachusetts Amherst, MIT Sea Grant at MIT, and the Center for Coastal Studies announced the confirmation this week in a study published in the journal Biological Invasions. The researchers found that the invasive Manila clam, Ruditapes philippinarum, has made Cape Cod and the greater Boston area its new home. According to UMass, the Northeast coastline had been "the last place in the Northern Hemisphere to have remained Manila-clam free" — meaning this discovery closes out one of the only remaining gaps in the species' near-total hemispheric spread.
How It Was Found
The discovery came together almost by accident. Lead author Aly Putnam, a postdoctoral researcher at UMass Amherst and lecturer at Smith College, first received a photo last summer from colleague and study co-author El Fernekees Hartshorn showing a suspected Manila clam shell. Putnam and fellow researcher Carolina Bastidas were leading a biodiversity workshop on Spectacle Island in Boston Harbor at the time and began paying closer attention to the coastline, quickly locating more of the clams. Coincidentally, a separate team led by the Center for Coastal Studies had already begun investigating reports of "weird clams" near Provincetown, Massachusetts. The two research groups combined efforts and confirmed the species was established in the area. "I realized that this was a golden opportunity to not only combine forces, but also to catch a detailed snapshot of the moment a new invasive species establishes itself," said study co-author and Williams College marine scientist James Carlton.
Where Manila Clams Actually Come From
Manila clams are native to a range stretching from Russia's Sakhalin Islands through Japan and southern China. Since at least the early 20th century, the species has been spread — both intentionally and accidentally — to coastlines throughout North America and Europe, quickly proliferating everywhere it landed and eventually growing into the roughly $7 billion-a-year global seafood industry it represents today. Putnam noted the New England arrival wasn't exactly a surprise: "Given that Manila clams are everywhere else in the Northern Hemisphere, it was only a matter of time before they showed up here, and we've been keeping an eye out for them."
Not Necessarily an Ecological Disaster
Unlike some more destructive invasive species, researchers say the Manila clam's arrival isn't automatically bad news. Because the clams can serve as a food source for other animals — including crabs, small mammals, and seabirds — their presence could actually relieve some predatory pressure on native shellfish. Carolina Bastidas pointed specifically to green crabs, an already-established invasive predator in New England waters, noting the clams "can relieve pressure on native species. For example, the predatory pressure of green crabs on softshell clams. So, there could also be positive impacts."
What Scientists Still Don't Know
Despite the discovery, researchers stress there's significant uncertainty about what happens next. Elsewhere in the world, dense Manila clam colonies have been known to compete with local shellfish for habitat and even hybridize with related species — but whether that pattern will repeat itself in New England remains unclear. "We do need more research to understand the Manila clam's potential effects on the shellfishing industry and ecological communities," Bastidas said. Putnam echoed that uncertainty, framing the discovery as just the starting point: "Finding the species is only the beginning. Now we are working to understand its distribution, if these populations are expanding and how these clams interact with other species in New England coastal systems. This research will help us determine whether this newcomer becomes a minor addition to the ecosystem or a more influential player in the years ahead."
A Rare Scientific Opportunity
Beyond the ecological questions, researchers are framing the discovery as an unusually valuable case study. Because the Manila clam is only now beginning to spread in this particular region, after already colonizing essentially every other coastline in the Northern Hemisphere, scientists have a rare real-time opportunity to observe the earliest stages of an invasive species' establishment — rather than studying an invasion after it has already run its course. That could offer broader insight into how marine invasions unfold and how quickly newly arrived species can reshape coastal ecosystems.
Why It Matters Beyond the Science
The discovery adds Manila clams to a growing list of seafood species — including lionfish, European green crabs, and Asian carp — whose invasive spread has sparked both ecological concern and, in some cases, culinary opportunity. Some coastal communities have found ways to turn invasive seafood species into new local food markets rather than treating them purely as a threat, though researchers caution it's too early to say whether that path makes sense for Manila clams in New England. For now, the discovery marks both an ecological milestone and a genuine scientific opportunity: a chance to watch, in real time, whether a beloved seafood delicacy becomes New England's newest coastal disruptor.