Not all invasive species are as dramatic or fearsome as a Burmese python or a wild pig, but that doesn’t diminish their impact on native ecosystems. The coasts of North America and Europe have faced the spread of the Manila clam (Ruditapes philippinarum) for at least the last century. Although a favorite among seafood lovers, shellfish are also taking over local shellfish habitats and even hybridizing with similar species.

After decades of slow conquest, the delicious mollusk is finally taking up residence along the New England coast. According to wildlife biologists writing in the magazine. Biological invasionsthe region marked the northern hemisphere’s last obstacle against the Manila clam.

“Since Manila clams are everywhere in the Northern Hemisphere, it was only a matter of time before they showed up here, and we’ve been keeping an eye on them,” study co-author Aly Putnam, an ecologist at the University of Massachusetts Amherst, said in a statement.

The first warning of the arrival of the mollusk came through a photo and a text message. Last summer, Putnam received a photograph from his colleague and study co-author, El Fernekees Hartshorn, depicting a supposed 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 attention to the coastlines. It wasn’t long before they located many more Manila clams.

Coincidentally, a completely independent team led by the Center for Coastal Studies had recently begun investigating reports of “strange clams” near Provincetown, Massachusetts. They soon combined forces, confirming that Manila clams were definitely beginning to thrive in the area.

“I realized this was a golden opportunity not only to combine forces, but also to capture a detailed snapshot of when a new invasive species becomes established,” added study co-author and Williams College marine scientist James Carlton.

The origins of the Manila clam are not found near Cape Cod. Instead, they are native to the Sakhalin Islands of Russia and the coasts of Japan and southern China. Clams were introduced intentionally and accidentally to North America and Europe in the early 20th century, where they proliferated rapidly. The food industry also took advantage of seafood, turning it into a $7 billion-a-year industry.

While dense colonies can negatively impact local ecologies, they also provide nutritious food for crabs, small mammals, and seabirds. Now that they are confirmed throughout the Northern Hemisphere, ecologists can begin to examine how the clams are spreading across New England and how they will affect their new homes. Although they are likely here to stay, it is not necessarily a terrible situation.

“On the positive side, because Manila clams can become a food source for other animals, they can relieve pressure on native species; for example, the predatory pressure of green crabs on soft-shell clams,” Bastidas explained. “Therefore, there could also be positive impacts.”

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