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Scientists may have a found a new invasive clam species in the Illinois River. L. Brian Stauffer/University of Illinois at Urbana-Champaign

Scientists may have found a new foreign species of clam in the United States and it is a hermaphrodite, so it wouldn’t need any help completely taking over the water.

The invasive clam the size of a fingernail was found in the Illinois River a little more than an hour southwest of Chicago — and Lake Michigan — and has been linked to the Corbicula genus, which has ties to the country since the early half of the 20th century. “It likely was brought to North America by immigrants from Asia who used the clams as food,” the University of Illinois explained. “Within a few decades, it had colonized many of the major waterways of North America.”

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A genetic and physical analysis, however, shows this new clam is distinct from the others in its family in the river. But in a study in the journal BioInvasions Records, the scientists hesitated to definitively call it a separate species. They instead said it is “apparently novel” because it’s possible the clam has already been discovered in another location in the U.S. or “when considering a broader sample of Corbicula lineages.”

Further complicating matters, Corbicula clams can create new offspring with other species of their kind or can be hermaphrodites and reproduce asexually, which makes it hard to completely understand a clam’s lineage. The asexual reproduction makes them highly invasive.

“This means that it takes only a single clam to spawn a new population,” aquatic ecologist Jeremy Tiemann said in the university statement.

Whether or not the tiny clam is a new species, it’s likely not a great sign for the local environment. Since this group of marine creatures first entered North America it has thoroughly spread through this continent and through South America. And previous research suggests that Corbicula interferes with native mussel species, including endangered ones, because it eats from the same food sources and doesn’t have any natural predators.

“Given the speed of colonization of Corbicula individuals across continental watersheds, this new invader could be a substantial threat to watersheds in both the Mississippi River and Great Lakes basins if it were to spread,” the authors wrote in their study.

On a more human scale, the freshwater clams could have negative effects on power plants, drinking water and irrigation canals: “Infestations of Corbicula individuals have yielded billions of dollars annually in damage to industry and infrastructure,” the study says. “Thus, early detection of Corbicula individuals may help to limit its environmental and economic effects.”

The U.S. Department of Agriculture says the clams can clog pipes and marine channels.

Corbicula clams are originally from temperate and tropical locations, including in Asia, Africa, and Australia, although they are most often known as Asian clams. Their family includes “some of the most common and successful aquatic nuisance species in the New World.”

See also:

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