New Species of Invasive Clam Found in Illinois River

A team of researchers from the University of Illinois, in collaboration with the University of Michigan, found a new species or form of invasive Asian clam in the Illinois River near the city of Marseilles, approximately 80 miles west of Lake Michigan.

The discovery, described in a paper published in the journal Bioinvasions Record, suggests that a new form of the invasive clam belonging to the genus Corbicula has finally made its way to North America.

"In the Midwest, you have invasive bivalves, including zebra mussels, and several species of invasive fish: Asian carp, black carp and even goldfish. There are exotic plants, like Eurasian milfoil. There is an invasive water flea from Africa, Asia and Australia. There also are several kinds of invasive snails," said Jeremy Tiemann, an aquatic ecologist at the Illinois Natural History Survey, in a press release. "All of these create problems for the natives."

The researchers found the invasive clam while searching for a federally endangered native clam through a mudflat. The researchers observed that the clam they spotted had unusual physical characteristics compared to other invasive clam species found in the region.

It is very difficult to identify new species under the genus Corbicula due to their unusual reproductive strategies. Corbicula is known to be androgenic clones and can also be hermaphrodites. Furthermore, the nuclear DNA of Corbicula tells one story, while their mitochondrial DNA suggests something different.

Despite being unable to properly classify the new invasive clam species, the researchers noted that it still presents a clear threat to native clam species. With no natural enemy in the area, the new invasive clam species could easily overpopulate, eating all the resources and driving away native clam species. Additionally, some experts think that invasive clam species can consume the larvae of the native species.

Aside from being a threat to native species, the new invasive clam species can also upset the river ecosystem as a whole. The start of new invasion could signal further erosions of ecosystem services traditionally provided by watersheds.