– Cornell University researchers have confirmed two new exotic species, both about the size of a flea, have established themselves in the Great Lakes, according to the U.S. Environmental Protection Agency.

The arrival and staying power of both species in western Lake Erie remains a mystery to scientists who say it is the farthest north that either has been tracked in the Western Hemisphere. Although neither is considered an invasive species because they have been found in low abundance compared with native zooplankton, they now join the more than 180 foreign species that have crept into the Great Lakes, which has one of the highest numbers of non-indigenous species in the world.

While experts say their introduction to the planet’s largest system of fresh water is alarming, the discovery validates arguments from public officials and environmental groups who say monitoring is necessary for early detection.

Cornell has been monitoring zooplankton populations in all the Great Lakes since 2012, but the new species were located through a separate program funded by the Great Lakes Restoration Initiative, which has provided billions of dollars in federal funding for conservation and restoration. Earlier this month, the Senate voted to fund the program with $300 million, breaking with President Donald Trump’s proposed budget that sought to cut funds to $30 million. The appropriations bill still needs to be signed by Trump by Oct. 1 to secure funding, but Chris Korleski, director of the EPA’s Great Lakes National Program Office, said he was “optimistic.”

“We now have information about the presence of a nonnative species that we didn’t have before” and wouldn’t have had without the restoration program, Korleski said.

Every spring and summer, Cornell researchers in the EPA’s research vessel, the Lake Guardian, tow nets across 72 areas in the Great Lakes to monitor zooplankton populations. But in recent years, they’ve searched closer to shore. While nonnative zooplankton species are considered rare, researchers have discovered four in the past three years, all in western Lake Erie.

“Generally speaking, western Lake Erie has the most diverse assemblages of these species out there, probably because of how nutrient rich it is, and how different it is than the other Great Lakes,” said taxonomist Joe Connolly. “It’s shallow, it’s relatively warm and you get a lot of strange things there.”

James Watkins, a senior research associate, said of finding unfamiliar organisms, “It’s often a big detective story.”

It’s unclear what risk these species could pose because their ecological effects when they were introduced in the southern U.S. haven’t been studied, researchers said. The university will further assess potential risk.