Researchers say two new exotic zooplankton species have crept into the Great Lakes.

The U.S. Environmental Protection Agency says Cornell University researchers confirmed the species are in Lake Erie.

The species are Diaphanosoma fluviatile, which is from Central and South America and the Caribbean, and Mesocyclops pehpeiensis, which is native to tropical and temperate areas of Asia.

Scientists don't know how the zooplankton entered the lake but say it's the farthest north either species has been tracked in the Western Hemisphere.

Experts say the discovery is the planet's largest fresh water system is alarming. Researchers are uncertain what risks the tiny creatures may pose. The university plans to monitor the situation but says both species haven't been deemed invasive because of their low abundance.

The findings are part of the EPA's biology monitoring program in the Great Lakes.