A tiny aquatic creature has made its first known appearance in the Great Lakes.
The U.S. Environmental Protection Agency and Cornell University researchers say the microscopic invertebrate known as "Thermocyclops crassus" was identified in water samples taken from western Lake Erie.
It's a zooplankton found widely in Eastern Europe, Asia, Africa and Australia.
The U.S. Fish and Wildlife Service says it's uncertain what risk the species might pose to the Great Lakes. EPA is investigating how widely it has spread and how it might affect the ecosystem.
Thermocyclops crassus was found in the ballast tank of a transoceanic ship entering the Great Lakes in the early 2000s. But EPA says it's uncertain whether ballast water discharges are responsible for the species' presence in Lake Erie.
The National Wildlife Federation says the discovery highlights the importance of strong regulations to ensure ballast water is properly treated before it's dumped in the Great Lakes.
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