From pythons to fungus, species invading US

"It's just a matter of time before one of these snakes gets to a visitor in the Florida Everglades," said Sen. Bill Nelson, D-Fla.

Nelson has introduced a bill to ban imports of the snakes, after years of trying to persuade federal wildlife officials to restrict their entry into the country.

Nelson was one of several senators who warned about the threat of invasive species at a hearing Wednesday.

From a mysterious fungus attacking bats in the Northeast to zebra mussels in the Great Lakes and snakehead fish in the Chesapeake Bay watershed, native wildlife is facing new threats nationwide.

Lawmakers are considering a variety of measures to address the problem, including a bill that would more closely regulate ballast water discharge to ensure that invasive species do not enter the country through oceangoing vessels. Ballast water, which keeps ships stable in rough seas, is blamed for carrying zebra mussels and many other invasive species into U.S. waters where they have overwhelmed native species and caused other environmental harm.

The Environmental Protection Agency has started regulating the ballast water of oceangoing ships for the first time under the Clean Water Act, although many state standards are more stringent. Environmentalists say more extensive treatment of ballast tanks is necessary to keep invasive species out.