ANCHORAGE, Alaska (AP) — Federal and university scientist have found new evidence that Alaska wood frogs may be hurt by warming water and pollution.

The state’s wood frogs and other North America amphibians have been affected by something that’s deforming and killing them.

Frogs in southcentral and eastern interior Alaska have been detected with missing limbs, abnormal eyes and other physical problems.

Researchers from Alaska Pacific University, the U.S. Fish and Wildlife Service and the University of California, Davis in a study published in the journal Ecosphere conclude that wood frog tadpoles found in warmer water that contains minute traces of copper are attacked more quickly and frequently than tadpoles in clear, cooler water.

In a laboratory study, tadpoles spent more time swimming deep if the water was clean, said Mari Reeves, a U.S. Fish and Wildlife Service ecologist. Tadpoles in water with copper spent more time being stationary and near the surface, making them vulnerable to attack that could damage their bodies.

A national program to examine die-offs and deformities of amphibians was launched in 2000.

A 10-year national study by the U.S. Fish and Wildlife Service found hotspots for wood frog deformities in the Kenai National Wildlife Refuge and the Tetlin National Wildlife Refuge.