Scientists investigate salamander deaths in Lake Erie

Biologists suspect one of the most toxic substances known could be killing off a type of salamander living in Lake Erie.

Mud puppies have been washing up on the shores of the lake at an alarming rate and no one knows why.

Some of the area's beaches and parks have to be cleaned up regularly to remove the dead animals.

Several theories have been proposed to explain why the mud puppies are dying, including:

• Their populations have become more abundant over the past 10 years, which could make them more susceptible to disease outbreaks
• Storms could be beating up their eggs
• The animals could be trapped in cold areas of the stratified lake

But these factors should affect other lake life as well. Fish and crayfish have been dying off, but not in the same numbers as the mud puppies.

Botulism bad for birds, mud puppies

Roger Kenyon, a senior fishery biologist with the Pennsylvania Fish and Boat Commission thinks botulism might be to blame.

Kenyon told CBC Radio's As It Happens that avian type E botulism appeared in the area about three years ago.

No one knows the source of the bacteria, which can exist in a no-oxygen environment as a spore.

The spores can release a neurotoxin that is picked up by birds, who drown or die from muscle function collapse.

Some dead birds have been found along with the mud puppies. To verify whether botulism is present, Kenyon said scientists need to test animals that are infected with botulism and haven't yet died of it. They are searching for specimens to test.

Kenyon added the toxin won't bother swimmers or people who eat well-cooked fish.