OTTUMWA, Iowa —
Across the country, scientists are beginning to register the stress that higher temperatures have placed on the environment.
On the night of the fish kill that Pedretti reported on the Des Moines River, state biologist Mark Flammang was called to the scene.
"We've had fish kills before but never to that extent," he said.
Often, he said, fish kills come when the oxygen content in the river goes low. But the measurements he took that night suggest to him instead that it was probably the unusually warm water.
Another fish kill in the Des Moines River happened just two weeks ago, and again the water temperature was high. This time, it was about 92 degrees in places, and it claimed about 13,500 fish, mostly river carpsuckers and channel catfish, he said.
Where those temperatures stand in terms of the river's history is difficult to know because there are few, if any, consistent records. But Flammang and locals familiar with the river think those temperatures were well above normal summertime averages.
"The water normally has a chill to it," said A.J. Bower, 26, who runs a local Web site for enthusiasts. But "the heat is killing the fish. You can tell it's not supposed to be that warm."
"Mother Nature," he said, "is kicking our butt."