By Dan Klepal
The Cincinnati Enquirer

A Sloan's crayfish collected Wednesday morning from a pool in Paddy's Run Creek at the base of a culvert near Shandon in Butler County. (Glenn Hartong photo) | ZOOM |

SHANDON, Ohio - After a few hours of trolling the bottom of Paddy's Run Wednesday, Roger Thoma had the world's largest collection of Sloan's crayfish at the bottom of a plastic bucket filled with murky water.

Thoma, a biologist with the Ohio Environmental Protection Agency, and a crew that included state transportation officials found more than 50 of the threatened tiny crayfish in a small section of Paddy's Run, where it crosses underneath Ohio 748, just north of this Butler County hamlet.

They took a seine, a large net, and dragged it back and forth in the stream, picking up everything on the bottom, from the inch-long crayfish to fish.

The Sloan's crayfish, a species considered threatened in its only habitat - the streams of southwestern Ohio and parts of Indiana - must be moved because of a road project that could make this section of the stream unlivable for the crayfish during construction.

"This is a good number," said Thoma, a crayfish expert and volunteer curator of the crayfish exhibit at Ohio State University's Museum of Biological Diversity. "We only have five or six Sloan's in our display at Ohio State. And we even found females with eggs, so that shows they are doing well and reproducing in the stream."

The road project and new culvert will benefit everything in the stream, from the crayfish to the sport fish, he said. Sloan's are a tasty meal for smallmouth and rock bass.

The only bad news Wednesday: The Sloan's primary competition - the Rusty crayfish, which is bigger, more aggressive and often mates with female Sloan's to keep them from reproducing with their own kind - also were found in the stream.

None were found in sampling a few years ago - and that change is a classic example of a less adaptable creature fading away with urbanization, while its more muscular cousin takes advantage of the situation, he said.

The area around the culvert is becoming urbanized, which leads to lawn fertilizer, oil, grease and some metals being washed into the stream from rainfall. Sloan's crayfish need clean water to survive, while the Rusty crayfish like nutrient-rich water.

"Urbanization is one of the worst things that can happen around a stream. No one has been able to figure out how to reverse the effects," Thoma said.

"We have to maintain the water quality, then the Sloan's will be fine because Rusty won't want to live there."

E-mail dklepal@yahoo.com