Fishing trips

About once a month, Brad Pobst and Bruce Moyers enter an obscure cave by crawling on their knees through narrow shafts full of mud and decaying plant life.

Some narrow sections force them to pass items from their backpacks one at a time. The tunnel eventually opens into a cavern where a creek cuts through a graveyard of crumbled limestone.

For at least eight hours, Pobst, Moyers and a research crew tag as many cave-dwelling grotto sculpin as they can catch.

Their intent is to shed light on the mystery of a 3-inch fish that dwells exclusively in the cave system beneath Perry County.

The grotto sculpin is a fish that lives in only six cave systems in central Perry County, Mo.

Ongoing genetic testing might unveil it as a new species of fish, said Moyers, 32, a graduate student at the University of Central Arkansas. Its parent fish, the banded sculpin, still exists in springs, streams and caves across the southeastern United States.

Grotto sculpin live in six caves in Perry County, which contains more than 650 known caves. In Missouri, Perry County contains the largest karst system, which is formed when water carves formations through limestone.

"Perry County is unique in that it does drain a lot of the surface water into the cave system," said UCA biology professor Ginny Adams, who researched the grotto sculpin as a graduate student at Southern Illinois University of Carbondale.

Rainwater often carries pollutants such as pesticides, sewage and trash, into the caves directly through sinkholes, which are cracks in the surface ground.

Much like a canary indicates the air quality in a mine shaft, the grotto sculpin indicates the water quality in caves.

In 1999, the sculpin completely died out in one cave, spurring the Missouri Conservation Department to embark on a long-term study of Perry County's water quality, which includes water from the surface streams, caves and wells. Within two years, the fish fully recolonized the cave.

Funded by a small grant from Southeast Missouri State University, Moyers and Pobst, a fisheries management biologist, began research in July.

Moyers will spend two years on the field to study the grotto sculpin's movement, population size, growth rate and lifespan.

The process involves tagging individual fish with a number to identify it and a color to indicate which cave it is in. The colors might determine which of the caves are interconnected by water passages, Moyers said.

Before tagging each fish, Moyers places them in a bucket of anesthesia, he said. Then he places them in a recovery bucket of fresh water before releasing them back into the cave.

Building on research by two graduate students in the early 1990s, Adams delved into the physical and functional differences between the grotto sculpin and banded scuplin.

Compared to surface-dwelling banded sculpin, the grotto sculpin has smaller eyes, smaller optical lobes in the brain, almost no skin pigment and faded bands along the tail and body, Adams said. A slower metabolism is a functional difference.

In one laboratory experiment, she placed one group of adult banded sculpin in constant darkness and another group in normal light conditions. The banded sculpin in darkness became reproductively mature almost immediately, Adams said. The discovery suggests that banded sculpin travel into caves to reproduce, she said. The newly hatched fish then travel back into the open.

When and how the banded sculpin became trapped and evolved into grotto sculpin is unknown, Adams said.

jmetelski@semissourian.com