Dedicated to the Conservation of Southeastern Fishes
Oak Ridge Scientists Returning Native Fish To Once Polluted Creek
April 10, 2008
White Oak Creek will never be like it once was, before they split the atom and corralled big swaths of East Tennessee farmland to help build The Bomb and win the most awful war ever. But scientists at Oak Ridge National Laboratory are trying.
As part of that effort, they're bringing back fish species that used to live there — stripetail and snubnose darters, rock bass, striped shiners, bluntnose minnows and northern hog suckers.
It's an experiment.
"With any stocking effort, you have to realize there's a certain chance of failure," said Mike Ryon, an aquatic ecologist who's leading the project. "Maybe they don't take. What looks good to you may not look so good to the fish."
White Oak Creek winds along the industrial backside of the ORNL campus, with steam pipes crisscrossing the waterway at regular points. It later passes through the lab's outlying acreage once used for nuclear-waste disposal - landfills known politely as Solid Waste Storage Areas.
Over the past 20 years, the lab's discharges have been reduced and dechlorinated, and the landfills have been capped to stem toxic leaks. Ryon and his team members in the Environmental Sciences Division are doing other things to improve the aquatic habitat, such as establishing a riparian zone — grasses, bushes and trees — along the creek.
"It helps filter out material before it gets to the stream," Ryon said, "and the root structure helps anchor the bank to keep it from eroding away."
On the first day of spring, as lab technicians Kitty McCracken and Gail Morris released some of the fish into the rain-swollen creek's upper reaches, Ryon was placing slabs of rock in the same vicinity. That's to make the stripetail darters feel more at home and improve the chances they'll reproduce.
"They spawn under flat rocks," Ryon said. "The male will create a cavity underneath the rock, and the female lays the eggs by turning upside down and attaching them to the rock. The male then stays there and fans and keeps the silt off and also guards against predation. It's been theorized that there's an area on the (male's) nape that creates anti-bacterial things that apply to the eggs to protect and make sure they hatch. They don't lay a lot of eggs, but they invest a lot in parental care, enabling them to reproduce among all these other creatures."
White Oak is similar to other polluted creeks on the Department of Energy's Oak Ridge reservation, but it's different because it's not an open system.
A series of dams and weirs was constructed over the years to slow the lab's radioactive discharges and control the creek's flow. Those barriers kept fish from swimming upstream or entering the White Oak system from the Clinch River, where the watershed ultimately drains.
Therefore, sensitive species of fish could not naturally repopulate the creek as the water quality improved over the years, as they did at East Fork Poplar Creek — the notoriously polluted creek that originates at the Y-12 nuclear weapons plant and eventually connects with Poplar Creek and the Clinch River.
That's why Ryon and his team are transporting fish — captured from similar streams in the Oliver Springs area — to the upper parts of White Oak Creek. It's hoped they will coexist with the 15 or so species of fish that survived the Cold War and the creek's changing environment.
More than 500 fish have been relocated in the past couple of months. The timing, for some species, is just before spawning season, and researchers hope to get a bonus with early reproduction from the creek's new residents.
Before they're released, each fish is measured and then tagged with a small injection of nontoxic paint under the skin.
"That is one ugly fish," McCracken said as James Scott, a fellow technician, handed her a good-sized hog sucker. She injected blue paint near the sucker's tail.
The color identifies the part of the creek where the fish will be released, and the location of the paint identifies the release date. This recorded information should prove helpful to researchers when they monitor the creek and do fish inventories in the months ahead.
"We can tell if they've moved around or if they are where we released them," Ryon said.
There is a scientific protocol for animal studies that must be approved and followed.
After fish are collected at other sites by electroshocking, they are kept in ORNL's Aquatic Ecology Lab overnight to make sure they weren't harmed by the process. Mortality is less than 1 percent, but Ryon said researchers want to make sure they don't release weak or vulnerable fish. That might skew the evaluation of White Oak Creek's viability as a habitat.
Before the fish are injected with paint, they are anesthetized in a bath of tricaine methanesulfonate (MS-222). That knocks them out temporarily, allows them to be measured without flopping around and, presumably, keeps them from feeling any pain from the injection. They return to form within a couple of minutes after being placed in a bucket of fresh water.
The stocking program will conclude soon. The first look at how the new fish are doing will come in May, when sampling is scheduled as part of ORNL's Biological Monitoring and Assessment Program, and another survey is scheduled for the summer.
Ryon is betting on success. "I have a really good feeling about this system," he said.