Unique tools aid environmental research at SRS

Marilyn Mason, a research tech at the lab, removes young adult medaka from the tank for maintenance.

The Savannah River Site  is home to a unique aquatic laboratory that raises rapidly-reproducing Japanese fish, known as medaka. Operated by the University of Georgia’s Savannah River Ecology Laboratory , the facility provides scientists with a rare toxicology tool for assessing the long-term health effects of environmental contaminants on wildlife and humans.

“The SREL Medaka Laboratory is a strategic asset for low-dose research in the DOE Complex,” said Jimmy McMillan, the assistant manager for Infrastructure and Environmental Stewardship at the SRS.

Benjamin B. Parrott, an assistant professor at SREL, who runs the lab, said the fish, which grow no larger than 1.4 inches, are a powerful resource for assessing the effects of exposure to radiological and heavy metal contaminants such as cesium and mercury as well as to emerging chemical contaminants.

He said the ease at which the fish reproduce serves as a significant advantage for obtaining large numbers for testing. Parrott also said medaka can easily produce a cohort of 200 fish in a day.

Testing is done in conjunction with SREL’s Low-Dose Irradiation Facility, also housed on the SRS. Medaka are transported to the low-dose facility where they are chronically exposed to low doses of ionizing radiation for periods of three to six months.

Parrott said this is intended to mimic exposure to a combination of contaminants that both humans and wildlife can be exposed to in the environment.

As research tools working in synchronization, the medaka lab and the low-dose facility allow scientists on the SRS to go beyond asking if environmental contaminants are lethal.  Now they can investigate the effects of chronic exposure to environmental contaminants on long-term health and aging.  Parrott said the tools can also provide the scientific data for assessing occupational exposure risks from low doses of radiation in the workplace.

He said the medaka’s biological makeup is also an asset.

“These organisms share much of the physiology and genes of humans,” Parrott said. Alligators and a few other species also have similar human physiology, but an alligator takes 13 years to reach adulthood. A medaka fish goes from an egg to an adult in three months; so we can quickly see the results of our testing.”

Parrott also describes the medaka as cost-efficient subjects because they are easy to feed and maintain.

The lab currently houses about 2,000 fish with the capacity to hold close to 10,000.  The four-room facility is equipped with 10-gallon, 30-gallon and 55-gallon glass aquatic tanks with monitors, filters and disinfecting systems.