|SREL Reprint #1851|
Enhanced Uranium Tolerance of an Exposed Population of
the Eastern Mosquitofish (Gambusia holbrooki Girard
Abstract. Genetic differences between populations of mosquitofish from a
uranium (U)-contaminated stream were identified by starch gel electrophoresis.
Fish collected from the uncontaminated mainstream of Upper Three Runs Creek
(South Carolina, USA) exhibited greater genetic variability than those collected
from the contaminated Tims Branch. Lower genetic variation displayed in Tims
Branch fish could reflect selection associated with toxicant stress, a genetic
bottleneck due to low population numbers at the contaminated site, or random
genetic drift. A toxicity assay was performed to determine if these genetically
distinct mosquitofish also displayed enhanced U tolerance. Times to death were
compared for fish from an uncontaminated site and offspring of fish taken from
the U-contaminated Tims Branch. After 7 days of exposure to 2.57 mg/L of U
as uranyl nitrate, 98% and 96% of the naive population had died in the replicate
tanks. In contrast, the final mortality for the offspring from the population
previously exposed to U were 25% and 57% in the replicate tanks. Fish derived
from the U-contaminated site were more tolerant than those from the
uncontaminated site. Because these were second generation fish, this tolerance
likely has a genetic basis.
SREL Reprint #1851
Keklak, M.M., M.C. Newman, and M. Mulvey. 1994. Enhanced uranium tolerance of an exposed population of Eastern mosquitofish (Gambusia holbrooki Girard 1859). Archives of Environmental Contamination and Toxicology 27:20-24.