SPATIAL AND TEMPORAL PATTERNS OF RADIOCESIUM CONTAMINATION IN MOSQUITOFISH, GAMBUSIA-HOLBROOKI (GIRARD, 1859), INHABITING A NUCLEAR-REACTORCOOLING RESERVOIR

Whole body concentrations of radiocesium (Cs-137) were determined for 772 mosquitofish (Gambusia holbrooki) collected from three locations o n the Pond B reservoir of the US Department of Energy's Savannah River Site in July and November 1991, and February and April 1992. Seasonal , site-, and sex-related differences in Cs-137 concentrations were res ted for significance, and results compared with those reported for mos quitofish collected from the same locations in April 1987. Results fro m 1991 to 1992 showed that Cs-137 concentrations were higher in mosqui tofish collected in February for both sexes at all sites. After accoun ting for differences in body size, males generally had higher concentr ations than females across seasons and sites. Site-related differences were not the same as those found in April 1987. Results from the pres ent study suggest that Cs-137 concentrations in mosquitofish undergo a seasonal cycling pattern, and that caution should be used when interp reting data collected from a single season, year or sex. (C) 1997 Else vier Science Limited.