BIOACCUMULATION OF CESIUM-137 IN YELLOW BULLHEAD CATFISH (AMEIURUS-NATALIS) INHABITING AN ABANDONED NUCLEAR-REACTOR RESERVOIR

Bioaccumulation of Cs-137 was investigated in yellow bullhead catfish (Ameiurus natalis) inhabiting an abandoned reactor reservoir, Pond B, Savannah River Site, Barnwell Co., South Carolina. We collected fish b y trap-netting, and determined ages from pectoral spines. Muscle and o ther tissues were assayed for Cs-137 by NaI-scintillation. Muscle Cs-1 37 was unrelated to sex (p = 0.859) or mass of fish (p = 0.224), but w as related to age (p = 0.036). Examination of least-squares means sugg ested that Cs-137 in muscle increased up to about age 3, but did not i ncrease with greater age (means for 1, 2, 3, 3, 5, and 6 year olds wer e 2,630, 3,011, 3,513, 3,417, 3,599, and 3,339 Bq/kg, respectively). A modified Richards model showed equilibrium Cs-137 concentration in mu scle (3,625 Bq/kg) was acquired in approximately 2.4 years. Growth dif fered between sexes (p < 0.001), and the time to asymptotic body mass was longer than the time to attain equilibrium Cs-137 concentration. M ales attained an asymptotic mass of 577 g in approximately 6.3 years; females attained an asymptotic mass of 438 g in approximately 5.9 year s. The cumulative Cs-137 burden of the population was 4.9 x 10(6) Bq, representing <0.001% of the Cs-137 inventory of the reservoir. Concent ration of Cs-137 varied among tissues (p < 0.001), with gill and muscl e the lowest and highest (634 and 3,712 Bq/kg, respectively). Concentr ation of (CS)-C-137 in ovaries declined with increasing ovary mass (p = 0.001; r(2) = 0.60). Until equilibrium is attained in these fish, Cs -137 concentration is directly related to increasing age rather than s ize.