Long-Term Effects of Lead Exposure on Three Generations of Brook Trout (Salvelinus fontinalis)

Exposure of three generations of brook trout (Salvelinus fontinalis) to mean total lead concentrations (0.9–474 μg/liter) showed that all second-generation trout exposed to 235 and 474 μg Pb/liter and 34% of those exposed to 119 μg Pb/liter developed severe spinal deformities (scoliosis). Scoliosis also appeared in 21% of the newly hatched third-generation alevins exposed to 119 μg Pb/liter, and weights of these fish 12 wk after hatch were significantly reduced. Gill, liver, and kidney tissues of first- and second-generation brook trout accumulated the greatest amount of lead. Only small amounts accumulated in the edible muscle. An equilibrium of lead residues was reached in liver and kidney tissue from second-generation fish after 70 wk of exposure, but not in gill tissue. Fish exposed to 119 μg Pb/liter and then placed in uncontaminated control water for 12 wk showed a 70, 78, and 74% loss in micrograms Pb per gram for gill, liver, and kidney tissue, respectively, and a 39, 56, and 35% loss, respectively, in the total micrograms of Pb in the whole tissue. Residue analysis of eggs, alevins, and juveniles showed that lead was accumulated during these life stages. The maximum acceptable toxicant concentration (MATC) for brook trout in water with a hardness of 44 mg/liter (as CaCO3) and a pH of 6.8–7.6 lies between 58 and 119 μg/liter for total lead and between 39 and 84 μg/liter for dissolved lead. The MATC was based on the development of scoliosis in second- and third-generation fish and the reduced growth of 12-wk-old third-generation trout. The 96-h LC50 for brook trout was 4100 μg/liter based on total lead and 3362 μg/liter based on dissolved lead; therefore, the application factor (MATC/96-h LC50) lies between 0.012 and 0.029 for both total and dissolved lead.