Absorption, distribution, and elimination of graded oral doses of methylmercury in juvenile white sturgeon

[[abstract]]Mercury (Hg) is toxic and is released into the environment from a wide variety of anthropogenic sources. Methylmercury (MeHg), a product of microbial methylation, enables rapid Hg bioaccumulation and biomagnification in the biota. Methylmercury is sequestered and made available to the rest of the biota through the benthic-detrital component leading to the high risk of exposure to benthic fish species, such as white sturgeon (Acipenser transmontanus). In the present study, a combined technique of stomach intubation, dorsal aorta cannulation, and urinary catheterization was utilized to characterize the absorption, distribution, and elimination of Hg in white sturgeon over a 48. h exposure. Mercury, as methylmercury chloride, at either 0, 250, 500, or 1000 μg. Hg/kg body weight, was orally intubated into white sturgeon, in groups of five. The blood was repeatedly sampled and urine collected from the fish over the 48. h post intubation period, and at 48. h, the fish were sacrificed for Hg tissue concentration and distribution determinations. The fractional rate of absorption (K), blood Hg concentration (μg/ml), tissue concentration (μg/g dry weight) and distribution (%), and urinary Hg elimination flux (μg/kg/h) are significantly different (p kidney > spleen > gill > heart > liver > brain > white muscle and remaining whole body. At 48. h, Hg was found to be preferentially distributed to metabolically active tissues. Digestibility is highest at the lowest MeHg dose. Measurable urinary Hg was observed in the fish treated with the highest MeHg dose, and a significant increase in the elimination flux was observed between 3 and 12. h post intubation