Heavy Metal Concentrations in Muscle, Liver and Kidney Tissue of Striped Dolphin, Stenella coeruleoalba, and Their Variations with Body Length, Weight, Age and Sex

Abstract

The concentrations of Fe, Mn, Zn, Cu, Pb, Ni, Cd and Hg in the muscle, liver and kidney of fifty nine striped dolphins captured during 1977- 1980 were determined by atomic absorption spectrophotometry. The levels of most the metals examined were higher in the liver than the other tissues, except for the highest renal Cd. The frequency distribution of the metal concentrations was mostly log-normal. For all of the organs, correlation of the metal concentrations to the body length, weight and age was positive for Fe, Pb, Ni, Cd and Hg, and negative for Mn, Zn and Cu. A higher correlation of the concentrations of Fe, Mn, Zn and Cu to the body length and weight than to the age indicates that the metabolic turnover is more important than age or exposure time in determining the levels of those metals. Whilst the concentration of Pb, Ni, Cd and Hg correlated closely with the age of dolphins, and this suggests that the age or exposure time is a dominant factor for accumulation of these metals.
The concentrations of Pb, Ni, Cd and Hg in the muscle, liver and kidney increased with age until 1 year, leveled off through 1 to 18 years by physical dilution with increased body weight, and thereafter steadily increased year by year, but in case of Hg such physical dilution effects were not significant. Relatively wide variation of the metal concentrations in the pup and 8-25 years females was probably due to the effects of suckling, and of parturition and lactation, respectively.