Mercury concentrations in the tissues of bottlenose dolphins (Tursiops truncatus) and striped dolphins (Stenella coeruloalba) stranded on the Croatian Adriatic coast

Abstract

The concentrations of total mercury in muscle (17 samples), liver (16 samples) and kidney tissues (16 samples) of both bottlenose (Tursiops truncatus) and striped dolphins (Stenella coeruloalba) were analyzed by cold vapour atomic absorption (AA) spectroscopy. The dolphins were found dead at different locations along the east Adriatic over a 10-year period starting in 1990. In this study, the magnitude of mercury contamination of dolphins which are indicators of contamination of the Adriatic as well as the Mediterranean Sea was determined. Our results represent the first investigation of heavy metal concentrations in dolphins sampled along the Croatian coast of the Adriatic Sea. Total mercury levels were high, ranging from 1.51 to 136.7 mg/kg in muscle, from 2.04 to 143.1 in kidney and from 10.35 to 1 833 mg/kg in liver tissues (expressed as wet weight). These results were examined for differences based upon age and tissue type. A high correlation was observed between total mercury concentration and age, and adult dolphins (10 samples) contained statistically significant higher concentrations of mercury compared to juvenile (seven samples) dolphins. Mercury concentrations were generally the highest in liver tissue. The presence of high mercury levels in dolphins is attributed to natural as well as anthropogenic sources.

Keywords

• mercury
• contamination
• bottlenose dolphins
• striped dolphins
• adriatic sea