Cetacean species found stranded along Croatian coast of the Adriatic Sea as bioindicators of non-essential trace elements in the environment

In tissues of toothed whales from the Adriatic Sea (muscle, liver, kidney, lung, spleen, adipose tissue and skin) the concentrations of cadmium (Cd), lead (Pb) and arsenic (As) were analysed. In total, 186 dolphins were analysed; 155 bottlenose (Tursiops truncatus), 25 striped (Stenella coeruleoalba) and 6 Risso's dolphins (Grampus griseus). Cadmium concentrations in tissue samples ranged from 0.001 mg/kg in muscle to 16.8 mg/kg wet weight in kidney. Arsenic concentrations in dolphin samples ranged from 0.010 to 12.9 mg/kg ww. The lowest As concentration was found in spleen and highest in liver of bottlenose dolphin. Cadmium and As levels in Risso's dolphins showed higher concentrations in all tissues in comparison to bottlenose and striped dolphins. >50 % of the measured Pb values for all three species of dolphins and examined tissues were lower than 0.1 mg/kg. The accumulation of Cd and As during the lifetime was confirmed. None of the dolphins analysed in this study were exposed to concentrations of Cd in the liver higher than 20 mg/kg wet weight, which can cause renal failure in marine mammals. Numerous species of marine mammals inhabit coastal environments alongside humans and utilize similar food sources, such as fish and cephalopods. Consequently, these mammals can function as valuable indicators of public health concerns.