1. Introduction
Heavy metals are environmental contaminants and can easily accumulate and biomagnificate in various species (fishes and mammalians) at the top of the aquatic food chain. Among marine mammalians, the common dolphin (Stenella coeruleoalba) is used as a sentinel species of environmental pollution. The aim of this study was to determine the content of toxic metals in organs of Stenella coeruleoalba in comparison with essential elements, and to assess marine environmental pollution and dolphin health status.
2. Materials and Methods
Samples of liver, lung, muscle, and skin of Stenella coeruleoalba (n = 18 dolphins) were digested with HNO3 (70%) and H2O2 (30%) and submitted to analysis in ICP-MS for the determination of toxic (Hg, Cd, Pb, and As) and potentially toxic (Cr and Ni) metals and essential micro (Se, Zn, Cu, Fe, and Mn) and macro (Na, Ca, K, and Mg) elements.
3. Results
The results showed the presence of all analyzed metals, with the highest Hg levels in all dolphin samples. The correlation between toxic (Hg, Cd, Pb, and As) and potentially toxic (Cr and Ni) metals and essential micro-elements (Zn, Se, and Cu) was expressed as molar ratios. The ratios were 1 (value considered as a protection index) for 66Zn/201Hg, 82Se/201Hg, and 63Cu/201Hg and for 66Zn/52Cr, 82Se/52Cr, and 63Cu/52Cr in all organs, showing that toxic metals cannot be detoxified by these essential metals. However, the concentrations of all micro and macroelements were normal and predictive of dolphins’ health status.
4. Conclusions
The presence of toxic metals in organs of dolphins is correlated to marine environmental pollution and influenced by their food habits. The content of micro and macro-elements, introduced through diet, informs dolphins’ health status, although detoxifying essential metals are unable to carry out protective action against toxic metals, probably due to the deficiency, sequestration, or presence of other pollutants.
Author Contributions
Conceptualization, C.N. and V.F.; formal analysis, C.N.; methodology, C.N. and V.F.; investigation, C.N.; data curation, C.N.; validation, C.N.; writing— original draft preparation, C.N. and E.P.; writing—review and editing, C.N., V.F., R.B. and E.P.; supervision, E.P. All authors have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Institutional Review Board Statement
There is no need of ethical approval for this study because the striped dolphins stranded death along the Sicilian coast were collected by the Istituto Zooprofilattico Sperimentale della Sicilia “A. Mirri”, Palermo (Italy).
Informed Consent Statement
Not applicable because this is a study not involving humans.
Data Availability Statement
This article reports preliminary data presented to 1Th IECTO 2024.
Conflicts of Interest
The authors declare no conflict of interest.
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