Trace elements concentration, tissue distribution, and associated health risks in wild and captive pantropical spotted dolphins (Stenella attenuata)

Abstract

Trace element (TEs) concentrations are key indicators for evaluating the health status of cetaceans. However, there is currently no research on TEs levels and tissue distributions in captive dolphins. Investigating TEs in wild and captive dolphins could provide critical insights into the effects of diets and habitats on TEs accumulation and improve healthcare protocols for captive dolphins. This study investigated concentrations of six TEs (Hg, Cd, Cr, Se, Cu, and Zn) in seven tissues (skin, muscle, liver, spleen, lung, kidney, and intestine) of wild (n = 8) and captive (n = 6) Stenella attenuata. The findings indicated that most studied wild and captive individuals exhibited medium levels of Hg, Cd, and Cr globally, with low health risks. However, alarming concentrations, such as 306 μg/g Hg in captive individuals and 178 μg/g Cd in wild individuals, suggested localized contamination persists. Tissue distributions of TEs indicated that ingestion and inhalation were the predominant exposure routes for wild and captive dolphins. Additionally, positive correlations between Hg levels in skin and liver and Cd levels in skin and kidney indicated that skin could serve as a healthy indicator for captive dolphins. Consuming odontocete tissue, even from healthy individuals, poses potential health risks to humans.