Lead, mercury, and selenium alter physiological functions in wild caimans (Caiman crocodilus)

Area of Science:

• Environmental toxicology
• Wildlife physiology
• Ecotoxicology

Background:

• Environmental contaminants pose global risks to ecosystems and wildlife.
• Mercury (Hg) and lead (Pb) are toxic, while selenium (Se) can mitigate Hg toxicity.
• Crocodilians bioaccumulate contaminants, but their physiological responses are understudied.

Purpose of the Study:

• Quantify Hg, Pb, and Se concentrations in spectacled caimans (Caiman crocodilus).
• Investigate the impact of these contaminants on osmoregulatory, hepatic, endocrine, and renal functions.
• Assess the potential protective role of Se against Hg toxicity.

Main Methods:

• Blood samples were collected from 23 wild spectacled caimans.
• Concentrations of Hg, Pb, and Se were measured.
• Physiological parameters related to key organ functions were analyzed.

Main Results:

• Mercury exposure correlated with disrupted osmoregulation (sodium), hepatic function (alkaline phosphatase), and endocrine processes (corticosterone).
• Lead exposure was linked to impaired hepatic function (glucose, alanine aminotransferase).
• The Se:Hg molar ratio showed a positive association with sodium and corticosterone, suggesting a protective effect of Se against Hg.

Conclusions:

• Hg and Pb significantly alter physiological mechanisms in wild caimans.
• The Se:Hg ratio indicates a potential mitigating role for selenium in mercury toxicity.
• Further research is crucial to understand the full consequences of trace element contamination in crocodilians.