Blood values of cortisol, glucose, and lactate in healthy green turtle (Chelonia mydas) and affected by fibropapillomatosis

Chelonia mydas is classified as threatened. Several factors have been indicated as threats to this species, either by reducing the resistance of turtles to various infectious agents, energy available for basic physiological processes, or by altering immunity due to the stress caused by these factors. The objective of this study was to evaluate the changes in plasma levels of glucose, lactate, and cortisol in healthy sea turtles (Chelonia mydas) and those affected by fibropapillomatosis submitted to different methods of containment and capture. The study sample comprised three experimental groups (G1, G2, and G3), including 140 animals. G1 was composed of 34 animals showing absence of fibropapilloma and captured in a federal conservation area in Fernando de Noronha, PE, Brazil. The groups G2 and G3 were composed of animals captured in the effluents released from steelworks in Vitoria, ES, Brazil; G2 was composed of 66 animals without signs of fibropapillomas and G3 was composed of 40 animals with fibropapillomas. We observed that plasma levels of cortisol and lactate were higher in the G1 group than those in the G2 group. In contrast, plasma glucose levels were lower in G1 than in G2. The results show that plasma levels of cortisol and lactate were higher in G3 than in G2. The mean plasma glucose levels were not significantly different between G3 and G2. We can conclude that in marine turtles, cortisol and lactate levels can be used as biomarkers of stress and should always be evaluated together.