Propriedades do sangue e efeito do mergulho forçado sobre o perfil hematológico de Podocnemis erythrocephala (Spix, 1824) (Testudines, Podocnemididae) do Médio Rio Negro, Amazonas

Abstract

Irapuca, Podocnemis erythrocephala, is the poorly studied turtle species among the Amazonian Podocnemis and suffers from large predatory pressure by the human population, causing a decline in their natural stocks. This study aimed to determine the hematological parameters, the morphological and cytochemical features of blood cells, as well as the effect of forced diving on the blood profile of P. erythrocephala, generating relevant information to the proposition of management plans and conservation strategies for this species. Analysis revealed that sex exercised little influence on the blood profile of the animals, unlike the growth. It was found that hatchlings showed lower eritrogram than immature and mature animals, unlike the concentrations of glucose and total cholesterol that were higher, confirming the high metabolic rate of hatchlings. Overall, the changes found in blood parameters reflected changes in physiological function of the behavior and natural history of the species. Due the effect of sex and development phase on the blood parameters, reference ranges were established for hatchlings, immature males, mature males, immature females and mature females. From the morphological analysis of blood cells from irapuca erythrocytes, thrombocytes, lymphocytes, azurophilic, heterophils, eosinophils and basophils were identified with morphological characteristics similar to those described for other Podocnemidid species. Cytochemical analysis indicated that heterophils, eosinophils and basophils are the most active cells of the immune system of this species, being primarily responsible for phagocytic activity due the presence of glycogen, lipid and peroxidase. No changes were observed on the eritrogram of animals subjected to 30 and 60 minutes of forced submersion. Increased levels of plasma lactate, calcium and magnesium, according to the dive time, reflected physiological adjustments to maintain the acid-base balance, whereas changes in the levels of total cholesterol and triglycerides indicated that during anoxia, the irapuca activated the ATP production from lipid catabolism, as a complementary way to anaerobic glycolysis. The irapuca proved to be a tolerant species to 60 minutes of forced diving, although higher periods might cause metabolic acidosis and depletion of energy substrates. These values constitute a basis for assessing the health status of wild irapucas.