Perfil hematológico e caracterização de hemoparasitos de arraias de água doce (Chondrichthyes: Potamotrygoninae) do baixo Rio Solimões, Amazonas

Abstract

The determination of the hematological and biochemical plasma profile and the hemoparasitic evaluation can facilitate the diagnosis of the health status of animals and contribute to animal production, management, and conservation of natural populations. The general objective of this thesis was to determine the hematological, leukocyte and plasma biochemical profiles, as well as to characterize the blood cells and the hemoparasites morphologically and morphometrically of two species of freshwater stingrays, Potamotrygon motoro and Potamotrygon orbignyi, from the lower Solimões River, Amazonas, Brazil. In chapter 1, the blood profile of 141 stingrays (92 P. motoro and 49 P. orbignyi) was evaluated, where no effect of sex was observed on the hematological parameters of the stingrays, on the other hand, the neonates of P. motoro presented a baseline hematological profile compared to juveniles. This chapter culminated in the establishment of reference hematological intervals for P. motoro and P. orbignyi in whitewater environments. In chapter 2, the morphological and morphometric characterization of the blood cells of the stingrays was performed, characterizing erythrocytes, erythroblasts, thrombocytes, lymphocytes, monocytes, heterophils, eosinophils and basophils. No evidence of erythrocyte abnormalities was found, and the morphological characteristics of the blood cells were similar to those observed in other species of freshwater stingrays. However, the size of erythrocytes, monocytes and heterophiles were significantly different among the stingray species analyzed. In chapter 3, the morphological and morphometric characterization of the hemoparasites present in the blood of the stingrays was performed. Trophozoites, pregamonts, macrogamonts and microgamonts of Cyrilia sp. were found infecting mostly erythrocytes, although parasitic forms have also been found free in circulating blood. The overall prevalence was 49.2 %, while parasitemia was low, ranging from 0 to 1.9 %. Erythrocytic hypertrophy was observed in erythrocytes infected with pregamonts, macrogamonts and microgamonts in both stingray species. In chapter 4, the impact of hemoparasitic infection on the hematological and plasma biochemical profile of stingrays was evaluated. There was no effect of species and sex on the prevalence and hemoparasitic parasitemia, as well as no effect on the blood parameters analyzed. On the other hand, the significant negative correlations of parasitemia with some blood parameters in both stingrays highlighted the harmful potential that hemoparasites can cause in situations with high parasite load. The results obtained in this thesis are pioneers for these Amazonian species in whitewater environments and will serve as a basis for the evaluation of the health status of wild stingrays and can be used for the identification of hematological disorders and for the monitoring of hemoparasitic infections.