Hematological and Plasma Biochemical Profile of Two Species of Freshwater Stingrays From the Amazon

Abstract

Abstract The demand for fish by-products and the need for nutritionally adequate and less expensive The evaluation of hematological and plasma biochemical parameters and the subsequent establishment of reference intervals can facilitate the diagnosis of the health status of animals and contribute to animal production, management, and conservation of natural populations. This work aimed to determine the hematological parameters of wild specimens of the stingrays Potamotrygon motoro and Potamotrygon orbignyi from the lower Solimões River region, Amazonas, Brazil, establishing reference blood values. One hundred forty-one stingrays were captured, 92 specimens of P. motoro and 49 of P. orbignyi, of both sexes and at different stages of development (neonates and juveniles). Hematological and plasma biochemical parameters were determined according to the methodology recommended in the literature. No effect of sex was observed on the hematological parameters of juvenile animals for both species. P. motoro neonates presented a distinct hematological profile, with significantly lower hematocrit values, hemoglobin, number of erythrocytes, mean corpuscular hemoglobin concentration, monocytes, plasma glucose, total proteins, albumin, and globulin. On the other hand, total cholesterol and urea levels were significantly higher in this same group compared to juveniles of the same species. Comparison between species revealed lower values of triglycerides and total cholesterol in P. orbignyi of both sexes. Due to the lack of sex effect, data from males and females of each species were grouped to establish more robust hematological reference intervals. The results obtained are pioneering for these Amazonian species in whitewater environments and will serve as a basis for evaluating the health status of wild stingrays. They can identify hematological disorders and monitor the animals' physiological adaptations to environmental changes.