Effects of anthropic disturbance on white blood cell differential count of Rhinella Arenarum at the Limay-Neuquén-Negro River basins

VILLANOVA JL; BIECZYNSKI, FLAVIA; ESPERT NURIA; VEDELAGO S; NATALE GS; VENTURINO A

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

SETAC LA

The main productive activities in North Patagonia are oil and gas exploitation and fruit culture. Such activities may generate pollutants that can reach natural and artificial watercourses, affecting aquatic life. In this context, hematologic biomarkers are relevant to assess health risks and environmental exposure to pollutants. Also, they are important for the development of measures that serve as early warning signals in polluted areas. The aim of our work was to evaluate leukocyte profile in adult individuals of Rhinella arenarum in aquatic environments affected by different anthropic activities. 10 sites were selected, 2 reference sites with low anthropic impact and 7 with different types and magnitudes of productive activity, among which is fruit culture production, oil and gas exploitation, mixed activities and urbanization. At each site, until 15 individuals were collected and blood was extracted from the femoral vein. Smears were prepared on clean slides, fixed, and stained with May Gründwald/Giemsa dye. The stained blood films were examined with an optic microscope under 1000 X with oil immersion for the identification and counting of leukocytes. At least 100 cells were counted or 150 fields were examined. Statistical analysis on cell type frequencies was carried out by the non-parametric Kruskall-Wallis test. Lymphocytes showed the highest frequencies (59,9%), followed by neutrophils (20,6%), and in lower proportion basophils (8,5%), eosinophils (5,5%) and monocytes (5,3%). The R. arenarum individuals inhabiting urbanized sites presented significant differences in the proportions of basophils and monocytes with respect to those inhabiting reference, petrochemical and fruit culture sites. Adults from urbanized and mixed sites presented less proportions of lymphocytes and differed statistically respect to petrochemical sites. No significant differences were found for eosinophil and neutrophil proportions. Our results suggest that individuals from urbanized sites may be exposed to greater amounts of xenobiotics, due to the high proportion of basophils and monocytes. On the other hand, reduction in lymphocyte counts has been reported associated with an increase in glucocorticoids in plasma, which may result from the stress situation of individuals. Thus, the reduced lymphocyte proportion in white blood cell differential count would result in a good biomarker of stress in the common toad adults from Río Negro, Limay and Neuquén basin.