Integrated use of biomarkers to evaluate the reproductive physiology of Astyanax fasciatus and Hoplias malabaricus males (Teleostei: Characiformes) in polluted reservoirs

The reproductive physiology of fish can be changed by the presence of pollutants in the water, which act as endocrine disrupting compounds (EDC). We evaluated the impacts of water contaminants in polluted reservoirs acting as possible EDC on the reproductive physiology of Astyanax fasciatus and Hoplias malabaricus males. We used biomarkers with different levels of biological organization. Hoplias malabaricus adult males were collected in the summer and winter at five different sites in the Tietê River Basin: the Ponte Nova reservoir (PN), considered a reference site due to the low anthropogenic influence; the Billings reservoir (BIL) at two different branches; and the Guarapiranga reservoir (GUA) at two different branches. Astyanax fasciatus adult males were collected at PN and BIL. BIL and GUA are subjected to great anthropogenic action. We analyzed gonadal histomorphology, testosterone (T), 11-ketotestosterone (11-KT), estradiol (E2) plasma levels, and gene expression of hepatic vitellogenin (vtgA) and pituitary follicle stimulating hormone (fshβ). In the PN reservoir (reference), the biomarkers analyzed in both species did not differ between the periods analyzed. This is an evidence that the animals keep the same reproductive activity during both seasons. The changes in the plasma concentration of gonadal steroids in both species in polluted reservoirs suggest the presence of EDC compounds in the water and/or adjusts of the physiological setpoint to allow the reproduction in such adverse conditions. The use of vtgA as biomarker suggests the presence of estrogenic compounds, mainly in BIL, but with a more evident response of H. malabaricus. However, even considering physiological changes, both species present testes during the maturation phase that allow the reproduction in an environment with a high degree of pollution.