Biological responses in the Rana Criolla (Leptodacthylus latrans) inhabiting a sewage-effluent receiving aquatic ecosystem of Argentina

RODRIGUEZ FERNANDEZ, S.; BACH, N.; NATALE, G.S.; CARRIQUIRIBORDE, P.

Barcelona

Congreso; SETAC Europe 25th Annual Meeting; 2015

Society of Environmental Toxicology and Chemistry, European Branch

In Argentina, sewage effluents are discharges on aquatic ecosystems raw or poorly treated. Previous studies showed the presence of both, traditional and emergent pollutants reaching the receiving waters. The objective of the present study was to assess the potential biological effects induced by sewages effluents on wild populations of the Rana Criolla frog (Leptodactylus latrans) inhabiting receiving aquatic ecosystem. Ten organisms (five females and five males) were collected either from the Girado stream (receiving the primary treated effluent from the Chascomús city sewage treatment plant) a from a reference site 15 Km south of La Plata City. External and internal abnormalities were inspected together with the assessment of the condition factor (K), the hepatosomatic (HIS) and gonadosomatic (GSI) indexes. In addition, catalase (CAT), ethoxy-resorufin-O-deethylase (ERO), benzyloxy-resorufin-O-dealkylase (BROD) activities together with total protein (PROT) and tiobarbituric reactive susbtances (TBARs) were assessed in the liver. Internal abnormalities were observed in 80% of the frogs from the Girado stream and none from the control site, characterized by swollen nervous tissue along the backbone. In addition, significant (p= 0.00001) reduction in the GSI (35%) was observed in the females frogs at the Girado. No differences were observed for K or male GSI. A significant (p= 0.028) increase of BROD activity (62%) was observed in Girado frogs. EROD was significantly (p= 0.042) higher in males than females (74%) of the control site, but this differences disappear in the exposed population showing a sex/site interaction effect (p= 0.043). CAT and TBARs were not statistically different among populations, but showed the same trend than BROD contributing to the same factor in the PCA analysis. In summary, frogs living under the sewage effluent influence showed internal abnormalities and less development in female gonads together with a disruption of the EROD activity in the males, an increase of phase I detoxifying enzyme BROD accompanied by a subtle enhance of the antioxidant system and increase of the lipid peroxidation. All these evidences, show a clear impact of the sewage discharges on the health of Rana Criolla and probably other wild amphibian species inhabiting receiving aquatic ecosystems. CONICET-PIP0723, ANPCyT-PICT1598.