Metabolic response in the freshwater bivalve Diplodon chilensis exposed to leachates from an open dump in a temporal pond

YUSSEPPONE M. S.; LUQUET C.; RÍOS DE MOLINA M.C.; ROCCHETTA I.

Lyon, Francia

Congreso; Colloque d´EcoPhysiologie Animale; 2013

Universidad Claude Bernard, Lab. de hidrosistemas naturales y antrópicos

Diplodon chilensis is the most abundant freshwater bivalve in lakes and rivers of Patagonia, Argentina. During last decades, water quality has decreased with urban progress, affecting aquatic life. We compared the metabolic response of D. chilensis exposed during 30 days in cages, in a polluted temporal water pond, near Chimehuín river (39˚54ˊS, 71˚06ˊW), and in a clean site (control) in the same river. The temporal pond presented lower oxygen concentration (DO: 5,5 mg/L), higher ammonium content (NH4+:3,6 mg/L), higher total iron and copper contents (Fe:11,85 mg/L, Cu: 0,34 mg/L), and higher turbidity (FTU: 128,5) compared to the control values (DO: 9 mg/L, NH4+:0,2 mg/L, Fe: 0,11 mg/L, Cu: 0,01 mg/L, FTU: 0). GSH content significantly decreased in digestive gland bivalves collected from the polluted site respect to the control (126.6±10.71 vs. 184.5±13.48nmol.mg-1 protein). No difference between sites in digestive gland superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) activity, neither in oxidative stress parameters (lipid peroxidation and carbonyls content) was observed. Lactate dehydrogenase (LDH) activity differed significantly between polluted (24.50±0.44 nmol.min-1.mg-1protein) and control site (19.00±1.34 nmol.min-1.mg-1protein) while malate dehydrogenase (MDH) activity remained unaltered. In gonads, GST activity was significantly lower in the polluted site (0.121±0,008 vs. 0.176±0,015 U.mg-1protein) while the anaerobic enzymes (LDH, MDH) activities did not change. On the other hand, gill samples from the polluted site showed higher GSH levels, SOD activity and carbonyls content, with no changes in the anaerobic enzyme activities. Despite the higher metal concentration observed in the polluted pond, the digestive gland and the gonad tissues did not show increased oxidative stress parameters or decreased defense system parameters, suggesting energy saving under this reducing environment. Increased anaerobic enzyme activity was detected only in the digestive gland, suggesting the use of an alternative metabolic pathway. Only gill samples, showed increased oxidative stress and antioxidant system parameters, which points out this tissue as the primary target for damage caused by this kind of pollution.