Long- term effects on transplanted caged- freshwater bivalves Diplodon chilensis to the assessment of water quality in a Patagonian river

M.D. RIOS DE MOLINA; V.A. BIANCHI; C.M. LUQUET; S.E. SABATINI; J.M. CASTRO; M.S. YUSSEPPONE

Roma

Congreso; 28 Congreso SETAC Europa; 2018

Population growth and human activity are contributing to habitat deterioration in Patagonian rivers with the consequent threat to water quality and biodiversity. The bivalve Diplodon chilensis is a key species in the macroinvertebrate fauna of Patagonian lakes and rivers which has been proposed as a sentinel organism in the area. We evaluated the long-term effects of transplantation of caged D. chilensis to different sites in the Chimehuin river (reference site (S1), downstream from an aquaculture facility (S2), and downstream from an open dump and from the sewage treatment plant (S3)) after 3, 6, 9 and 12 months of exposure. We combined the antioxidant response, oxidative damage, ROS production and energetic status, with water and sediment analysis (physic-chemical and biological variables, and organic matter content). Physic-chemical variables varied according to site and time of exposure. Sites S2 and S3 showed generally higher chlorophyll a concentration and total coliform bacteria values compared to site S1, whereas organic matter contentin the sediment was elevated only at site S2. In D. chilensis, gill SOD and GSTactivity was higher in both S2 and S3 than in S1 by the end of the exposure time.During the last month of exposure (month 12), GSH levels dropped dramaticallyand lipid peroxidation levels increased in individuals from S2 and S3 sites.Digestive gland factor (DGF) and energy values in digestive gland were increasedat sites S2 and S3, from 6 to 9 months of exposure. Our results indicate that despite the large flow rate of Chimehuin river water quality is deteriorated in areas impacted by anthropic activities (aquaculture, solid waste disposal and sewage).This effect is reflected by a physiological response of D. chilensis, which isespecially significant during period of their highest metabolic activity (austral fall/ winter).