title: Effects of pulp and paper mill discharges on caged rainbow trout (Oncorhynchus mykiss): biomarker responses along a pollution gradient in the Biobio River, Chile.
abstract: Caging experiments were conducted using hatchery-reared, immature, female rainbow trout (Oncorhynchus mykiss) in three previously defined areas of the Biobio River (south central Chile) representing a pollution gradient from the pulp and paper mill discharges area: a pre-impact area (upstream area, reference location), an impact area (area directly influenced), and a postimpact area (downstream area, less influenced). No significant changes were observed in the physiological index as represented by condition factor (K) and liver somatic index during different sampling times (after 11, 21, and 30 d of exposure). Ethoxyresorufin-O-deethylase activities were significantly higher in trout caged at the impact and postimpact discharges areas (two- to fourfold) compared with the reference (pre-impact) area, and a strong inhibition of acetylcholinesterase activity, reaching 50%, was observed mainly in fish caged at the impact area. A significant endocrine-disrupting effect (reproductive level) was evidenced by significant increments in gonad somatic index and plasma vitellogenin levels combined with an induction of gonad maturation (presence of vitellogenic oocytes) in trout caged at the impact and postimpact areas. These results, generated by an in situ approach, confirmed our group's findings for trout exposed to sediment in the laboratory: discharges of pulp mill effluent in the Biobio River are associated with the effects evaluated at different biological levels.
authors.affiliation: Aquatic Systems Research Unit EULA-Chile Environmental Sciences Centre, University of Concepción, Chile. luorrego@udec.cl
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Orrego
authors.forename: Abed
authors.initials: A
authors.lastname: Burgos
authors.forename: Gustavo
authors.initials: G
authors.lastname: Moraga-Cid
authors.forename: Barbara
authors.initials: B
authors.lastname: Inzunza
authors.forename: Margarita
authors.initials: M
authors.lastname: Gonzalez
authors.forename: Ariel
authors.initials: A
authors.lastname: Valenzuela
authors.forename: Ricardo
authors.initials: R
authors.lastname: Barra
authors.forename: Juan F
authors.initials: JF
authors.lastname: Gavilán
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000032:analysis*; D002677:Chile; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods*; D005260:Female; D006066:Gonads; D007220:Industrial Waste / Q000009:adverse effects*; D007221:Industry; D017686:Oncorhynchus mykiss / Q000502:physiology*; D010209:Paper; D012098:Reproduction / Q000187:drug effects; D045483:Rivers; D012741:Sexual Maturation; D014819:Vitellogenins / Q000097:blood; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D014877:Water Pollution, Chemical / Q000009:adverse effects
chemical_list: D015415:Biomarkers; D007220:Industrial Waste; D014819:Vitellogenins; D014874:Water Pollutants, Chemical; D019363:Cytochrome P-450 CYP1A1; D000109:Acetylcholine