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.

Regional Cumulative Effects Monitoring Framework: Gaps and Challenges for the Biobío River Basin in South Central Chile

“…Although water quality criteria for protecting aquatic life are met in most parts of the basin, there is evidence of a loss in native fi sh abundance and diversity in the same gradient (Habit et al 2006b), where native fi shes are strongly impacted downstream of industrial effl uent discharges (Aedo et al 2009). There is evidence of physiological changes in fi sh (Orrego et al 2005(Orrego et al , 2006Chiang et al 2011a), at low concentrations of pollutants. Along with these kinds of human activities, the change in land use and urban development has put a major threat on water bodies in the basin, with cities expanding near wetlands, lakes and rivers (Aguayo et al 2009).…”

“…In this aspect the selection of the spatiotemporal scale of assessment is also highly relevant: changes in communitybased measures are useful to establish the ecosystem's condition and to reveal damage, however community-based monitoring is infl uenced by processes operating at different spatial and temporal scales, which lack the potential to establishing cause-effect relationships, and understanding the causes is crucial for potential restoration/protection of that aquatic ecosystem. On the other hand, the use of population parameters, individual responses, and tissue level effects (physiological and biochemical variables) have been demonstrated to be suitable tools that provide evidence on the effects of industrial discharges (Munkittrick 2004;Lowell et al 2005;Sepúlveda et al 2002;Theodorakis et al 2006;Larsson et al 2000;Sandström & Neuman, 2003;Donald 2003;Karels & Oikari, 2000;van den Heuvel et al 2007;Orrego et al 2005Orrego et al , 2006Chiang et al 2011a). Responses at these levels offer a warning signal of environmental risk for the fi sh fauna, providing a protective value to monitoring programs.…”

Reduced embryonic survival in rainbow trout resulting from paternal exposure to the environmental estrogen 17α-ethynylestradiol during late sexual maturation

“…These contaminants are widely distributed in aquatic environments and are identified through both direct chemical detection in surface waters as well as their known biological impacts in North America (Kolpin et al 2002, Goksoyr 2006, Woodling et al 2006, South America (Orrego et al 2006), Europe (Jobling et al 1998, Liney et al 2005, and Asia (Hashimoto et al 2000). The effects of environmental estrogens are primarily mediated by either their binding to or interference with estrogen receptors.…”

Attitudinal Determinants of Willingness-to-Pay for River Ecosystem Improvements in Central Chile: A Choice Experiment

“…In particular, the negative effect of pulp mill wastewater on river ecosystem quality has received attention in Chile (Vasconi, 2006;Espinosa, 2001). Despite substantial efforts to reduce wastewater toxicity, wastewater quality is still believed to impact aquatic organisms negatively (Orrego et al, 2006). Consequently, river ecosystems downstream of pulp mills are severely compromised even today (Vasconi, 2006).…”