Reproductive, physiological, and biochemical responses in juvenile female rainbow trout (oncorhynchus mykiss) exposed to sediment from pulp and paper mill industrial discharge areas

Abstract

Four pulp and paper mills discharge their effluents in the same section of the Biobio River in central southern Chile. Pulp mill effluents are a very complex mixture with characteristics that depend on the type of raw material, the process technology, and the effluent treatment. To investigate the effect of pulp mill effluent discharges, immature Oncorhynchus mykiss were exposed to river sediments in the laboratory for 29 d. Three sampling areas were defined in a spatial gradient in the river: Preimpact, impact, and postimpact zones relative to the pulp and paper mill discharge areas. Ethoxyresorufin-O-deethylase activities were significantly higher in fish exposed to impact and postimpact sediments when compared to those exposed to preimpact sediments, and higher levels of vitellogenin were observed in the plasma of female fish exposed to impact and postimpact sediments. Histological analysis of the gonadal tissue showed an induction of gonadal maturation in fish exposed to sediment coming from the impact and postimpact zones (oocytes in a vitellogenic state). No site differences were observed in erythrocytes, although differences were noted in the leukocytes in the exposure areas. Finally, the biomarker approach showed evidence that the sediment associated with pulp mill effluent discharges produces some effects in fish under laboratory conditions.

Use of Immunofluorescence with Frozen Sections for the Detection of Vitellogenin Year-2 Class Natural Population Rainbow Trout-A Preliminary Investigation

“…In the early stages of gonad maturation, steroid hormones work in a positive feedback mechanism to increase VTG concentrations in the blood. However, during the later maturation stages, steroids are regulated via negative feedback loops causing decreases in blood VTG [8]. By comparison, sample 9 had the highest VTG plasma concentration in the female group, but had the lowest female GSI and the majority oocytes were in immature stages I and II.…”

“…VTG content was determined using a previously described ELISA protocol using a 96 well flat bottom, half volume, and high binding polystyrene plate [8]. The plate was incubated with rainbow trout VTG (Biosense Laboratories™, Bergen, Norway) as the standard, and the trout plasma samples.…”

“…This makes VTG useful in bioassays to determine the phenotypic sex of fish, the developmental stage, or to evaluate potential feminizing effects of exposure to endocrine disrupting chemicals (EDCs) by measuring plasma levels/presence in tissues [6,7]. VTG can be detected using an enzyme-linked-Immunosorbent assay (ELISA) [8]. It uses a micro plate with primary and secondary antibodies linked to an enzyme which produces a colorimetric reaction in proportion to the concentration of protein antigen within the sample.…”

Distribution and sources of phytosterols in coastal and river sediments of south central Chile

“…Nevertheless, other inputs of vascular plant phytosterols into coastal waters may come from upland forests, mangroves, oil palm, or coconut plantations (Ali et al, 2009), waste waters (Quemeneur & Marty, 1994;Liu et al, 2010) and the pulp and paper mill industry (Owens, 1991;Sepúlveda et al, 2003;Orrego et al, 2005aOrrego et al, , 2009). Important research efforts has been undertaken to evaluate the impact of the discharge of pulp mill effluents on fish reproductive behavior (e.g., Walker et al, 2002;Dubé et al, 2008), because it has been shown that fishes exposed to wood-derived sterols present endocrine disruption (Mellanen et al, 1996;MacLatchy et al, 1997;Nakari & Erkomaa, 2003).…”

“…In fact, Bertin et al (2011) recently showed remarkably high levels of 17α-ethinylestradiol in coastal sediments, enough to cause endocrine disorders in fish inhabiting some of the aquatic ecosystems of this region. In addition, several studies have shown endocrine-disrupting effects in caged rainbow trout located downstream from pulp mill discharges in the BioBío River (Orrego et al, 2005a(Orrego et al, , 2006(Orrego et al, , 2009. There is an important production of cellulose in south-central Chile of about 3.32 million ton annually; accordingly, phytosterols derived from this activity are incorporated into aquatic systems.…”