Abstract
Industrial wastewaters and urban discharges contain complex mixtures of chemicals capable of impacting reproductive performance in freshwater fish, called endocrine-disrupting compounds (EDCs). In Chile, the issue was highlighted by our group beginning over 15 years ago, by analyzing the impacts of pulp and paper mill effluents (PPME) in the Biobio, Itata, and Cruces River basins. All of the rivers studied are important freshwater ecosystems located in the Mediterranean region of Central Chile, each with a unique fish biodiversity. Sequentially, we developed a strategy based on laboratory assays, semicontrolled-field experiments (e.g., caging) and wild fish population assessments to explore the issue of reproductive impacts on both introduced and native fish in Chile. The integration of watershed, field, and laboratory studies was effective at understanding the endocrine responses in Chilean freshwater systems. The studies demonstrated that regardless of the type of treatment, pulp mill effluents can contain compounds capable of impacting endocrine systems. Urban wastewater treatment plant effluents (WWTP) were also investigated using the same integrated strategy. Although not directly compared, PPME and WWTP effluent seem to cause similar estrogenic effects in fish after waterborne exposure, with differing intensities. This body of work underscores the urgent need for further studies on the basic biology of Chilean native fish species, and an improved understanding on reproductive development and variability across Chilean ecosystems. The lack of knowledge of the ontogeny of Chilean fish, especially maturation and sexual development, with an emphasis on associated habitats and landscapes, are impediment factors for their conservation and protection against the threat of EDCs. The assessment of effects on native species in the receiving environment is critical for supporting and designing protective regulations and remediation strategies, and for conserving the unique Chilean fish biodiversity.
Highlights
Endocrine disruption (ED) has become a serious environmental threat across the world [1], and there is global concern for the potential endocrine impacts of individual chemicals and mixtures
No significant differences in gonadosomatic indices (GSI) were detected, but an increase in the frequency of maturing oocytes were observed in the immature females exposed in impact and post impact sites
If we focus on the responses of native fish, at the community level, a decrease in diversity (H), species richness (S) and abundance have been observed in a longitudinal gradient of the Biobıó River, contrary to the normal patterns known for rivers not influenced by these industries [11]
Summary
Endocrine disruption (ED) has become a serious environmental threat across the world [1], and there is global concern for the potential endocrine impacts of individual chemicals and mixtures. Similar response patterns were observed, as significant increases in EROD and VTG levels of rainbow trout caged in the impact and post impact areas after a 29 d exposure This increase in plasma VTG (4-fold of control), was again coupled with an increase in gonad maturity in even younger juvenile female fish (40 ± 13 g), provided clear evidence of persistent endocrine disrupting effects associated with pulp mill discharges. Male testosterone increased significantly at Los Angeles impact site at 7 d of exposure and no significant changes were observed at the Santa Barbara location (Figure 5B) Both WWTP effluents showed different effects, probably due to the differential features of the population living in both towns: FIGURE 4 | Laboratory bioassays and field cage experiments with Oncorhynchus mykiss exposed to wastewater treatment plant effluents located in Biobıó River basin. This study showed evidence of reproductive disruption at different levels of biological organization, suborganismal responses, and additional population level effects in TABLE 1 | Most relevant biological responses to EDCs in rainbow trout at Chile
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