Endocrine Disruptor Impacts on Fish From Chile: The Influence of Wastewaters

Indexación ScopusIndustrial 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. © Copyright © 2021 Barra, Chiang, Saavedra, Orrego, Servos, Hewitt, McMaster, Bahamonde, Tucca and Munkittrick.https://www.frontiersin.org/articles/10.3389/fendo.2021.611281/ful

Inability of Resin Acid Exposure to Elevate EROD Activity in Rainbow Trout (Oncorhynchus mykiss)

Abstract The induction of mixed function oxygenase enzymes, including ethoxyresorufin-o-deethylase (EROD), has been reported in fish downstream of bleached kraft mills in both Scandinavia and Canada. The compound(s) responsible have not been identified. Several experiments were conducted to determine if resin acids can induce EROD activity in rainbow trout (Oncorhynchus mykiss). Interperitoneal injections (i.p.) of dehydroabietic and abietic acid (50 mg/kg) did not elevate EROD activity after 2, 4 or 10 days. Dehydroabietic acid i.p. at 500 mg/kg did not increase EROD activity after 4 days. A mixture of ten resin acids i.p. at 370 mg/kg or water borne exposure at 100 µg/L did not induce EROD after 4, 8, or 16 days. Rosin gum i.p. at 370 mg/kg also did not induce EROD. These results suggest that resin acids are not the compounds primarily responsible for EROD induction below bleached kraft pulp mills.</jats:p

Spatial variability of ocean fertilizing nutrients in the dust-emitting ephemeral river catchments of Namibia

Research into global hot-spots of dust emission has focused on exposed fine-grained sediments in palaeo- or ephemeral dryland lake basins including Etosha (Namibia) and Makgadikgadi (Botswana) in southern Africa. Namibia's western ephemeral river valleys are also known to produce dust but have remained largely overlooked as a regionally-significant source. Nutrient enrichment of valley sediments and proximity to the South Atlantic suggests aeolian dust could play an important role in ocean fertilisation. The fertility of valley dust is dependent on fluvial sediments originating in the upper catchments on the Southern African Central Plateau. In this study we investigate climate, geology, vegetation and land use variability and how these may influence the nitrogen, phosphorus and iron availability in the catchments. We intensely sampled the Huab, Kuiseb and Tsauchab river systems to map the spatial distribution of nutrients from upper catchments to river termini. Samples were analysed for the bioavailable fractions of iron, nitrogen and phosphorus as well as total nitrogen and phosphorus. Results show that the lower valley reaches are sources of aeolian dust enriched in nutrients. Nitrogen levels correlate with precipitation and vegetation levels and phosphorus levels with geology. However, differences in upper catchment sediment nutrient levels were not representative of downstream nutrient differences between valleys. Rather, it is the hydrological and geomorphological processes of the ephemeral river systems that are key for producing the enriched sediments in the lower reaches. We demonstrate that the ephemeral river valleys of western Namibia are an extensive and enriched source of mineral dust that could play a critical role in marine productivity of the southern Atlantic

A Tier-Testing Strategy for Managing Programs of Environmental Effects Monitoring

Abstract A good environmental effects monitoring program (EEM) provides answers to clear, well-defined questions. The answers should be quantitative and lead directly to decisions about the effluent being studied and about further EEM studies. Preliminary studies should trigger more in-depth monitoring only when predefined thresholds are exceeded. When in-depth work suggests that further studies are unnecessary, there should be a return to a lower level of effort. These criteria lead directly to a tiered strategy for managing EEM that defines the sequence and choice of studies through successive cycles. The benefits of a tiered approach are (1) rules that all stakeholders can understand and comply with; (2) monitoring limited to that which is essential; and (3) assurance that all appropriate elements are included, but only when necessary. Within the context of the new pulp and paper EEM program, tier testing is an efficient, logical and systematic strategy for managing monitoring.</jats:p

Reproductive Dysfunction and MFO Activity in Three Species of Fish Exposed to Bleached Kraft Mill Effluent at Jackfish Bay, Lake Superior

Abstract Our recent studies have demonstrated reproductive dysfunction in white sucker (Catostomus commersoni), longnose sucker (C. catostomus) and lake whitefish (Coregonus clupeaformis) populations exposed to bleached kraft mill effluent (BKME). Although all three species show elevated levels of hepatic mixed function oxygenase (MFO) activity and depressed circulating steroid levels, we have been unable to provide clear evidence of whether these two events are directly linked to whole organism changes. Although depressed steroid levels appear to be linked to delayed sexual maturity, changes in fecundity and reduced secondary sexual characteristics in white sucker and lake whitefish, longnose sucker show no impacts of reduced steroid levels on reproductive performance. Installation of secondary treatment at this pulp mill did not alleviate the steroidal dysfunction or MFO induction. However, samples collected after a two week maintenance shutdown showed a return to reference levels of MFO activity in both sexes and of steroid levels in male fish. The relationship between elevated MFO activity and depressed steroid levels is unclear, but detailed experiments suggest that the two phenomena are not directly linked. White sucker show depressed steroid production and impaired reproductive regulation independent of MFO activity.</jats:p