Effects of sewage effluent discharge on the abundance, condition and mortality of hulafish, Trachinops taeniatus (Plesiopidae)

The Effects of Wastewater Reuse on Smallmouth Bass (Micropterus dolomieu) Relative Abundance in the Shenandoah River Watershed, USA

Municipal and industrial wastewater effluent is an important source of water for lotic systems, especially during periods of low flow. The accumulated wastewater effluent flows-expressed as a percentage of total streamflow (ACCWW%)-contain chemical mixtures that pose a risk to aquatic life; fish may be particularly vulnerable when chronically exposed. Although there has been considerable focus on individual-level effects of exposure to chemical mixtures found in wastewater effluent, scaling up to population-level effects remains a challenging component needed to better understand the potential consequences of exposure in wild populations. This may be particularly important under a changing climate in which wastewater reuse could be essential to maintain river flows. We evaluated the effects of chronic exposure to wastewater effluent, as measured by ACCWW%, on the relative abundance of young-of-year (YOY), juvenile, and adult smallmouth bass (Micropterus dolomieu) populations in the Shenandoah River Watershed (USA). We found that increases in ACCWW% in the previous year and during the prespawn period were negatively correlated with the relative abundance of YOY, resulting in an average 41% predicted decrease in abundance (range = 0.5%-94% predicted decrease in abundance). This lagged effect suggests that adult fish reproductive performance may be compromised by chemical exposure during periods of high ACCWW%. No relationships between ACCWW% and juvenile or adult relative abundance were found, suggesting that negative effects of ACCWW% on YOY abundance may be offset due to compensatory mechanisms following higher ACCWW% exposure. Understanding the effects of wastewater effluent exposure at multiple levels of biological organization will help in the development of management strategies aimed at protecting aquatic life. Environ Toxicol Chem 2024;00:1-11. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Characterizing transcriptomic responses of southern flounder (Paralichthys lethostigma) chronically exposed to Deepwater Horizon oiled sediments

To obtain a deeper understanding of the transcriptomic responses to oil in southern flounder (Paralichthys lethostigma), we performed quantitative PCR and RNA sequencing on liver and gill tissue after a chronic exposure (35 days) to Deepwater Horizon crude oiled sediment and after a 30-day recovery period. We wanted to understand which specific genes are differentially expressed in liver and gill tissues directly after oiled sediment exposure and with the addition of a recovery period. Furthermore, we wanted to examine specific enriched pathways in these two tissues to determine the impact of exposure with and without a recovery period on biological processes (e.g. immune function). Liver and gill tissues were chosen because they represent two distinct organs that are highly important to consider when examining the impacts of oiled sediment exposure. The liver is the classic detoxification organ, while the gill is in direct contact with sediment in benthic fishes. Examination of these two tissues, therefore, generates a broad understanding of the transcriptomic consequences of oil exposure across an organism. Gene expression for interleukin 8 (il8) and interleukin 1B (il1β) was significantly increased versus control measurements for fish exposed to oiled sediments for 35 days in gill tissue. Hierarchical clustering of gene expression showed that tissue type was the main driver of gene expression (rather than treatment). The inclusion of a 30-day post-exposure recovery period showed a return of il8 and il1β gene expression in the gill to baseline expression levels. However, the recovery period increased the number of differentially expressed genes and significantly affected canonical pathways in both tissue types. Pathways related to cholesterol biosynthesis were significantly suppressed in oil-exposed flounder with a recovery period, but not in the exposed flounder without a recovery period. At the end of the exposure, 17 pathways were significantly affected in the gill, including thyroid hormone metabolism-related pathways, which were the most influenced. Liver tissue from the recovered fish had the greatest number of enriched pathways for any tissue or time point (187). Cellular and humoral immune response pathways were considerably impacted in the liver after the recovery period, suggesting that the immune system was attempting to respond to potential damage caused from the chronic oil exposure. Our results demonstrate that liver and gill tissues from southern flounder were differentially altered by Deepwater Horizon oiled sediment exposure and that a 30-day recovery period after exposure substantially shifted gene expression and canonical pathway profiles.

Benzo[a]pyrene (BaP) exposure generates persistent reactive oxygen species (ROS) to inhibit the NF-κB pathway in medaka (Oryzias melastigma)

Benzo[a]pyrene (BaP), a common environmental pollutant, can modulate the immune-associated signal pathway NF-κB, which is one of the critical signal pathways involved in various immune responses. BaP exposure usually generates reactive oxygen species (ROS), but whether ROS are predominantly involved in the modulation mechanism of the NF-κB pathway has not been clearly understood. In this study, an in vivo examination of Oryzias melastigma demonstrated that BaP exposure led to a down-regulation of the NF-κB pathway and increased levels of ROS. Conversely, in vitro results using the medaka liver cell line DIT-29 and a widely applied H₂O₂ method showed the opposite: up-regulation of the NF-κB pathway. However, the down-regulation of NF-κB upon BaP exposure in vitro was inhibited by the addition of a ROS inhibitor, indicating ROS are involved in the modulation of NF-κB. The discrepancy between in vivo and in vitro results of ROS impacts on NF-κB activation might be related to the concentration and persistence of ROS. Using a modified luminol detection system, BaP was found to generate sustained physiological concentrations of ROS for 24 h, while an H₂O₂ bolus generated ROS for less than 30 min. Furthermore, a steady-state sub-micromolar H₂O₂ system (H₂O₂ss) was developed in parallel as a positive control of ROS, by which H₂O₂ could be maintained for 24 h. Comparative evaluation using H₂O₂, H₂O₂ss and BaP exposures on the medaka cell line with pGL4.32 demonstrated that the persistent physiological concentrations of ROS generated upon BaP exposure or treatment with H₂O₂ss inhibited the NF-κB pathway, but direct H₂O₂ exposure had the opposite effect. Moreover, a western-blot assay and EMSA detection further confirmed the modulation of the NF-κB pathway in DIT-29. Taken together, this study shows that BaP exposure inhibits the NF-κB pathway by generating sustained physiological concentrations of ROS.

Sex-biased regulation of respiratory burst, phagocytic activity and plasma immune factors in lined seahorse (Hippocampus erectus) after subchronic benzo[a]pyrene exposure

Both wild and aquacultured seahorses are currently under great threat from marine pollution, notably from the potent contaminant and carcinogen benzo[a]pyrene (BaP). However, very little data are available regarding the immunomodulating effects of BaP in seahorses. Therefore, in this study, we exposed lined seahorses (Hippocampus erectus) for 7 d to BaP at three dosages (0.5, 5, and 50 μg/L) to evaluate sexual dimorphism in immune response. We measured eight immune parameters in the blood, including respiratory burst (RB), phagocytic activity (PA), monocytes/leucocytes, immunoglobulin M, complement 3, complement, interferon-a, and interleukin-2. Male seahorses had significantly higher parameters than females, except in terms of monocytes/leucocytes (P < 0.05). Although flow cytometry showed that RB and PA variation per BaP dose were roughly similar across sexes, RB and PA exhibited distinct patterns. Additionally, fluorescence intensity and leucocyte percentage were positively correlated in PA but not RB for all treatment and sex combinations. Through ELISA, we showed that the other six parameters had complex responses that nevertheless varied in a BaP-dosage and sex-dependent manner. Overall, adult male seahorses had higher immunocompetence than females before BaP exposure, and sexual dimorphism continued to be apparent during BaP exposure. Furthermore, all eight parameters were sensitive to BaP. Based on these results, we highly recommend H. erectus as a sentinel species for crude contamination, whereas PA and RB are valuable bioindicators of marine contaminants such as BaP.

Benthic recovery after fish farming cessation: a "beyond-BACI" approach

The development of a benthic environment after fish-farming cessation was examined. To ascertain whether recovery occurred, several abiotic (granulometry, acid-volatile sulfides, total phosphorus and redox potential) and biotic (polychaete abundance) variables were monitored using a "beyond-BACI" approach. Before the cessation of farming, the geochemical conditions and polychaete assemblages differed among the impacted and control sites. After cessation, an improvement of the geochemical conditions was achieved. A significant tendency toward a recovery of the polychaete assemblage in the impacted area was observed, but significant differences still remained compared with the control sites. The acid-volatile sulfide level was responsible for these differences. The abundance of polychaete families associated with organically enriched sediments diminished at the impacted site after cessation, whereas the abundance of some sensitive and omnivorous families increased. The "beyond-BACI" approach provided a wider framework than other approaches, enabling us to differentiate the natural variability from those changes induced by the fish farm and farming cessation.

Monitoring anthropogenic sewage pollution on mangrove creeks in southern Mozambique: a test of Palaemon concinnus Dana, 1852 (Palaemonidae) as a biological indicator

Tropical coastal ecosystems, such as mangroves, have a great ecological and socioeconomic importance for adjacent systems and local populations, but intensive environmental impact monitoring is still lacking, mainly in East Africa. This study evaluated the potential anthropogenic disturbance on Palaemon concinnus population structure and fitness. Palaemon concinnus populations from one peri-urban (domestic sewage impacted) and two pristine mangrove creeks were studied by sampling nearly 100 shrimps per location every 15 days for 12 months. The shrimps at the peri-urban location were larger, experienced longer reproductive periods, presented higher proportion of ovigerous females and better embryo quality when compared with shrimps inhabiting pristine locations. Physiological indices (RNA/DNA ratio) were similar between shrimps at pristine and peri-urban mangroves. However, a higher level of parasitation by a Bopyridae isopod, Pseudione elongata indicated some degree of stress on the host at the peri-urban mangrove, with potential effects on the host population dynamics.

Determination of acute and early life stage toxicity of fat-plant effluent using zebrafish (Danio rerio)

The present study examines the effects of an effluent from a fat plant (FP) on zebrafish (Danio rerio) embryos and larvae using the whole effluent toxicity testing methods (WET). The method is based on acute toxicity using 96-h larval mortality and chronic toxicity using endpoints such as the time to hatch, hatching success, deformity, growth rate, swim-up failure, accumulative mortality, and sex ratio. On the basis of larval mortality the 96-h LC(50) (the concentration was lethal to 50% of newly hatching zebrafish larvae) was 68.9%. In chronic toxicity test, newly fertilized embryos (<5-h old) were exposed to 1, 6, 12, 25, 50% effluent concentrations in a 24-h static renewal system at (27 +/- 0.5) degrees C until 15-day posthatch. The results showed that all chronic endpoints were significantly different from the control at 50% dilution. Embryos began to show lesions on third day at higher concentrations (12, 25, 50% FP effluent concentrations). Treatment group of 25% dilution showed delayed time to hatch. Morphological abnormalities were observed in newly hatched larvae at 25 and 50% FP effluent concentrations. At 25% dilution, sex ratio of larvae was alternated and there was feminization phenomenon. On the basis of the study, the FP effluent tested here may cause increasing embryotoxicity in the zebrafish embryos. We conclude that the test using zebrafish is feasible to evaluate both acute and chronic toxicities of industrial effluents.

The effects of anthropogenic organic matter inputs on stable carbon and nitrogen isotopes in organisms from different trophic levels in a southern Mediterranean coastal area

Stable isotope ratios were used to determine the impact of anthropogenically derived organic matter from onshore and offshore fish farming and a sewage outfall on organisms at different trophic levels (primary producers and consumers) on the south-east coast of Sicily (Italy, Mediterranean). Representative macroalgae and consumers were collected in three sampling locations: "Impact" and two putative "Controls" sited to the north of the impacted location. While delta(13)C values of both organic matter sources and consumers varied little between locations, delta(15)N spatial variability was higher and delta(15)N was shown to be a good descriptor of organic enrichment and uptake of anthropogenically derived material within coastal food webs. Isotopic data were analysed using a multivariate approach. Organic matter sources and benthic components were more sensitive to pollution than nektobenthic species and revealed that the effects of anthropogenic activities seem to be detectable over a wide area. The study site is characterised by wide waste dispersal, which brings a reduction in impact in the area directly affected by organic matter inputs and enlarges the area of moderate impact.

Acute and early life stage toxicity of industrial effluent on Japanese medaka (Oryzias latipes)

To develop the whole effluent toxicity testing methods (WET), embryo larval stage toxicity test using Japanese medaka (Oryzias latipes) was conducted to evaluate an effluent from a banknote printing plant (BPP). The method is based on acute toxicity using endpoint of 96-h larval morality and on chronic toxicity using endpoints such as the time to hatch, hatching success, deformity, growth rate, swim-up failure, accumulative mortality and sexual ratio. In test for 96-h larval mortality, LC50 (the concentration was lethal to 50% of newly hatching medaka larvae) was 72.9%. In chronic toxicity test, newly fertilized embryos (<5-h old) were exposed to 1%, 6.25%, 12.5%, 25%, 50% effluent concentrations and to 200 mug/l BPA in a 24-h static renewal system at 25+/-1 degrees C until 15 day post-hatch. The results showed that all chronic endpoints were significantly different from the control at 50% dilution (p < 0.01). Embryos began to show lesions on 4th day at higher concentrations (12.5%, 25%, 50% BPP effluent concentrations). Treatment group of 25% dilution showed delayed time to hatch. A reduction in body weight was observed at 25% dilutions for males and females, respectively. Deformities were observed in newly hatched larvae at 25% and 50% BPP effluent concentrations. At 25% dilution, sex ratio of larvae was alternated and there was feminization phenomenon. We conclude that embryo larval stage test using medaka is feasible to evaluate both acute and chronic toxicities and potential endocrine disrupting activity of industrial effluents.

Mutagenicity assessment of effluents from textile/dye industries of Sanganer, Jaipur (India): a case study

Sanganer town, district Jaipur (Rajasthan, India), is famous worldwide for its dyeing and printing industries. There are about 400 industries involved in textile printing processes, which discharge effluents into nearby ponds and drains, without any treatment. These effluents contain highly toxic dyes, bleaching agents, salts, acids, and alkalis. Heavy metals like cadmium, copper, zinc, chromium, and iron are also found in the dye effluents. Textile workers are exposed to such waters with no control over the length and frequency of exposure. Further, as the untreated effluents are discharged into the environment they can cause severe contamination of surface and underground water. Environmental pollution caused by such textile effluents results in adverse effects on flora, fauna, and the general health of not only the textile workers, but also the residents of Sanganer town. Therefore, to assess the possible genotoxic health risk and environmental genotoxicity due to the textile industry effluents, this study was carried out using the Ames Salmonella/microsome mutagenicity assay. The results clearly indicate that the effluents and the surface water of Amani Shah drainage have high mutagenic activity. Further, the drainage water and the dry bed of the drainage (during summer months) are not fit for agricultural or other recreational purposes. A low level of mutagenicity in the underground water of Sanganer again emphasizes the grave pollution problem existing in the area. Multiple post hoc comparison tests (LSD, Tukey's) were used for comparison of sample site, dose, and length of exposure. Quadratic Model was found to adequately fit the observed data.

Coastal fish indicate human-induced changes in the Mediterranean littoral

Coastal fish assemblages were studied to assess two sorts of human impacts in southwestern Apulia (SE Italy, Mediterranean Sea). Fish assemblages were evaluated by visual census along two rocky locations impacted by a sewage outfall discharging nearshore (S) and by date-mussel (Lithophaga lithophaga) fisheries (F), respectively, and at two control locations (Cs). Multivariate analyses showed that fish assemblage structures at S and F differed from those at Cs. Asymmetric ANOVAs indicated that species richness were significantly lower both at S (approximately 27%) and at F (approximately 35%) compared with Cs. Total fish abundance was 5- to 7-fold higher at S than at Cs, while the values recorded at F were comparable to those of Cs. At S, average abundances of planktivorous fish and POM feeders were higher, and those of labrids and sparids of the genus Diplodus were lower, respectively, than at Cs. Labrids of the genus Symphodus and small serranids were significantly less abundant at F than Cs. Data suggested that coastal fish respond to the impact caused by the sewage discharge and provided a framework to assess potential benefits of its future displacement to deeper waters. For the first time, moreover, this study provided suggestive evidence that the habitat destruction caused by the illegal date-mussel fisheries may affect fish assemblages.