Contaminants of Emerging Concern in the Lower Volta River, Ghana, West Africa: The Agriculture, Aquaculture, and Urban Development Nexus.

Contaminants of emerging concern (CECs) are ubiquitous in aquatic environments across all continents and are relatively well known in the developed world. However, few studies have investigated their presence and biological effects in low- and middle-income countries. We provide a survey of CEC presence in the Volta River, Ghana, and examine the microbial consequences of anthropogenic activities along this economically and ecologically important African river. Water and sediment samples were taken by boat or from shore at 14 sites spanning 118 km of river course from the Volta estuary to the Akosombo dam. Sample extracts were prepared for targeted analysis of antimicrobial CECs, N,N-diethyl-meta-toluamide, and per- and polyfluoroalkyl substances (PFAS; water only). Concurrent samples were extracted to characterize the microbial community and antibiotic-resistant genes (ARGs). Antibiotics and PFAS (PFAS, 2-20 ng/L) were found in all water samples; however, their concentrations were usually in the low nanograms per liter range and lower than reported for other African, European, and North American studies. N,N-Diethyl-meta-toluamide was present in all samples. The number of different genes detected (between one and 10) and total ARG concentrations varied in both water (9.1 × 10-6 to 8.2 × 10-3 ) and sediment (2.2 × 10-4 to 5.3 × 10-2 ), with increases in gene variety at sites linked to urban development, sand mining, agriculture, and shellfish processing. Total ARG concentration spikes in sediment samples were associated with agriculture. No correlations between water quality parameters, CEC presence, and/or ARGs were noted. The presence of CECs in the lower Volta River highlights their global reach. The overall low concentrations of CECs detected is encouraging and, coupled with mitigation measures, can stymie future CEC pollution in the Volta River. Environ Toxicol Chem 2022;41:369-381. © 2021 SETAC.

Environmental estrogens in an urban aquatic ecosystem: II. Biological effects.

Urban aquatic ecosystems are often overlooked in toxicological studies even though they serve many ecosystem functions and sustain fish populations despite large-scale habitat alterations. However, urban fish populations are likely exposed to a broad range of stressors, including environmental estrogens (EEs) that may affect anatomy, physiology and reproduction of exposed fish. Although significant progress has been made in establishing ecological consequences of EE exposure, these studies have focused largely on hydrologically simple systems that lack the complexity of urban aquatic environments. Therefore, the objective of this study was to assess the occurrence and biological effects of EEs across a large urbanized aquatic ecosystem. A multi-pronged study design was employed relying on quantitative determination of select EEs by liquid chromatography tandem mass spectrometry and repeated biological monitoring of wild-caught and caged fish for indications of endocrine disruption. Over three years, EEs were measured in aqueous samples (n=42 samples) and biological effects assessed in >1200 male fish across the 2000km(2) aquatic ecosystems of the Greater Metropolitan Area of Chicago, IL. Our study demonstrated that in addition to water reclamation plant (WRP) effluents, non-WRP sources contribute significant EE loads to the aquatic ecosystem. While resident and caged male fish responded with the induction of the egg-yolk protein vitellogenin, an indicator of EE exposure, neither resident nor caged sunfish exhibited prevalent histopathological changes to their reproductive organs (i.e., intersex) that have been reported in other studies. Vitellogenin induction was greater in spring than the fall and was not correlated with body condition factor, gonadosomatic index or hepatosomatic index. Exposure effects were not correlated with sites downstream of treated effluent discharge further affirming the complexity of sources and effects of EEs in urban aquatic ecosystems.

Effects of triclosan and triclocarban, two ubiquitous environmental contaminants, on anatomy, physiology, and behavior of the fathead minnow (Pimephales promelas).

Triclosan (TCS) and triclocarban (TCC) are two common antimicrobial agents found in many personal care products and subsequently are detected ubiquitously in wastewater effluent and receiving waters. Both compounds are of recent regulatory interest due to their omnipresence in the environment, including in humans. Although TCS and TCC have been suggested to be endocrine active, little information exists about their effects on organismal end points in development (growth, escape performance), anatomy (morphological indices, histology), physiology (vitellogenin), and behavior of exposed aquatic organisms. In this study, newly hatched fathead minnows were exposed for 12 days, and mature male and female fathead minnows (Pimephales promelas) were exposed for 21 days to environmentally realistic concentrations (nanograms per liter) of these two compounds singularly and in mixtures. At the end of the exposure, larvae were assessed for growth and predator-avoidance performance, and a subset of mature fish was assessed for plasma vitellogenin induction, expression of secondary sexual characteristics, relative size of liver and gonads, and histopathological changes to both organs. The remaining exposed mature fish were placed in breeding pairs of one male and one female minnow from the same treatment to assess their ability to defend a nest site and reproduce. Exposure to either antimicrobial compound, alone or as a mixture, caused no changes to larval fish, gonad size, or vitellogenin concentrations in mature fathead minnows. In contrast, decreased aggression was seen in adult male fathead minnows exposed to TCC (1.6 µg/l) or a mixture (560 ng/l TCS + 179 ng/l TCC and 1.6 µg/l TCS + 450 ng/l TCC). Decreased aggression would likely decrease their ability to defend and hold a nest site needed for spawning and reproduction. Substantial variability was found in the severity of observed effects within treatments, suggesting that environmentally realistic concentrations of these compounds may only affect particularly sensitive individuals.

Assessing the effects of historical exposure to endocrine-active compounds on reproductive health and genetic diversity in walleye, a native apex predator, in a large riverine system.

In this combined field and laboratory study, we assessed whether populations of native walleye in the Upper Mississippi River experienced altered genetic diversity correlated with exposure to estrogenic endocrine-active compounds (EACs). We collected fin-clips for genetic analysis from almost 600 walleye (13 sites) and subsampled 377 of these fish (6 sites) for blood and reproductive organs. Finally, we caged male fathead minnows at 5 sampling sites to confirm the presence of estrogenic EACs. Our findings indicate that male walleye in four river segments produced measurable concentrations of plasma vitellogenin (an egg-yolk protein and, when expressed in male fish, a biomarker of acute estrogenic exposure), a finding consistent with the presence of estrogenic EACs and consistent with published historical data for at least three of these study sites (Grand Rapids, St. Paul, and Lake City on Lake Pepin). Patterns of vitellogenin induction were consistent for native walleye and caged fathead minnows. No widespread occurrence of histopathological changes, such as intersex was found compared with published reports of intersex at the furthest downstream study site. To assess possible effects of estrogenic exposure on the genetic diversity of walleye populations at the study sites, we DNA-fingerprinted individual fish using 10 microsatellite loci. Genetic differences were observed between populations; however, these differences were consistent with geographic distance between populations, with the largest observed difference in genetic diversity found between fish upstream and downstream of St. Anthony Falls (and/or Lock and Dam 1 of the Mississippi River), traditionally a historical barrier to upstream fish movement. Although the persistent occurrence of endocrine disruption in wild fish populations is troubling, we did not detect degradation of reproductive organs in individual walleye or alteration in genetic diversity of walleye populations.

Affinity and matrix effects in measuring fish plasma vitellogenin using immunosorbent assays: considerations for aquatic toxicologists.

Enzyme-linked immunosorbent assays (ELISAs) are important tools in aquatic toxicology and have become crucial in assessing exposure concentrations in the aquatic environment and acute physiological responses in exposed organisms. These assays utilize the inherent properties of antibodies to recognize and selectively bind a target molecule, while largely ignoring other molecules to provide semiquantitative values. A variety of methodologies to measure plasma vitellogenin using ELISAs have generated widely divergent data. Limitations of the ELISA method are known in the wider immunology field, though aquatic toxicologists may be less familiar with these limitations. We evaluated several mechanisms contributing to the divergent vitellogenin data in the literature. Antibody affinities and the matrix in which standard curves are constructed are possible error generators. These errors can be amplified by large sample dilutions necessary to fall within the standard curve. It is important for the aquatic toxicology research community to realize the limitations and understand the pitfalls of absolute plasma vitellogenin data in their studies.

Effects of biologically-active chemical mixtures on fish in a wastewater-impacted urban stream.

Stream flow in urban aquatic ecosystems often is maintained by water-reclamation plant (WRP) effluents that contain mixtures of natural and anthropogenic chemicals that persist through the treatment processes. In effluent-impacted streams, aquatic organisms such as fish are continuously exposed to biologically-active chemicals throughout their life cycles. The North Shore Channel of the Chicago River (Chicago, Illinois) is part of an urban ecosystem in which >80% of the annual flow consists of effluent from the North Side WRP. In this study, multiple samplings of the effluent and stream water were conducted and fish (largemouth bass and carp) were collected on 2 occasions from the North Shore Channel. Fish also were collected once from the Outer Chicago Harbor in Lake Michigan, a reference site not impacted by WRP discharges. Over 100 organic chemicals with differing behaviors and biological effects were measured, and 23 compounds were detected in all of the water samples analyzed. The most frequently detected and highest concentration (>100µg/L) compounds were ethylenediaminetetraacetic acid and 4-nonylphenolmono-to-tetraethoxycarboxylic acids. Other biologically-active chemicals including bisphenol A, 4-nonylphenol, 4-nonylphenolmono-to-tetraethoxylates, 4-tert-octylphenol, and 4-tert-octylphenolmono-to-tetraethoxylates were detected at lower concentrations (<5µg/L). The biogenic steroidal hormones 17ß-estradiol, estrone, testosterone, 4-androstene-3,17-dione, and cis-androsterone were detected at even lower concentrations (<0.005µg/L). There were slight differences in concentrations between the North Side WRP effluent and the North Shore Channel, indicating minimal in-stream attenuation. Fish populations are continuously exposed to mixtures of biologically-active chemicals because of the relative persistency of the chemicals with respect to stream hydraulic residence time, and the lack of a fresh water source for dilution. The majority of male fish exhibited vitellogenin induction, a physiological response consistent with exposure to estrogenic compounds. Tissue-level signs of reproductive disruption, such as ovatestis, were not observed.

Selective uptake and biological consequences of environmentally relevant antidepressant pharmaceutical exposures on male fathead minnows.

Antidepressant pharmaceuticals have been reported in wastewater effluent at the nanogram to low microgram-per-liter range, and include bupropion (BUP), fluoxetine (FLX), sertraline (SER), and venlafaxine (VEN). To assess the effects of antidepressants on reproductive anatomy, physiology, and behavior, adult male fathead minnows (Pimephales promelas) were exposed for 21 days either to a single concentration of the antidepressants FLX, SER, VEN, or BUP, or to an antidepressant mixture. The data demonstrated that exposure to VEN (305 ng/L and 1104 ng/L) and SER (5.2 ng/L) resulted in mortality. Anatomical alterations were noted within the testes of fish exposed to SER and FLX, both modulators of the neurotransmitter serotonin. Additionally, FLX at 28 ng/L induced vitellogenin in male fish--a common endpoint for estrogenic endocrine disruption. Significant alterations in male secondary sex characteristics were noted with single exposures. Effects of single compound exposures neither carried over, nor became additive in the antidepressant mixtures, and reproductive behavior was not affected. Analysis of brain tissues from the exposed fish suggested increased uptake of FLX, SER and BUP and minimal uptake of VEN when compared to exposure water concentrations. Furthermore, the only metabolite detected consistently in the brain tissues was norfluoxetine. Similar trends of uptake by brain tissue were observed when fish were exposed to antidepressant mixtures. The present study demonstrates that anatomy and physiology, but not reproductive behavior, can be disrupted by exposure to environmental concentrations of some antidepressants. The observation that antidepressant uptake into fish tissues is selective may have consequences on assessing the mode-of-action and effects of these compounds in future studies.

Larval exposure to environmentally relevant mixtures of alkylphenolethoxylates reduces reproductive competence in male fathead minnows.

The ubiquitous presence of nonylphenolethoxylate/octylphenolethoxylate (NPE/OPE) compounds in aquatic environments adjacent to wastewater treatment plants (WWTP) warrants an assessment of the endocrine disrupting potential of these complex mixtures on aquatic vertebrates. In this study, fathead minnow larvae were exposed for 64 days to a mixture of NPE/OPE, which closely models the NPE/OPE composition of a major metropolitan WWTP effluent. Target exposure concentrations included a total NPE/OPE mixture load of 200% of the WWTP effluent concentration (148microg/L), 100% of the WWTP effluent concentration (74microg/L) and 50% of the WWTP effluent concentration (38microg/L). The NPE/OPE mixture contained 0.2% 4-t-octylphenol, 2.8% 4-nonylphenol, 5.1% 4-nonylphenolmonoethoxylate, 9.3% 4-nonylphenoldiethoxylate, 0.9% 4-t-octylphenolmonoethoxylate, 3.1% 4-t-octylphenoldiethoxylate, 33.8% 4-nonylphenolmonoethoxycarboxylate, and 44.8% 4-nonylphenoldiethoxycarboxylate. An additional exposure of 5microg/L 4-nonylphenol (nominal) was conducted. The exposure utilized a flow-through system supplied by ground water and designed to deliver consistent concentrations of applied chemicals. Following exposure, larvae were raised to maturity. Upon sexual maturation, exposed male fish were allowed to compete with control males in a competitive spawning assay. Nest holding ability of control and exposed fish was carefully monitored for 7 days. All male fish were then sacrificed and analyzed for plasma vitellogenin, developmental changes in gonadal tissues, alterations in the development of secondary sexual characters, morphometric changes, and changes to reproductive behavior. When exposed to the 200% NPE/OPE treatment most larvae died within the first 4 weeks of exposure. Both the 100% and 50% NPE/OPE exposures caused a significant decrease in reproductive behavior, as indicated by an inability of many of the previously exposed males to acquire and hold a nest site required for reproduction. In contrast, the 5microg/L 4-nonylphenol exposure resulted in significantly enhanced reproductive behavior compared to that of control males and a majority of the nesting sites were held by previously exposed males. No significant change in the development of gonadal tissues was observed. The 100% NPE/OPE exposure resulted in a significant reduction in the gonadal somatic index and in the prominence of secondary sexual characteristics of exposed larvae. This study indicates that NPE/OPE mixtures have an effect on the reproductive competence of previously exposed male fathead minnows. In addition, 4-nonylphenol concentrations utilized in all exposures were below regulatory guidelines, suggesting that evaluation of 4-nonylphenol alone may not be sufficient for identifying potentially adverse effects of this suite of compounds usually found as mixtures in the aquatic environment.