Chemical contaminants, health indicators, and reproductive biomarker responses in fish from rivers in the Southeastern United States

Designing a Clean Label Fish Patty with Olive, Citric, Pomegranate, or Rosemary Extracts

The natural functional ingredients derived from pomegranate (41.4% punicalagin), rosemary (5.8% carnosic acid and carnosol), hydroxytyrosol (7.3%), and citrus (55% hesperidin) fruits were combined separately with acerola (17% vitamin C) and essential oils rich in fatty acids (45% α-linolenic (ALA) and 40% docosahexaenoic (DHA)) provide a natural substitute of synthetic preservatives for fish patties, avoiding E-numbers on labels. Microbiological and physicochemical properties of the formulations were examined, sensory analysis was conducted, and changes in their shelf life due to storage for 14 days under chilled storage, adding these ingredients, were determined. The results obtained showed that the fish patties reported a high level of protein (14%), low fat (<2%), with a high contribution of phosphorus and selenium minerals, and higher levels of ALA up to 40% (in the case of rosemary extract (R)) and DHA by 30% (Ct), compared to the Control sample. The fish patties suffered microbiological, flavor, and odor spoilage and rapid lipid oxidation associated with rancidity. It can be said that the fish preparations have a duration of less than 7 days (between 4–6 days), except for the preparation with pomegranate extract (P) that has a longer life, from 7 to 11 days. Consequently, replacing synthetic additives by natural extracts offers a new clean label product with potential health benefits that resembles the commercial fish patties.

Histopathologic Prevalence and Severity of Testicular Oocytes in Smallmouth Bass from Two Archival Collections

During recent decades, survey studies have documented the widespread presence of oocytes in the testes of male Smallmouth Bass Micropterus dolomieu collected from surface waters throughout the United States. There are few published reports of testicular oocytes (TO) in Smallmouth Bass before the 1990s, so it is difficult to know how long this has been occurring. Consequently, this study was conducted to evaluate the prevalence and severity of TO occurrence in whole fish specimens from two archival collections-the Smithsonian Institution's National Museum of Natural History in Suitland, Maryland, and Cornell University's Museum of Vertebrates in Ithaca, New York. Gonads were excised from 167 preserved male Smallmouth Bass that were originally collected between 1875 and 2004, and routine histologic sections were prepared and examined. The severity of TO was determined using a semiquantitative scoring system. Overall, 52.1% of male Smallmouth Bass were found to have TO. Affected fish had been collected in 11 of the 18 represented states, and TO were found in specimens harvested during decades as early as the 1880s and 1900s. Unfortunately, the small number of samples acquired at the earliest time periods precluded analyses of prevalence and severity trends over time. The results of this study demonstrated that the phenomenon of TO in male Smallmouth Bass is at least a century old and confirmed the widespread nature of this finding throughout the species' historic range. Further research efforts should focus on determining the baseline prevalence of TO in laboratory-reared male Smallmouth Bass that have not been exposed to endocrine active substances or the effects of experimental estrogen exposure on such fish.

Exposure and potential effects of pesticides and pharmaceuticals in protected streams of the US National park Service southeast region

Globally, protected areas offer refugia for a broad range of taxa including threatened and endangered species. In the United States (US), the National Park Service (NPS) manages public lands to preserve biodiversity, but increasing park visitation and development of surrounding landscapes increase exposure to and effects from bioactive contaminants. The risk (exposure and hazard) to NPS protected-stream ecosystems within the highly urbanized southeast region (SER) from bioactive contaminants was assessed in five systems based on 334 pesticide and pharmaceutical analytes in water and 119 pesticides in sediment. Contaminant mixtures were common across all sampled systems, with approximately 24% of the unique analytes (80/334) detected at least once and 15% (49/334) detected in half of the surface-water samples. Pharmaceuticals were observed more frequently than pesticides, consistent with riparian buffers and concomitant spatial separation from non-point pesticide sources in four of the systems. To extrapolate exposure data to biological effects space, site-specific cumulative exposure-activity ratios (Σ_EAR) were calculated for detected surface-water contaminants with available ToxCast data; common exceedances of a 0.001 Σ_EAR effects-screening threshold raise concerns for molecular toxicity and possible, sub-lethal effects to non-target, aquatic vertebrates. The results illustrate the need for continued management of protected resources to reduce contaminant exposure and preserve habitat quality, including prioritization of conservation practices (riparian buffers) near stream corridors and increased engagement with upstream/up-gradient property owners and municipal wastewater facilities.

Steroidogenic acute regulatory protein transcription is regulated by estrogen receptor signaling in largemouth bass ovary

Estrogenic contaminants in the environment are linked to the occurrence of reproductive abnormalities in many aquatic species, including largemouth bass (Micropterus salmoides; LMB). Previous work has shown that many different types of xenoestrogens regulate expression of the Steroidogenic Acute Regulatory protein (StAR), a cholesterol-transporting protein vital to steroid hormone biosynthesis; however, the regulatory mechanisms of StAR are incompletely characterized in fish. To learn more about endogenous expression patterns of StAR in the ovary, LMB were collected from the St. John's River (Florida, USA) over an entire breeding season to investigate StAR expression. Plasma 17β-estradiol (E2) and StAR mRNA levels were positively correlated in females, and StAR mRNA levels displayed ~ 100-fold increase between primary oocyte growth stages and final maturation. To further study the regulation of StAR, female LMB in the laboratory were fed at ≃2% of their weight on a diet laden with 17α-ethinylestradiol (EE2, 70 or 200 ng EE2 per gram feed). Diets were designed to achieve a physiologically-relevant exposure to EE2, and StAR expression was assessed in vivo. We observed a dose-dependent suppression of StAR mRNA levels, however both diets led to high, pharmacological levels in the blood and do not represent normal physiological ranges of estrogens. In the 200 ng EE2/gm feed group, ovarian StAR mRNA levels were suppressed to approximately 5% of that of the LMB control group. These investigations suggest that LMB StAR increases in expression during oocyte maturation and that it is suppressed by E2 feedback when estrogen levels are high, through the HPG axis. A 2.9 kb segment of the LMB StAR promoter was examined for putative E2 response elements using in silico software, and a putative estrogen receptor binding element (ERE/-1745) was predicted in the promoter. The functionality of the ERE was examined using MA-10 mouse Leydig cells transfected with the LMB StAR promoter. Estrogen receptor (ER) interaction with ERE/-1745 was evaluated under basal and human chorionic gonadotropin (hCG)-treated conditions in the presence and absence of E2. Chromatin immunoprecipitation (ChIP) experiments revealed that ESR1 binding to the promoter was enriched under basal conditions and E2 exposure elicited an increase in enrichment (4-fold) above that observed under basal conditions. ESR2 was not strongly enriched at the ERE/-1745 site, suggesting that StAR may be preferentially regulated by LMB estrogen receptor 1 (esr1). Taken together, these different experiments provide evidence that LMB StAR is under the control of estrogens and that ESR1 binds directly to the LMB StAR promoter in an E2-responsive manner.

Necropsy-based Wild Fish Health Assessment

Anthropogenic influences from increased nutrients and chemical contaminants, to habitat alterations and climate change, can have significant effects on fish populations. Adverse effects monitoring, utilizing biomarkers from the organismal to the molecular level, can be used to assess the cumulative effects on fishes and other organisms. Fish health has been used worldwide as an indicator of aquatic ecosystem health. The necropsy-based fish health assessment provides data on visible abnormalities and lesions, parasites, condition and organosomatic indices. These can be compared by site, season and sex, as well as temporally, to document change over time. Severity ratings can be assigned to various observations to calculate a fish health index for more quantitative assessment. A drawback of the necropsy-based assessment is that it is based on visual observations and condition factors, which are not as sensitive as tissue and subcellular biomarkers for sublethal effects. Additionally, it is rarely possible to identify causes or risk factors associated with observed abnormalities. So, for instance a raised lesion or "tumor" on the fins, lips or body surface may be a neoplasm. However, it could also be a response to a parasite, chronic inflammation or hyperplasia of normal cells in response to an irritant. Conversely, neoplasms, certain parasites, other infectious agents and many tissue changes are not visible and so may be underestimated. However, during the necropsy-based assessment, blood (plasma), tissues for histopathology (microscopic pathology), genomics and other molecular analyses, and otoliths for aging can be collected. These downstream analyses, together with geospatial analyses, habitat assessments, water quality and contaminant analyses can all be important in comprehensive ecosystem evaluations.

Food web contaminant dynamics of a large Atlantic Slope river: Implications for common and imperiled species

Persistent and bioaccumulative contaminants often reach concentrations that threaten aquatic life by causing alterations in organism behavior and development, disruption of biological processes, reproductive abnormalities, and mortality. The objectives of this research were to determine the aquatic food web structure and trophic transfer and accumulation of contaminants within a riverine ecosystem and identify potential stressors to the health of an imperiled fish, the robust redhorse (Moxostoma robustum) and other species of conservation concern in a large Atlantic Slope (USA) river. Trophic position was determined for food web taxa by stable isotope analyses of representative producers, consumers, and organic matter of the Yadkin-Pee Dee River of North Carolina and South Carolina. Contaminant analyses were performed on water, sediment, organic matter, and aquatic biota to assess the prevalence and accumulation of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), current use pesticides (CUPs), polycyclic aromatic hydrocarbons (PAHs), and selected metals. Contaminants were prevalent in the environment and food web components of the river. PCBs were detected in 32% of biotic samples (mean 0.24μg/g dry weight [DW], range 0.01-3.33μg/g DW), and DDTs (legacy OCPs and metabolites) were detected in 90% (mean 0.014μg/g DW, range 0.0004-0.29μg/g DW). The trace metals manganese and cadmium exceeded published threshold effect concentrations in sediment (460 and 0.99μg/g DW, respectively). Mercury was detected in all food web samples exhibiting a mean of 0.61μg/g DW and range 0.006-2.35μg/g DW (mean 0.13μg/g wet weight [WW], range 0.001-0.6μg/g WW). Concentrations exceeded the 0.2μg/g WW aquatic life criterion for mercury in 38% of fish samples. Fish trophic magnification factors (TMFs; range 0.33-3.75) indicated that contaminant accumulation occurred from both water and dietary sources. The combination of analytical approaches applied here provides new insight into contaminant dynamics with conservation implications.

Reductions in fish-community contamination following lowhead dam removal linked more to shifts in food-web structure than sediment pollution

Recent increases in dam removals have prompted research on ecological and geomorphic river responses, yet contaminant dynamics following dam removals are poorly understood. We investigated changes in sediment concentrations and fish-community body burdens of mercury (Hg), selenium (Se), polychlorinated biphenyls (PCB), and chlorinated pesticides before and after two lowhead dam removals in the Scioto and Olentangy Rivers (Columbus, Ohio). These changes were then related to documented shifts in fish food-web structure. Seven study reaches were surveyed from 2011 to 2015, including controls, upstream and downstream of the previous dams, and upstream restored vs. unrestored. For most contaminants, fish-community body burdens declined following dam removal and converged across study reaches by the last year of the study in both rivers. Aldrin and dieldrin body burdens in the Olentangy River declined more rapidly in the upstream-restored vs. the upstream-unrestored reach, but were indistinguishable by year three post dam removal. No upstream-downstream differences were observed in body burdens in the Olentangy River, but aldrin and dieldrin body burdens were 138 and 148% higher, respectively, in downstream reaches than in upstream reaches of the Scioto River following dam removal. The strongest relationships between trophic position and body burdens were observed with PCBs and Se in the Scioto River, and with dieldrin in the Olentangy River. Food-chain length - a key measure of trophic structure - was only weakly related to aldrin body burdens, and unrelated to other contaminants. Overall, we demonstrate that lowhead dam removal may effectively reduce ecosystem contamination, largely via shifts in fish food-web dynamics versus sediment contaminant concentrations. This study presents some of the first findings documenting ecosystem contamination following dam removal and will be useful in informing future dam removals.

Impairment of reproduction of adult zebrafish (Danio rerio) by binary mixtures of environmentally relevant concentrations of triclocarban and inorganic mercury

Effects of chemical mixtures at environmentally relevant concentrations on endocrine systems of aquatic organisms are of concern. Triclocarban (TCC) and inorganic mercury (Hg²⁺) are ubiquitous in aquatic environments, and are known to interfere with endocrine pathways via different mechanisms of toxic action. However, effects of mixtures of the two pollutants on aquatic organisms and associated molecular mechanisms were unknown. This study examined effects of binary mixtures of TCC and Hg²⁺ on histopathological and biochemical alteration of reproductive organs in zebrafish (Danio rerio) after 21 d exposure. The results showed that: 1) At concentrations studied, TCC alone caused little effect on hepatic tissues, but it aggravated lesions in liver caused by Hg²⁺ via indirect mechanisms of disturbing homeostasis and altering concentrations of hormones; 2) Histological lesions were more severe in gonads of individuals, especially males, exposed to the binary mixture. Exposure to TCC alone (2.5 or 5μg/L) (measured concentration 140 or 310ng/L) or Hg²⁺ alone (5μg/L or 10μg/L (measured concentration 367 or 557ng/L) slightly retarded development of oocytes, whereas co-exposure to nominal concentrations of 5μg/L TCC and 10μg /L Hg²⁺ promoted maturation of oocytes. In males, maturation of sperm was slightly delayed by exposure to either TCC or Hg²⁺, while their combinations caused testes to be smaller and sperm to be fewer compared with fish exposed to either of the contaminants individually; 3) Lesions observed in fish exposed to binary mixtures might be due to altered transcription of genes involved in steroidogenesis, such as cyp19a, 3beta-HSD, cyp17, 17beta-HSD and modulated concentrations of testosterone and estradiol in blood plasma. The observed results further support the complexity of toxic responses of fish exposed to lesser concentrations of binary chemical mixtures. Since it is impossible to collect empirical information in controlled studies of all possible combinations of toxicants, the application of omics methods might improve the predictive capabilities of results of single classes of chemicals.

No evidence of exposure to environmental estrogens in two feral fish species sampled from the Yarra River, Australia: A comparison with Northern Hemisphere studies

Environmental estrogens originate from a variety of sources including sewage treatment plant (STP) effluents and adverse physiological effects (endocrine disruption) have been observed in several fish species sampled downstream of STP discharges. In this study we examined common carp (Cyprinus carpio) and roach (Rutilis rutilis) for signs of exposure to environmental estrogens in the iconic Yarra River, Melbourne, Australia. The Yarra River flows through the city of Melbourne and more than 2 million people live within the catchment. Two STPs discharge water into the Yarra River within the middle reaches, and the areas immediately downstream of these discharge locations were the focus of this study. Carp and roach were chosen as test species since both have been utilised extensively for endocrine disruption research throughout Europe, North America and Asia, and data from various international studies was used for comparison with the results of the present study. Neither species showed evidence of exposure to environmental estrogens, with no elevation of plasma vitellogenin levels in males and no incidence of intersex gonads. Most physiological endpoints in both species from this study were within ranges reported in carp and roach from reference sites in other studies, however some degenerative histological changes in both male and female gonads were observed. Surface water samples showed no estrogenic activity (measured by the yeast-estrogen screen, YES), but did display strong anti-estrogenic and weak androgenic activity (measured by the yeast-androgen screen, YAS). Whilst the results show no evidence of impacts from environmental estrogens in the Yarra River, the presence of both anti-estrogenic and androgenic activity in water samples, as well as some gonadal changes in carp is concerning and indicates that our focus needs to broaden, in order to look for biological impacts in resident fauna that might be due to environmental pollutants other than environmental estrogens.

In situ experiments to assess effects of constraints linked to caging on ecotoxicity biomarkers of the three-spined stickleback (Gasterosteus aculeatus L.)

The aim of this study was to evaluate the effects of caging constraints on multiple fish biomarkers used during ecotoxicological studies (biometric data, immune and antioxidant systems, and energetic status). Two of these constraints were linked to caging: starvation and fish density in cages, and one in relation to the post-caging handling: a short transport. Three in situ experiments were conducted with three-spined sticklebacks (Gasterosteus aculeatus). The first experiment compared the effects of three densities (low, medium, and high). The second experiment compared effects of starvation in fish fed every two days with fish that were not fed. Finally comparisons between sticklebacks which have suffered a short car transport after caging and sticklebacks killed without preliminary transport were made. The lack of food had no effect on fish energetic reserves but negatively affected their condition index and their immune system. Transport and high density induced oxidative stress, defined as an overproduction of reactive oxygen species and a stimulation of the antioxidant system. These two constraints also harmed the leucocyte viability. In order not to have any impact on ecotoxicity biomarkers during in situ experiments, it is preferable to decrease fish density in cages, prevent transport before dissections, and feed fish when the caging lasts more than two weeks.

Critical perspectives on mercury toxicity reference values for protection of fish

Environmental management decisions at mercury-contaminated sediment sites are predicated on the understanding of risks to various receptors, including fish. Toxicity reference values (TRVs) for interpreting risks to fish have been developed to assess mercury concentrations in fish or fish prey. These TRVs were systematically evaluated based on several lines of evidence. First, their conceptual basis and specific derivation were evaluated, including a close review of underlying toxicity studies. Second, case studies were reviewed to investigate whether TRVs are predictive of effects on fish populations in the field. Third, TRVs were compared with available information regarding preindustrial and present-day background concentrations of mercury in fish. The findings show that existing TRVs are highly uncertain, because they were developed using limited data from studies not designed for TRV derivation. Although field studies also entail uncertainty, several case studies indicate no evidence of adverse effects despite mercury exposures that exceed the available TRVs. Some TRVs also fall within the range of background mercury concentrations in predatory or prey fish. Lack of information on the selenium status of mercury-exposed fish is a critical confounding factor, and the form of methylmercury used in toxicity testing may also contribute to differences between TRV-based predictions and field observations of mercury effects on fish. On balance, the available information indicates that several of the TRVs reviewed are lower than necessary to protect fish populations. The 20% effect concentration from a previously published dose-response analysis appears closer to an effect threshold, based on available laboratory data. Additional research is needed to provide a stronger basis to establish dose-response relationships for mercury effects on fish.

Novel associations between contaminant body burdens and biomarkers of reproductive condition in male Common Carp along multiple gradients of contaminant exposure in Lake Mead National Recreation Area, USA

Adult male Common Carp were sampled in 2007/08 over a full reproductive cycle at Lake Mead National Recreation Area. Sites sampled included a stream dominated by treated wastewater effluent, a lake basin receiving the streamflow, an upstream lake basin (reference), and a site below Hoover Dam. Individual body burdens for 252 contaminants were measured, and biological variables assessed included physiological [plasma vitellogenin (VTG), estradiol-17β (E2), 11-ketotestosterone (11KT)] and organ [gonadosomatic index (GSI)] endpoints. Patterns in contaminant composition and biological condition were determined by Principal Component Analysis, and their associations modeled by Principal Component Regression. Three spatially distinct but temporally stable gradients of contaminant distribution were recognized: a contaminant mixture typical of wastewaters (PBDEs, methyl triclosan, galaxolide), PCBs, and DDTs. Two spatiotemporally variable patterns of biological condition were recognized: a primary pattern consisting of reproductive condition variables (11KT, E2, GSI), and a secondary pattern including general condition traits (condition factor, hematocrit, fork length). VTG was low in all fish, indicating low estrogenic activity of water at all sites. Wastewater contaminants associated negatively with GSI, 11KT and E2; PCBs associated negatively with GSI and 11KT; and DDTs associated positively with GSI and 11KT. Regression of GSI on sex steroids revealed a novel, nonlinear association between these variables. Inclusion of sex steroids in the GSI regression on contaminants rendered wastewater contaminants nonsignificant in the model and reduced the influence of PCBs and DDTs. Thus, the influence of contaminants on GSI may have been partially driven by organismal modes-of-action that include changes in sex steroid production. The positive association of DDTs with 11KT and GSI suggests that lifetime, sub-lethal exposures to DDTs have effects on male carp opposite of those reported by studies where exposure concentrations were relatively high. Lastly, this study highlighted advantages of multivariate/multiple regression approaches for exploring associations between complex contaminant mixtures and gradients and reproductive condition in wild fishes.

Ecotoxicology of polychlorinated biphenyls in fish--a critical review

Polychlorinated biphenyls (PCBs) are widespread persistent anthropogenic contaminants that can accumulate in tissues of fish. The toxicity of PCBs and their transformation products has been investigated for nearly 50 years, but there is a lack of consensus regarding the effects of these environmental contaminants on wild fish populations. The objective of this review is to critically examine these investigations and evaluate publicly available databases for evidence of effects of PCBs in wild fish. Biological activity of PCBs is limited to a small proportion of PCB congeners [e.g., dioxin-like PCBs (DL-PCBs)] and occurs at concentrations that are typically orders of magnitude higher than PCB levels detected in wild fish. Induction of biomarkers consistent with PCB exposure (e.g., induction of cytochrome P450 monooxygenase system) has been evaluated frequently and shown to be induced in fish from some environments, but there does not appear to be consistent reports of damage (i.e., biomarkers of effect) to biomolecules (i.e., oxidative injury) in these fish. Numerous investigations of endocrine system dysfunction or effects on other organ systems have been conducted in wild fish, but collectively there is no consistent evidence of PCB effects on these systems in wild fish. Early life stage toxicity of DL-PCBs does not appear to occur at concentrations reported in wild fish embryos, and results do not support an association between PCBs and decreased survival of early life stages of wild fish. Overall, there appears to be little evidence that PCBs have had any widespread effect on the health or survival of wild fish.

One-dimensional proteomic profiling of Danio rerio embryo vitellogenin to estimate quantum dot toxicity

BACKGROUND

Vitellogenin (Vtg) is the major egg yolk protein (YP) in most oviparous species and may be useful as an indicator in ecotoxicological testing at the biochemical level. In this study, we obtained detailed information about the Vtgs of Danio rerio embryos by cutting SDS-PAGE gel lanes into thin slices, and analyzing them slice-by-slice with (MALDI-TOF) mass spectrometry.

RESULTS

We conducted three proteomic analyses, comparing embryonic Danio rerio Vtg cleavage products after exposure for 48 h to CdSecore/ZnSshell quantum dots (QDs), after exposure to a mixture of the components used for quantum dot synthesis (MCS-QDs), and in untreated embryos. The Vtg mass spectrometric profiles of the QDs-treated embryos differed from those of the unexposed or MCS-QDs-treated embryos.

CONCLUSION

This study demonstrates the possible utility of Vtg profiling in D. rerio embryos as a sensitive diagnostic tool to estimate nanoparticle toxicity.

Putting pharmaceuticals into the wider context of challenges to fish populations in rivers

The natural range of fish species in our rivers is related to flow, elevation, temperature, local habitat and connectivity. For over 2000 years, humans have altered to varying degrees the river habitat. In the past 200 years, we added to the environmental disruption by discharging poorly treated sewage, nutrients and industrial waste into our rivers. For many rivers, the low point arrived during the period of 1950s-1970s, when rapid economic development overrode environmental concerns and dissolved oxygen concentrations dropped to zero. In these more enlightened times, gross river pollution is a thing of the past in the Developed World. However, persistent legacy chemical contaminants can be found in fish long after their discharge ceased. Changes in habitat quality and morphology caused and continue to cause the disappearance of fish species. The range of fish stressors has now increased as temperatures rise, and non-native fish introductions bring new diseases. The threat from pharmaceuticals to fish populations remains hypothetical, and no studies have yet linked change in fish populations to exposure.

Reproductive health indicators of fishes from Pennsylvania watersheds: association with chemicals of emerging concern

Fishes were collected at 16 sites within the three major river drainages (Delaware, Susquehanna, and Ohio) of Pennsylvania. Three species were evaluated for biomarkers of estrogenic/antiandrogenic exposure, including plasma vitellogenin and testicular oocytes in male fishes. Smallmouth bass Micropterus dolomieu, white sucker Catostomus commersonii, and redhorse sucker Moxostoma species were collected in the summer, a period of low flow and low reproductive activity. Smallmouth bass were the only species in which testicular oocytes were observed; however, measurable concentrations of plasma vitellogenin were found in male bass and white sucker. The percentage of male bass with testicular oocytes ranged from 10 to 100%, with the highest prevalence and severity in bass collected in the Susquehanna drainage. The percentage of males with plasma vitellogenin ranged from 0 to 100% in both bass and sucker. Biological findings were compared with chemical analyses of discrete water samples collected at the time of fish collections. Estrone concentrations correlated with testicular oocytes prevalence and severity and with the percentage of male bass with vitellogenin. No correlations were noted with the percentage of male sucker with vitellogenin and water chemical concentrations. The prevalence and severity of testicular oocytes in bass also correlated with the percent of agricultural land use in the watershed above a site. Two sites within the Susquehanna drainage and one in the Delaware were immediately downstream of wastewater treatment plants to compare results with upstream fish. The percentage of male bass with testicular oocytes was not consistently higher downstream; however, severity did tend to increase downstream.

Current concepts in neuroendocrine disruption

In the last few years, it has become clear that a wide variety of environmental contaminants have specific effects on neuroendocrine systems in fish, amphibians, birds and mammals. While it is beyond the scope of this review to provide a comprehensive examination of all of these neuroendocrine disruptors, we will focus on select representative examples. Organochlorine pesticides bioaccumulate in neuroendocrine areas of the brain that directly regulate GnRH neurons, thereby altering the expression of genes downstream of GnRH signaling. Organochlorine pesticides can also agonize or antagonize hormone receptors, adversely affecting crosstalk between neurotransmitter systems. The impacts of polychlorinated biphenyls are varied and in many cases subtle. This is particularly true for neuroedocrine and behavioral effects of exposure. These effects impact sexual differentiation of the hypothalamic-pituitary-gonadal axis, and other neuroendocrine systems regulating the thyroid, metabolic, and stress axes and their physiological responses. Weakly estrogenic and anti-androgenic pollutants such as bisphenol A, phthalates, phytochemicals, and the fungicide vinclozolin can lead to severe and widespread neuroendocrine disruptions in discrete brain regions, including the hippocampus, amygdala, and hypothalamus, resulting in behavioral changes in a wide range of species. Behavioral features that have been shown to be affected by one or more these chemicals include cognitive deficits, heightened anxiety or anxiety-like, sociosexual, locomotor, and appetitive behaviors. Neuroactive pharmaceuticals are now widely detected in aquatic environments and water supplies through the release of wastewater treatment plant effluents. The antidepressant fluoxetine is one such pharmaceutical neuroendocrine disruptor. Fluoxetine is a selective serotonin reuptake inhibitor that can affect multiple neuroendocrine pathways and behavioral circuits, including disruptive effects on reproduction and feeding in fish. There is growing evidence for the association between environmental contaminant exposures and diseases with strong neuroendocrine components, for example decreased fecundity, neurodegeneration, and cardiac disease. It is critical to consider the timing of exposures of neuroendocrine disruptors because embryonic stages of central nervous system development are exquisitely sensitive to adverse effects. There is also evidence for epigenetic and transgenerational neuroendocrine disrupting effects of some pollutants. We must now consider the impacts of neuroendocrine disruptors on reproduction, development, growth and behaviors, and the population consequences for evolutionary change in an increasingly contaminated world. This review examines the evidence to date that various so-called neuroendocrine disruptors can induce such effects often at environmentally-relevant concentrations.

Variation in trace-element accumulation in predatory fishes from a stream contaminated by coal combustion waste

Extensive and critical evaluation can be required to assess contaminant bioaccumulation in large predatory fishes. Species differences in habitat use, resource use, and trophic level, often influenced by body form, can result in diverging contaminant bioaccumulation patterns. Moreover, the broad size ranges inherent with large-bodied fish provide opportunity for trophic and habitat shifts within species that can further influence contaminant exposure. We compared contaminant bioaccumulation in four fish species, as well as two herbivorous invertebrates, from a coal combustion waste contaminated stream. Muscle, liver, and gonad tissue were analyzed from fish stratified across the broadest size ranges available. Effects of trophic position (δ (15)N), carbon sources (δ (13)C), and body size varied among and within species. Mercury and cesium concentrations were lowest in the invertebrates and increased with trophic level both among and within fish species. Other elements, such as vanadium, cadmium, barium, nickel, and lead, had greater levels in herbivorous invertebrates than in fish muscle. Sequestration by the fish livers averted accumulation in muscle. Consequently, fish liver tissue appeared to be a more sensitive indicator of bioavailability, but exceptions existed. Despite liver sequestration, within fishes, muscle concentrations of many elements still tended to increase by trophic level. Notable variation within some species was observed. These results illustrate the utility of stable isotope data in exploring differences of bioaccumulation within taxa. Our analyses suggest a need for further evaluation of the underlying sources of this variability to better understand contaminant bioaccumulation in large predatory fishes.

Intersex in teleost fish: are we distinguishing endocrine disruption from natural phenomena?

Intersex is defined as the simultaneous presence of male and female gonadal tissue in a gonochoristic (fixed-sex) species. The intersex condition has been documented in both wild and laboratory animals, including fish, amphibians, and reptiles. In aquatic animals, intersex is often viewed as a signature effect of exposure to endocrine disrupting compounds. At least 37 fish species from 17 families have been identified with intersex gonads in 54 field survey studies. However, reports of the occurrence of intersex at reference sites have led to speculation that a baseline level of intersex is "normal". The objective of this critical review was to assess factors potentially associated with baseline levels of intersex in fish and to examine the mechanisms involved in the intersex condition in order to identify priority research areas. Based on current literature, the relationship between intersex and physiological parameters such as plasma sex steroids and vitellogenin is not well characterized or conclusive. Moreover, the literature is not definitive on whether field studies are distinguishing between natural intersex and intersex due to stressors. High throughput transcriptomics will improve understanding of how intersex condition manifests after exposure to aquatic pollution and it is recommended that studies consider both males with and without intersex that inhabit the same polluted site in order to differentiate pathways associated with xenobiotic responses versus molecular pathways associated with intersex. Other experimental design considerations for field studies examining intersex include data collection on life history (e.g. migratory patterns) and improved reference site characterization.

Polybrominated diphenyl ether metabolism in field collected fish from the Gila River, Arizona, USA--levels, possible sources, and patterns

Polybrominated diphenyl ethers (PBDEs) were determined in fish collected from the Gila River, Arizona, a tributary of the Colorado River in the lower part of the Colorado River Basin. Fish samples were collected at sites on the Gila River downstream from Hayden, Phoenix, and Arlington, Arizona in late summer 2003. The Gila River is ephemeral upstream of the Phoenix urban area due to dams and irrigation projects and has limited perennial flow downstream of Phoenix due to wastewater and irrigation return flows. Fifty PBDE congeners were analyzed by high resolution gas chromatography/high resolution mass spectrometry using labeled surrogate standards in composite samples of male and female common carp (Cyrpinus carpio), largemouth bass (Micropterus salmoides) and channel catfish (Ictalurus punctatus). The predominant PBDE congeners detected and quantified were 47, 100, 153, 49, 28, and 17. Concentrations of total PBDEs in these fish ranged from 1.4 to 12700 ng g(-1) wet weight, which are some of the highest concentrations reported in fish from the United States. Differences in metabolism of several PBDE congeners by carp is clear at the Phoenix site; congeners with at least one ring of 2,4,5-substitution are preferentially metabolized as are congeners with 2,3,4-substitution.

Evaluation of spatial and temporal changes in biomarker responses in the common carp (Cyprinus carpio L.) for biomonitoring the Meriç Delta, Turkey

The aim of this study is to examine the activity of several biomarkers in carp, Cyprinus carpio L., to determine their response to xenobiotics, such as organochlorine pesticides (OCPs), in the Meriç Delta. Fish were collected from contaminated sites and from areas regarded as relatively less contaminated in four sampling periods. Hepatic glutathione S-transferase (GST), carboxylesterase (CaE), lactate dehydrogenase, aspartate aminotransferase, and acid phosphatase activities were measured as biomarkers in the fish. For all fish, the condition factor and hepatosomatic index, were calculated to determine the condition of the fish. The results of this study indicated that the mean GST activity showed an increase in fish from the Meriç-Ergene junction site and a decrease in Enez site with respect to fish from Meriç site. Furthermore, the study shows that spatial and temporal changes of biomarkers such as GST and CaE might be useful for the assessment of environmental contamination in the Meriç Delta.

Comparison of zebrafish (Danio rerio) and fathead minnow (Pimephales promelas) as test species in the Fish Sexual Development Test (FSDT)

Results are presented from a validation (with 5 laboratories) of the Fish Sexual Development Test (FSDT) developed to detect endocrine disrupters (EDs) and included in the OECD (Organisation for Economic Co-operation and Development) working program. The aromatase-inhibiting fungicide prochloraz was tested in zebrafish (Danio rerio) and fathead minnow (Pimephales promelas). The fish were exposed during sexual differentiation and development from 0 to 60 days post hatch (dph). After exposure, the vitellogenin (VTG) concentrations were quantified in head/tail homogenate and the sex ratio was determined (defined as female, male, intersex or undifferentiated). NOEC/LOEC and EC(x) designs were compared to optimize the test approach. Results show that both species are highly sensitive to prochloraz during sexual development. They respond by skewing of the sex ratio towards male phenotype and by a VTG decline in females. The NOEC/LOEC approach is preferred because sex ratio is difficult to analyze with a regression model. The mean NOEC/LOEC for prochloraz on the sex ratio was 43.3/134 μg/L and 101/293 μg/L for zebrafish and fathead minnow, respectively. The mean NOEC/LOEC on the decline in female VTG concentration was 65/110 μg/L and ~30/68 μg/L respectively. In conclusion, zebrafish and fathead minnow are suitable species in the FSDT and their sexual differentiation is equally labile to EDs.

Water quality evaluation of two interconnected dam lakes with field-captured and laboratory-acclimated fish, Cyprinus carpio

Karakaya and Sultansuyu Dam Lakes, located in the eastern part of Turkey, are important water sources, both for irrigation and fishery. The main goal of the study was to investigate water qualities of dam lakes using a set of biomarkers in the fish Cyprinus carpio. For this aim, field sample and laboratory-acclimated fish were compared to identify changes in selected biomarkers. The activities of ethoxyresorufin-O-deethylase, glutathione S-transferase, glutathione reductase, and carboxylesterase were determined in liver samples. Also, plasma and liver lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase activities were assayed. Brain acetylcholinesterase and carboxylesterase activities were also determined. The hepatosomatic index and condition factors were calculated. Plasma vitellogenin assays were evaluated for the presence of xenoestrogen. Physicochemical values of water samples showed the existence of eutrophication risk, and also, some chemicals in both lakes were determined to be over tolerable limits. The comparisons of samples from both dam lake and laboratory-acclimated fish showed that the lakes may be at risk of pollution by some xenobiotics, namely xenoestrogens and acetylcholinesterase-inhibiting agents.

Intersex condition of shoal bass in the Flint River, Georgia

We examined male shoal bass Micropterus cataractae from the Flint River, Georgia, to determine the prevalence of intersex. During March and April 2010, we sampled 61 shoal bass from six sites along the Flint River. Testes were examined histologically and classified as intersex if the presence of oocytes was noted. Using a severity index, we compared samples collected on different dates and from different locations according to age and testis weight. No significant variations were noted among any of the groupings. Further investigation is needed to determine whether the intersex condition in shoal bass is severe enough to warrant concern and whether it is a natural phenomenon.

Assessment of seasonal and sex-related variability of biomarkers in carp (Cyprinus carpio L.) from Karakaya Dam Lake, Turkey

This study examines seasonal changes in the activities of selected biomarkers in carp (Cyprinus carpio L.) from Karakaya Dam Lake and evaluates the influence of gender and environmental factors on those activities. Physicochemical characteristics of water were evaluated in the lakewater. Fish were sampled on seasonal basis, and liver ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase, glutathione reductase, plasma lactate dehydrogenase, aspartate and alanine aminotransferase, and brain acetylcholinesterase (AChE) activities were assayed. Plasma vitellogenin level and hepatosomatic index and condition factors were also determined. Strong seasonal variations were observed but there were no gender differences among selected markers. The highest vitellogenin level of male fish was detected as 606ng/mL which represents the estrogenicity of water in the lake in September 2005. In addition, the seasonal changes of some biomarkers such as EROD and AChE showed that the lake may be at risk of pollution by some xenobiotics arising from agricultural and/or industrial activities.

Dietary intake of persistent organic pollutants and potential health risks via consumption of global aquatic products

The concentration levels of typical persistent organic pollutants such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) including dioxin-like PCBs (DL-PCBs) and non-dioxin-like PCBs, organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) in global aquatic products from major producing countries were summarized. Daily intakes of these compounds via consumption of various aquatic products for global consumers were also estimated based on available literature data. Risk assessment based upon existing criteria for OCPs and PBDEs shows that there is minimal risk to global consumers from consumption of aquatic products, with the exception of products from specific regions located around known heavy-point sources. Exposure to dioxins through consumption of aquatic products, excluding marine fish, is also in the range of the acceptable level, lower than 4 pg World Health Organization toxic equivalent (WHO-TEQ)/kg bw/d; however, dioxin intake via marine fish may cause hazards to human health, especially for Europeans. Regarding PCBs, there is cancer risk for global consumers via consumption of aquatic products, especially marine fish, based on cancer and noncancer hazard ratio assessment. Generally, European consumers have higher exposure levels of PCDD/Fs and DL-PCBs, while Americans and Asians have relatively higher exposure levels of OCPs and PCBs. In contrast, all global populations are found to have lower exposure levels of PBDEs, which may be attributed to its relatively shorter history of use compared with PCBs and OCPs. Finally, the estimated total amounts of PCBs, OCPs, and PBDEs stored in global aquatic products constitute only a small portion of the total amount that has been used, and the majority obviously occurs in other environmental media or even remains in commercial products.

Sources, interactions, and ecological impacts of organic contaminants in water, soil, and sediment: an introduction to the special series

Agricultural and urban activities result in the release of a large number of organic compounds that are suspected of impacting human health and ecosystems: herbicides, insecticides, human and veterinary pharmaceuticals, natural and synthetic hormones, personal care products, surfactants, plasticizers, fire retardants, and others. Sorbed reservoirs of these compounds in soil represent a potentially chronic source of water contamination. This article is an introduction to a series of technical papers stemming from a symposium at the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America 2008 Annual Meeting, which was held jointly with The Geological Society of America, The Gulf Coast Association of Geological Scientists, and the Houston Geological Society, under one of the Joint Meeting's overarching themes: Emerging Trace Contaminants in Surface and Ground Water Generated from Waste Water and Solid Waste Application. The symposium emphasized the role of soils as sources, sinks, and reaction catalysts for these contaminants and the occurrence and fate of these contaminants in surface and underground water supplies. Topics covered included novel advances in analytical techniques, transport of infectious agents, occurrence and fate of veterinary pharmaceuticals, characterization of sorption mechanism, biotic and abiotic transformation reactions, the role of soil components, occurrence and fate in wastewater treatment systems, transport of engineered nanoparticles, groundwater contamination resulting from urban runoff, and issues in water reuse. Overviews of the reports, trends, gaps in our knowledge, and topics for further research are presented in this special series of papers. The technical papers in this special series reflect current gains in knowledge and simultaneously underscore how poorly we are able to predict the fate and, hence, the associated risk to ecological and human receptors of these contaminants.

Occurrence of Ascocotyle (Phagicola) longa Ransom, 1920 (Digenea: Heterophyidae) in Mugil incilis from Cartagena Bay, Colombia

Fishborne metacercariae have not been reported in Colombia. During an 8-month period, 250 mullet/lisa (Mugil incilis) were examined for trematode metacercariae in the liver. Average prevalence and intensity were 93.4+/-2.5% and 8476+/-1238 cysts per gram of liver, respectively. Monthly prevalence of the trematode, identified as Ascocotyle (Phagicola) longa Ransom (1920), was always high (>79%) and there was no difference between sampling periods (P>0.05). Trematode intensity in lisa had a significant negative effect on host size (R=-0.325, P<0.001), condition factor (R=-0.352, P<0.001), and liver-somatic index (R=-0.372, P<0.001); in contrast, a positive relationship was found with gill-somatic index (R=0.446, P<0.001). Histopathological analysis indicated the presence of abundant cysts together with inflammatory reactions involving macrophage aggregates and necrosis. These results suggest that trematodes infecting the liver of M. incilis affect the growth and well-being of these fish, and their consumption could represent a major risk for human infection.

Changes in the relative expression pattern of multiple vitellogenin genes in adult male and larval zebrafish exposed to exogenous estrogens

Production of the lipoprotein vitellogenin (Vg) is induced in fish upon exposure to estrogens and is a biomarker of endocrine disruption in fish. In some fish, three types of Vg (VgA, VgB, and VgC) are recognized and transcribed from at least three distinct Vg genes (vtg). We investigated expression of vtg coding for Vg1A/B, Vg2A/B, and VgC in adult male and larval zebrafish exposed to various estrogenic substances. Quantitative PCR was conducted for transcripts of each vtg and a control gene (beta-actin). Male fish were exposed to 17beta-estradiol (E2) and 17alpha-ethinylestradiol, total RNA was extracted from excised liver, and histopathology of liver, trunk kidney, and gonads was conducted. Larval fish were exposed to 10 different estrogenic substances and total RNA was extracted from groups of whole larvae. In adult male fish, the relative fold change varied, but pattern of expression change (i.e., Vg1A/B > Vg2A/B > VgC) was consistent. Larger males exposed to E2 had significantly higher induction of each vtg. In larval zebrafish, the relative fold change in vtg expression varied according to specific estrogenic substance tested, but the pattern of change (i.e., Vg2A/B > Vg1A/B > VgC) was consistent for each substance that induced vtg.

Environmental contaminants in freshwater fish and their risk to piscivorous wildlife based on a national monitoring program

Organochlorine chemical residues and elemental concentrations were measured in piscivorous and benthivorous fish at 111 sites from large U.S. river basins. Potential contaminant sources such as urban and agricultural runoff, industrial discharges, mine drainage, and irrigation varied among the sampling sites. Our objectives were to provide summary statistics for chemical contaminants and to determine if contaminant concentrations in the fish were a risk to wildlife that forage at these sites. Concentrations of dieldrin, total DDT, total PCBs, toxaphene, TCDD-EQ, cadmium, chromium, mercury, lead, selenium, and zinc exceeded toxicity thresholds to protect fish and piscivorous wildlife in samples from at least one site; most exceedences were for total PCBs, mercury, and zinc. Chemical concentrations in fish from the Mississippi River Basin exceeded the greatest number of toxicity thresholds. Screening level wildlife risk analysis models were developed for bald eagle and mink using no adverse effect levels (NOAELs), which were derived from adult dietary exposure or tissue concentration studies and based primarily on reproductive endpoints. No effect hazard concentrations (NEHC) were calculated by comparing the NOAEL to the food ingestion rate (dietary-based NOAEL) or biomagnification factor (tissue-based NOAEL) of each receptor. Piscivorous wildlife may be at risk from a contaminant if the measured concentration in fish exceeds the NEHC. Concentrations of most organochlorine residues and elemental contaminants represented no to low risk to bald eagle and mink at most sites. The risk associated with pentachloroanisole, aldrin, Dacthal, methoxychlor, mirex, and toxaphene was unknown because NOAELs for these contaminants were not available for bald eagle or mink. Risk differed among modeled species and sites. Our screening level analysis indicates that the greatest risk to piscivorous wildlife was from total DDT, total PCBs, TCDD-EQ, mercury, and selenium. Bald eagles were at greater risk to total DDT and total PCBs than mink, whereas risks of TCDD-EQ, mercury, and selenium were greater to mink than bald eagle.

Persistence of organochlorine chemical residues in fish from the Tombigbee River (Alabama, USA): Continuing risk to wildlife from a former DDT manufacturing facility

Organochlorine pesticide and total polychlorinated biphenyl (PCB) concentrations were measured in largemouth bass from the Tombigbee River near a former DDT manufacturing facility at McIntosh, Alabama. Evaluation of mean p,p'- and o,p'-DDT isomer concentrations and o,p'- versus p,p'-isomer proportions in McIntosh bass indicated that DDT is moving off site from the facility and into the Tombigbee River. Concentrations of p,p'-DDT isomers in McIntosh bass remained unchanged from 1974 to 2004 and were four times greater than contemporary concentrations from a national program. Total DDT in McIntosh bass exceeded dietary effect concentrations developed for bald eagle and osprey. Hexachlorobenzene, PCBs, and toxaphene concentrations in bass from McIntosh also exceeded thresholds to protect fish and piscivorous wildlife. Whereas concentrations of DDT and most other organochlorine chemicals in fish have generally declined in the U.S. since their ban, concentrations of DDT in fish from McIntosh remain elevated and represent a threat to wildlife.

Optimization and validation of a California halibut environmental estrogen bioassay using a heterologous ELISA

Vitellogenin, the estrogen-inducible yolk protein precursor, serves as an indicator of exposure to estrogen mimicking environmental contaminants. An ELISA for the measurement of California halibut plasma vitellogenin was optimized and validated using a commercially-available antibody developed for another flatfish species, turbot. Attempts to enhance assay performance by addition of a biotinylated antibody, polyethylene glycol, and Tween-20, and altering the preincubation step are described. Inclusion of overnight preincubation was critical for low detection limits. Increasing the amount of Tween-20 to 0.05% in buffers was most effective in achieving accurate quantification of spiked plasma samples. At the IC50, the average recovery of spiked plasma samples was 104% and the interplate CV was 12%. The working range of the assay was 33-1000 ng/mL, while the detection limit in a plasma sample is 2.2 microg/mL. The performance of this assay compared very well to a homologous assay demonstrating that commercially-available antibodies can facilitate the development of bioassays for local environmentally-relevant species. The dose response relationship of halibut Vg to the model compounds 17beta-estradiol and pnonylphenol show that it is a suitable model for further studies of estrogen mimicking contaminants.

Relations between and among contaminant concentrations and biomarkers in black bass (Micropterus spp.) and common carp (Cyprinus carpio) from large U.S. rivers, 1995-2004

Environmental contaminant and biomarker monitoring data from major U.S. river basins were summarized for black bass (Micropterus spp.) and common carp (Cyprinus carpio) sampled over a nine year period. Cumulative frequency distributions revealed taxon differences for many organochlorine residue concentrations, elemental contaminant concentrations, and biomarkers, but few gender differences were evident for chemical concentrations. Concentrations of dacthal, pentachloroanisole, p,p'-DDE, endosulfan sulfate, barium, cadmium, copper, manganese, lead, selenium, vanadium, and zinc were greater in carp than bass, but concentrations of mercury and magnesium were greater in bass. Gender differences were evident in bass for mercury and in carp for zinc, but the differences were small compared to taxon differences. Greater vitellogenin concentrations, 17beta-estradiol concentrations, 17beta-estradiol/11-ketotestosterone ratios, and percent oocyte atresia in female carp compared to female bass may be related to the sequential spawning of carp. Regression analyses indicated that as much as 78% of biomarker variation was explained by chemical contaminant concentrations. Sites grouped consistently by river basin in the chemical contaminant principal components analysis (PCA) models and were driven by mercury, magnesium, barium, mirex, and oxychlordane. PCA models for the biomarkers did not group the sites by basin for either bass or carp. Statistical analyses and data interpretation were limited by the study design. The implications of these limitations are discussed. Recommendations to be considered during the planning of future monitoring studies include the exclusion of gender- and species-specific sampling for certain chemical contaminants considering analytical methods with appropriate sensitivities; and allowing for the addition of new chemical and biological variables as methods and information needs evolve.