Evidence of detrimental effects of environmental contaminants on growth and reproductive physiology of white sturgeon in impounded areas of the Columbia River

Identifying monitoring information needs that support the management of fish in large rivers

Management actions intended to benefit fish in large rivers can directly or indirectly affect multiple ecosystem components. Without consideration of the effects of management on non-target ecosystem components, unintended consequences may limit management efficacy. Monitoring can help clarify the effects of management actions, including on non-target ecosystem components, but only if data are collected to characterize key ecosystem processes that could affect the outcome. Scientists from across the U.S. convened to develop a conceptual model that would help identify monitoring information needed to better understand how natural and anthropogenic factors affect large river fishes. We applied the conceptual model to case studies in four large U.S. rivers. The application of the conceptual model indicates the model is flexible and relevant to large rivers in different geographic settings and with different management challenges. By visualizing how natural and anthropogenic drivers directly or indirectly affect cascading ecosystem tiers, our model identified critical information gaps and uncertainties that, if resolved, could inform how to best meet management objectives. Despite large differences in the physical and ecological contexts of the river systems, the case studies also demonstrated substantial commonalities in the data needed to better understand how stressors affect fish in these systems. For example, in most systems information on river discharge and water temperature were needed and available. Conversely, information regarding trophic relationships and the habitat requirements of larval fishes were generally lacking. This result suggests that there is a need to better understand a set of common factors across large-river systems. We provide a stepwise procedure to facilitate the application of our conceptual model to other river systems and management goals.

Organochlorine and Metal Contaminants in the Blood Plasma of Green Sturgeon Caught in Washington Coastal Estuaries

Non-invasive monitoring was used to evaluate the concentrations of 40 contaminants in the blood plasma of the North American Green Sturgeon Acipenser medirostris caught and released from three estuaries in Washington State. The highest contaminant concentrations were found in fish caught in the most urbanized sites. Few statistical differences were found when evaluating contaminant levels according to sex, maturation stage, or distinct population segments of Green Sturgeon. The results indicate that recent exposure to legacy contaminants was reflected in Green Sturgeon plasma. Aldrin, 4,4-DDE, α-HCH, copper, and selenium were the most frequently detected contaminants. This study also explored the challenges of assessing toxicity in threatened species using non-lethal approaches. There is currently a lack of environmental contaminant monitoring data in estuaries frequented by Green Sturgeon and limited plasma to tissue toxicity correlations.

Toxicokinetic Models for Bioconcentration of Organic Contaminants in Two Life Stages of White Sturgeon (Acipenser transmontanus)

The white sturgeon (Acipenser transmontanus) is an endangered ancient fish species that is known to be particularly sensitive to certain environmental contaminants, partly because of the uptake and subsequent toxicity of lipophilic pollutants prone to bioconcentration as a result of their high lipid content. To better understand the bioconcentration of organic contaminants in this species, toxicokinetic (TK) models were developed for the embryo-larval and subadult life stages. The embryo-larval model was designed as a one-compartment model and validated using whole-body measurements of benzo[a]pyrene (B[a]P) metabolites from a waterborne exposure to B[a]P. A physiologically based TK (PBTK) model was used for the subadult model. The predictive power of the subadult model was validated with an experimental data set of four chemicals. Results showed that the TK models could accurately predict the bioconcentration of organic contaminants for both life stages of white sturgeon within 1 order of magnitude of measured values. These models provide a tool to better understand the impact of environmental contaminants on the health and the survival of endangered white sturgeon populations.

Sublethal, sex-specific, osmotic, and metabolic impairments in embryonic and adult round stingrays from a location exposed to environmental contamination in southern California, USA

Organic contaminants are known to affect a suite of physiological processes across vertebrate clades. However, despite their ancient lineage and important roles in maintaining healthy ecosystems, elasmobranchs (sharks, skates, and rays) are understudied with regard to sublethal effects of contaminant exposure on metabolic processes. Perturbations resulting from contaminant exposure can divert energy away from maintaining physiological homeostasis, particularly during energetically challenging life stages, such as pregnancy and embryonic development. Using the round stingray (Urobatis halleri) as a model elasmobranch species, we captured adult males and pregnant females (matrotrophic histotrophy) and their embryos from two populations differing in their environmental exposure to organic contaminants (primarily polychlorinated biphenyls (PCBs)). Pregnant females from the PCB-exposed population experienced significant decreases from early- to late-pregnancy in tissue mass and quality not seen in reference females. PCB-exposed pregnant females also failed to maintain plasma urea concentrations as pregnancy progressed, which was accompanied by a loss in muscle protein content. Despite the energetic demands of late-term pregnancy, females had significantly greater liver lipid content than reproductively inactive adult males. PCB-exposed adult males also had high metabolic capacity (i.e., enzyme activity) for most substrate groupings of all sex-site groups, suggesting that males may be even more negatively impacted by contaminant exposure than pregnant females. Evidence that in utero exposure to PCBs via maternal offloading impairs embryo outcomes is accumulating. Embryos from the PCB-contaminated site had lower tissue quality measures and indications that sex-based differences were manifesting in utero as males had higher metabolic capacities than females. This study indicates that accumulated PCB contaminants are not physiologically inert in the stingray.

First observations of intersex development in paddlefish Polyodon spathula

This study reports the first cases of intersex (abnormal development of both male and female reproductive tissues in a gonad) paddlefish Polyodon spathula, an Acipenseriform species of large rivers in the central U.S. and in aquaculture worldwide. Despite a large, multi-decadal data set in Oklahoma, Montana, and North Dakota, intersex development was not observed until 2019, when two individuals were harvested from the Grand Lake/Neosho River stock in Oklahoma. This suggests that intersex development in mid-water, zooplanktivorous paddlefish is rarer than in bottom-dwelling sturgeons for which intersex development is regularly observed. Although contaminants are implicated in causing intersex development in other Acipenseriformes, more investigation is needed.

Development of a thin-film solid-phase microextraction (TF-SPME) method coupled to liquid chromatography and tandem mass spectrometry for high-throughput determination of steroid hormones in white sucker fish plasma

Steroid hormones (SH) play a number of important physiological roles in vertebrates including fish. Changes in SH concentration significantly affect reproduction, differentiation, development, or metabolism. The objective of this study was to develop an in vitro high-throughput thin-film solid-phase microextraction (TF-SPME)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for targeted analysis of endogenous SH (cortisol, testosterone, progesterone, estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2)) in wild white sucker fish plasma where the concentrations of the analytes are substantially low. A simple TF-SPME method enabled the simultaneous determination of free and total SH concentrations. The use of biocompatible coating allowed direct extraction of these hormones from complex biological samples without prior preparation. The carryover was less than 3%, thereby ensuring reusability of the devices and reproducibility. The results showed that TF-SPME was suitable for the analysis of compounds in the polarity range between 1.28 and 4.31 such as SH at different physicochemical properties. The proposed method was validated according to bioanalytical method validation guidelines. The limit of detection (LOD) and limit of quantification(LOQ) for cortisol, testosterone, progesterone, E1, E2, and EE2 were from 0.006 to 0.150 ng/mL and from 0.020 to 0.500 ng/mL, respectively. The recovery for the method was about 85%, and the accuracy and precision of the method for cortisol, testosterone, and progesterone were ≤ 6.0% and ≤ 11.2%, respectively, whereas those for E1, E2, and EE2 were ≤ 15.0% and ≤ 10.2%, respectively. On the basis of this study, TF-SPME demonstrated several important advantages such as simplicity, sensitivity, and robustness under laboratory conditions. Graphical abstract.

Organochlorine pesticides: Agrochemicals with potent endocrine-disrupting properties in fish

Organochlorine pesticides (OCPs) are persistent environmental contaminants that act as endocrine disruptors and organ system toxicants. These pesticides (e.g. dichlorodiphenyltrichloroethane (DDT), dieldrin, toxaphene, among others) are ranked as some of the most concerning chemicals for human health. These pesticides (1) act as teratogens, (2) are neuroendocrine disruptors, (3) suppress the immune and reproductive systems, and (4) dysregulate lipids and metabolism. Using a computational approach, we revealed enriched endocrine-related pathways in the Comparative Toxicogenomics Database sensitive to this chemical class, and these included reproduction (gonadotropins, estradiol, androgen, steroid biosynthesis, oxytocin), thyroid hormone, and insulin. Insight from the Tox21 and ToxCast programs confirm that these agrochemicals activate estrogen receptors, androgen receptors, and retinoic acid receptors with relatively high affinity, although differences exist in their potency. We propose an adverse outcome pathway for OCPs toxicity in the fish testis as a novel contribution to further understanding of OCP-induced toxicity. Organochlorine pesticides, due to their persistence and high toxicity to aquatic and terrestrial wildlife as well as humans, remain significant agrochemicals of concern.

Health indicators and contaminant levels of a critically endangered species in the Gironde estuary, the European sturgeon

The European sturgeon, Acipenser sturio, is a highly endangered species that almost disappeared in the last decades. Thanks to yearly restocking of the population, this species is still found in the Gironde estuary (France), where juveniles grow during several years before leaving to the ocean. The aims of this study were to evaluate the pressure exerted on these fish by known organic and inorganic contaminants during their stay at the Gironde estuary, and to get information on the fish's health in this context. Monthly captures over the year 2014 provided 87 fish from the cohorts 2012 and 2013 mainly, and from cohorts 2008, 2009, and 2011, all fish born in hatchery. We report the very first analyses of contaminant levels and of biological markers measured in the blood of these fish. Low inorganic contamination was found, composed of seven metals mainly Zn (< 5 μg mL^-1), Fe (< 1.5 μg mL^-1), Cu (< 0.8 μg mL^-1), Se (< 0.8 μg mL^-1), As (< 0.25 μg mL^-1), Co (< 0.14 μg mL^-1), and Mn (< 0.03 μg mL^-1). Concerning persistent organic contaminants, the sum of seven PCBs varied from 1 to 10 ng g^-1 plasma, that of eight OCPs from 0.1 to 1 ng g^-1, and that of eight PBDEs from 10 to 100 pg g^-1. Higher levels of contaminants were measured during spring as compared to summer. The sex steroid hormone plasma levels (estradiol, testosterone, and 11-ketotestosterone) were quite low, which was predictable for juveniles. The transcription of reproduction-involved genes (EstR, AR, LHR, sox9) in blood cells was demonstrated for the first time. Some of them were correlated with organic contaminant levels PCBs and OCPs. Other gene transcriptions (sodCu and bax) were correlated with PCBs and OCPs. However, the DNA damage level measured here as comet tail DNA and micronuclei ratio in red blood cells were in the very low range of the values commonly obtained in fish from pristine areas. The data presented here can serve as a reference base for future monitoring of this population of sturgeons.

Critical review: Grand challenges in assessing the adverse effects of contaminants of emerging concern on aquatic food webs

Much progress has been made in the past few decades in understanding the sources, transport, fate, and biological effects of contaminants of emerging concern (CECs) in aquatic ecosystems. Despite these advancements, significant obstacles still prevent comprehensive assessments of the environmental risks associated with the presence of CECs. Many of these obstacles center around the extrapolation of effects of single chemicals observed in the laboratory or effects found in individual organisms or species in the field to impacts of multiple stressors on aquatic food webs. In the present review, we identify 5 challenges that must be addressed to promote studies of CECs from singular exposure events to multispecies aquatic food web interactions. There needs to be: 1) more detailed information on the complexity of mixtures of CECs in the aquatic environment, 2) a greater understanding of the sublethal effects of CECs on a wide range of aquatic organisms, 3) an ascertaining of the biological consequences of variable duration CEC exposures within and across generations in aquatic species, 4) a linkage of multiple stressors with CEC exposure in aquatic systems, and 5) a documenting of the trophic consequences of CEC exposure across aquatic food webs. We examine the current literature to show how these challenges can be addressed to fill knowledge gaps. Environ Toxicol Chem 2019;38:46-60. © 2018 SETAC.

Tissue Contaminant Burdens in San Francisco Estuary White Sturgeon (Acipenser transmontanus): Implications for Population Recovery

The San Francisco Estuary (SFE) is heavily influenced by anthropogenic activities, including historic and chronic contaminant inputs. These contaminants can adversely affect SFE fish populations, particularly white sturgeon, because they are a benthic dwelling, long-lived species. We measured a suite of metals and organic contaminants in liver and gonad tissues of 25 male and 32 female white sturgeon as well as several physiological indicators of sturgeon health. Most sturgeon (68% of males and 83% of females) were estimated to be between 13 and 17 years of age. Sturgeon tissues had elevated concentrations of several metals, including As, Ba, Cd, Cu, Cr, Pb, Hg, Ni, Se, and Zn. The most frequently detected organic contaminants in sturgeon livers and gonads were DDE, PCBs, PBDEs, and galaxolide. Selenium was detected at levels similar to those shown to cause impaired liver physiology and reproductive success in white sturgeon. Observed Hg levels were higher than those shown to result in lower condition factor and gonadosomatic indices in white sturgeon. Liver galaxolide levels correlated with decreased plasma estradiol levels in female sturgeon. The Cd, As, and Cu warrant further investigation, because they were detected at levels known to impair fish health. Our results suggest contaminants are negatively affecting SFE white sturgeon health and fitness. Future SFE white sturgeon contaminant research is suggested.

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.

Pesticide- and sex steroid analogue-induced endocrine disruption differentially targets hypothalamo-hypophyseal-gonadal system during gametogenesis in teleosts - A review

Pesticide-induced endocrine disruption often mimics sex steroidal action resulting in physiological functional disarray of hypothalamo-hypophyseal-gonadal (HHG) system at multiple levels. Among various group of pesticides, organochlorine and organophosphate family of pesticides are known to impart sex steroidal mimicking activity with slightly higher resemblance to estrogens when compared to androgenic action. This review will highlight the effects of organochlorine (for e.g. endosulfan) and organophosphate (for e.g. malathion) pesticides in comparison with sex-steroid analogue-induced changes on HHG axis during gametogenesis in few teleost fish models. Interestingly, the effects of these compounds have produced differential effects in juveniles and adults which also vary based on exposure dosage and duration. Further, the treatments had caused at times sexually dimorphic effects indicating that the action of these compounds bring out serious implications in sexual development. A comprehensive overview has been provided by considering all these aspects to recognize the adverse impacts of pesticide-induced endocrine disruption with special reference to endosulfan and malathion as those had been applied even today or used before for controlling agricultural pests in several Asian countries including India. This review also compares the effects of sex-steroid analogues where in sex reversal to reproductive dysfunction is evident, which may imply the extent of sexual plasticity in teleosts compared to other vertebrates.

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.

The role of biomarkers in the assessment of aquatic ecosystem health

Ensuring the health of aquatic ecosystems and identifying species at risk from the detrimental effects of environmental contaminants can be facilitated by integrating analytical chemical analysis with carefully selected biological endpoints measured in tissues of species of concern. These biological endpoints include molecular, biochemical, and physiological markers (i.e., biomarkers) that when integrated, can clarify issues of contaminant bioavailability, bioaccumulation, and ecological effects while enabling a better understanding of the effects of nonchemical stressors. In the case of contaminant stressors, an understanding of chemical modes of toxicity can be incorporated with diagnostic markers of aquatic animal physiology to help understand the health status of aquatic organisms in the field. Furthermore, new approaches in functional genomics and bioinformatics can help discriminate individual chemicals, or groups of chemicals among complex mixtures that may contribute to adverse biological effects. Although the use of biomarkers is not a new paradigm, such approaches have been underused in the context of ecological risk assessment and natural resource damage assessment. From a regulatory standpoint, these approaches can help better assess the complex effects from coastal development activities to assessing ecosystem integrity pre- and post development or site remediation.

Health status of Largescale Sucker (Catostomus macrocheilus) collected along an organic contaminant gradient in the lower Columbia River, Oregon and Washington, USA

The health of Largescale Sucker (Catostomus macrocheilus) in the lower Columbia River (USA) was evaluated using morphometric and histopathological approaches, and its association with organic contaminants accumulated in liver was evaluated in males. Fish were sampled from three sites along a contaminant gradient. In 2009, body length and mass, condition factor, gonadosomatic index, and hematocrit were measured in males and females; liver and gonad tissue were collected from males for histological analyses; and organ composites were analyzed for contaminant content in males. In 2010, additional data were collected for males and females, including external fish condition assessment, histopathologies of spleen, kidney and gill and, for males, liver contaminant content. Multivariate analysis of variance indicated that biological traits in males, but not females, differed among sites in 2009 and 2010. Discriminant function analysis indicated that site-related differences among male populations were relatively small in 2009, but in 2010, when more variables were analyzed, males differed among sites in regards to kidney, spleen, and liver histopathologies and gill parasites. Kidney tubular hyperplasia, liver and spleen macrophage aggregations, and gill parasites were generally more severe in the downstream sites compared to the reference location. The contaminant content of male livers was also generally higher downstream, and the legacy pesticide hexachlorobenzene and flame retardants BDE-47 and BDE-154 were the primary drivers for site discrimination. However, bivariate correlations between biological variables and liver contaminants retained in the discriminant models failed to reveal associations between the two variable sets. In conclusion, whereas certain non-reproductive biological traits and liver contaminant contents of male Largescale Sucker differed according to an upstream-downstream gradient in the lower Columbia River, results from this study did not reveal the specific environmental factors responsible for the differences in health status among fish populations.

Correlation of gene expression and contaminant concentrations in wild largescale suckers: a field-based study

Toxic compounds such as organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ether flame retardants (PBDEs) have been detected in fish, birds, and aquatic mammals that live in the Columbia River or use food resources from within the river. We developed a custom microarray for largescale suckers (Catostomus macrocheilus) and used it to investigate the molecular effects of contaminant exposure on wild fish in the Columbia River. Using Significance Analysis of Microarrays (SAM) we identified 72 probes representing 69 unique genes with expression patterns that correlated with hepatic tissue levels of OCs, PCBs, or PBDEs. These genes were involved in many biological processes previously shown to respond to contaminant exposure, including drug and lipid metabolism, apoptosis, cellular transport, oxidative stress, and cellular chaperone function. The relation between gene expression and contaminant concentration suggests that these genes may respond to environmental contaminant exposure and are promising candidates for further field and laboratory studies to develop biomarkers for monitoring exposure of wild fish to contaminant mixtures found in the Columbia River Basin. The array developed in this study could also be a useful tool for studies involving endangered sucker species and other sucker species used in contaminant research.

Evaluation of Organochlorine Pesticides and Sex Steroids in Lower Niagara River Lake Sturgeon

As a long-lived, late-maturing species, lake sturgeon Acipenser fulvescens are vulnerable to the bioaccumulation of contaminants, which may impact reproductive physiology. The purpose of this study was to use a nondestructive method to investigate the relationship between endocrine-disrupting contaminants and sex steroids in lake sturgeon from the lower Niagara River. We screened blood plasma samples from lower Niagara River lake sturgeon (n  =  63) during April and May of 2012 for concentrations of 17 organochlorine (OC) contaminants that may affect endocrine function, as well as for abnormal levels of sex steroids testosterone (T) and 17β-estradiol (E2). We found detectable levels of two OC contaminants in the blood plasma of lake sturgeon, DDE (n  =  21) and γ-BHC (n  =  1). In both cases, plasma contaminant concentration was well below levels known to adversely affect sturgeon reproductive physiology. In addition, qualitative analysis of chromatographs from plasma extracts did not show the presence of other peaks that matched polychlorinated biphenyl standard peaks. Comparisons of plasma steroid levels with those of others from the literature gave no indication of endocrine disruption, though plasma T levels were notably high in the lower Niagara River population. We conclude that plasma OC levels are below threshold levels found in the scientific literature that would affect lake sturgeon reproductive physiology, and that it is unlikely that significant contaminant-mediated endocrine disruption is occurring in this population.

Effects of Columbia River water on early life-stages of white sturgeon (Acipenser transmontanus)

The white sturgeon (Acipenser transmontanus) population that resides in the Columbia River in British Columbia (BC), Canada, has suffered recruitment failures for more than three decades. During the summers of 2008 and 2009, studies were performed to determine whether exposure to water downstream of a metal smelter in Trail, BC affected survival or growth of early life-stages of white sturgeon through 60+ days post-fertilization (dpf). In both years, there were no significant differences in survival of fish that were exposed to water from downstream compared to water from upstream of the smelter. At 20-21dpf, average mortality was 2.4 percent and 12 percent in upstream water for 2008 and 2009, respectively, which was similar to the average mortality of 3.8 percent and 7.2 percent in downstream water for 2008 and 2009, respectively. Relatively great mortality after 20-21dpf complicated analysis of the subchronic exposure, but use of a survival analysis indicated that the average fish died at 25-29dpf, regardless of whether the water to which they were exposed came from upstream or downstream of the smelter. In addition, measured concentrations of metals in river water were less than the threshold for adverse effects on early life stages of white sturgeon. Based upon these analyses, it is not likely that current concentrations of metals in the Columbia River in southern BC are adversely affecting survival of early life stages of white sturgeon larvae.

Organochlorine contaminants in blubber from stranded marine mammals collected from the Northern Oregon and Southern Washington coasts: implications for re-introducing California Condors, Gymnogyps californianus, in Oregon

Re-introduction of California Condors into Oregon is currently being considered, but there are concerns about the safety of potential food sources of this species. Condors are opportunistic feeders and a largely available food source for this species will be stranded marine mammal carcasses. We analyzed 37 blubber samples from 7 different marine mammal species collected from the Oregon and Southern Washington coasts for 18 organochlorine (OC) pesticides and 16 polychlorinated biphenyls (PCBs). Dichlorodiphenyldichloroethylene (DDE) was the most prevalent OC contaminant, making up more than 58 % of the total OC concentration measured. There were no significant differences in OC content between species or sexes.

Sensitivity of early life stages of white sturgeon, rainbow trout, and fathead minnow to copper

Populations of white sturgeon (WS; Acipenser transmontanus) are in decline in several parts of the United States and Canada, attributed primarily to poor recruitment caused by degradation of habitats, including pollution with contaminants such as metals. Little is known about sensitivity of WS to contaminants or metals such as copper (Cu). Here, acute (96 h) mortalities of WS early life stages due to exposure to Cu under laboratory conditions are reported. Two standard test species, rainbow trout (Oncorhynchus mykiss) and fathead minnow (Pimephales promelas), were exposed in parallel to determine relative sensitivity among species. Swim-up larvae [15 days post-hatch (dph)] and early juveniles (40-45 dph) of WS were more sensitive to Cu (LC(50) = 10 and 9-17 μg/L, respectively) than were yolksac larvae (8 dph; LC(50) = 22 μg/L) and the later juvenile life stage (100 dph; LC(50) = 54 μg/L). WS were more sensitive to Cu than rainbow trout and fathead minnow at all comparable life stages tested. Yolksac larvae of rainbow trout and fathead minnow were 1.8 and 4.6 times, respectively, more tolerant than WS, while swim-up and juvenile life stages of rainbow trout were between 1.4- and 2.4-times more tolerant than WS. When plotted in a species sensitivity distribution with other fishes, the mean acute toxicity value for early life stage WS was ranked between the 1st and 2nd centile. The WS life stage of greatest Cu sensitivity coincides with the beginning of active feeding and close association with sediment, possibly increasing risk. WS early life stages are sensitive to aqueous copper exposure and site-specific water quality guidelines and criteria should be evaluated closely to ensure adequate protection.

Responses of laboratory exposed catfish (Clarias gariepinus) to environmentally relevant concentrations of p,p'-DDT

Technical grade DDT is annually sprayed for malaria control in many under developed countries world wide. Despite the controversy surrounding the use of DDT, minimal research concerning the effects on indigenous fish species in these areas has been conducted. In this study, the objectives were to identify some of the effects of sprayed p,p'-DDT on the common African sharptooth catfish species (Clarias gariepinus) under laboratory conditions. The effects were assessed by exposing specimens to three environmentally relevant concentrations of p,p'-DDT (0.66, 1.36 and 2.72 μg/l) for 21 days and analysing a suite of biomarkers in the plasma, gonads and body morphometrics. The biomarkers were specifically selected based on their practicality in developing countries, which could potentially be utilised for continued monitoring, and included alkali-labile phosphate (ALP), calcium, magnesium and zinc as the indirect measures of vitellogenin, gonadosomatic index, gonad mass manipulated using analysis of covariance, and condition factor. The results showed no significant (p<0.05) dose-dependent changes in the plasma, gonads and body condition of C. gariepinus, indicating that these species were not responsive to the p,p'-DDT concentrations when exposed sub-chronically. This lack of a response suggested that mature C. gariepinus are tolerant to 21 days exposure of low levels of p,p'-DDT.

Toxic effects of PCB126 and TCDD on shortnose sturgeon and Atlantic sturgeon

Exposure to chemical contaminants is often invoked to explain recruitment failures to populations of sturgeon worldwide, but there is little empirical evidence to support the idea that young sturgeon are sensitive at environmentally relevant concentrations. The authors used shortnose sturgeon (Acipenser brevirostum) and Atlantic sturgeon (Acipenser oxyrinchus) as models to investigate the sensitivities of sturgeon to early-life-stage toxicities from embryonic exposures to graded doses of polychlorinated biphenyl 126 (PCB126) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Survival to hatching of shortnose sturgeon decreased with increasing dose, although the duration of the embryonic period was not significantly altered by exposure in either species. Morphometric features of larvae of both species were affected by dose, including shortening of the body, reduction in head size, reduction in quantity of yolk reserves, and reduction in eye size. Eye development in both species was delayed with increasing dose for both chemicals. The persistence of larvae in a food-free environment decreased inversely with dose in both species, with sharp declines occurring at PCB126 and TCDD doses of ≥1 ppb and ≥0.1 ppb, respectively. Dose-responsive early-life-stage toxicities reported here are among the more sensitive found in fish and occurred at burdens similar to those found in situ in a sympatric bottom-dwelling bony fish in the Hudson River Estuary. The present study is among the first demonstrating the sensitivity of any sturgeon to the hallmark early-life-stage toxicities induced by aryl hydrocarbon receptor agonists.

Functional characterization of bitter-taste receptors expressed in mammalian testis

Mammalian spermatogenesis and sperm maturation are susceptible to the effects of internal and external factors. However, how male germ cells interact with and respond to these elements including those potentially toxic substances is poorly understood. Here, we show that many bitter-taste receptors (T2rs), which are believed to function as gatekeepers in the oral cavity to detect and innately prevent the ingestion of poisonous bitter-tasting compounds, are expressed in mouse seminiferous tubules. Our in situ hybridization results indicate that Tas2r transcripts are expressed postmeiotically. Functional analysis showed that mouse spermatids and spermatozoa responded to both naturally occurring and synthetic bitter-tasting compounds by increasing intracellular free calcium concentrations, and individual male germ cells exhibited different ligand-activation profiles, indicating that each cell may express a unique subset of T2r receptors. These calcium responses could be suppressed by a specific bitter-tastant blocker or abolished by the knockout of the gene for the G protein subunit α-gustducin. Taken together, our data strongly suggest that male germ cells, like taste bud cells in the oral cavity and solitary chemosensory cells in the airway, utilize T2r receptors to sense chemicals in the milieu that may affect sperm behavior and fertilization.

Effects of subchronic exposure of early life stages of white sturgeon (Acipenser transmontanus) to copper, cadmium, and zinc

Populations of sturgeon (Acipenseridae) are declining in many places in the world because of several potential factors, including overharvesting, habitat alteration, and pollution. In North America, populations of the white sturgeon (Acipenser transmontanus) have been experiencing poor annual recruitment in major river systems for more than three decades. Metal pollution has been hypothesized as a potential contributing factor to the poor recruitment in some of the water bodies. In general, little is known about the toxicity of metals such as Cu, Cd, and Zn to white sturgeon and their potential influence on survival of embryos and juveniles. The present study was conducted to establish baseline toxicity data for the subchronic exposure of early life stages of white sturgeon to Cu, Cd, and Zn that can be used in metal-related risk assessments. Embryos, larvae, and fry were exposed to increasing concentrations of dissolved Cu, Cd, or Zn for 66 d using laboratory-based flow-through exposure systems. Hatching success was greater than 79% for all controls, and no significant differences were observed among treatment groups or between treatments and controls. Chronic lethal concentrations at which 20% mortality occurred (LC20s) for Cd (1.5 µg/L), Cu (5.5 µg/L), and Zn (112 µg/L) obtained for white sturgeon in the present study were comparable to those of sensitive salmonid species. Based on LC20 values for 19 or 58 d posthatch white sturgeon, the United States national ambient water quality criteria and the Canadian water quality guidelines for the protection of aquatic life that have been established for Cd, Cu, and Zn protect white sturgeon early life stages.

Environmental chemical mediated male reproductive toxicity: Drosophila melanogaster as an alternate animal model

Industrialization and indiscriminate use of agrochemicals have increased the human health risk. Recent epidemiological studies raised a concern for male reproduction given their observations of reduced sperm counts and altered semen quality. Interestingly, environmental factors that include various metals, pesticides and their metabolites have been causally linked to such adversities by their presence in the semen at levels that correlate to infertility. The epidemiological observations were further supported by studies in animal models involving various chemicals. Therefore, in this review, we focused on male reproductive toxicity and the adverse effects of different environmental chemicals on male reproduction. However, it is beyond the scope of this review to provide a detailed appraisal of all of the environmental chemicals that have been associated with reproductive toxicity in animals. Here, we provided the evidence for reproductive adversities of some commonly encountered chemicals (pesticides/metals) in the environment. In view of the recent thrust for an alternate to animal models in research, we subsequently discussed the contributions of Drosophila melanogaster as an alternate animal model for quick screening of toxicants for their reproductive toxicity potential. Finally, we emphasized the genetic and molecular tools offered by Drosophila for understanding the mechanisms underlying the male reproductive toxicity.

Importance of environmental endocrinology in fisheries management and aquaculture of sturgeons

Less is known about the reproductive endocrinology of sturgeons compared to modern teleosts. However, tools to assess the reproductive endocrinology and effects of environmental factors on reproduction do exist. This review utilizes case studies to describe the parameters involved in environmental endocrinology and the management and recovery efforts for the phylogenetically ancient sturgeon and paddlefish (Clade Chondrostei). Specifically, we discuss the use of environmental endocrinology to determine sex and stage of maturity and identify oviposition on spawning grounds, the importance of understanding endocrine disruption pathways, the challenges and benefits of assessing stress in wild populations of sturgeon, and three major physiological events in the reproductive development of farmed sturgeon understanding of which appears to be crucial for improving sturgeon aquaculture.

Polybrominated diphenyl ethers in outmigrant juvenile Chinook salmon from the lower Columbia River and Estuary and Puget Sound, Washington

Previous studies have examined the presence, distribution, and concentrations of toxic contaminants in two major waterways in the Pacific Northwest: the lower Columbia River and Estuary (LCR&E) and Puget Sound, Washington. However, those studies have not reported on the levels of polybrominated diphenyl ethers (PBDEs) in juvenile Chinook salmon (Onchorynchus tshawytscha). Populations of Chinook salmon from the LCR&E and Puget Sound are declining, and some stocks are currently listed as "threatened" under the Endangered Species Act. Bioaccumulation of contaminants, including PBDEs, by juvenile Chinook salmon in the LCR&E and Puget Sound is of concern due to the potential toxicity of the contaminants and associated sublethal effects in fish. In this article, we present the concentrations of PBDEs measured in gutted bodies and stomach contents of outmigrant juvenile Chinook salmon collected at six sites in the LCR&E and four sites in Puget Sound. For comparison, we also analyzed gutted bodies of juvenile Chinook salmon from eight hatcheries in the LCR&E as well as samples of the hatchery fish feeds. The mean summation SigmaPBDE concentrations measured in bodies of juvenile Chinook salmon from the different sites ranged from 350 to 2800 ng/g lipid weight, whereas those in stomach contents ranged from less than the quantitation limit (<2 ng/g wet weight) to 39 ng/g wet weight. The levels of PBDEs in the hatchery fish were significantly lower than those measured in the salmon samples collected from the LCR&E and Puget Sound. These results show that outmigrant juvenile Chinook salmon in the LCR&E and Puget Sound have been exposed to PBDEs in the environment and that these chemicals are bioaccumulating in their tissues; thus, the potential effects of PBDEs on these salmon should be further investigated.

Public Health Implications of Household Pharmaceutical Waste in the United States

Household pharmaceuticals are ubiquitous and untold quantities are wasted annually. Most often, people dispose of household pharmaceuticals by flushing them down the toilet, pouring them down the drain, or throwing them away in the trash. Pharmaceuticals disposed in this manner compromise the safety of our environment. This article provides a comprehensive review on the public health issue of household pharmaceutical waste, describing its epidemiology, explaining its effects on aquatic and human life, estimating its cost burden, and discussing strategies for reducing environmental exposure to it. In doing so, this article proposes two key objectives for our nation: (1) reduce the amount of household pharmaceuticals wasted and (2) devise environmentally friendly and cost-effective ways for handling this waste once it has been generated.

Reduction of vitellogenin synthesis by an aryl hydrocarbon receptor agonist in the white sturgeon (Acipenser transmontamus)

Migrating white sturgeon (Acipenser transmontamus) may be subject to agricultural, municipal, and industrial wastewater effluents that likely contain different classes of endocrine-disrupting contaminants. Concern is mounting about the negative effects of environmental estrogens on fish reproduction; however, in environmental mixtures, the affects from estrogenic compounds may be suppressed by aryl hydrocarbon receptor (AhR) ligands. Indeed, reductions in 17beta-estradiol-induced (0.01 and 1 mg/kg) vitellogenin (VTG) levels were observed in white sturgeon coinjected with beta-naphthoflavone (BNF; 50 mg/kg), a model for contaminants that activate the AhR. Variation in the time of injection was used to attempt to correlate VTG inhibition to ethoxyresorufin-O-deethylase activity. No evidence was found to suggest that the inhibition of VTG is a direct result of enhanced estrogen metabolism by BNF-induced enzymes. Results of the present study are relevant for monitoring programs that measure VTG, because these results show that AhR-active environmental contaminants can repress VTG synthesis, which commonly is used as an indicator of estrogen-mimicking contaminants. Furthermore, suppression of natural estrogen signaling by AhR agonists may have significant effects on fish reproduction.

p,p'-DDE induces apoptosis of rat Sertoli cells via a FasL-dependent pathway

One,1-dichloro-2,2 bis(p-chlorophenyl) ethylene (p,p′-DDE), the major metabolite of 2,2-bis(4-Chlorophenyl)-1,1,1-trichloroethane (DDT), is a known persistent organic pollutant and male reproductive toxicant. It has antiandrogenic effect. However, the mechanism by which p,p′-DDE exposure causes male reproductive toxicity remains unknown. In the present study, rat Sertoli cells were used to investigate the molecular mechanism involved in p,p′-DDE-induced toxicity in male reproductive system. The results indicated that p,p′-DDE exposure at over 30 μM showed the induction of apoptotic cell death. p,p′-DDE could induce increases in FasL mRNA and protein, which could be blocked by an antioxidant agent, N-acetyl-l-cysteine (NAC). In addition, caspase-3 and -8 were activated by p,p′-DDE treatment in these cells. The activation of NF-κB was enhanced with the increase of p,p′-DDE dose. Taken together, these results suggested that exposure to p,p′-DDE might induce apoptosis of rat Sertoli cells through a FasL-dependent pathway.

Relationships between anthropogenic chemical contaminant exposure and associated changes in reproductive parameters in male English sole (Parophrys vetulus) collected from Hylebos Waterway, Puget Sound, Washington

Effects of chemical contaminant exposure on gonadal development in adult male English sole (Parophrys vetulus) from Hylebos Waterway and Colvos Passage, Puget Sound, Washington were investigated. Hylebos Waterway sediment is contaminated with polycyclic aromatic hydrocarbons (PAHs) and organochlorines (OCs), and Colvos Passage, a nearby nonurban area, is minimally contaminated. Fish from Hylebos Waterway had higher concentrations of both PAHs and OCs in tissues than fish from Colvos Passage. Overall, little correlation was observed between PAH exposure and biological parameters, but strong correlations were observed between OCs and the biological parameters. Migration of fish from less contaminated areas into the Hylebos Waterway during the reproductive season might have influenced these results, based on temporal changes in fish age and contaminant concentrations.

Changes in population, growth, and physiological indices of Longnose dace (Rhinichthys cataractae) in the Red Deer River, Alberta, Canada

The Red Deer River, Alberta, Canada is a prairie river that is impacted by the point-source input of Red Deer's municipal wastewater effluent and non-point- source agricultural runoff. We used population, growth, and physiological performance end points in longnose dace (Rhinichthys cataractae), an endemic and abundant minnow, to evaluate changes in fish health over a 220 km section of the Red Deer River. Longnose dace immediately downstream of Red Deer had elevated catch per unit effort with larger body and liver sizes compared to upstream of Red Deer sites, likely due to elevated riverine productivity from Red Deer's wastewater effluent. Longnose dace immediately downstream of Red Deer showed depressed testosterone production capacity and elevated ethoxyresorufin-O-deethylase (EROD) activity, which is consistent with exposure to endocrine-disrupting compounds and aromatic hydrocarbons, respectively. Longnose dace 150-180 km downstream of Red Deer had reduced liver and gonad sizes, elevated EROD, and increased 11-ketotestosterone production capacity compared to upstream of Red Deer sites, possibly related to a non-point-source agricultural influence on water quality. Longnose dace populations at the most downstream sites were missing the oldest age classes and might reach sexual maturity faster than at upstream sites, which is consistent with a younger age structure. Our results highlight the importance of assessing multiple performance end points to reveal physiological or reproductive effects in natural fish populations. We have demonstrated how longnose dace populations change over a river impacted by municipal wastewater and agricultural runoff; further studies are required to determine if these changes will influence the long-term viability of longnose dace in the Red Deer River.

Using blood plasma for monitoring organochlorine contaminants in juvenile white sturgeon, Acipenser transmontanus, from the lower Columbia River

Organochlorine (OC) pesticide concentrations in blood plasma samples from 88 juvenile white sturgeon collected from the lower Columbia River were measured and compared to plasma sex steroid and OC tissue levels previously measured in corresponding fish. Significant squared correlation coefficients between summation operator DDT concentrations in sturgeon plasma and gonads and livers were 0.37 and 0.32, respectively. Significant negative correlations between plasma testosterone concentration and plasma Sigma DDT concentration in male fish (r(2)=0.26), plasma 17beta estradiol concentration and plasma Sigma DDT concentration in female fish (r(2)=0.38) and condition factor and plasma Sigma DDT concentration in all fish were found (r(2)=0.17). These results suggest that blood plasma may be a suitable nondestructive method for monitoring adult sturgeon population for persistent OC contaminants.

Early embryonic exposure to polychlorinated biphenyls disrupts heat-shock protein 70 cognate expression in zebrafish

Polychlorinated biphenyls (PCBs) are persistent environmental contaminants that have documented neurological effects in children exposed in utero. To better define neuronally linked molecular targets during early development, zebrafish embryos were exposed to Aroclor 1254, a mixture of PCB congeners that are common environmental contaminants. Microarray analysis of the zebrafish genome revealed consistent significant changes in 38 genes. Of these genes, 55% (21) are neuronally related. One gene that showed a consistent 50% reduction in expression in PCB-treated embryos was heat-shock protein 70 cognate (Hsc70). The reduction in Hsc70 expression was confirmed by real-time polymerase chain reaction (PCR), revealing a consistent 30% reduction in expression in PCB-treated embryos. Early embryonic exposure to PCBs also induced structural changes in the ventro-rostral cluster as detected by immunocytochemistry. In addition, there was a significant reduction in dorso-rostral neurite outgrowth emanating from the RoL1 cell cluster following PCB exposure. The serotonergic neurons in the developing diencephalon showed a 34% reduction in fluorescence when labeled with a serotonin antibody following PCB exposure, corresponding to a reduction in serotonin concentration in the neurons. The total size of the labeled neurons was not significantly different between treated and control embryos, indicating that the development of the neurons was not affected, only the production of serotonin within the neurons. The structural and biochemical changes in the developing central nervous system following early embryonic exposure to Aroclor 1254 may lead to alterations in the function of the affected regions.