Responses of white sucker (Catostomus commersoni) to 20 years of process and waste treatment changes at a bleached kraft pulp mill, and to mill shutdown

Impacts of endocrine disrupting chemicals on reproduction in wildlife and humans

Endocrine disrupting chemicals (EDCs) are ubiquitous in aquatic and terrestrial environments. The main objective of this review was to summarize the current knowledge of the impacts of EDCs on reproductive success in wildlife and humans. The examples selected often include a retrospective assessment of the knowledge of reproductive impacts over time to discern how the effects of EDCs have changed over the last several decades. Collectively, the evidence summarized here within reinforce the concept that reproduction in wildlife and humans is negatively impacted by anthropogenic chemicals, with several altering endocrine system function. These observations of chemicals interfering with different aspects of the reproductive endocrine axis are particularly pronounced for aquatic species and are often corroborated by laboratory-based experiments (i.e. fish, amphibians, birds). Noteworthy, many of these same indicators are also observed in epidemiological studies in mammalian wildlife and humans. Given the vast array of reproductive strategies used by animals, it is perhaps not surprising that no single disrupted target is predictive of reproductive effects. Nevertheless, there are some general features of the endocrine control of reproduction, and in particular, the critical role that steroid hormones play in these processes that confer a high degree of susceptibility to environmental chemicals. New research is needed on the implications of chemical exposures during development and the potential for long-term reproductive effects. Future emphasis on field-based observations that can form the basis of more deliberate, extensive, and long-term population level studies to monitor contaminant effects, including adverse effects on the endocrine system, are key to addressing these knowledge gaps.

A 30-Year Study of Impacts, Recovery, and Development of Critical Effect Sizes for Endocrine Disruption in White Sucker (Catostomus commersonii) Exposed to Bleached-Kraft Pulp Mill Effluent at Jackfish Bay, Ontario, Canada

Jackfish Bay is an isolated bay on the north shore of Lake Superior, Canada that has received effluent from a large bleached-kraft pulp mill since the 1940s. Studies conducted in the late 1980s found evidence of reductions in sex steroid hormone levels in multiple fish species living in the Bay, and increased growth, condition and relative liver weights, with a reduction in internal fat storage, reduced gonadal sizes, delayed sexual maturation, and altered levels of circulating sex steroid hormones in white sucker (Catostomus commersonii). These early studies provided some of the first pieces of evidence of endocrine disruption in wild animals. Studies on white sucker have continued at Jackfish Bay, monitoring fish health after the installation of secondary waste treatment (1989), changes in the pulp bleaching process (1990s), during facility maintenance shutdowns and during a series of facility closures associated with changing ownership (2000s), and were carried through to 2019 resulting in a 30-year study of fish health impacts, endocrine disruption, chemical exposure, and ecosystem recovery. The objective of the present study was to summarize and understand more than 75 physiological, endocrine, chemical and whole organism endpoints that have been studied providing important context for the complexity of endocrine responses, species differences, and challenges with extrapolation. Differences in body size, liver size, gonad size and condition persist, although changes in liver and gonad indices are much smaller than in the early years. Population modeling of the initial reproductive alterations predicted a 30% reduction in the population size, however with improvements over the last couple of decades those population impacts improved considerably. Reflection on these 30 years of detailed studies, on environmental conditions, physiological, and whole organism endpoints, gives insight into the complexity of endocrine responses to environmental change and mitigation.

Long-Term Studies of Fish Health before and after the Closure of a Bleached Kraft Pulp Mill in Northern Ontario, Canada

Changes in ecosystems after the removal of stress provide a rich source of information for conservation science. We used a long-term regional data set on the performance of white sucker (Catostomus commersonii) collected before and after the closure of a pulp mill to explore recovery in fish. Physiological indicators, including liver enzymes and plasma steroids, showed some compelling changes after the closure of the mill consistent with reduced exposure to pulp mill effluent but did not unequivocally demonstrate recovery. However, persistent signals in these fish may indicate effects of impoundment or discharge of sewage. We also used quantile regression with environmental covariates and bootstrap iteration to determine if systematic variation remained in relative body weight, liver weight, and gonad weight. In fish formerly exposed to pulp mill effluent, we found evidence of improvements (male gonad weight and liver weight of males and females), degradation (gonad weight of females), and no change (body weight). Although the observed patterns may be associated with closure of the mill, some differences were also found at regional locations, suggesting roles of additional stressors and challenging the clear association of change at the Mattagami River exposure site with the closure of the mill. However, fish captured at this location show responses consistent with regional locations, suggesting no residual impacts and highlights the challenges of identifying changes in fish even after large and known interventions. Environ Toxicol Chem 2021;40:162-176. © 2020 SETAC.

Principles and Challenges for Multi-Stakeholder Development of Focused, Tiered, and Triggered, Adaptive Monitoring Programs for Aquatic Environments

In Canada, there is almost 30 years of experience in developing tiered and triggered adaptive monitoring programs focused on looking at whether environmental concerns remain when pulp and paper mills, or metal mines, are in compliance with their discharge limits. These environmental effects monitoring programs were based on nationally standardized designs. Many of the programs have been developed through multi-stakeholder working groups, and the evolution of the program faced repeated frictions and differing opinions on how to design environmental monitoring programs. This paper describes key guidance to work through the initial steps in program design, and includes scientific advice based on lessons learned from the development of the Canadian aquatic environmental effects monitoring program.

Assessing wild fish exposure to ligands for sex steroid receptors from pulp and paper mill effluents in the Biobio River Basin, Central Chile

Bioactive substances in the Biobio River Basin in Chile were examined by deploying Semi Permeable Membrane Devices (SPMDs) upstream and downstream of 4 pulp mill effluent discharges. Androgenic and estrogenic activity of SPMD extracts were then evaluated using in vitro fish sex steroid receptor binding assays. The results indicated the occurrence of estrogenic type compounds associated with one of the mill discharges. A significant correlation among the presence of these compounds, an increase in gonadosomatic index GSI and induction of hepatic EROD activity of two native fish species was observed. However, no significant presence of mature oocytes in female gonads was detected. Although EROD induction was observed in sites impacted by mill effluents, an increase of its activity occurred towards the downstream areas, suggesting other non-mill sources. More research is needed to understand the environmental changes in context of the new technological improvements in treatment systems to MBBR (Moving Bed Biofilm Reactor) recently implemented by the pulp mill industries.

Assessing recovery of in vitro steroid production in male rainbow darter (Etheostoma caeruleum) in response to municipal wastewater treatment plant infrastructure changes

The present study examined in vitro 11-ketotestosterone and testosterone production by the testes of rainbow darter (Etheostoma caeruleum) collected from selected reference sites and downstream of 2 municipal wastewater treatment plants (MWWTPs; Waterloo and Kitchener) on the central Grand River (Ontario, Canada), over a 6-yr period (2011-2016). The main objective was to investigate if infrastructure upgrades at the Kitchener MWWTP in 2012 resulted in a recovery of this response in the post-upgrade period (2013-2016). Two supporting studies showed that the fall season is appropriate for measuring in vitro sex steroid production because it provides stable detection of steroid patterns, and that the sample handling practiced in the present study did not introduce a bias. Infrastructure upgrades of the Kitchener MWWTP resulted in significant reductions in ammonia and estrogenicity. After the upgrades, 11-ketotestosterone production by MWWTP-exposed fish increased in 2013 and it continued to recover throughout the study period of 2014 through 2016, returning to levels measured in reference fish. Testosterone production was less sensitive and it lacked consistency. The Waterloo MWWTP underwent some minor upgrades but the level of ammonia and estrogenicity remained variable over time. The production of 11-ketotestosterone and testosterone in rainbow darter below the Waterloo MWWTP was variable and without a clear recovery pattern over the course of the present study. The results of the present study demonstrated that measuring production of sex steroids (especially 11-ketotestosterone) over multiple years can be relevant for assessing responses in fish to environmental changes such as those resulting from major infrastructure upgrades. Environ Toxicol Chem 2018;37:501-514. © 2017 SETAC.

Population impacts in white sucker (Catostomus commersonii) exposed to oil sands-derived contaminants in the Athabasca River

Biological and chemical endpoints were measured in white sucker collected downstream of Athabasca oil sands developments (AB, Canada) and compared with those at Calling Lake (AB, Canada), a reference location upstream of the Athabasca oil sands deposit. Naphthenic acid concentrations were also measured at 14 sites in the Athabasca River watershed. Concentrations of naphthenic acids were elevated in tributaries adjacent to oil sands mining developments. Tributary naphthenic acid profiles were more similar to aged oil sands process water than samples from the Athabasca River, suggesting an influence of tailings in the tributaries. White sucker showed higher energy storage in the Athabasca River as indicated by significantly higher condition and liver size. White sucker were not investing that energy into reproductive effort as measured by gonad size and fecundity, which were significantly reduced relative to the reference location. White sucker showed increased exposure to polycyclic aromatic hydrocarbons as indicated by hepatic cytochrome P4501A (CYP1A) activity and fluorescent bile metabolites, as well as higher concentrations of naphthenic acids in bile. Cadmium, copper, nickel, and selenium were also elevated in white sucker liver tissue compared with the reference location. Based on the exposure profile and response pattern observed, effects on energy storage and utilization in white sucker from the Athabasca River most likely resulted from exposure to polycyclic aromatic hydrocarbons derived from petrogenic and pyrolytic sources. Environ Toxicol Chem 2017;36:2058-2067. © 2017 SETAC.

Tumours in white suckers from Lake Michigan tributaries: pathology and prevalence

The prevalence and histopathology of neoplastic lesions were assessed in white sucker Catostomus commersonii captured at two Lake Michigan Areas of Concern (AOCs), the Sheboygan River and Milwaukee Estuary. Findings were compared to those observed at two non-AOC sites, the Root and Kewaunee rivers. At each site, approximately 200 adult suckers were collected during their spawning migration. Raised skin lesions were observed at all sites and included discrete white spots, mucoid plaques on the body surface and fins and large papillomatous lesions on lips and body. Microscopically, hyperplasia, papilloma and squamous cell carcinoma were documented. Liver neoplasms were also observed at all sites and included both hepatocellular and biliary tumours. Based on land use, the Kewaunee River was the site least impacted by human activities previously associated with fish tumours and had significantly fewer liver neoplasms when compared to the other sites. The proportion of white suckers with liver tumours followed the same patterns as the proportion of urban land use in the watershed: the Milwaukee Estuary had the highest prevalence, followed by the Root, Sheboygan and Kewaunee rivers. The overall skin neoplasm (papilloma and carcinoma) prevalence did not follow the same pattern, although the percentage of white suckers with squamous cell carcinoma exhibited a similar relationship to land use. Testicular tumours (seminoma) were observed at both AOC sites but not at the non-AOC sites. Both skin and liver tumours were significantly and positively associated with age but not sex.

Defining the role of omics in assessing ecosystem health: Perspectives from the Canadian environmental monitoring program

Scientific reviews and studies continue to describe omics technologies as the next generation of tools for environmental monitoring, while cautioning that there are limitations and obstacles to overcome. However, omics has not yet transitioned into national environmental monitoring programs designed to assess ecosystem health. Using the example of the Canadian Environmental Effects Monitoring (EEM) program, the authors describe the steps that would be required for omics technologies to be included in such an established program. These steps include baseline collection of omics endpoints across different species and sites to generate a range of what is biologically normal within a particular ecosystem. Natural individual variability in the omes is not adequately characterized and is often not measured in the field, but is a key component to an environmental monitoring program, to determine the critical effect size or action threshold for management. Omics endpoints must develop a level of standardization, consistency, and rigor that will allow interpretation of the relevance of changes across broader scales. To date, population-level consequences of routinely measured endpoints such as reduced gonad size or intersex in fish is not entirely clear, and the significance of genome-wide molecular, proteome, or metabolic changes on organism or population health is further removed from the levels of ecological change traditionally managed. The present review is not intended to dismiss the idea that omics will play a future role in large-scale environmental monitoring studies, but rather outlines the necessary actions for its inclusion in regulatory monitoring programs focused on assessing ecosystem health.

Historical decline and altered congener patterns of polychlorinated dibenzo-p-dioxins and dibenzofurans in fish and sediment in response to process changes at a pulp mill discharging into Jackfish Bay, Lake Superior

Improved regulations for pulp and paper mill effluents and an industry shift away from elemental chlorine bleaching in the 1990s greatly reduced the release of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) into the environment. However, the high potential of these contaminants to persist in sediment and bioaccumulate in biota means that they have remained a concern. To document current contamination from bleached kraft pulp mill effluent, PCDD/Fs were measured in white sucker (Catostomus commersoni) collected from Jackfish Bay, Lake Superior. These values were contrasted to historically reported fish data as well as PCDD/F patterns from dated sediment cores. Patterns of PCDD/Fs in sediment cores from Jackfish Bay and reference sites demonstrated a relationship between contamination and mill process changes. During the peak PCDD/F contamination period (1991), when the mill was still using elemental chlorine, the contamination patterns in fish and sediment were distinct and dominated by 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran. Following the reduction in the use of elemental chlorine during the early 1990s, a rapid decline was observed in PCDD/F contamination of fish tissue, and levels are now approaching background conditions with congener patterns more reflective of atmospheric sources. Although surface sediments from Jackfish Bay continue to have elevated PCDD/Fs, with some locations exceeding sediment quality guidelines, they do not appear to be highly bioavailable to benthic fish.

Development of an adaptive monitoring framework for long-term programs: An example using indicators of fish health

Detecting unwanted changes associated with localized human activities in aquatic ecosystems requires defining the value of an indicator expected at a site in the absence of development. Ideally, adequate and comparable baseline data will be collected at an exposure location before that development, but this is rarely done. Instead, comparisons are made using various designs to overcome the inadequate or missing baseline data. Commonly these comparisons are done over short periods, using information from local reference sites to estimate variability expected at the exposed site. Results of these truncated designs are often evaluated using p values that may have little bearing on ecologically relevant changes. To remedy the reliance of studies on small datasets collected at reference sites, other designs emphasize regional analyses, but these may be insensitive to site-specific changes. Some designs also may forego discussing the consequences of detecting any differences. A new monitoring framework has been proposed to use existing solutions, simplify analysis, and focus on the detection of meaningful changes. It is illustrated here by using data on fish health from a large-scale, long-term program in the Moose River basin in northern Ontario. This framework advocates interpretation of data at multiple scales: within-site, locally, and regionally. The primary focus is on estimating a range from a probability distribution of historical data collected at a specific location where 95% of future observations are predicted to occur. Changes at the exposed site are also compared with historical and contemporary expectations from proximate and regional reference sites. Critical effect sizes also can be derived from regional reference data to evaluate the magnitude of differences observed between any 2 sites. Any unexpected changes inform future monitoring decisions provided by a priori guidance. Adoption of this framework extends the utility of monitoring programs in which commitments to long-term collections have been made, advocates harmonization of studies over time and space, and focuses attention on unusual observations.

Characterization of a Novel Hepadnavirus in the White Sucker (Catostomus commersonii) from the Great Lakes Region of the United States

The white sucker Catostomus commersonii is a freshwater teleost often utilized as a resident sentinel. Here, we sequenced the full genome of a hepatitis B-like virus that infects white suckers from the Great Lakes Region of the United States. Dideoxy sequencing confirmed that the white sucker hepatitis B virus (WSHBV) has a circular genome (3,542 bp) with the prototypical codon organization of hepadnaviruses. Electron microscopy demonstrated that complete virions of approximately 40 nm were present in the plasma of infected fish. Compared to avi- and orthohepadnaviruses, sequence conservation of the core, polymerase, and surface proteins was low and ranged from 16 to 27% at the amino acid level. An X protein homologue common to the orthohepadnaviruses was not present. The WSHBV genome included an atypical, presumptively noncoding region absent in previously described hepadnaviruses. Phylogenetic analyses confirmed WSHBV as distinct from previously documented hepadnaviruses. The level of divergence in protein sequences between WSHBV and other hepadnaviruses and the identification of an HBV-like sequence in an African cichlid provide evidence that a novel genus of the family Hepadnaviridae may need to be established that includes these hepatitis B-like viruses in fishes. Viral transcription was observed in 9.5% (16 of 169) of white suckers evaluated. The prevalence of hepatic tumors in these fish was 4.9%, and only 2.4% of fish were positive for both virus and hepatic tumors. These results are not sufficient to draw inferences regarding the association of WSHBV and carcinogenesis in white sucker.

IMPORTANCE We report the first full-length genome of a hepadnavirus from fishes. Phylogenetic analysis of this genome indicates divergence from genomes of previously described hepadnaviruses from mammalian and avian hosts and supports the creation of a novel genus. The discovery of this novel virus may better our understanding of the evolutionary history of hepatitis B-like viruses of other hosts. In fishes, knowledge of this virus may provide insight regarding possible risk factors associated with hepatic neoplasia in the white sucker. This may also offer another model system for mechanistic research.

Omics for aquatic ecotoxicology: control of extraneous variability to enhance the analysis of environmental effects

There are multiple sources of biological and technical variation in a typical ecotoxicology study that may not be revealed by traditional endpoints but that become apparent in an omics dataset. As researchers increasingly apply omics technologies to environmental studies, it will be necessary to understand and control the main source(s) of variability to facilitate meaningful interpretation of such data. For instance, can variability in omics studies be addressed by changing the approach to study design and data analysis? Are there statistical methods that can be employed to correctly interpret omics data and make use of unattributed, inherent variability? The present study presents a review of experimental design and statistical considerations applicable to the use of omics methods in systems toxicology studies. In addition to highlighting potential sources that contribute to experimental variability, this review suggests strategies with which to reduce and/or control such variability so as to improve reliability, reproducibility, and ultimately the application of omics data for systems toxicology.

Linking mechanistic toxicology to population models in forecasting recovery from chemical stress: A case study from Jackfish Bay, Ontario, Canada

Recovery of fish and wildlife populations after stressor mitigation serves as a basis for evaluating remediation success. Unfortunately, effectively monitoring population status on a routine basis can be difficult and costly. In the present study, the authors describe a framework that can be applied in conjunction with field monitoring efforts (e.g., through effects-based monitoring programs) to link chemically induced alterations in molecular and biochemical endpoints to adverse outcomes in whole organisms and populations. The approach employs a simple density-dependent logistic matrix model linked to adverse outcome pathways (AOPs) for reproductive effects in fish. Application of this framework requires a life table for the organism of interest, a measure of carrying capacity for the population of interest, and estimation of the effect of stressors on vital rates of organisms within the study population. The authors demonstrate the framework using linked AOPs and population models parameterized with long-term monitoring data for white sucker (Catostomus commersoni) collected from a study site at Jackfish Bay, Lake Superior, Canada. Individual responses of fish exposed to pulp mill effluent were used to demonstrate the framework's capability to project alterations in population status, both in terms of ongoing impact and subsequent recovery after stressor mitigation associated with process changes at the mill. The general approach demonstrated at the Jackfish Bay site can be applied to characterize population statuses of other species at a variety of impacted sites and can account for effects of multiple stressors (both chemical and nonchemical) and dynamics within complex landscapes (i.e., meta-populations including emigration and immigration processes).

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.

An inter-laboratory study on the variability in measured concentrations of 17β-estradiol, testosterone, and 11-ketotestosterone in white sucker: implications and recommendations

Endocrine-disrupting chemicals are exogenous substances that can impact the reproduction of fish, potentially by altering circulating concentrations of 17β-estradiol (E2), testosterone (T), and 11-ketotestosterone (11-KT). Common methods to measure steroids in plasma samples include radioimmunoassays (RIAs) and enzyme-linked immunosorbant assays (ELISAs). The present study examines variability in E2, T, and 11-KT across 8 laboratories measuring reference and pulp mill effluent-exposed white sucker (Catostomus commersoni) plasma. We examine the contribution of assay type (RIA vs ELISA), standardized hormone extraction, location of values on the standard curve (upper and lower limits), and other variables on the ability to distinguish hormone levels between reference and exposed fish and the impact of these variables on quantitation of hormones in different laboratories. Of the 8 participating laboratories, 7 of 8 and 7 of 7 identified differences between sites for female E2 and female T, respectively, and 7 of 7 and 4 of 5 identified no differences between male T and male 11-KT. Notably, however, the ng/mL concentration of steroids measured across laboratories varied by factors of 10-, 6-, 14-, and 10-fold, respectively. Within laboratory intra-assay variability was generally acceptable and below 15%. Factors contributing to interlaboratory variability included calculation errors, assay type, and methodology. Based on the interlaboratory variability detected, we provide guidelines and recommendations to improve the accuracy and precision of steroid measurements in fish ecotoxicology studies.

Health of white sucker within the St. Louis River area of concern associated with habitat usage as assessed using stable isotopes

In Spring 2011, 200 adult white sucker were collected in four areas of the St. Louis River area of concern (AOC), located in Minnesota and Wisconsin, USA. The areas included the upper AOC as a reference area, the upper estuary, St. Louis Bay and Superior Bay. Grossly visible abnormalities were documented and preserved for microscopic analyses, as were five to eight representative pieces of liver tissue. A piece of dorsal muscle was preserved for stable isotope analyses and otoliths removed for age determination. The incidence of raised skin lesions (mucoid plaques) was high (31 %), however, microscopically only 4.5 % of the white suckers had neoplasia (papillomas). The remaining lesions were epidermal hyperplasia. Superior Bay had the lowest percentage of skin/lip lesions (10 %), while St. Louis Bay had the highest (44 %). St. Louis Bay also had the highest incidence of skin neoplasms (12 %). No hepatocellular neoplasms were documented, however bile duct tumors were observed in 4.5 % of the suckers. Foci of cellular alteration were observed in fish from all sites except the upper AOC. Stable isotope data indicated that most of the suckers relied on the St. Louis River AOC for the majority (>75 %) of their diet, indicating they were resident within the AOC and not in Lake Superior. The amount of diet obtained from the upper estuary was a significant predictor of skin lesion incidence. Hence, habitat use within the AOC appears to be an important risk factor for skin and possibly, liver lesions.

Field-based approach for assessing the impact of treated pulp and paper mill effluent on endogenous metabolites of fathead minnows (Pimephales promelas)

A field-based metabolomic study was conducted during a shutdown of a pulp and paper mill (PPM) to assess the impacts of treated PPM effluent on endogenous polar metabolites in fathead minnow (FHM; Pimephales promelas) livers. Caged male and female FHMs were deployed at a Great Lakes area of concern during multiple periods (pre-, during, and post-shutdown) near the outflow for a wastewater treatment plant. Influent to this plant is typically 40% PPM effluent by volume. Additional FHMs were exposed to reference lake water under laboratory conditions. A bioassay using T47D-KBluc cells showed that estrogenic activity of receiving water near the outflow declined by 46% during the shutdown. We then used (1)H NMR spectroscopy and principal component analysis to profile abundances of hepatic endogenous metabolites for FHMs. Profiles for males deployed pre-shutdown in receiving water were significantly different from those for laboratory-control males. Profiles were not significantly different for males deployed during the shutdown, but they were significant again for those deployed post-shutdown. Impacts of treated effluent from this PPM were sex-specific, as differences among profiles of females were largely nonsignificant. Thus, we demonstrate the potential utility of field-based metabolomics for performing biologically based exposure monitoring and evaluating remediation efforts occurring throughout the Great Lakes and other ecosystems.

Evaluating cumulative effects of anthropogenic inputs in Prince Edward Island estuaries using the mummichog (Fundulus heteroclitus)

Estuarine eutrophication as a result of agricultural land use, including the use of chemical fertilizers, is increasing worldwide. Prince Edward Island (PEI), Canada has very high agricultural intensity by international standards with approximately 44% of the land area under production, and some watersheds in excess of 75% agricultural land-use. The type of agriculture is also intensive with primarily row crops that have high chemical fertilizer and pesticide usage. In light of these stressors, the hypothesis of this study was that mummichog (Fundulus heteroclitus) population parameters would change with point and nonpoint source pollution, and that multivariate statistics could be used to draw associations with specific stressors. Fish were sampled on a monthly basis from May through August at 7 estuaries spanning a range of land use, nutrient, and contaminant loadings. A suite of environmental variables were simplified into 3 principal components: PC1 representing agricultural land use, N loading, and plant habitat, PC2 being dominated by sediment sand and silt distribution, and PC3 largely reflecting P loading and sediment organic matter. There were significant differences in abundance of both adult and young-of-the-year mummichog, and these changes associated most strongly with PC1, the largely N-driven agricultural influences. In contrast, somatic variables such as liver and gonad size did not show strong association with the environmental quality principal component scores. The sand and silt PC2 appeared to have the opposite association with the biological data, with siltier environments correlating to older, larger, less dense populations of mummichog. Although pesticide residues were detected in estuarine sediment, there was no clear relationship between these and watershed agricultural intensity or biochemical indicators. There was, however, a strong relationship between agricultural environmental variables (PC1) and in vitro steroid production that is suggestive of a potential chemical effect. Eutrophication appeared to be a primary stressor affecting mummichog populations, as nutrient enrichment was associated with changes in habitat variables and these in turn were associated with high mummichog density. Thus, mummichog population demographics appear to have use as an indicator of adverse or worsening conditions in estuaries. We concluded that, based on the subset of environmental factors evaluated, the nonpoint-source inputs of sediments and nutrients exerted the greatest influence on mummichog populations in PEI estuaries.

Assessment of status of white sucker (Catostomus commersoni) populations exposed to bleached kraft pulp mill effluent

Credible ecological risk assessments often need to include analysis of population-level impacts. In the present study, a predictive model was developed to investigate population dynamics for white sucker (Catostomus commersoni) exposed to pulp mill effluent at a well-studied site in Jackfish Bay, Lake Superior, Canada. The model uniquely combines a Leslie population projection matrix and the logistic equation to translate changes in the fecundity and the age structure of a breeding population of white sucker exposed to pulp mill effluent to alterations in population growth rate. Application of this density-dependent population projection model requires construction of a life table for the organism of interest, a measure of carrying capacity, and an estimation of the effect of stressors on vital rates. A white sucker population existing at carrying capacity and subsequently exposed to pulp mill effluent equivalent to a documented exposure experienced during the period 1988 to 1994 in Jackfish Bay would be expected to exhibit a 34% to 51% annual decrease in recruitment during the first 5 yr of exposure and approach a population size of 71% of carrying capacity. The Jackfish Bay study site contains monitoring data for biochemical endpoints in white sucker, including circulating sex steroid concentrations, that could be combined with population modeling to utilize the model demonstrated at the Jackfish Bay study site for investigation of other white sucker populations at sites that are less data-rich.

Expression profiling and gene ontology analysis in fathead minnow (Pimephales promelas) liver following exposure to pulp and paper mill effluents

Many studies link pulp and paper mill effluent (PPME) exposure to adverse effects in fish populations present in the mill receiving environments. These impacts are often characteristic of endocrine disruption and may include impaired reproduction, development and survival. While these physiological endpoints are well-characterized, the molecular mechanisms causing them are not yet understood. To investigate changes in gene transcription induced by exposure to a PPME at several stages of treatment, male and female fathead minnows (FHMs) were exposed for 6 days to 25% (v/v) secondary (biologically) treated kraft effluent (TK) or 100% (v/v) combined mill outfall (CMO) from a mill producing both kraft pulp and newsprint. The gene expression changes in the livers of these fish were analyzed using a 22K oligonucleotide microarray. Exposure to TK or CMO resulted in significant changes in the expression levels of 105 and 238 targets in male FHMs and 296 and 133 targets in females, respectively. Targets were then functionally analyzed using gene ontology tools to identify the biological processes in fish hepatocytes that were affected by exposure to PPME after its secondary treatment. Proteolysis was affected in female FHMs exposed to both TK and CMO. In male FHMs, no processes were affected by TK exposure, while sterol, isoprenoid, steroid and cholesterol biosynthesis and electron transport were up-regulated by CMO exposure. The results presented in this study indicate that short-term exposure to PPMEs affects the expression of reproduction-related genes in the livers of both male and female FHMs, and that secondary treatment of PPMEs may not neutralize all of their metabolic effects in fish. Gene ontology analysis of microarray data may enable identification of biological processes altered by toxicant exposure and thus provide an additional tool for monitoring the impact of PPMEs on fish populations.

Genotoxicity and toxicity evaluations of ECF cellulose bleaching effluents using the Allium cepa L. test

Toxicity and genotoxicity tests were performed on root cells of Allium cepa in order to evaluate wastewater quality following an ECF cellulose bleaching process. The results revealed a toxic effect of the effluent, with inhibition of meristem growth and generally lower values of metaphase, anaphase and telophase indices at pH 10.5 than pH 7 for all effluent concentrations. The genotoxicity effect was different from the toxic effect given that the micronucleus and the chromosomal aberration tests in anaphase-telophase cells were low over all ranges of the studied effluent concentrations.

Consequences of acute stress and cortisol manipulation on the physiology, behavior, and reproductive outcome of female Pacific salmon on spawning grounds

Life-history theory predicts that stress responses should be muted to maximize reproductive fitness. Yet, the relationship between stress and reproduction for semelparous salmon is unusual because successfully spawning individuals have elevated plasma cortisol levels. To tease apart the effects of high baseline cortisol levels and stress-induced elevation of cortisol titers, we determined how varying degrees of cortisol elevation (i.e., acute and chronic) affected behavior, reproductive physiology, and reproductive success of adult female pink salmon (Oncorhynchus gorbuscha) relative to different states of ovulation (i.e., ripe and unripe). Exhaustive exercise and air exposure were applied as acute stressors to manipulate plasma cortisol in salmon either confined to a behavioral arena or free-swimming in a spawning channel. Cortisol (eliciting a cortisol elevation to levels similar to those in post-spawn female salmon) and metyrapone (a corticosteroid synthesis inhibitor) implants were also used to chemically manipulate plasma cortisol. Cortisol implants elevated plasma cortisol, and impaired reproductive success; cortisol-treated fish released fewer eggs and died sooner than fish in other treatment groups. In contrast, acute stressors elevated plasma cortisol and the metyrapone implant suppressed plasma cortisol, but neither treatment significantly altered reproductive success, behavior, or physiology. Our results suggest that acute stressors do not influence behavior or reproductive outcome when experienced upon arrival at spawning grounds. Thus, certain critical aspects of salmonid reproduction can become refractory to various stressful conditions on spawning grounds. However, there is a limit to the ability of these fish to tolerate elevated cortisol levels as revealed by experimental elevation of cortisol.

Proteomic profiles of white sucker (Catostomus commersonii) sampled from within the Thunder Bay Area of Concern reveal up-regulation of proteins associated with tumor formation and exposure to environmental estrogens

White sucker (Catostomus commersonii) sampled from the Thunder Bay Area of Concern were assessed for health using a shotgun approach to compile proteomic profiles. Plasma proteins were sampled from male and female fish from a reference location, an area in recovery within Thunder Bay Harbour, and a site at the mouth of the Kaministiquia River where water and sediment quality has been degraded by industrial activities. The proteins were characterized using reverse-phase liquid chromatography tandem to a quadrupole-time-of-flight (LC-Q-TOF) mass spectrometer and were identified by searching in peptide databases. In total, 1086 unique proteins were identified. The identified proteins were then examined by means of a bioinformatics pathway analysis to gain insight into the biological functions and disease pathways that were represented and to assess whether there were any significant changes in protein expression due to sampling location. Female white sucker exhibited significant (p = 0.00183) site-specific changes in the number of plasma proteins that were related to tumor formation, reproductive system disease, and neurological disease. Male fish plasma had a significantly different (p < 0.0001) number of proteins related to neurological disease and tumor formation. Plasma concentrations of vitellogenin were significantly elevated in females from the Kaministiquia River compared to the Thunder Bay Harbour and reference sites. The protein expression profiles indicate that white sucker health has benefited from the remediation of the Thunder Bay Harbour site, whereas white sucker from the Kaministiquia River site are impacted by ongoing contaminant discharges.

Health status of native fish (Percilia gillissi and Trichomycterus areolatus) downstream of the discharge of effluent from a tertiary-treated elemental chlorine-free pulp mill in Chile

Few data exist on the possible effects of pulp and paper effluent discharge on native fish populations in the Southern Hemisphere, relative to the research done in the Northern Hemisphere. The present research examined two native fish species (Trichomycterus areolatus and Percilia gillissi) for effects at both the molecular and individual level due to the discharge of effluent from a tertiary treated elemental chlorine-free pulp mill into a fluvial system in Central Chile over three seasons (February 2007, October 2007, January 2008). Different responses were observed between species and between sexes. There was an increase in the production of gonadal 17β-estradiol in the females of both species but a drop in 11-ketotestosterone production in P. gillissi males. Female gonadal size was increased, especially during the summer period, with corresponding increases the frequency of advanced oocyte development, and in the oocyte diameter in both species. Hepatic ethoxyresorufin-O-deethylase (EROD) activity was elevated for both species downstream of the discharge point, although overall it was higher in P. gillissi than T. areolatus. Decreases in the frequency of smaller-sized fish for both species, as well as a drop in the size of the adults downstream of the discharge point, were observed. The present study is the first evidence of endocrine disruption in native freshwater fish associated with modern pulp mills in South America. This study establishes possible links in the reproductive alterations observed at the subindividual and individual levels that could explain the changes observed at the population level.

Kraft mill effluent survey: progress toward best management practices for reducing effects on fish reproduction

Pulp and paper mill effluents have been linked to effects on fish reproduction for more than 25 years. To date, the causes of these effects and remedial strategies have eluded investigators. Recent work has shown that the degree of reproductive effect caused by a mill effluent is related to the overall organic content. If verified, this could lead to breakthroughs for best management practices (BMPs). For this study, the effluents from seven kraft mills were assessed for their ability to reduce egg production in fathead minnow (Pimephales promelas) in the laboratory. At the same time, the effluents were analyzed for three parameters thought to be good indicators of organic losses: biochemical oxygen demand (BOD), methyl-substituted 2-cyclopentenones (cellulose degradation products), and a gas chromatographic (GC) profile index, which integrates the total area of the chromatographic peaks of solvent-extracted effluents using low-resolution mass spectrometry. The results showed that the degree to which the effluents reduced egg production increased with increased organic losses as characterized by BOD and the GC profile index. Therefore, these parameters could be used to guide BMPs at kraft mills according to specific targets: BOD < 20 mg/L and GC profile index equivalent to effluent with BOD of 20 mg/L. Such targets should be achievable by good in-plant control of organic losses and optimized effluent biotreatment systems.

Effects of pulp and paper mill effluent on fish: a temporal assessment of fish health across sampling cycles

The Canadian environmental effects monitoring (EEM) program is a regulated, cyclical, industry-funded program designed to determine whether receiving water impacts exist when a mill is in compliance with its discharge limits. The results from three cycles of the fish monitoring program (1992 to 2004) are available from over 200 surveys of fish compared between sites located upstream and downstream of pulp and paper mill effluent outfalls. Previous meta-analyses have shown a national average response pattern across cycles characterized by an increase in endpoints measuring energy storage and growth and a decrease in a reproductive endpoint, consistent with a response of nutrient enrichment in combination with some form of metabolic disruption. Although the national average pattern of effects was temporally consistent, there was some variability in the magnitude of effects among cycles. Questions were raised as to whether the intercycle variability was due to changes in effluent quality or due, at least in part, to other factors. The present study compares responses over the first three cycles, and shows that the choice of sentinel species is likely to be a major contributing factor to the variability in observed effects. Subset analyses using studies from mills that used the same sentinel species across cycles reveal fairly uniform responses and little evidence of significant improvements in overall fish health from cycles one to three. However, a meta-analysis using 1991 data collected from 10 mills before the implementation of the EEM program and data from the same mills collected during cycles one to three of the program reveal significantly reduced effects on relative liver weight and potential improvements in other endpoints.