Joseph P. Dietrich

Disease susceptibility of salmon exposed to polybrominated diphenyl ethers (PBDEs)

The health effects of the flame retardant polybrominated diphenyl ethers (PBDEs) in fish are not well understood. To determine the potential effects of this ubiquitous contaminant class on fish health, juvenile subyearling Chinook salmon (Oncorhynchus tshawytscha) were fed a diet that reflected the PBDE congeners found in the stomach contents of subyearling Chinook salmon collected from the highly urbanized and industrialized lower Willamette River in the Columbia River Basin of North America. The diet, consisting of five PBDE congeners (BDE-47, BDE-99, BDE-100, BDE-153 and BDE-154), was fed to the salmon at 2% of their body weight in food per day for 40 days. Two concentrations of the diet (1x and 10x PBDE) were fed to the salmon. The 1x PBDE diet reflected the concentration of PBDEs (190 ng PBDEs/g food) found in the stomach contents of juvenile subyearling Chinook salmon; the 10x diet was prepared at 10 times that concentration. The fish were then exposed to the marine bacterial pathogen Listonella anguillarum to assess susceptibility to infectious disease. Juvenile Chinook salmon fed the 1x PBDE diet were more susceptible to L. anguillarum than salmon fed the control diet. This suggests that juvenile salmonids in the lower Willamette River exposed to PBDEs may be at greater risk for disease than nonexposed juvenile salmonids. In contrast, salmon that consumed the 10x PBDE diet were not more susceptible to the pathogen than salmon fed the control diet. The mechanisms for the dichotomous results observed in disease susceptibility between salmon fed the 1x and 10x PBDE diets are currently not known but have also been observed in other species exposed to PBDEs with respect to immune function.

Preliminary assessment of transport processes influencing the penetration of chlorine into wastewater particles and the subsequent inactivation of particle-associated organisms.

The diffusion of a chemical disinfectant into wastewater particles may be viewed as a serial two-step process involving transport through a macroporous network of pathways to micropores that lead into dense cellular regions. Previous research reveals that ultraviolet (UV) light penetration into wastewater particles is limited primarily to macropores, resulting in a residual concentration of targeted organisms in post-disinfected effluents that reflects the number of organisms embedded in the dense cellular regions of particles. Conversely, chlorine was demonstrated as part of this research to penetrate into both the macroporous and microporous network of pathways, implying that the application of chlorine may be designed feasibly to achieve a desired level of inactivation of particle-associated organisms. In the short term, a disinfection model previously developed for UV irradiation may be used to assess the inactivation of particle-associated organisms with chlorine. However, in the long-term, a more rigorous and complete understanding of the transport of chemical disinfectants into particles can be explored utilizing existing mathematical expressions commonly used to model mass transport into porous media. The parameters of interest in this modeling approach include the reaction rate of chlorine with particulate material, the diffusion rate of chlorine within a particle, the mass-transfer rate coefficient across the particles boundary, and the particle porosity.

4 - Effects on Fish of Polycyclic Aromatic HydrocarbonS (PAHS) and Naphthenic Acid Exposures

Polycyclic aromatic hydrocarbons (PAHs) are derived from both natural and anthropogenic sources and are released from a wide range of industries and everyday activities. Unlike many other organic chemical contaminants that are manufactured and regulated, PAHs continue to be released on a global scale because of the worlds dependence on fossil fuels. This chapter briefly reviews the transformation of PAHs in the aquatic environment, highlighting their efficient metabolism in fish and focuses on evidence that links PAH exposure to a wide range of biological dysfunctions in fish. These dysfunctions include neoplasia, reduced reproductive success and other types of endocrine disruption, immunotoxicity, postlarval growth and somatic condition, transgenerational impacts, and finally, recent findings showing that the embryonic development of fish is severely affected by extremely low concentrations of PAH exposure. A brief review of the effects of naphthenic acids on fish is also included because these compounds are increasingly recognized as major factors in the toxicity of process waters from a variety of petroleum sources, most notably the immense oil sands deposits found in Alberta, Canada. It is recommended that future research for understanding and mitigating the effects of PAHs in fish and associated aquatic ecosytems should include the following. • Using models to link molecular-up-to-organismal level effects to population-relevant metrics. • Building on current case studies demonstrating the effects of PAHs on the health of fish in their natural environments in order to derive regulatory approaches. Current approaches that rely on biota to sediment accumulation factors (BSAF) will not work with contaminants that are efficiently metabolized by species of concern. • Focusing considerable resources on better analytical chemistry for both PAHs and naphthenic acids. Currently, our ability to understand and mitigate the effects of these substances is heavily limited by constraints in analysis.

A diffusion limited sorption kinetics model with polydispersed particles of distinct sizes and shapes

We propose a numerical model to compute spatial and temporal variations of the dissolved and sorbed phase concentrations within porous particles of different sizes and shapes that undergo dynamic mass transfer with the surrounding bulk concentration. The model accommodates intra-particle reversible sorption kinetics, film resistance at particle surfaces, and first-order decays in both intra- and extra-particle aqueous volumes. The model allows consideration of mixtures of polydispersed particles of distinct sizes and shapes. A finite-difference formulation of the model provides quantification of novel uptake terms that determine magnitudes of mass transfer between extra-particle aqueous phase and the particles. The model also allows consideration of non-linear irreversible site-limited intra-particle surface reactions for identical particles of spherical, cylindrical, and rectangular geometries. Applications for several examples illustrate the general behavior. Experimental data of iodine concentrations from a wastewater sample were well represented by the pore-diffusion model with site-limited sorption.

Effects of Legacy Persistent Organic Pollutants (POPs) in Fish—Current and Future Challenges

Persistent organic pollutants (POPs) are ubiquitous environmental contaminants that are not readily degraded in the environment. They are typically lipophilic, bioaccumulating in tissues of aquatic organisms and biomagnifying in freshwater and marine food webs. POPs include a wide range of halogenated legacy contaminants [e.g., polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), chlordanes, hexachlorobenzene (HCB)] that have been banned because of their toxicity to humans and wildlife; compounds such as polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzodioxins (PCDDs) that can be produced naturally (e.g., through forest fires and volcanic eruptions) or through industrial processes; and chemicals of emerging concern [e.g., polybrominated diphenyl ethers (PBDEs) and perfluorinated compounds]. Although many POPs are no longer being released into the environment, they continue to be reported at toxic concentrations in fish, and there is much that is not yet understood about their modes of action and their ecological effects on aquatic habitats. This chapter reviews current information on (1) uptake and metabolism of these compounds by fish; (2) their biological effects, including their actions as endocrine disruptors, reproductive, developmental, neurological, immunological, and metabolic toxicants and carcinogens; and (3) recent efforts to evaluate the ecological risks of exposure to such compounds on fish populations and aquatic communities.

The impact of temperature stress and pesticide exposure on mortality and disease susceptibility of endangered Pacific salmon

Anthropogenic stressors, including chemical contamination and temperature stress, may contribute to increased disease susceptibility in aquatic animals. Specifically, the organophosphate pesticide malathion has been detected in surface waters inhabited by threatened and endangered salmon. In the presence of increasing water temperatures, malathion may increase susceptibility to disease and ultimately threaten salmon survival. This work examines the effect of acute and sublethal exposures to malathion on ocean-type subyearling Chinook salmon held under two temperature regimes. Chinook salmon were exposed to malathion at optimal (11 °C) or elevated (19 and 20 °C) temperatures. The influence of temperature on the acute toxicity of malathion was determined by generating 96-h lethal concentration (LC) curves. A disease challenge assay was also used to assess the effects of sublethal malathion exposure. The malathion concentration that resulted in 50% mortality (LC50; 274.1 μg L(-1)) of the Chinook salmon at 19 °C was significantly less than the LC50 at 11 °C (364.2 μg L(-1)). Mortality increased 11.2% in Chinook salmon exposed to malathion at the elevated temperature and challenged with Aeromonas salmonicida compared to fish held at the optimal temperature and exposed to malathion or the carrier control. No difference in disease challenge mortality was observed among malathion-exposed and unexposed fish at the optimal temperature. The interaction of co-occurring stressors may have a greater impact on salmon than if they occur in isolation. Ecological risk assessments considering the effects of an individual stressor on threatened and endangered salmon may underestimate risk when additional stressors are present in the environment.

Dietary Exposure to Individual Polybrominated Diphenyl Ether Congeners BDE-47 and BDE-99 Alters Innate Immunity and Disease Susceptibility in Juvenile Chinook Salmon

Polybrominated diphenyl ethers (PBDEs), used as commercial flame-retardants, are bioaccumulating in threatened Pacific salmon. However, little is known of PBDE effects on critical physiological functions required for optimal health and survival. BDE-47 and BDE-99 are the predominant PBDE congeners found in Chinook salmon collected from the Pacific Northwest. In the present study, both innate immunity (phagocytosis and production of superoxide anion) and pathogen challenge were used to evaluate health and survival in groups of juvenile Chinook salmon exposed orally to either BDE-47 or BDE-99 at environmentally relevant concentrations. Head kidney macrophages from Chinook salmon exposed to BDE-99, but not those exposed to BDE-47, were found to have a reduced ability in vitro to engulf foreign particles. However, both congeners increased the in vitro production of superoxide anion in head kidney macrophages. Salmon exposed to either congener had reduced survival during challenge with the pathogenic marine bacteria Listonella anguillarum. The concentration response curves generated for these end points were nonmonotonic and demonstrated a requirement for using multiple environmentally relevant PBDE concentrations for effect studies. Consequently, predicting risk from toxicity reference values traditionally generated with monotonic concentration responses may underestimate PBDE effect on critical physiological functions required for optimal health and survival in salmon.

Trends in organic pollutants and lipids in juvenile Snake River spring Chinook salmon with different outmigrating histories through the Lower Snake and Middle Columbia Rivers

A three-year field study was conducted from 2006 to 2008 to monitor the spatial and temporal trends of organic pollutants in migrating juvenile Snake River spring Chinook salmon (Oncorhynchus tshawytscha) sampled from the Lower Snake and Middle Columbia River Basins. Specifically, hatchery-reared juvenile salmon were monitored as they navigated the Federal Columbia River Power System (FCRPS) by either transport barge (Barged) or remained in the river (In-River) from Lower Granite Dam to a terminal collection dam, either John Day Dam or Bonneville Dam. Levels of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine (OC) pesticides were detected in the bodies of both In-River and Barged salmon during the 2006, 2007 and 2008 outmigrating season. At the terminal dam, In-River fish had greater concentrations of persistent organic pollutants POPs than Barged salmon. Of the POPs detected, dichlorodiphenyltrichloroethanes (DDTs) were found at the greatest concentrations in the salmon bodies. These elevated lipid-normalized concentrations in the In-River fish were due to lipid depletion in all years as well as increased exposure to POPs in some years as indicated by an increase in wet weight contaminant concentrations. Salmon were also exposed to polycyclic aromatic hydrocarbons (PAHs) as indicated by the phenanthrene (PHN) signal for biliary fluorescent aromatic compounds (FACs) at the hatcheries or prior to Lower Granite Dam. There were detectable levels of biliary FACs as fish migrated downstream or were barged to the terminal dam. Therefore, the potential exists for these organic pollutants and lipid levels to cause adverse effects and should be included as one of the variables to consider when examining the effects of the FCRPS on threatened and endangered juvenile salmon.

An Evaluation of the Influence of Stock Origin and Out-migration History on the Disease Susceptibility and Survival of Juvenile Chinook Salmon

Various methods have been developed to mitigate the adverse effects of the Federal Columbia River Power System on juvenile Pacific salmon out-migrating through the Columbia River basin. In this study, we found that hatchery-reared spring Chinook salmon Oncorhynchus tshawytscha in the river are in varying degrees of health, which may affect delayed mortality and the assessment of the effectiveness of management actions to recover listed stocks (e.g., barging fish downstream versus leaving fish in the river). A laboratory disease challenge with Listonella anguillarum was completed on fish from Rapid River Hatchery and Dworshak National Fish Hatchery (NFH) with different out-migration histories: (1) transported by barge, (2) removed from the river before barging, or (3) left to travel in-river. Barged fish from Rapid River Hatchery experienced less mortality than fish from Dworshak NFH. No statistical differences were found between the hatcheries with fish that had in-river out-migration histories. We suggest that the stressors and low survival associated with out-migration through the hydropower system eliminated any differences that could have been present. However, 18-25% of the fish that were barged or collected before barging died in the laboratory before the disease challenge, compared with less than 2% of those that traveled in-river. Owing to disproportionate prechallenge mortality, the disease-challenged populations may have been biased; thus, they were also considered together with the prechallenge mortalities. The synthesis of prechallenge and disease-challenged mortalities and health characteristics evaluated during out-migration indicated that the benefit of barging was not consistent between the hatcheries. This finding agrees with adult survival and delayed mortality estimates for the individual hatcheries determined from adult returns. The results suggest that the health status of fish and their history before entering the hydropower system (hatchery of origin and out-migration path) are critical variables affecting the conclusions drawn from studies that evaluate mitigation strategies.

Potential Health Risks Associated with Particles in Reclaimed Wastewater

Human dose-response data from seven pathogens commonly associated with waterborne illness were used in conjunction with acceptable levels of risk specified by the United States EPA to determine an allowable particle limit for reclaimed water assuming varying degrees of pathogen association. Assuming particles contain a single pathogen, particle limits ranged from 213,000 particles/L for E. coli ETEC to 400 particles/billion L for rotavirus. Particle concentrations in the effluent from nine reclamation facilities that employed advanced filtration exceeded calculated allowable particle limits for one or more pathogens despite achieving permitted water quality standards. Hence, current methods of estimating particle densities (e.g., turbidity and suspended solids) and indicator organisms are potentially incongruent with acceptable levels of risk specified by the United States EPA. The significance of this incongruence is dependent on the uncertain frequency of pathogen association with wastewater particles.