Changes in thyroid function of nestling tree swallows (Tachycineta bicolor) in relation to polycyclic aromatic compounds and other environmental stressors in the Athabasca Oil Sands Region.

In the Canadian Athabasca Oil Sands Region (AOSR), nestling tree swallows (Tachycineta bicolor) raised near mining-related activities accumulated greater concentrations of polycyclic aromatic compounds (PACs) that contributed to their poorer condition, growth, and reproductive success. Here, we report changes in thyroid function of the same 14 day old (do) nestlings (N ≤ 68) at these mining-related sites (OS1, OS2) compared to reference nestlings (REF1), and in relation to multiple environmental stressors that influence avian thyroid function. Thyroid function was compromised for OS1 nestlings but generally comparable between OS2 and REF1 chicks. In 2012, circulating total triiodothyronine (TT3) and thyroxine (TT4) were similar among all nestlings. The OS1 chicks had more active thyroid glands based on histological endpoints. Hepatic T4 outer-ring deiodinase (T4-ORD) activity was suppressed in OS1 and OS2 chicks. Despite inter-annual differences, OS1 chicks continued experiencing compromised thyroid function with significantly higher circulating TT4 and more active thyroid glands in 2013. The OS2 chicks had less active thyroid glands, which conceivably contributed to their suppressed growth (previously reported) relative to the heavier OS1 nestlings with more active thyroid glands. Thyroid gland activity was more influenced by the chicks' accumulation of (muscle), than exposure (feces) to naphthalene, C2-naphthalenes, and C1-fluorenes. Of four major volatile organic contaminants, sulfur dioxide (SO2) primarily influenced thyroid gland activity and structure, supporting previous findings with captive birds. When collectively considering environmental-thyroidal stressors, chicks had a greater thyroidal response when they experienced colder temperatures, accumulated more C2-naphthalenes, and consumed aquatic-emerging insects with higher PAC burdens than terrestrial insects (carbon (δ13C)). We hypothesize that the more active thyroid glands and higher circulating TT4 of the OS1 chicks supported their growth and survival despite having the highest PAC burdens, whereas the lack of thyroid response in the OS2 chicks combined with high PAC burdens, contributed to their smaller size, poorer condition and poorer survival.

Reproductive and developmental changes in tree swallows (Tachycineta bicolor) are influenced by multiple stressors, including polycyclic aromatic compounds, in the Athabasca Oil Sands.

Mining in the Athabasca Oil Sands Region (AOSR) has contributed extensively to increased exposure of wildlife to naturally occurring polycyclic aromatic compounds (PACs), yet little is known about the toxicity of PACs to wildlife in this region. We identified reproductive and developmental changes in tree swallows (Tachycineta bicolor) breeding in close proximity to mining-related activities in the AOSR, and determined these changes in relation to the birds' exposure and accumulation of 41 PACs (parent-, alkylated-PAHs), dibenzothiophenes (DBTs; previously published), diet (carbon (δ13C), nitrogen (δ15N)), volatile organic compounds, and weather variables. Tree swallow pairs (N = 43) were compared among mining-related (OS1, OS2) and reference (REF1, REF2) sites. At OS2, clutch initiation was slightly advanced (2012) but reproductive success (65%) was much lower than at the other sites (≥ 79%). Fledgling production by each pair was influenced by the timing of clutch initiation (years combined); in a highly inclement brood rearing period (2013), additional influences included the nestlings' exposure to ΣDBTs, accumulation of C1-naphthalene, the trophic position of the prey in their diet (δ15N), and record-breaking rainfall. Nestlings at OS2 were significantly lighter at day (d) 9 and d14, and in poorer body condition (d9). Nestling body mass was influenced by multiple stressors that varied by site: mass of younger nestlings (d9) was related to dietary source (δ13C; e.g., wetlands, terrestrial fields), exposure and/or accumulation of C1-phenanthrenes, C2-fluorenes, Σalkyl-PAHs and ΣDBTs, while for older nestlings (d14), body mass was related to sex, hatch date and/or rainfall during brood rearing. The swallows' exposure and accumulation of parent-PACs, alkyl-PACs and DBTs, the timing of hatching, their diet and exposure to highly inclement rains, contributed to their reproductive and developmental changes.

Stable nitrogen isotopes of nestling tree swallows indicate exposure to different types of oil sands reclamation.

Tree swallows (Tachycineta bicolor) inhabiting reclaimed wetlands on the oil sands in northern Alberta are potentially exposed to elevated levels of oil sands constituents such as polycyclic aromatic compounds (PAC) through diet. While increased detoxification enzyme activity as measured using 7-ethoxyresorufin O-deethylase in nestlings is a generally accepted indicator of exposure to oil sands constituents, there is no apparent method to detect dietary exposure specific to oil sands processed material (OSPM). In this study, stable C and N isotopes were analyzed from muscle and feathers of nestling tree swallows (15 d old) to distinguish dietary exposure of birds near reference and OSPM wetlands. High δ¹5N and low δ¹³C values in the nestling tissues differentiated those from the OSPM wetlands and reference sites. Lower δ¹5N values of nestlings compared to the δ¹5N values of larval chironomids from an earlier study suggested that the majority of the diet of the nestlings was derived from non-OSPM sources, despite residence near and on the OSPM wetlands. Our finding of limited utilization of OSPM resources by tree swallows indicates either low abundance or diversity of dietary items emerging from OSPM wetlands, or sensory avoidance of prey from those wetlands. Minimal consumption of OSPM-derived dietary sources may be attributed to published findings of limited adverse effects on tree swallow reproduction, or growth and development for these same nestlings. This study demonstrated that stable isotope analysis, particularly for N isotopes, may serve as a useful tool to trace dietary exposure to OSPM constituents as part of avian ecotoxicology assessments of reclaimed wetlands on the oil sands.

Food web structure in oil sands reclaimed wetlands.

Boreal wetlands play an important role in global carbon balance. However, their ecosystem function is threatened by direct anthropogenic disturbance and climate change. Oil sands surface mining in the boreal regions of Western Canada denudes tracts of land of organic materials, leaves large areas in need of reclamation, and generates considerable quantities of extraction process-affected materials. Knowledge and validation of reclamation techniques that lead to self-sustaining wetlands has lagged behind development of protocols for reclaiming terrestrial systems. It is important to know whether wetlands reclaimed with oil sands process materials can be restored to levels equivalent to their original ecosystem function. We approached this question by assessing carbon flows and food web structure in naturally formed and oil sands-affected wetlands constructed in 1970-2004 in the postmining landscape. We evaluated whether a prescribed reclamation strategy, involving organic matter amendment, accelerated reclaimed wetland development, leading to wetlands that were more similar to their natural marsh counterparts than wetlands that were not supplemented with organic matter. We measured compartment standing stocks for bacterioplankton, microbial biofilm, macrophytes, detritus, and zoobenthos; concentrations of dissolved organic carbon and residual naphthenic acids; and microbial production, gas fluxes, and aquatic-terrestrial exports (i.e., aquatic insect emergence). The total biomass of several biotic compartments differed significantly between oil sands and reference wetlands. Submerged macrophyte biomass, macroinvertebrate trophic diversity, and predator biomass and richness were lower in oil sands-affected wetlands than in reference wetlands. There was insufficient evidence to conclude that wetland age and wetland amendment with peat-mineral mix mitigate effects of oil sands waste materials on the fully aquatic biota. Although high variability was observed within most compartments, our data show that 20-year-old wetlands containing oil sands material have not yet reached the same level of function as their reference counterparts.

Immunotoxicity and disease resistance in Japanese quail (Corturnix coturnix japonica) exposed to malathion.

The purpose of this study was to evaluate the impact of malathion on the immune system of wild birds, using Japanese quail (Coturnix coturnix japonica) as a model. Quail were exposed to malathion in drinking water at environmentally realistic concentrations (0 ppm, 1 ppm, and 10 ppm). In the fifth week, several arms of the immune response were tested using the T-cell based phytohemagglutinin (PHA) skin test, the B-cell mediated antibody response, and the chemiluminescence assay measuring innate immunity. After the sixth week of malathion exposure, quail were challenged with E. coli O2. The bursa of Fabricius and the spleen were assessed for histopathology. No clinical signs of malathion toxicity were observed. Morbidity or mortality subsequent to E. coli exposure tended (P = 0.08) to be higher in the high exposure group (50.0%) compared to the control (22.2%) group. There was no difference in the innate immune response in the malathion exposed birds, however, humoral immunity was suppressed (P = 0.03) with the higher malathion exposure. Histopathological evaluation revealed an immunosuppressive effect of malathion on the bursa of Fabricius; bursal atrophy, decreased B-cell density and increased apoptosis in the medulla, and increased connective tissue thickness of the follicular epithelium. Antibody suppression was correlated with bursal changes and peripheral blood lymphocyte count, the organ and cells involved in antibody production. Following the same pattern as other immunotoxicity tests, the PHA T-cell proliferative response also tended to be suppressed in the high exposure group. This study provides evidence that subchronic, moderate malathion exposure is immunotoxic to quail and that testing integrated, functional immunity using an infectious challenge is a better predictor of immunotoxicity than individual responses to immunotoxicity tests. The secondary antibody response, circulating lymphocyte populations, and bursal histopathology were the most sensitive indicators of immune status, as these predicted decreased disease resistance with malathion exposure.

Subchronic lead exposure, immunotoxicology and increased disease resistance in Japanese quail (Corturnix coturnix japonica).

The present study investigated the effects of lead (Pb) on immune responses in quail (Coturnix coturnix japonica) and the pathological impact of exposure to an infectious agent (E. coli O2). Fifty-four, 4-week-old quail were exposed to lead acetate in drinking water at 5 or 50 ppm. All birds were vaccinated with Newcastle Vaccine (NDV) during the third week of contaminant (Pb) exposure. In the fourth week, several arms of the immune response were tested using the T cell based phytohemagglutinin (PHA) skin test, the B cell mediated antibody response to NVD, and the chemiluminescence assay measuring innate immunity. Immunohistochemistry (IHC) was used to determine the expression of toll like receptor-3 (TLR-3) in the bursa of Fabricius. In the fifth week, quail were challenged with 200 µL of E. coli O2 (1×10(4) colony forming units (CFU)/mL). No clinical signs of Pb toxicity were observed. Morbidity/mortality subsequent to E. coli exposure was lowest in the high exposure group (27.8%) compared to low exposure (44.4%) and control (55.5%) groups. There was no difference in the T-cell-mediated PHA response, primary or secondary immune response or the innate response in Pb exposed groups; however, bursal TLR-3 increased (p<0.05) with higher Pb exposure. No evidence supported that subchronic Pb exposure was immunotoxic to quail at 5 or 50 ppm in drinking water. In contrast, our results provide evidence of a hormetic effect, with Pb exposed birds having lower morbidity and better survival than controls. Subchronic Pb exposure may be immunostimulatory rather than suppressive as predicted in earlier studies based on testing individual immune parameters.

Whole blood chemiluminescence response in broiler chickens on different experimental diets and challenged with Clostridium perfringens.

UNLABELLED: 1. OBJECTIVES: To validate the whole blood chemiluminescence (WBCL) assay in chickens, a simple and rapid method of measuring production of reactive oxygen species by circulating polymorphonuclear (PMN) leukocytes. To determine the physiological response and innate immune response associated with oral challenge with Clostridium perfringens in broiler chickens under different nutritional conditions. 2. In Experiment 1, birds were orally challenged with C. perfringens 1. type A or sham-challenged saline on days 14-21 post-hatch and fed protein-balanced diets containing 160 or 180 g crude protein/kg and 0.98 or 1.75% glycine in a 2 x 2 x 2 factorial arrangement of treatments. 2. Challenged birds had higher WBCL responses and more severe intestinal lesions than unchallenged birds. Birds fed diets containing 1.75% glycine had more intestinal lesions than those fed 0.98% glycine. 3. In Experiment 2 birds were fed protein-balanced diets containing 0.76, 2.10, 3.43 or 4.77% glycine. The birds fed 0.76% glycine diet had lower WBCL responses compared to birds fed the other three diets. Intestinal lesions were worse in the birds fed the highest, 4.77% glycine diet than in those fed the 0.76 or 2.10% glycine diets. 4. We conclude that the WBCL assay is a practical and sensitive means of assessing innate immune function in birds. The results suggest that both bacterial challenge and glycine content of chickens' diet influence their lesion scores and innate immune function.

Organochlorine contamination and physiological responses in nestling tree swallows in Point Pelee National Park, Canada.

Point Pelee National Park in southwestern Ontario, Canada--a major migratory route and vital breeding area for many birds--has localized areas of organochlorine (OC) contamination from the 1950s and 1960s. During 2002, we investigated the effect of tissue OC contaminant levels on the physiology and growth of nestling tree swallows (Tachycineta bicolor). Polychlorinated biphenyl (PCB) contamination in the nestlings positively correlated with hepatic ethoxy-, benzyloxy-, and pentoxyresorufin-o-dealkylase enzyme activities and liver size. Despite detectable physiologic changes associated with body burdens of PCBs, reproductive success of breeding pairs was not affected. Hatching date was negatively correlated with PCB levels, alkoxyresorufin-O-dealkylase (alkROD) activities, liver size, and serum protein levels. alkROD activities were largely dependent on hatching date because insect prey contaminated with PCBs were only abundant during a limited period of time during the breeding season.