Ecological Harm and Economic Damages of Chemical Contamination to Linked Aquatic-Terrestrial Food Webs: A Study-Design Tool for Practitioners.

Contamination of aquatic ecosystems can have cascading effects on terrestrial consumers by altering the availability and quality of aquatic insect prey. Comprehensive assessment of these indirect food-web effects of contaminants on natural resources and their associated services necessitates using both ecological and economic tools. In the present study we present an aquatic-terrestrial assessment tool (AT2), including ecological and economic decision trees, to aid practitioners and researchers in designing contaminant effect studies for linked aquatic-terrestrial insect-based food webs. The tool is tailored to address the development of legal claims by the US Department of the Interior's Natural Resource Damage Assessment and Restoration Program, which aims to restore natural resources injured by oil spills and hazardous substance releases into the environment. Such cases require establishing, through scientific inquiry, the existence of natural resource injury as well as the determination of the monetary or in-kind project-based damages required to restore this injury. However, this tool is also useful to researchers interested in questions involving the effects of contaminants on linked aquatic-terrestrial food webs. Stylized cases exemplify how application of AT2 can help practitioners and researchers design studies when the contaminants present at a site are likely to lead to injury of terrestrial aerial insectivores through loss of aquatic insect prey and/or dietary contaminant exposure. Designing such studies with ecological endpoints and economic modeling inputs in mind will increase the relevance and cost-effectiveness of studies, which can in turn improve the outcomes of cases and studies involving the ecological effects of contaminants on food webs. Environ Toxicol Chem 2023;42:2029-2039. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Reprint of: CYP1A protein expression and catalytic activity in double-crested cormorants experimentally exposed to Deepwater Horizon Mississippi Canyon 252 oil.

Double-crested cormorants (Phalacrocorax auritus, DCCO) were orally exposed to Deepwater Horizon Mississippi Canyon 252 (DWH) oil to investigate oil-induced toxicological impacts. Livers were collected for multiple analyses including cytochrome P4501A (CYP1A) enzymatic activity and protein expression. CYP1A enzymatic activity was measured by alkoxyresorufin O-dealkylase (AROD) assays. Activities specific to the O-dealkylation of four resorufin ethers are reported: benzyloxyresorufin O-debenzylase (BROD), ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), and pentoxyresorufin O-depentylase (PROD). CYP1A protein expression was measured by western blot analysis with a CYP1A1 mouse monoclonal antibody. In study 1, hepatic BROD, EROD, and PROD activities were significantly induced in DCCO orally exposed to 20ml/kg body weight (bw) oil as a single dose or daily for 5 days. Western blot analysis revealed hepatic CYP1A protein induction in both treatment groups. In study 2 (5ml/kg bw oil or 10ml/kg bw oil, 21day exposure), all four hepatic ARODs were significantly induced. Western blots showed an increase in hepatic CYP1A expression in both treatment groups with a significant induction in birds exposed to 10ml/kg oil. Significant correlations were detected among all 4 AROD activities in both studies and between CYP1A protein expression and both MROD and PROD activities in study 2. EROD activity was highest for both treatment groups in both studies while BROD activity had the greatest fold-induction. While PROD activity values were consistently low, the fold-induction was high, usually 2nd highest to BROD activity. The observed induced AROD profiles detected in the present studies suggest both CYP1A4/1A5 DCCO isoforms are being induced after MC252 oil ingestion. A review of the literature on avian CYP1A AROD activity levels and protein expression after exposure to CYP1A inducers highlights the need for species-specific studies to accurately evaluate avian exposure to oil.

CYP1A protein expression and catalytic activity in double-crested cormorants experimentally exposed to deepwater Horizon Mississippi Canyon 252 oil.

Double-crested cormorants (Phalacrocorax auritus, DCCO) were orally exposed to Deepwater Horizon Mississippi Canyon 252 (DWH) oil to investigate oil-induced toxicological impacts. Livers were collected for multiple analyses including cytochrome P4501A (CYP1A) enzymatic activity and protein expression. CYP1A enzymatic activity was measured by alkoxyresorufin O-dealkylase (AROD) assays. Activities specific to the O-dealkylation of four resorufin ethers are reported: benzyloxyresorufin O-debenzylase (BROD), ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), and pentoxyresorufin O-depentylase (PROD). CYP1A protein expression was measured by western blot analysis with a CYP1A1 mouse monoclonal antibody. In study 1, hepatic BROD, EROD, and PROD activities were significantly induced in DCCO orally exposed to 20ml/kg body weight (bw) oil as a single dose or daily for 5 days. Western blot analysis revealed hepatic CYP1A protein induction in both treatment groups. In study 2 (5ml/kg bw oil or 10ml/kg bw oil, 21day exposure), all four hepatic ARODs were significantly induced. Western blots showed an increase in hepatic CYP1A expression in both treatment groups with a significant induction in birds exposed to 10ml/kg oil. Significant correlations were detected among all 4 AROD activities in both studies and between CYP1A protein expression and both MROD and PROD activities in study 2. EROD activity was highest for both treatment groups in both studies while BROD activity had the greatest fold-induction. While PROD activity values were consistently low, the fold-induction was high, usually 2nd highest to BROD activity. The observed induced AROD profiles detected in the present studies suggest both CYP1A4/1A5 DCCO isoforms are being induced after MC252 oil ingestion. A review of the literature on avian CYP1A AROD activity levels and protein expression after exposure to CYP1A inducers highlights the need for species-specific studies to accurately evaluate avian exposure to oil.

Coordinating ecological restoration options analysis and risk assessment to improve environmental outcomes.

Ecological risk assessment as currently practiced has hindered consideration of ecosystem services endpoints and restoration goals in the environmental management process. Practitioners have created barriers between procedures to clean up contaminated areas and efforts to restore ecosystem functions. In this article, we examine linkages between contaminant risk assessment approaches and restoration efforts with the aim of identifying ways to improve environmental outcomes. We advocate that project managers and other stakeholders use an ecological planning framework, with restoration options included upfront in the risk assessment. We also considered the opportunities to incorporate ecosystem services as potential assessment endpoints in the Problem Formulation stages of a risk assessment. Indeed, diverse perspectives of stakeholders are central to understand the relevance of social, cultural, economic, and regional ecology as influences on future use options for the landscape being restored. The measurement endpoints used to characterize the existing ecological conditions for selected ecosystem services can also be used to evaluate restoration success. A regional, landscape, or seascape focus is needed throughout the risk assessment process, so that restoration efforts play a more prominent role in enhancing ecosystem services. In short, we suggest that practitioners begin with the question of "how can the ecological risk assessment inform the decision on how best to restore the ecosystem?"

Polybrominated diphenyl ethers in bald (Haliaeetus leucocephalus) and golden (Aquila chrysaetos) eagles from Washington and Idaho, USA.

Little is known about the exposure and accumulation of polybrominated diphenyl ethers (PBDEs) in the 2 species of eagles inhabiting North America. The authors analyzed the livers of 33 bald eagles and 7 golden eagles collected throughout Washington and Idaho, USA, for 51 PBDE congeners. Total PBDEs ranged from 2.4 ng/g to 9920 ng/g wet weight. Bald eagles and eagles associated with large urban areas had the highest PBDE concentrations; golden eagles and eagles from more sparsely populated areas had the lowest concentrations. Congener patterns in the present study (brominated diphenyl ether [BDE]-47, BDE-99, BDE-100, BDE-153, and BDE-154 dominating concentrations) were similar to those reported for other bird species, especially raptors. However, the authors also found elevated contributions of BDE-209 in golden eagles and BDE-77 in both species. Patterns in bald eagle samples reflected those in fillets of fish collected from the same general locations throughout Washington, suggesting local exposure to runoff-based contamination, whereas patterns in golden eagle samples suggest a difference in food chain uptake facilitated by atmospheric transport and deposition of BDE-209 and its degradation products into the terrestrial system. Data from the present study represent some of the first reported on burdens of PBDEs in juvenile and adult eagles from North America. The high PBDE liver concentrations associated with large metropolitan areas and accumulation of deca-BDE congeners are a cause for concern.

Marsh wrens as bioindicators of mercury in wetlands of Great Salt Lake: do blood and feathers reflect site-specific exposure risk to bird reproduction?

Nonlethal sampling of bird blood and feathers are among the more common ways of estimating the risk of mercury exposure to songbird reproduction. The implicit assumption is that mercury concentrations in blood or feathers of individuals captured in a given area are correlated with mercury concentrations in eggs from the same area. Yet, this assumption is rarely tested. We evaluated mercury concentrations in blood, feathers, and eggs of marsh wrens in wetlands of Great Salt Lake, Utah, and, at two spatial scales, specifically tested the assumption that mercury concentrations in blood and feather samples from birds captured in a defined area were predictive of mercury concentrations in eggs collected in the same area. Mercury concentrations in blood were not correlated with mercury concentrations in eggs collected within the same wetland unit, and were poorly correlated with mercury concentrations in eggs collected at the smaller home range spatial scale of analysis. Moreover, mercury exposure risk, as estimated via tissue concentrations, differed among wetland units depending upon whether blood or egg mercury concentrations were sampled. Mercury concentrations in feathers also were uncorrelated with mercury concentrations in eggs, and were poorly correlated with mercury concentrations in blood. These results demonstrate the potential for contrasting management actions that may be implemented based solely on the specific avian tissue that is sampled, and highlight the importance of developing avian tissues as biomonitoring tools for assessing local risk of mercury exposure to bird reproduction.

Behavioral, clinical, and pathological characterization of acid metalliferous water toxicity in mallards.

From September to November 2000, United States Fish and Wildlife Service biologists investigated incidents involving 221 bird deaths at 3 mine sites located in New Mexico and Arizona. These bird deaths primarily involved passerine and waterfowl species and were assumed to be linked to consumption of acid metalliferous water (AMW). Because all of the carcasses were found in or near pregnant leach solution ponds, tailings ponds, and associated lakes or storm water retention basins, an acute-toxicity study was undertaken using a synthetic AMW (SAMW) formulation based on the contaminant profile of a representative pond believed to be responsible for avian mortalities. An acute oral-toxicity trial was performed with a mixed-sex group of mallards (Anas platyrhynchos). After a 24-h pretreatment food and water fast, gorge drinking was evident in both SAMW treatment and control groups, with water consumption rates greatest during the initial drinking periods. Seven of nine treated mallards were killed in extremis within 12 h after the initiation of dose. Total lethal doses of SAMW ranged from 69.8 to 270.1 mL/kg (mean ± SE 127.9 ± 27.1). Lethal doses of SAMW were consumed in as few as 20 to 40 min after first exposure. Clinical signs of SAMW toxicity included increased serum uric acid, aspartate aminotransferase, creatine kinase, potassium, and P levels. PCV values of SAMW-treated birds were also increased compared with control mallards. Histopathological lesions were observed in the esophagus, proventriculus, ventriculus, and duodenum of SAMW-treated mallards, with the most distinctive being erosion and ulceration of the kaolin of the ventriculus, ventricular hemorrhage and/or congestion, and duodenal hemorrhage. Clinical, pathological, and tissue-residue results from this study are consistent with literature documenting acute metal toxicosis, especially copper (Cu), in avian species and provide useful diagnostic profiles for AMW toxicity or mortality events. Blood and kidney Cu concentrations were 23- and 6-fold greater, respectively, in SAMW mortalities compared with controls, whereas Cu concentrations in liver were not nearly as increased, suggesting that blood and kidney concentrations may be more useful than liver concentrations for diagnosing Cu toxicosis in wild birds. Based on these findings and other reports of AMW toxicity events in wild birds, we conclude that AMW bodies pose a significant hazard to wildlife that come in contact with them.

Fipronil toxicity in northern bobwhite quail Colinus virginianus: reduced feeding behaviour and sulfone metabolite formation.

Fipronil is a phenyl pyrazole insecticide registered for agricultural use in many countries. Avian exposure to fipronil occurs mainly by ingesting contaminated insects or seeds. There is little information regarding the toxicological effects of fipronil in avian species and even less research documenting avian behavioural responses to fipronil ingestion. We examined the effects of a single oral dose of fipronil in northern bobwhite quail, the most fipronil-sensitive species tested to date, in respect to signs of intoxication and the metabolic fate of fipronil. Fipronil-treated birds did not eat or drink following pesticide administration, and as a result lost a significant amount of body mass. Treated birds also appeared withdrawn and did not respond to disturbance within the first hour after treatment. Identifiable signs of fipronil toxicity were not observed until at least 2d after treatment. Chemical analyses indicated a difference between fipronil and fipronil-sulfone residue distribution and bioaccumulation, with significantly higher (30- to 1000-fold) tissue concentrations of the sulfone detected at all time points from 8 to 96 h post-dose in brain, liver and adipose tissues. Tissue sulfone concentrations increased significantly in fipronil-treated birds, peaking at 72 h post-dose. Body mass decreased at all time points in dosed birds. The coincidence of the particular intoxication symptoms with the time course of rise in brain sulfone levels after fipronil dosing gives insight into possible mechanisms of toxicity in this highly sensitive species.

Responses of glutamate cysteine ligase and glutathione to oxidants in deer mice (Peromyscus maniculatus).

Sensitivities of a wildlife species, deer mice, to oxidants were evaluated. A single dose (1589 mg/kg body weight by intraperitoneal injection) of carbon tetrachloride, a typical hepatotoxicant, caused changes in GCL activity and GSH content in multiple organs of deer mice. Hepatic GCL activity and GSH content were depleted substantially (P<0.01), renal GCL activity increased (P<0.05). Blood, brain and heart GCL activities increased (P<0.05), whereas GSH contents decreased significantly. Deer mice were exposed to Pb, or Pb together with Cu and Zn via drinking water for 4 weeks. GCL activities were not significantly affected by treatments. GSH contents were increased significantly by Pb alone, Pb with medium and high concentrations of Cu and Zn. Effects of multi-metal-contaminated soil were investigated via lactational, juvenile and lifelong exposure to feed supplemented with soils. Metal-contaminated soils did not lead to significant effects in pups via lactation, 50-day exposure altered GSH content marginally, while 100-day exposure resulted in marked GCL activity depletion. After 100-day exposure, GCL activities of the medium soil-, high soil- and Pb-treated deer mice were only 53%, 40% and 46% of the control, respectively (P<0.0001).

Optimization and application of glutamate cysteine ligase measurement in wildlife species.

Glutamate cysteine ligase (GCL), synthesizing gamma-glutamylcysteine from glutamate and cysteine, is the rate-limiting enzyme in glutathione (GSH) biosynthesis. GCL activity measurement was optimized in tissues from deer mice, Sprague Dawley rats, and mallard ducks. Varying glutamic acid concentrations from 5 to 80 mM did not affect GCL activities markedly, whereas cysteine concentrations from 2.5 to 40 mM influenced GCL activities substantially. Optimal cysteine concentrations for deer mouse, Sprague Dawley rat, and mallard duck (respectively) were 30, 30, and 20 mM in liver, 10, 10, and 20 mM in kidney, 20, 20, and 30 mM in brain, and 30 mM in heart for all three species. Responses of mallard duck GCL activity to acid metalliferous water were evaluated. After subacute exposure, low doses increased GCL activity and GSH content in liver by 48.3% and 54.4%, respectively. High doses reduced GCL activities significantly in liver and kidney to 31.2% and 43.0% of the control, respectively.

Effects of perchlorate exposure on resting metabolism, peak metabolism, and thyroid function in the prairie vole (Microtus ochrogaster).

Perchlorate, the oxidizer component in most solid rocket propellant formulations, is known to inhibit the uptake of iodide into the thyroid gland, thereby reducing production of the thyroid hormones, triiodothyronine and thyroxine (T4). Thyroid hormones regulate metabolism in endothermic organisms and are responsible for maintenance of homeothermic body temperatures. Little is known about the effects of perchlorate on metabolic capacity. The objectives of the present study were to determine if subchronic (51 d; 0, 1, and 10 mg/kg/d) and chronic (180 d; 0.75 mg/kg/d) perchlorate exposure in adult male prairie voles (Microtus ochrogaster) would alter resting metabolic rates as a result of decreased circulating thyroid hormone concentrations and to determine if perchlorate exposure disrupts thermogenesis in mammals exposed to cold stress. Voles exposed to perchlorate for 51 or 180 d experienced no significant alterations in resting metabolic rates at any point during the exposure period. Additionally, the treatment had no effect on peak metabolic rates or plasma thyroid hormone concentrations. However, thyroid gland T4 concentrations were significantly lower in perchlorate-exposed voles than in controls, indicating that thyroid gland T4 content may be a more sensitive endpoint than other thyroid variables for assessing perchlorate exposure. Overall, the present study did not provide evidence for energetic alterations associated with perchlorate exposure at concentrations that are higher than those typically found in groundwater or surface water in the environment.