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At least 235 records · Page 13Linked to original sources

USGS2018

Characterization of Plasmodium relictum, a cosmopolitan agent of avian malaria

Background Microscopic research has shown that Plasmodium relictum is the most common agent of avian malaria. Recent molecular studies confirmed this conclusion and identified several mtDNA lineages, suggesting the existence of significant intra-species genetic variation or cryptic speciation. Most identified lineages have a broad range of hosts and geographical distribution. Here, a rare new lineage of P. relictum was reported and information about biological characters of different lineages of this pathogen was reviewed, suggesting issues for future research. Methods The new lineage pPHCOL01 was detected in Common chiffchaff Phylloscopus collybita, and the parasite was passaged in domestic canaries Serinus canaria . Organs of infected birds were examined using histology and chromogenic in situ hybridization methods. Culex quinquefasciatus mosquitoes, Zebra finch Taeniopygia guttata, Budgerigar Melopsittacus undulatus and European goldfinch Carduelis carduelis were exposed experimentally. Both Bayesian and Maximum Likelihood analyses identified the same phylogenetic relationships among different, closely-related lineages pSGS1, pGRW4, pGRW11, pLZFUS01, pPHCOL01 of P. relictum. Morphology of their blood stages was compared using fixed and stained blood smears, and biological properties of these parasites were reviewed. Results Common canary and European goldfinch were susceptible to the parasite pPHCOL01, and had markedly variable individual prepatent periods and light transient parasitaemia. Exo-erythrocytic and sporogonic stages were not seen. The Zebra finch and Budgerigar were resistant. Neither blood stages nor vector stages of all examined P. relictum lineages can be distinguished morphologically. Conclusion Within the huge spectrum of vertebrate hosts, mosquito vectors, and ecological conditions, different lineages of P. relictum exhibit indistinguishable, markedly variable morphological forms. Parasites of same lineages often develop differently in different bird species. Even more, the variation of biological properties (parasitaemia dynamics, blood pathology, prepatent period) in different isolates of the same lineage might be greater than the variation in different lineages during development in the same species of birds, indicating negligible taxonomic value of such features. Available lineage information is excellent for parasite diagnostics, but is limited in predictions about relationships in certain host-parasite associations. A combination of experiments, field observations, microscopic and molecular diagnostics is essential for understanding the role of different P. relictum lineages in bird health.

Malaria Journal↗

USGS2012

Molecular detection of hematozoa infections in tundra swans relative to migration patterns and ecological conditions at breeding grounds

Tundra swans ( Cygnus columbianus ) are broadly distributed in North America, use a wide variety of habitats, and exhibit diverse migration strategies. We investigated patterns of hematozoa infection in three populations of tundra swans that breed in Alaska using satellite tracking to infer host movement and molecular techniques to assess the prevalence and genetic diversity of parasites. We evaluated whether migratory patterns and environmental conditions at breeding areas explain the prevalence of blood parasites in migratory birds by contrasting the fit of competing models formulated in an occupancy modeling framework and calculating the detection probability of the top model using Akaike Information Criterion (AIC). We described genetic diversity of blood parasites in each population of swans by calculating the number of unique parasite haplotypes observed. Blood parasite infection was significantly different between populations of Alaska tundra swans, with the highest estimated prevalence occurring among birds occupying breeding areas with lower mean daily wind speeds and higher daily summer temperatures. Models including covariates of wind speed and temperature during summer months at breeding grounds better predicted hematozoa prevalence than those that included annual migration distance or duration. Genetic diversity of blood parasites in populations of tundra swans appeared to be relative to hematozoa prevalence. Our results suggest ecological conditions at breeding grounds may explain differences of hematozoa infection among populations of tundra swans that breed in Alaska.

Alaska↗

USGS2014

Environmental and physiological influences to isotopic ratios of N and protein status in a montane ungulate in winter

Winter severity can influence large herbivore populations through a reduction in maternal proteins available for reproduction. Nitrogen (N) isotopes in blood fractions can be used to track the use of body proteins in northern and montane ungulates. We studied 113 adult female caribou for 13 years throughout a series of severe winters that reduced population size and offspring mass. After these severe winters, offspring mass increased but the size of the population remained low. We devised a conceptual model for routing of isotopic N in blood in the context of the severe environmental conditions experienced by this population. We measured δ 15 N in three blood fractions and predicted the relative mobilization of dietary and body proteins. The δ 15 N of the body protein pool varied by 4‰ and 46% of the variance was associated with year. Annual variation in δ 15 N of body protein likely reflected the fall/early winter diet and winter locations, yet 15% of the isotopic variation in amino acid N was due to body proteins. Consistent isotopic differences among blood N pools indicated that animals tolerated fluxes in diet and body stores. Conservation of body protein in caribou is the result of active exchange among diet and body N pools. Adult females were robust to historically severe winter conditions and prioritized body condition and survival over early investment in offspring. For a vagile ungulate residing at low densities in a predator-rich environment, protein restrictions in winter may not be the primary limiting factor for reproduction.

Alaska↗

USGS2014

Suppressing bullfrog larvae with carbon dioxide

Current management strategies for the control and suppression of the American Bullfrog ( Lithobates catesbeianus = Rana catesbeiana Shaw) and other invasive amphibians have had minimal effect on their abundance and distribution. This study evaluates the effects of carbon dioxide (CO 2 ) on pre- and prometamorphic Bullfrog larvae. Bullfrogs are a model organism for evaluating potential suppression agents because they are a successful invader worldwide. From experimental trials we estimated that the 24-h 50% and 99% lethal concentration (LC 50 and LC 99 ) values for Bullfrog larvae were 371 and 549 mg CO 2 /L, respectively. Overall, larvae that succumbed to experimental conditions had a lower body condition index than those that survived. We also documented sublethal changes in blood chemistry during prolonged exposure to elevated CO 2 . Specifically, blood pH decreased by more than 0.5 pH units after 9 h of exposure and both blood partial pressure of CO 2 (pCO 2 ) and blood glucose increased. These findings suggest that CO 2 treatments can be lethal to Bullfrog larvae under controlled laboratory conditions. We believe this work represents the necessary foundation for further consideration of CO 2 as a potential suppression agent for one of the most harmful invaders to freshwater ecosystems.

Journal of Herpetology↗

USGS2007

Bioenergetic and pharmacokinetic model for exposure of common loon (Gavia immer) chicks to methylmercury

A bioenergetics model was used to predict food intake of common loon (Gavia immer) chicks as a function of body mass during development, and a pharmacokinetics model, based on first-order kinetics in a single compartment, was used to predict blood Hg level as a function of food intake rate, food Hg content, body mass, and Hg absorption and elimination. Predictions were tested in captive growing chicks fed trout (Salmo gairdneri) with average MeHg concentrations of 0.02 (control), 0.4, and 1.2 ??g/g wet mass (delivered as CH3HgCl). Predicted food intake matched observed intake through 50 d of age but then exceeded observed intake by an amount that grew progressively larger with age, reaching a significant overestimate of 28% by the end of the trial. Respiration in older, nongrowing birds probably was overestimated by using rates measured in younger, growing birds. Close agreement was found between simulations and measured blood Hg, which varied significantly with dietary Hg and age. Although chicks may hatch with different blood Hg levels, their blood level is determined mainly by dietary Hg level beyond approximately two weeks of age. The model also may be useful for predicting Hg levels in adults and in the eggs that they lay, but its accuracy in both chicks and adults needs to be tested in free-living birds. ?? 2007 SETAC.

Environmental Toxicology and Chemistry↗

USGS1990

Lead hazards within the range of the California condor

The prevalence of lead in Golden Eagles (Aquila chrysaetos) occurring within the recent historical range of the California Condor (Gymnogyps californianus) was determined by analyzing blood samples from 162 Golden Eagles captured between June 1985 and December 1986 at three sites. We found no significant differences between sex and age classes in blood lead levels nor were there differences between residents and migrants. Significant differences were found between months with the highest blood lead levels occurring during the fall/winter period. Approximately one-third (35.8%) of the Golden Eagle population sampled had elevated blood lead levels, values similar to those reported for free-flying California Condors. Given this rate of exposure, if the proposed releases of California Condors back to the wild are to succeed, whether in their former range or elsewhere, any potential for lead poisoning must be reduced. It is essential that we identify the sources of the lead, the seasonal and geographic distribution of these sources, and develop management strategies to reduce or eliminate the hazard.

California↗

USGS2000

Condition bias of hunter-shot ring-necked ducks exposed to lead

We evaluated the condition bias hypothesis for ring-necked ducks ( Aythya collaris ) exposed to lead by testing the null hypothesis that ducks shot by hunters do not differ in physiological condition from those collected randomly from the same location. After adjusting for structural body size and log(e) concentration of blood lead, we found that overall body condition differed significantly between collection types and age classes, and marginally between sexes. Ingesta-free body mass of ring-necked ducks sampled randomly averaged 8.8% greater than those shot over decoys, and 99% of this difference was accounted for by lipid reserves. Ingesta, ash, and protein did not differ between collection types; however, after-hatching-year (AHY) birds had 5.1% more ash and 4.8% more protein than did hatching-year (HY) birds. The only sex difference was that males had 4.1% more protein than did females. Ingesta-free body mass, lipids, and protein were negatively related to concentration of blood lead. Collection type-by-concentration of blood lead and age-by-sex-by-concentration of blood lead interactions were not significant. To the extent that lead pellets persist as a cause of disease or mortality, waterfowl biologists should account for lead exposure as a possible source of condition bias when estimating population parameters and modeling survival of ring-necked ducks and other waterfowl species prone to ingest lead. These findings further underscore the problem that ingested lead shotgun pellets pose for waterfowl.

Louisiana↗

USGS1993

Environmental contaminants in bald eagles in the Columbia River Estuary

Eggs, blood, and carcasses of bald eagles ( Haliaeetus leucocephalus ) and fish were collected and breeding success of eagles was monitored in the Columbia River estuary, 1980-87, to determine if contaminants were having an effect on productivity. High levels of dichloro diphenyl dichloroethylene (DDE), polychlorinated biphenyls (PCB's), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were found in eggs, blood from adults, and 2 eagle carcasses. Detectable levels of DDE and PCB's were found in blood of nestlings indicating they were exposed to these contaminants early in life. Increasing concentrations of DDE and PCB's with age also indicated accumulation of these contaminants. Adult eagles also had higher levels of mercury (Hg) in blood than subadults or young indicating accumulation with age. The high levels of DDE and PCB's were associated with eggshell thinning (x̄ = 10%) and with productivity (x̄ = 0.56 young/occupied site) that was lower than that of healthy populations (i.e., ≥1.00 young/occupied site). DDE and PCB's had a deleterious effect on reproduction of bald eagles in the estuary. The role dioxins play in eagle reproduction remains unclear, but concentrations in eagle eggs were similar to those in laboratory studies on other species where dioxins adversely affected hatchability of eggs. Probable sources of these contaminants include dredged river sediments and hydroelectric dams, and the proper management of each may reduce the amount of contaminants released into the Columbia River estuary.

Oregon, Washington↗

USGS1990

Effects of winter undernutrition on body composition and physiological profiles of white-tailed deer

We examined the effects of undernutrition and recovery on body composition and blood and urinary profiles of 6 captive white-tailed deer ( Odocoileus virginianus ) between 18 December 1984 and 3 May 1985. Deer were weighed, and blood and urine were collected every 2 weeks from 10 January to 3 May. At Weeks 2, 8, and 14, body composition was estimated by the dilution of tritiated water technique and standard predictive equations. Feed intake decreased and cumulative mass loss increased during nutritional restriction. Baseline body composition included 62.1 ± 0.9 (SE)% water, 11.9 ± 1.0% fat, 20.5 ± 0.7% protein, and 4.5 ± 0.0% ash. Percent protein loss was linearly related (r 2 = 0.91, P < 0.001) to percent mass loss. Peak mass loss from the beginning of the study (12.8 ± 2.0%) occurred at Week 12; estimated protein loss was 12.5%. Fat reserves were 85% depleted from Week 2 to Week 14. Elevated packed cell volume (PCV), serum calcium (Ca), cholesterol, triglycerides, and cortisol; and diminished serum urea nitrogen, thyroxine (T4), urinary urea nitrogen: creatinine and potassium: creatinine were associated with reduced food intake, mass loss, and decreases in body water, fat, and protein. Altered values of most of these blood and urinary characteristics reflected initiation of nutritional recovery after nutrition improved. Sequential data collection and the use of a combination of indices in blood or urine will yield the most useful assessments of animal nutrition and condition.

Minnesota↗

USGS1998

Lead poisoning and trace elements in common eiders Somateria mollissima from Finland

We collected carcasses of 52 common eider Somateria mollissima adults and ducklings and blood samples from 11 nesting eider hens in the Gulf of Finland near Helsinki in 1994, 1995 and 1996. Samples of liver tissue were analysed for arsenic, cadmium, chromium, copper, iron, lead, magnesium, manganese, mercury, molybdenum, selenium and zinc. Blood was analysed for lead, mercury and selenium. Most of the 21 adults examined at necropsy were emaciated with empty gizzards, and no ingested shotgun pellets or other metal were found in any of the birds. Three adult females had a combination of lesions and tissue lead residues characteristic of lead poisoning. Two of these birds had acid-fast intranuclear inclusion bodies in renal epithelial cells and high concentrations of lead (73.4 and 73.3 ppm; all liver residues reported on dry weight basis) in their livers. The third was emaciated with a liver lead concentration of 47.9 ppm. An adult male had a liver lead concentration of 81.7 ppm, which is consistent with severe clinical poisoning. Two other adults, one male and one female, had liver lead concentrations of 14.2 and 8.03 ppm, respectively. Lead concentrations in the blood of hens ranged from 0.11 to 0.63 ppm wet weight. Selenium residues of A?60 ppm were found in the livers of five adult males. Selenium concentrations in the blood of hens ranged from 1.18 to 3.39 ppm wet weight. Arsenic concentrations of 27.5-38.5 ppm were detected in the livers of four adult females. Detectable concentrations of selenium, mercury and molybdenum were found more frequently in the livers of adult males arriving on the breeding grounds than in incubating females, while the reverse was true for arsenic, lead and chromium. Mean concentrations of selenium, copper and molybdenum were higher in the livers of arriving males than in the livers of incubating hens, but hens had greater concentrations of iron and magnesium. Concentrations of trace elements were lower in the livers of ducklings than in the livers of adults.

Wildlife Biology↗

USGS2001

Immune status of free-ranging green turtles with fibropapillomatosis from Hawaii

Cell-mediated and humoral immune status of free-ranging green turtles ( Chelonia mydas ) in Hawaii (USA) with and without fibropapillomatosis (FP) were assessed. Tumored and non-tumored turtles from Kaneohe Bay (KB) on the island of Oahu and from FP-free areas on the west (Kona/Kohala) coast of the island of Hawaii were sampled from April 1998 through February 1999. Turtles on Oahu were grouped (0–3) for severity of tumors with 0 for absence of tumors, 1 for light, 2 for moderate, and 3 for most severe. Turtles were weighed, straight carapace length measured and the regression slope of weight to straight carapace length compared between groups (KB0, KB1, KB2, KB3, Kona). Blood was assayed for differential white blood cell count, hematocrit, in vitro peripheral blood mononuclear cell (PBMC) proliferation in the presence of concanavalin A (ConA) and phytohaemagglutinin (PHA), and protein electrophoresis. On Oahu, heterophil/lymphocyte ratio increased while eosinophil/monocyte ratio decreased with increasing tumors score. Peripheral blood mononuclear cell proliferation indices for ConA and PHA were significantly lower for turtles with tumor scores 2 and 3. Tumor score 3 turtles (KB3) had significantly lower hematocrit, total protein, alpha 1, alpha 2, and gamma globulins than the other four groups. No significant differences in immune status were seen between non-tumored (or KB1) turtles from Oahu and Hawaii. There was no significant difference between groups in regression slopes of body condition to carapace length. We conclude that turtles with severe FP are imunosuppressed. Furthermore, the lack of significant difference in immune status between non-tumored (and KB1) turtles from Oahu and Kona/Kohala indicates that immunosuppression may not be a prerequisite for development of FP.

Hawai'i↗

USGS2001

Hematological and serum chemistry norms for sandhill and whooping cranes

The normal values used as a diagnostic tool and for comparison of cranes were established in the early 1970's. In that early study, no effort was made to look at factors such as age, sex, or subspecies. In addition, during the early study disease problems (primarily disseminated visceral coccidiosis) and nutritional problems were undiagnosed and uncontrolled. For 2 years during the annual health examinations of cranes at the USGS Patuxent Wildlife Research Center (Patuxent), we collected blood from healthy cranes for analysis. We found significant differences between the values reported from the 1970's and the values seen in this study for 8 blood parameters for Florida sandhill cranes (Grus canadensis pratensis), 6 blood parameters for greater sandhill cranes (G. c. tabida), and 6 blood parameters for whooping cranes (Grus americana). In addition, there were significant differences for some hematology and serum chemistry values based on the age of the cranes.

Book chapter↗

USGS2006

Phosphorus amendment reduces hematological effects of lead in mallards ingesting contaminated sediments

Lead poisoning of waterfowl has been reported for decades in the Coeur d?Alene River Basin (CDARB) in Idaho as a result of the ingestion of lead-contaminated sediments. This study was conducted to determine whether the addition of phosphoric acid to sediments would reduce the bioavailability and toxicity of lead to mallards (Anas platyrhynchos) as related to adverse hematological effects and altered plasma chemistries. Mallards received diets containing 12% clean sediment (controls) or 12% sediment from three different CDARB sites containing 4520, 5390, or 6990 :g/g lead (dw) with or without phosphoric acid amendment. Blood lead concentrations were significantly higher in all CDARB treatment groups and ranged from geometric mean values of 5.0 ug/g for the first two sites to 6.2 ug/g for the third site. With amendments, all blood lead concentrations became 41% to 64% lower. Red blood cell ALAD activity was depressed by 90% or more with lead-contaminated sediment from all sites and did not differ with amended diets. Free erythrocyte protoporphyrin (FEP) concentrations were elevated by contaminated sediment from all sites. Amendment decreased the elevations in FEP by as much as 80%. Hematocrit values and hemoglobin concentrations were lower for all lead site sediments by as much as 30% for site 3. Plasma enzyme activities for ALT, CK, and LDH-L were elevated by as much as 2.2-fold, and plasma creatinine concentration was 1.7-fold higher for site 3 sediment. Amendments restored hematocrit, hemoglobin, and plasma enzyme activities so that they did not differ from controls. Although amendments of phosphorus substantially reduced the bioavailability of lead and alleviated many of the adverse hematological effects, lead concentrations in the blood of mallards fed the amended sediments were still above those believed to be harmful to waterfowl under the present conditions.

Archives of Environmental Contamination and Toxico↗

USGS2011

Toxic effects of dietary methylmercury on immune function and hematology in American kestrels (Falco sparverius)

Fifty-nine adult male American kestrels ( Falco sparverius ) were assigned to one of three diet formulations including 0 (control), 0.6, and 3.9 μg/g (dry wt) methylmercury (MeHg). Kestrels received their diets daily for 13 weeks to assess the effects of dietary MeHg on immunocompetence. Immunotoxic endpoints included assessment of cell-mediated immunity (CMI) using the phytohemagglutinin (PHA) skin-swelling assay and primary and secondary antibody-mediated immune responses (IR) via the sheep red blood cell (SRBC) hemagglutination assay. Select hematology and histology parameters were evaluated to corroborate the results of functional assays and to assess immunosuppression of T and B cell-dependent components in spleen tissue. Kestrels in the 0.6 and 3.9 μg/g MeHg groups exhibited suppression of CMI, including lower PHA stimulation indexes ( p = 0.019) and a 42 to 45% depletion of T cell-dependent splenic lymphoid tissue ( p = 0.006). Kestrels in the 0.6 μg/g group exhibited suppression of the primary IR to SRBCs ( p = 0.014). MeHg did not have a noticeable effect on the secondary IR ( p = 0.166). Elevation of absolute heterophil counts ( p < 0.001), the heterophil to lymphocyte ratio ( p < 0.001), and total white blood cell counts ( p = 0.003) was apparent in the 3.9 μg/g group at week 12. Heterophilia, or the excess of heterophils in peripheral blood above normal ranges, was apparent in seven of 17 (41%) kestrels in the 3.9 μg/g group and was indicative of an acute inflammatory response or physiological stress. This study revealed that adult kestrels were more sensitive to immunotoxic effects of MeHg at environmentally relevant dietary concentrations than they were to reproductive effects as previously reported.

Environmental Toxicology and Chemistry↗

USGS2024

Methylmercury effects on birds: A review, meta-analysis, and development of toxicity reference values for injury assessment based on tissue residues and diet

Birds are used as bioindicators of environmental mercury (Hg) contamination, and toxicity reference values are needed for injury assessments. We conducted a comprehensive review, summarized data from 168 studies, performed a series of Bayesian hierarchical meta-analyses, and developed new toxicity reference values for the effects of methylmercury (MeHg) on birds using a benchmark dose analysis framework. Lethal and sublethal effects of MeHg on birds were categorized into nine biologically relevant endpoint categories and three age classes. Effective Hg concentrations where there was a 10% reduction (EC10) in the production of juvenile offspring (0.55 µg/g wet wt adult blood-equivalent Hg concentrations, 80% credible interval: [0.33, 0.85]), histology endpoints (0.49 [0.15, 0.96] and 0.61 [0.09, 2.48]), and biochemical markers (0.77 [<0.25, 2.12] and 0.57 [0.35, 0.92]) were substantially lower than those for survival (2.97 [2.10, 4.73] and 5.24 [3.30, 9.55]) and behavior (6.23 [1.84, >13.42] and 3.11 [2.10, 4.64]) of juveniles and adults, respectively. Within the egg age class, survival was the most sensitive endpoint (EC10 = 2.02 µg/g wet wt adult blood-equivalent Hg concentrations [1.39, 2.94] or 1.17 µg/g fresh wet wt egg-equivalent Hg concentrations [0.80, 1.70]). Body morphology was not particularly sensitive to Hg. We developed toxicity reference values using a combined survival and reproduction endpoints category for juveniles, because juveniles were more sensitive to Hg toxicity than eggs or adults. Adult blood-equivalent Hg concentrations (µg/g wet wt) and egg-equivalent Hg concentrations (µg/g fresh wet wt) caused low injury to birds (EC1) at 0.09 [0.04, 0.17] and 0.04 [0.01, 0.08], moderate injury (EC5) at 0.6 [0.37, 0.84] and 0.3 [0.17, 0.44], high injury (EC10) at 1.3 [0.94, 1.89] and 0.7 [0.49, 1.02], and severe injury (EC20) at 3.2 [2.24, 4.78] and 1.8 [1.28, 2.79], respectively. Maternal dietary Hg (µg/g dry wt) caused low injury to juveniles at 0.16 [0.05, 0.38], moderate injury at 0.6 [0.29, 1.03], high injury at 1.1 [0.63, 1.87], and severe injury at 2.4 [1.42, 4.13]. We found few substantial differences in Hg toxicity among avian taxonomic orders, including for controlled laboratory studies that injected Hg into eggs. Our results can be used to quantify injury to birds caused by Hg pollution.

Environmental Toxicology and Chemistry↗

USGS2011

Lead exposure and poisoning of songbirds using the Coeur d'Alene River Basin, Idaho, USA

Previous studies have found widespread Pb poisoning of waterfowl in the Coeur d'Alene River Basin in northern Idaho, USA, which has been contaminated by mining and smelting activities. We studied the exposure of ground-feeding songbirds to Pb, sampling 204 American robins ( Turdus migratorius ), song sparrows ( Melospiza melodia ), and Swainson's thrushes ( Catharus ustulatus ) throughout the basin. These songbirds had mean blood Pb concentrations (mg/kg, dry weight) of less than 0.19 at a reference area (25 mg Pb/kg soil), 1.09 at moderately contaminated sites (170 to 1300 mg Pb/kg soil), and 2.06 at highly contaminated sites (2000 to 5000 mg Pb/kg soil). Based on guidelines for evaluating blood Pb in birds, 6% of robins from the highly contaminated sites had background concentrations, 24% were subclinically poisoned, 52% were clinically poisoned, and 18% were severely clinically poisoned with Pb. Blood Pb concentrations were lower in song sparrows than in robins and lowest in Swainson's thrushes. More than half of the robins and song sparrows from all contaminated sites and more than half of the Swainson's thrushes from highly contaminated sites showed at least 50% inhibition of the activity of the enzyme δ-aminolevulinic acid dehydratase (ALAD), commonly used as a measure of exposure to Pb. The highest hepatic Pb concentration of 61 mg/kg (dry weight) was detected in a song sparrow. Using Al as a marker for soil in songbird ingesta, we estimated average soil ingestion rates as 20% in robins, 17% in song sparrows, and 0.7% in Swainson's thrushes. Soil Pb in ingesta accounted for almost all of the songbirds' exposure to Pb. Based on these results, it is recommended that ecological risk assessments of ground-feeding songbirds at contaminated sites include soil ingestion as a pathway of exposure to Pb.

Idaho↗

USGS1989

Preliminary characterization of a virus causing infectious anemia among stocks of salmonid fish in the western United States

Since 1982, anemias occurring in stocks of yearling coho ( Oncorhynchus kisutch ) and chinook salmon (Oncorhynchus tshawytscha ) have been associated with serious losses at hatcheries in the Pacific Northwest, USA. The anemia is often accompanied by infections with external fungus (e.g. Saprolegnia) or the bacterial pathogens Cytophaga psychrophila or Renibacterium salmoninarum (Holt and Rohovec 1984, Leek 1987). The losses associated with the anemia are thought to be caused by these secondary infections. Blood smears that were made from anemic fish and stained with Giemsa or pinacyanol chloride showed erythrocytic inclusions ranging in size from 1 to 8 um and varying in number per cell. Thin sections of infected red blood cells (RBC) examined by electron microscopy revealed virus particles approximately 70 nm in diameter. The virions were scattered in the cytoplasm of the RBC or contained within membrane bound organelles. These virus particles were morphologically distinct from the iridovirus, erythrocytic necrosis virus (ENV), which is also associated with anemia (Holt and Rohovec 1984, Leek 1987). Evidence suggests that the etiological agent of this new anemic disease, termed erythrocytic inclusion body syndrome (EIBS) by Leek (1987), is a previously undescribed virus infecting salmon. The purpose of this study was to experimentally transmit the disease to healthy fish, to determine the blood parameters associated with infection, and to investigate the nature of the virus associated with EIBS.

Book chapter↗

USGS1994

Flow cytometry for monitoring contaminant exposure in black-crowned night-herons

The flow cytometry method (FCM) was employed to determine cellular DNA content of black-crowned night-heron ( Nycticorax nycticorax ) embryos and 10-day-old chicks collected at sites differing in types of chemical contamination. The coefficient of variation of DNA content (CV) in blood collected from embryos suggested cytogenetic damage at a site in Louisiana known to be contaminated with petroleum. Blood CV from chicks suggested genetic damage at a site in Texas also known to be contaminated with petroleum. Spleen CVs in chicks were significantly lower than respective means from the reference site. The CVs of chick blood and liver and spleen negatively correlated, suggesting recovery of spleen and liver cells after exposure to a clastogenic compound. Thus, the lower CVs may also have been indicative of genetic damage. Based on the findings of this study, FCM is a potential indicator of certain environmental contaminants in black-crowned night-herons.

Archives of Environmental Contamination and Toxico↗