Coal fly ash basins as an attractive nuisance to birds: parental provisioning exposes nestlings to harmful trace elements.

Birds attracted to nest around coal ash settling basins may expose their young to contaminants by provisioning them with contaminated food. Diet and tissues of Common Grackle (Quiscalus quiscala) nestlings were analyzed for trace elements to determine if nestlings were accumulating elements via dietary exposure and if feather growth limits elemental accumulation in other tissues. Arsenic, cadmium, and selenium concentrations in ash basin diets were 5× higher than reference diets. Arsenic, cadmium, and selenium concentrations were elevated in feather, liver, and carcass, but only liver Se concentrations approached levels of concern. Approximately 15% of the total body burden of Se, As, and Cd was sequestered in feathers of older (>5 days) nestlings, whereas only 1% of the total body burden of Sr was sequestered in feathers. Feather concentrations of only three elements (As, Se, and Sr) were correlated with liver concentrations, indicating their value as non-lethal indicators of exposure.

Genetic status of the wood stork (Mycteria americana) from the southeastern United States and the Brazilian Pantanal as revealed by mitochondrial DNA analysis.

The wood stork (Mycteria americana) is a colonial wading bird that inhabits the Neotropical region from the southeastern United States (US) to northern Argentina. The species is considered to be endangered in the US due to degradation of its foraging and breeding habitat. In other parts of its range, such as in the Brazilian Pantanal region, breeding populations of this species appear to be stable. We compared the levels of genetic variability and population structuring of the US and the Pantanal breeding populations using mitochondrial DNA (mtDNA) control region sequences. Twenty-seven haplotypes were identified among 88 wood stork samples collected from eight breeding colonies in the US and eight in the Pantanal. Patterns indicative of heteroplasmy were observed in 35.3% of the mtDNA sequences that were examined. Significantly higher levels of haplotype diversity were observed in the Pantanal samples compared to those from the US, suggesting that during the last century, demographic declines or a recent evolutionary bottleneck reduced the levels of mtDNA variability of the US population. Analyses of genetic structuring revealed non-significant genetic differentiation between these regions, indicating that either the populations were only recently separated or that gene flow continues to occur at low levels. Haplotype network analysis indicated low current levels of gene flow between populations that were closely related in the past.

Shifts in relative tissue delta15N values in snowy egret nestlings with dietary mercury exposure: a marker for increased protein degradation.

Shifts in tissue nitrogen isotope composition may be a more sensitive general indicator of stress than measurement of high-turnover defensive biomolecules such as metallothionein and glutathione. As a physical resource transmitted along the trophic web, perturbations in protein nitrogen metabolism may also help resolve issues concerning the effects of contaminants on organisms and their consequential hierarchical linkages in ecotoxicology. Snowy egret nestlings (Egretta thula) fed mercury-contaminated diets of constant nitrogen isotope composition exhibited increased relative delta15N values in whole liver (p = 0.0011) and the acid-soluble fraction (ASF) of the liver (p = 0.0005) when compared to nestlings fed a reference diet. When nitrogen isotope data were adjusted for the source term of the diet, liver mercury concentrations corresponded with both whole liver relative 15N enrichment (r2 = 0.79, slope 0.009, p < 0.0001) and relative 15N enrichment in the acid-soluble fraction of the liver (r2 = 0.85, slope 0.026, p < 0.0001). Meanwhile, significant differences were not observed in hepatic levels of the metal-binding peptides metallothionein and glutathione despite a nearly 3-fold difference in liver mercury content. Because increases in tissue delta15N values result from increased rates of protein breakdown relative to synthesis, we propose that the increased relative liver delta15N values reflect a shift in protein metabolism. The relationship between ASF and mercury was significantly stronger (p < 0.0001) than that for whole liver, suggesting that the relationship is driven by an increase in bodily derived amino acids in the acid-soluble, free amino acid pool.

Maternal transfer of contaminants to eggs in common grackles (Quiscalus quiscala) nesting on coal fly ash basins.

Coal combustion is a major source of trace elements to the environment. Aquatic disposal of wastes from this process can result in reproductive failure in many wildlife species, but little is known regarding impacts on avian fauna. Individual eggs were collected from common grackles (Quiscalus quiscala) nesting in association with coal fly ash settling basins and a reference site to determine if females from the contaminated site transfered trace elements to their eggs. Whole clutches were also collected from both sites to examine inter- and intra-clutch variability of maternally transferred contaminants. Selenium was the only trace element found in significantly higher concentrations in ash basin eggs (x = 5.88 +/- 0.44 microg/g DW) than in reference eggs (x = 2.69 +/- 0.13 microg/g DW). Selenium concentrations in eggs from the ash basins were above background levels, but did not exceed higher proposed Se toxicity thresholds. Inter- and intra-clutch variation was higher for ash basin clutches than reference clutches. The relationship between selenium concentrations and laying order (estimated by egg mass) was not statistically significant, but increased Se concentration in the second egg of most ash basin clutches followed by declining concentrations in subsequent eggs suggested that further examination of this pattern might be warranted.

Radiocesium in fish from the Savannah River and Steel Creek: potential food chain exposure to the public.

This study examined radiocesium (137Cs) levels in fish from the vicinity of the Department of Energy's Savannah River Site (SRS), a former nuclear weapons production facility in South Carolina. Fish from the Savannah River were sampled above (upstream), along, and below (downstream) the SRS, and from Steel Creek, a tributary that runs through the SRS. There was some off-site contamination of 137Cs in the Savannah River watershed due to low-level releases from past nuclear production on the SRS. The null hypotheses tested were that there would be no differences in 137Cs levels as a function of location along the river, and between species collected from the river and from Steel Creek on the SRS. For six of eight species of fish collected from the Savannah River, there were no differences in 137Cs levels in muscle from fish collected above, along, or below the SRS; exceptions were bowfin and shellcracker. Fish collected from Steel Creek had significantly higher levels (by about an order of magnitude) of 137Cs in muscle tissue than fish collected in the Savannah River. However, no fish from either Steel Creek or the Savannah River had 137Cs levels above the European Economic Community limit for fresh meat of 0.6 Bq/g. Lifetime cancer risk was calculated using the cancer slope factor of 3.2 x 10(-11)/pCi, and various fish consumption scenarios reflecting actual data from Savannah River fishermen. Using mean 137Cs concentrations and median fish consumption for 70 years for Black males-the group with the highest consumption-the excess lifetime risk associated with the eight species of fish in the Savannah River ranged from 9.0 x 10(-7) to 1.0 x 10(-5). The same calculation for fish from Steel Creek gave risk estimates from 1.4 to 8.0 x 10(-5). The 95% level for consumption by Blacks, however, was about 70 kg/year. Black fishermen consuming that amount of bass from Steel Creek would sustain a lifetime risk of 3.1 x 10(-4), whereas the same consumption of Savannah River bass would yield a risk estimate of 1.5 x 10(-5).

Annual and regional variation in mercury concentrations in wood stork nestlings.

Mercury concentrations were measured in blood, down, and feathers from approximately 300 wood stork nestlings in one South Carolina, USA, and four Georgia, USA, colonies from 1996 to 1999. Coastal nestlings generally had lower mercury concentrations than those from inland colonies. Inter-year differences were also apparent, particularly for coastal colonies, where nestling mercury concentrations were higher in 1998 than in 1997 or 1999. In 1998, a wet winter followed by a dry spring and summer produced ideal freshwater foraging conditions and mercury concentrations in coastal nestlings were higher than during the two dry years. There was little inter-year variation in mercury concentrations in nestlings from inland colonies, as parent storks from these colonies forage exclusively in freshwater habitats regardless of rainfall patterns. These results suggest that greater risk of mercury exposure to nestlings is associated with use of freshwater foraging habitats.

Ecological half-life of 137Cs in fish from a stream contaminated by nuclear reactor effluents.

Radiocesium (137Cs) concentrations were determined during 1974, 1981 and 1998 for seven species of fish inhabiting a stream (Steel Creek) contaminated by effluents from a nuclear reactor to examine the decline of this radionuclide in a natural ecosystem. Median 137Cs concentrations were highest in Micropterus salmoides (largemouth bass) during each year of the investigation (1974 = 6.67 Bq g(-1) dry wt. of whole body; 1981 = 3.72 Bq g(-1); 1998 = 0.35 Bq g(-1)), but no patterns of differences were observed among Aphredoderus sayanus (pirate perch), Esox americanus (redfin pickerel), Lepomis auritus (redbreast sunfish), L. gulosus (warmouth), L. punctatus (spotted sunfish), and Notropis cummingsae (dusky shiner). Results demonstrated a rapid decline in 137Cs within fish from Steel Creek during the 24-year period. For example, 137Cs concentrations in all fish species declined significantly among years, even after accounting for radioactive decay. The observed percent declines in 137Cs concentrations of individual species were 3-4 times greater between 1974 and 1981 compared to that expected by physical decay alone, and 2-3 times greater during 1981-1998. Ecological half-lives (EHLs) of 137Cs in fish ranged from 4.43 years in A. sayanus to 6.53 years in L. gulosus. The EHL for 137Cs in all fish species combined was 5.54 years. Current levels of 137Cs in fish from Steel Creek (1.16 Bq g(-1) dry wt. of whole body to below detection limits) indicate that the consumption of fish from this ecosystem poses little risk to humans and sensitive wildlife species. These results demonstrate the importance of incorporating the concept of ecological half-life into determinations concerning the length and severity of potential risks associated with radiocontaminants.

Foraging ecology of the endangered wood stork recorded in the stable isotope signature of feathers.

Down feathers and regurgitant were collected from nestling wood storks (Mycteria americana) from two inland and two coastal breeding colonies in Georgia. The stable isotopic ratios of carbon (13C/12C) and nitrogen (15N/14N) in these materials were analyzed to gain insights into the natal origins of juvenile storks and the foraging activities of adults. Down feathers differed in δ13C between inland and coastal colonies, having average isotopic values that reflected the sources of carbon fixed in biomass at the base of the food web. Feathers from the inland colonies differed between colonies in δ15N, while those from the coastal colonies did not. These patterns primarily reflected the foraging activities of parent storks, with individuals capturing differing percentages of prey of distinct trophic status at each colony. Collectively, the carbon and nitrogen isotopic signatures of feather keratin were used to distinguish nestlings from each colony, except for instances where storks from different colonies foraged in common wetlands. The stable isotopic composition of food items in regurgitant was used to reconstruct the trophic structure of the ecosystems in which wood storks foraged. Predicted foraging activities based on the isotopic composition of keratin were generally consistent with the percentage of prey types (freshwater vs. saltwater and lower trophic level vs. upper trophic level consumer) observed in regurgitant, except for the coastal colony at St. Simons Island, where the δ13C of feathers strongly suggested that freshwater prey were a significant component of the diet. This inconsistency was resolved by aerial tracking of adults during foraging excursions using a fixed-wing aircraft. Observed foraging activities supported interpretations based on the stable isotope content of feathers, suggesting that the latter provided a better record of overall foraging activity than regurgitant analysis alone. Observed foraging patterns were compared to the predictions of a statistical model that determined habitat utilization based on habitat availability using a geographic information system (GIS) database. Observed foraging activities and those predicted from feathers both suggested that some adult storks preferred to feed their young freshwater prey, even when saltwater resources were more accessible in the local environment. This conclusion supports the contention that wood stork populations are sensitive to changes in the distribution of freshwater habitats along the southeastern coastal plain of the United States.

Association between lower serum free T4 and greater mood instability and depression in lithium-maintained bipolar patients.

OBJECTIVE: This investigation evaluated the relationship between changes in thyroid indices and mood stability during lithium and carbamazepine prophylaxis for bipolar disorder. METHOD: In the first 2 years, 30 patients with bipolar mood disorder were randomly assigned to 1 year of lithium and then 1 year of carbamazepine, or vice versa; in the third year, they received lithium plus carbamazepine. By stepwise regression analysis, the degree and timing of lithium- and carbamazepine-induced thyroid changes and their subsequent relationship to long-term mood stability were evaluated. RESULTS: During the lithium phase, there was a significant inverse relationship between morbidity and mean serum level of free T4, i.e., a lower mean serum level of free T4 was associated with more affective episodes and greater severity of depression as shown by the Beck Depression Inventory. During the carbamazepine phase, there was an inverse relationship between mean level of total T4 and global severity rating. During the combination phase, no relationships between thyroid indices and clinical outcome were significant. CONCLUSIONS: In the lithium phase, a low level of free T4 was associated with more affective episodes and greater severity of depression. Whether this mood instability is causally related to low free T4 levels and whether it can be attenuated with T4 replacement remain to be studied in a controlled setting.

Antidepressant discontinuation-related mania: critical prospective observation and theoretical implications in bipolar disorder.

BACKGROUND: Development of manic symptoms on antidepressant discontinuation has primarily been reported in unipolar patients. This case series presents preliminary evidence for a similar phenomenon in bipolar patients. METHOD: Prospectively obtained life chart ratings of 73 bipolar patients at the National Institute of Mental Health were reviewed for manic episodes that emerged during antidepressant taper or discontinuation. Medical records were utilized as a corroborative resource. Six cases of antidepressant discontinuation-related mania were identified and critically evaluated. RESULTS: All patients were taking conventional mood stabilizers. The patients were on antidepressant treatment a mean of 6.5 months prior to taper, which lasted an average of 20 days (range, 1-43 days). First manic symptoms emerged, on average, 2 weeks into the taper (range, 1-23 days). These 6 cases of antidepressant discontinuation-related mania involved 3 selective serotonin reuptake inhibitors (SSRIs), 2 tricyclic antidepressants (TCAs), and 1 serotonin-norepinephrine reuptake inhibitor. Mean length of the ensuing manic episode was 27.8 days (range, 12-49 days). Potential confounds such as antidepressant induction, phenomenological misdiagnosis of agitated depression, physiologic drug withdrawal syndrome, and course of illness were carefully evaluated and determined to be noncontributory. CONCLUSION: These 6 cases suggest a paradoxical effect whereby antidepressant discontinuation actually induces mania in spite of adequate concomitant mood-stabilizing treatment. These preliminary observations, if replicated in larger and controlled prospective studies, suggest the need for further consideration of the potential biochemical mechanisms involved so that new preventive treatment approaches can be assessed.

Hematozoa in the endangered wood stork from Georgia.

Thin blood smears of 75 wood storks (Mycteria americana) from Georgia (USA) were made during the summers of 1994-96 and examined for blood parasites. Haemoproteus crumenium was found in one of 71 juveniles and in two adults from a sample of two subadults and two adults. Intensity of infection in the juvenile and in each of the two adults was 11, 3, and 2 parasites/5,000 erythrocytes, respectively. This is the first record of H. crumenium in the wood stork from Georgia and the second published record of H. crumenium infecting this host in North America. Additionally, one juvenile was infected with a microfilarid.

Valproate prophylaxis in a prospective clinical trial of refractory bipolar disorder.

OBJECTIVE: The authors studied the efficacy of valproate plus lithium and of triple therapy with lithium, carbamazepine, and valproate in refractory bipolar illness. METHOD: The subjects were 24 bipolar outpatients who had completed an intended 3-year crossover study comparing lithium, carbamazepine, and their combination. Patients entered a 1-year phase of valproate plus lithium because of inadequate response or major side effects, and patients with inadequate responses were offered an additional year of treatment with all three mood-stabilizing drugs. RESULTS: Six (33%) of the 18 evaluable patients had moderate to marked responses to valproate plus lithium; four of these six had not responded to any previous treatment condition. Three of seven patients responded to triple therapy, although only one response was marked. CONCLUSIONS: Some outpatients with bipolar disorder refractory to lithium and carbamazepine received clinically relevant prophylactic benefit from valproate when used with lithium or in triple therapy.

An El Jobo Mastodon Kill at Taima-taima, Venezuela.

Excavation at Taima-taima in 1976 recovered artifacts of the El Jobo complex in direct association with the butchered remains of a juvenile mastodon. Radiocarbon dates on associated wood twigs indicate a minimum age of 13,000 years before the present for the mastodon kill, a dating significantly older than that of the Clovis complex in North America. The El Jobo complex must have evolved independently in northern South America.