Andrew K. Davis

In situ formation of lead phosphates in soils as a method to immobilize lead.

Considerable evidence, both theoretical and experimental, support the assertion that lead phosphates are the most stable environmental soil lead form and that they may form rapidly when adequate phosphate is present. This study demonstrated that the weathering of galena to insoluble lead phosphates in soils at a port facility historically used for shipment of ore concentrates is due to the presence of adequate soil phosphate. Geochemical modeling indicated that the addition of a phosphate amendment to Pb-bearing soil would result in lead phosphate formation with an estimated aqueous lead solubility of 0.1 μg/L in soil

Effect of handling time and repeated sampling on avian white blood cell counts

Abstract The practice of obtaining white blood cell (leukocyte) profiles and heterophil/lymphocyte (H/L) ratios from avian blood smears has become increasingly popular to assess immune function in wild birds. I captured 28 House Finches (Carpodacus mexicanus) and made blood smears from samples obtained from them at 3, 30, and 60 min after capture to evaluate the effect of routine handling time on leukocyte profiles and H/L ratios. Total leukocyte counts decreased significantly with time, but the proportions of each leukocyte type remained the same over the 1-h time period. There was a nonsignificant increase in H/L ratios over time, but comparison with a group of birds held for 1 h before bleeding suggested that this was the result of the repeated bleedings, not handling time. I conclude that researchers should make every effort to obtain blood samples for making smears as soon as possible after capturing birds to ensure an accurate assessment of total leukocyte counts, but that routine handling times under 1 h do not affect H/L ratios.

Leukocyte Profiles in Wild House Finches with and without Mycoplasmal Conjunctivitis, a Recently Emerged Bacterial Disease

Leukocyte profiles (relative numbers of white blood cell types) have been used by a growing number of ecological studies to assess immune function and stress in wild birds. House Finches (Carpodacus mexicanus) in eastern North America are susceptible to an eye disease caused by the bacterium Mycoplasma gallisepticum, providing the opportunity to examine whether leukocyte profiles are associated with infection status and other host characteristics. In this study, we compared blood smears from 297 wild House Finches with and without conjunctivitis to examine whether leukocyte profiles were associated with the presence and severity of mycoplasmal conjunctivitis. We also evaluated the influence of age, sex, and molt on leukocyte profiles in both diseased and nondiseased birds. Of 243 House Finches of known age and sex sampled, 30% showed clinical signs of mycoplasmal conjunctivitis. House Finches with conjunctivitis had significantly higher heterophil to lymphocyte (H/L) ratios and harbored greater numbers and proportions of heterophils and monocytes than nondiseased birds. Leukocyte profiles of noninfected birds did not differ significantly with respect to sex, but young birds had significantly greater numbers of lymphocytes and total white blood cells than adults. Molting birds had significantly more eosinophils than nonmolting birds. Finally, House Finches with the most severe outward signs of conjunctivitis showed the most dramatic leukocyte changes relative to noninfected individuals, and increasing H/L ratios and monocytes in diseased birds were paralleled in a subset of birds that were recaptured during the study period. These results are consistent with patterns observed in domestic poultry and suggest that understanding patterns of leukocyte differentials in this host-pathogen system could improve our understanding of innate immunity and infectious disease risk in other wild passerines.

Peer reviewed: understanding the water quality of pit lakes.

The increase in deep pit mining in western North America raises concerns about the environmental impact of mine closure.

POPULATIONS OF MONARCH BUTTERFLIES WITH DIFFERENT MIGRATORY BEHAVIORS SHOW DIVERGENCE IN WING MORPHOLOGY

The demands of long-distance flight represent an important evolutionary force operating on the traits of migratory species. Monarchs are widespread butterflies known for their annual migrations in North America. We examined divergence in wing morphology among migratory monarchs from eastern and western N. America, and nonmigratory monarchs in S. Florida, Puerto Rico, Costa Rica, and Hawaii. For the three N. American populations, we also examined monarchs reared in four common environment experiments. We used image analysis to measure multiple traits including forewing area and aspect ratio; for laboratory-reared monarchs we also quantified body area and wing loading. Results showed wild monarchs from all nonmigratory populations were smaller than those from migratory populations. Wild and captive-reared eastern monarchs had the largest and most elongated forewings, whereas monarchs from Puerto Rico and Costa Rica had the smallest and roundest forewings. Eastern monarchs also had the largest bodies and high measures of wing loading, whereas western and S. Florida monarchs had less elongated forewings and smaller bodies. Among captive-reared butterflies, family-level effects provided evidence that genetic factors contributed to variation in wing traits. Collectively, these results support evolutionary responses to long-distance flight in monarchs, with implications for the conservation of phenotypically distinct wild populations.

Groundwater transport of arsenic and chromium at a historical tannery, Woburn, Massachusetts, U.S.A.

The geochemical environment in hide piles at a historical tanning and rendering site (Woburn, Massachusetts, U.S.A.) is strongly reducing, as reflected by the presence of H2S and CH3HS in the pile offgas. The presence of a reducing environment in the Subjacent groundwater, along with DOC (≥ 100mg/l) from hide breakdown, results in reduction of As(V) to As(III), and subsequent methylation to monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA). The reducing conditions also result in precipitation of FeS(am), while hydrophilic organic acids have increased Cr(III) solubility. Three spatially sequential geochemical redox facies were recognized in groundwater downgradient from the hide piles. Typically, a reduced core zone was present adjacent to the hide piles, characterized by S2− ≥ 1mg/l, Fe2+ 20mg/l, NH3 (5–200 mg/l) and the sporadic presence of measurable S2− (1–2 mg/l), to an oxidizing peripheral zone characterized by conditions representative of background (i.e. DO> 1mg/l, Eh> 0mV, Fe2+ NH3), accompanied by precipitation of amorphous ferric hydroxide, sorption of As and co-precipitation-sorption of Cu, Pb and Zn. Electron microprobe analysis of hide-pile materials demonstrated authigenic precipitation of amorphous ferric hydroxide and gypsum, in agreement with the results of geochemical modeling.

Comparison of Hematological Stress Indicators in Recently Captured and Captive Paedomorphic Mole Salamanders, Ambystoma talpoideum

Abstract Measuring stress in animals is an important component of many research studies, and it has traditionally been performed via sampling levels of corticosterone in plasma. A secondary, “hematological” approach used most commonly by researchers of birds, mammals, and other taxa involves evaluating leukocyte profiles from blood smears. Such research has shown that leukocytes have a characteristic response to stress, although in amphibians this phenomenon is not as well studied. In general, stress can induce a rise in the ratio of neutrophils to lymphocytes. We evaluated the hematological response of paedomorphic Mole Salamanders (Ambystoma talpoideum) to captivity stress, specifically focusing on this parameter, but also examining other white blood cell types. Individuals captured in the wild and held in captivity for ten days before sampling had significantly more neutrophils, fewer lymphocytes, and higher ratios of neutrophils to lymphocytes than those captured from the same locations and sampled within one hour. Captive individuals also had significantly higher numbers of eosinophils. These results are consistent with hematological research in birds and other taxa and highlight the utility of this approach for measuring stress in amphibians.

Temperature variability and moisture synergistically interact to exacerbate an epizootic disease

Climate change is altering global patterns of precipitation and temperature variability, with implications for parasitic diseases of humans and wildlife. A recent study confirmed predictions that increased temperature variability could exacerbate disease, because of lags in host acclimation following temperature shifts. However, the generality of these host acclimation effects and the potential for them to interact with other factors have yet to be tested. Here, we report similar effects of host thermal acclimation (constant versus shifted temperatures) on chytridiomycosis in red-spotted newts (Notophthalmus viridescens). Batrachochytrium dendrobatidis (Bd) growth on newts was greater following a shift to a new temperature, relative to newts already acclimated to this temperature (15°C versus 25°C). However, these acclimation effects depended on soil moisture (10, 16 and 21% water) and were only observed at the highest moisture level, which induced greatly increased Bd growth and infection-induced mortality. Acclimation effects were also greater following a decrease rather than an increase in temperature. The results are consistent with previous findings that chytridiomycosis is associated with precipitation, lower temperatures and increased temperature variability. This study highlights host acclimation as a potentially general mediator of climate–disease interactions, and the need to account for context-dependencies when testing for acclimation effects on disease.

Wing Color Predicts Future Mating Success in Male Monarch Butterflies

Abstract Predictors of male monarch butterfly mating success have eluded researchers for years. Although it has long been known that there is variation in male mating success in this species, the source of this variation remains unclear. We used digital image analysis techniques to measure fine-scale variation in three components of the orange color (hue, saturation and brightness of the orange) of the forewings of 174 males at a level of detail that has not been possible until recently, and we compared this information to the mating success of the males in captivity. A second experiment involved addition of orange coloration to the wings of 93 males before mating trials. Our results indicate that one component of the orange color (saturation) correlated with mating success in our first experiment. Furthermore, wing color manipulations had no effect, but the original saturation values of the males in the second experiment were directly related to mating success. Our results provide the first evidence that wing color in monarch butterflies relates to mating success, and they serve as an important starting point for future research.

Factors controlling lead bioavailability in the Butte mining district, Montana, USA.

Microprobe analyses of 38 soil and 5 mine-waste samples from Butte, Montana, demonstrated that the samples contain predominantly sulphide/sulphate and oxide/phosphates of lead (Pb)-bearing phases associated with mine waste. The sulphide/sulphate assemblage consists primarily of galena altering to anglesite and plumbojarosite, with secondary jarosite precipitating and rinding the Pb-bearing minerals. In addition, galena was encapsulated within pyrite or quartz grains. The oxide/phosphate assemblage consists of pH-neutral soils in which a plausible paragenetic sequence of PbO to Pb phosphates, PbMnO, or PbFeO is proposed, dependent on the activity of P, Mn, Fe, and Cl in the soil. In addition, Pb-bearing grains are occasionally armoured by the presence of a 1- to 3-(μm rind of authigenic silicate. The low solubility of the Pb-bearing minerals resulting from encapsulation in non-Pb-bearing reaction rinds may provide an explanation for the limited Pb bioavailability observed when Butte soils were fed to rats (Freemanet al., 1992). Further evidence of the lack of absorption of lead from these soils is provided by the results of a blood-Pb study indicating very low blood-Pb levels in Butte children. The lower bioavailability of Pb from mining sites, compared to smelting and urban environments, is also due to kinetic limitations that control dissolution rates of Pb-bearing solids relative to the residence time of soil in the gastrointestinal (Gl) tract. When the test soil was fed to New Zealand White rabbits, only 9% of the total Pb was solubilised in the stomach, and therefore available for absorption. Anin vitro assay, developed to estimate maximum available Pb from soil, demonstrates that ingestion of mine-waste-bearing soil results in limited Pb dissolution, and produces results similar to thein vivo testing.