Spatial and temporal variation of lead, cadmium, and zinc in feathers of great tit and blue tit nestlings in Central Poland

Validity of Geolocation and Distance to Exposure Sources from Geographical Information Systems for Environmental Monitoring of Toxic Metal Exposures Based on Correlation with Biological Samples: a Systematic Review

PURPOSE OF REVIEW

In epidemiologic studies, biomarkers are the best possible choice to assess individual exposure to toxic metals since they integrate all exposure sources. However, measuring biomarkers is not always feasible, given potential budgetary and time constraints or limited availability of samples. Alternatively, approximations to individual metal exposure obtained from geographic information systems (GIS) have become popular to evaluate diverse metal-related health outcomes. Our objective was to conduct a systematic review of epidemiological studies that evaluated the validity of GIS-based geolocation and distance to pollutant sources as an approximation of individual metal exposure based on correlation with biological samples.

RECENT FINDINGS

We considered 11 toxic metals: lead (Pb), cadmium (Cd), antimony (Sb), aluminum (Al), arsenic (As), chromium (Cr), nickel (Ni), mercury (Hg), tungsten (W), uranium (U), and vanadium (V). The final review included 12 manuscripts which included seven metals (Pb, Cd, Al, As, Cr, Hg, and Ni). Many studies used geolocation of the individuals to compare exposed (industrial, urban, agricultural, or landfill sources) and unexposed areas and not so many studies used distance to a source. For all metals, except lead, there was more animal than human biosampling to conduct biological validation. We observed a trend towards higher levels of Cd, Cr, Hg, and Pb in biosamples collected closer to exposure sources, supporting that GIS-based proxies for these metals might approximate individual exposure. However, given the low number and heterogeneity of the retrieved studies, the accumulated evidence is, overall, not sufficient. Given the practical benefits and potential of modern GIS technologies, which allow environmental monitoring at a reasonable cost, additional validation studies that include human biosampling are needed to support the use of GIS-based individual exposure measures in epidemiologic studies.

Do the diverse environments of Baltic coastal zone affect hematological and biochemical alterations in the blood of mute swans (Cygnus olor)?

Based on studies of the wintering population of mute swans in large urban agglomerations, it is possible to identify and infer the impact of environmental pollution in coastal regions near Baltic Sea on the physiological and biochemical changes in the blood of waterfowls. Hematological and biochemical changes in the blood in relation to chemical elements in their feathers are a useful tool for general ecophysiological conclusions. Hematological changes and blood chemistry in Mute Swan Cygnus olor is particularly environmentally dependent, therefore we examined hematological picture (red blood cells RBC, white blood cells WBC, heterophiles, eosinophils, basophils, monocytes, lymphocytes, hemoglobin, heterophile to lymphocyte ratio H/L, biochemical indicators (glucose, uric acid, total cholesterol, triglycerides, calcium, inorganic phosphorus, magnesium, total protein), stability of erythrocyte membranes, concentration of Ca, P, Mg in the blood, concentration of Al, Zn, Rh, Cu, Ru, Fe, Pb in feathers, in wintering population of 172 mute swans of different age (juvenile, adult) and gender, in three coastal types of areas of Southern Polish zone of Baltic Sea (Słupsk, Gdynia, Sopot). Percentage of changes in the morphological indices in the blood of mute swans with three independent characteristics (environment, sex, age) revealed that hemoglobin content exhibited the highest value (R² = 53.8%) in the analysis of morphological indices; the effect of RBC, WBC, and basophils was much lower (WBC > RBC > basophils). Male and female erythrocytes from the coastal of Gdynia were more fragile than those of birds from coasts of Sopot and Słupsk. We found that osmotic fragility is altered in juvenile swans from Słupsk area and males from Gdynia area. The consequence was a higher level of hemolyzed erythrocytes in their blood. The effect of type of environment, age-, and sex-related impact on hematological indices and biomarkers of biochemical alterations in the blood of swans and comparison of these data with bioaccumulation of chemical elements in feathers of swans inhabiting 3 types of environment of Baltic coastal zone show significant differences in the hematological and biochemical indices. Albumins and globulins maintain the blood cations balance, however, changes in their concentrations in the blood suggest an impact on physiological mechanisms and body condition of swans.

Biomarkers of oxidative stress, metabolic processes, and lysosomal activity in the muscle tissue of the great tit (Parus major) living in sodium industry and agricultural areas in Inowrocław region (central part of northern Poland)

An region of ecological hazard (EHR) is an area where, as a result of intensive human economic activity, degradation of components of the natural environment has taken place, leading to the deterioration of the ecological balance. EHR management is a globalised ever-increasing challenge. To eliminate the hazardous effect of these pollutants, research has been accelerated worldwide. The current study analyzed the specific biomarkers of the lipid and protein oxidation, total antioxidative status, activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione reductase and peroxidase), lysosomal enzymes (alanyl aminopeptidase, leucyl aminopeptidase, acid phosphatase), and biomarkers of aerobic and anaerobic metabolic pathways (activities of alanine and aspartate aminotransferases, succinate dehydrogenase, lactate dehydrogenase, lactate and pyruvate levels) in skeletal muscle tissue of wild great tit nestlings in environments with different levels of anthropogenic pressure such as sodium industry and agriculture in the central part of northern Poland (Inowrocław EHR). Control samples were collected from Tuchola Forest and Borkowo village, where no direct sources of contamination were found. The relevance of the study was to assess the changes in lysosomal functioning caused by pollution-induced oxidative stress that may indicate multidirectional adaptative mechanisms of metabolic processes occurring in the wild birds to compensate for the negative effects of contamination. It was shown that the initiation of oxidative stress caused by anthropogenic pollution shifted the balance of the normal functioning of lysosomal enzymes towards their increased activity. A general tendency towards an increase in the intensity of lipid peroxidation processes with an increasing level of oxidatively modified proteins (aldehydic and ketonic derivatives) and a simultaneous reduction in the TAS was observed in the muscle tissue of great tits living in the anthropogenically modified areas. The intensity of lipid peroxidation and protein damage caused changes and reorganization of the energy-related metabolic pathways in the muscle tissue of wild great tits living in the sodium industry and agricultural areas of the EHR.

Trace metals and metalloids in Andean flamingos (Phoenicoparrus andinus) and Puna flamingos (P. jamesi) at two wetlands with different risk of exposure in the Bolivian Altiplano

Birds are widely used as bioindicators in monitoring programs in wetlands. We compare concentrations of seven trace metals and metalloids (TMM) As, Cd, Cu, Fe, Hg, Pb, Znin both feathers and blood in two flamingo species in two high-altitude wetlands in Bolivia, with different levels of anthropogenic point source pollution. Lake Uru Uru (LUU) receives discharges from mining operations, and also effluents from the nearby city of Oruro, while Laguna Colorada (LCo) does not receive contaminants from anthropogenic sources. We sampled water and sediments at each site, as well as flamingos in three age classes in an effort to establish a benchmark for long-term monitoring. Metal concentrations in water did not differ between sites, whereas Zn and Pb concentrations of TMM in sediments were higher at LUU, and Hg higher at LCo. TMM concentrations were highly specific for all separate elements, but results point to differences between Andean flamingo (Phoenicoparrus andinus) chicks and the rest of the classes considered. As flamingo chicks did not molt before sampling, we pose that TMM concentrations in their blood and feathers may respond mainly to local conditions. Eggshells provide additional information, since adults transfer some TMM during egg development. Long-term monitoring in these species should include different age classes and sample both feathers and eggshells to monitor the environmental conditions and bioaccumulation of TMM in these species. Future studies should include sites devoid of natural sources of TMM to help distinguish sources of contamination, since some TMM (As and Pb) may be naturally in high concentrations in remote areas, like Laguna Colorada.

Genetic structure of urban and non-urban populations differs between two common parid species

Landscape conversions induced by human activities can affect dispersal patterns of various bird species and, as a result, affect genetic structure of their populations. Genetic differentiation of bird populations may be enhanced by habitat variation, especially in urban-non-urban systems. The majority of population genetic studies focus on single species, which inflicts limitations for direct comparisons of genetic responses of avian populations to urbanization. Here, we used a set of microsatellite markers to examine genetic diversity, gene flow and population structure in two common parid species, great tits Parus major and blue tits Cyanistes caeruleus occupying three sites in habitats with contrasting urbanization level in central Poland. We found low but significant divergence of urban park population with both suburban and non-urban forest great tit populations, while no differentiation was found between suburban forest and non-urban forest populations. In contrast, no evidence for genetic differentiation was found between blue tit populations from the urban park, suburban forest and non-urban forest sites. We conclude that great tits and blue tits respond to urbanization-related changes in a different way, which may be a result of different rates of migration and/or dispersal, likely higher in blue tits. Some impact may be also induced by interspecific competition. We suggest that changing the focus of urban genetic research from single to multiple species may provide novel insights into how natural populations respond to the processes of urbanization.

Are Feathers of a Songbird Model Species (The Great Tit, Parus major) Suitable for Monitoring Perfluoroalkyl Acids (PFAAs) in Blood Plasma?

Feathers have been shown to be useful in the biomonitoring of environmental contaminants, such as metals and persistent organic pollutants. However, little is known regarding the levels of perfluoroalkyl acids (PFAAs) in feathers and the applicability of these structures for the biomonitoring of these compounds. In the present study, we report the extent to which feathers are suitable for monitoring PFAA concentrations in the blood plasma of an insectivorous songbird model species, the great tit (Parus major), settled at and in the vicinity of a fluorochemical plant in Antwerp, Belgium. For most of the target analytes (out of the 15 investigated), the feather PFAA concentrations near the plant are the highest ever reported in free-living birds. As PFAA concentrations did not differ in the adjacent sites, no pollution gradient with distance from the plant was observed. In addition, the PFAA concentrations were not associated with the age and sex of the birds. Perfluorooctanoic acid (PFOA) concentrations were significantly higher in P. major feathers than in blood plasma, but for most other PFAAs, these differences were not observed. The concentrations of perfluorooctanesulfonate (PFOS) and PFOA in P. major feathers and plasma were significantly and positively correlated when combining data from all sites but often not at individual sites. This result was likely caused by lower sample sizes at the individual sites and the use of matrices that represent different time periods. Our results suggest that P. major feathers cannot be used to estimate PFOA and PFOS concentrations in blood plasma, except when there is a great deal of variation in pollutant concentrations among sites/individual birds. Both matrices represent different time frames, providing complementary information on environmental PFAA concentrations, as illustrated by the observation that more PFAA compounds could be detected in P. major feathers than in blood plasma.

Effects of experimental lead exposure on physiological indices of nestling great tits Parus major: haematocrit and heterophile-to-lymphocyte ratio

Lead (Pb) is recognized as one of the most toxic trace elements that can induce a wide range of negative health effects in wildlife. Because the investigation of basic environment-sensitive physiological indicators is easy to perform in wild birds, they have been considered as valuable bioindicators of lead contamination. The harmfulness of lead poisoning can depend on the type of exposure, and in most studies of birds, an effect of chronic lead exposition has been considered. In this study, we investigated whether a single exposure to specific doses of lead affected such physiological indices as haematocrit and the heterophil-to-lymphocyte ratio (H/L ratio). For this purpose, we conducted an experiment based on intentional lead supplementation, with the use of two different doses, applied to randomly chosen great tit (Parus major) nestlings from randomly selected broods. A few days after the exposure (when the nestlings were 15 days old), we determined haematocrit and the H/L ratio as potentially sensitive physiological indicators of lead intoxication. We found that the treatment with lead resulted in a significant decline in haematocrit level. In addition, we found that the age when lead exposure occurred can be considered as an important factor influencing haematocrit variation. A decrease in haematocrit was observed on consecutive days of nestling life. In contrast, the H/L ratio did not show any significant response to lead exposure. These results clearly show that the assessment of haematocrit level for nestling great tits can provide a simple and rapid method of indirect evaluation of physiological effects of lead intoxication caused by a single exposure.

Ecotype Variation in Trace Element Content of Hard Tissues in the European Roe Deer (Capreolus capreolus)

Animals living in anthropogenic habitats bear a multitude of costs, which are directly or indirectly associated with human activities. Among others, an elevated exposure to environmental pollution can have negative consequences for wildlife populations. We examined the differences in the concentrations of trace elements between the field and forest ecotype of the European roe deer (Capreolus capreolus). Naturally, roe deer inhabited various types of woodlands (forest ecotype), but within the last century, they adapted to life in a human-transformed agricultural areas (field ecotype), which could be associated with an increased exposure to pollution. In this study, we measured concentrations of seven trace metals (barium, copper, iron, lead, manganese, strontium, zinc) and fluoride in skull bones and permanent teeth of more than 230 roe deer from 8 study plots in East-Central Europe. We found that field roe deer had higher concentrations of four trace metals (copper, iron, lead, strontium) and fluoride compared with forest roe deer. These differences were consistent with variations in the general level of environmental contamination within the study plots, as assessed with trace element content in wild plants. Our study indicates that bone and teeth of the European roe deer can be used as a valid indicator of environmental pollution. Also, we expect that elevated exposure of field roe deer to environmental pollution can have negative consequences for wild populations of this species, as well as for the consumers of venison.

Toxic metals and associated sporulated bacteria on Andean hummingbird feathers

Human activities in the Sabana de Bogotá, Colombia, release toxic metals such as lead (Pb) and chromium (Cr) into the environment polluting the air, water, and soil. Because birds are in contact with these pollutants and their sources, they may serve as bioindicator organisms. We evaluated the use of hummingbird feathers obtained from individuals captured in three sites of the Sabana de Bogotá as bioindicators of toxic metal pollution using spectrophotometric and spectroscopic methods based on single-feather samples. We also characterized the bacterial microbiota associated with hummingbird feathers by molecular identification using the 16S rRNA with a special focus on sporulated bacteria. Finally, we described the interactions which naturally occur among the feathers, their associated bacteria, and pollutants. We found differences in Pb and Cr concentrations between sampling sites, which ranged from 2.11 to 4.69 ppm and 0.38 to 3.00 ppm, respectively. This may reflect the impact of the activities held in those sites which release pollutants to the environment. Bacterial assemblages mainly consisted of sporulated bacilli in the Bacillaceae family (65.7 % of the identified morphotypes). We conclude that the feathers of wild tropical birds, including hummingbirds, can be used as lead and chromium bioindicators and that bacteria growing on feathers may in fact interact with these two toxic metals.

Effects of dietary lead exposure on vitamin levels in great tit nestlings - An experimental manipulation

Exposure to metal pollution negatively affects animal physiology, including nutrient metabolism, but in the wild an effect can seldom be attributed to a single metal. Moreover, little is known about how the metabolism of vitamins, essential micronutrients for developing juveniles, is affected by toxic metals. Therefore we experimentally investigated the effects of lead (Pb), a widespread toxic metal, on four fat-soluble vitamins A (total and retinol), D3, E (total and α-tocopherol) and K and carotenoids (lutein, zeaxanthin and unidentified) in great tit (Parus major) nestlings. In addition to a control group where no Pb was provided, two Pb-dosed groups were compared to a metal exposed group in the vicinity of a Ni-Cu smelter. We examined whether Pb treatment affects vitamin homeostasis and how the response of Pb-treated birds relates to that of a population under industrial exposure of Pb and other metals. For this purpose, vitamin and carotenoid levels were quantified with UPLC-MS from plasma of 7 days-old nestlings. All metal exposed groups showed increased vitamin A and retinol levels. However, vitamin levels were not directly associated with fecal Pb levels, with the exception of retinol, which was positively correlated with fecal Pb. Alpha-tocopherol, lutein and zeaxanthin levels were positively associated with body mass and wing growth rate. To conclude, Pb exposure increased plasma vitamin A and retinol levels while the levels of other vitamins and carotenoids rather reflected secondary pollution effects via differences in habitat and diet quality at the smelter site. Our findings suggest Pb exposed nestlings may allocate the vitamins needed for growth and development to fight the physiological stress thus compromising their fitness.

Avian Conservation Areas as a Proxy for Contaminated Soil Remediation

Remediation prioritization frequently falls short of systematically evaluating the underlying ecological value of different sites. This study presents a novel approach to delineating sites that are both contaminated by any of eight heavy metals and have high habitat value to high-priority species. The conservation priority of each planning site herein was based on the projected distributions of eight protected bird species, simulated using 900 outputs of species distribution models (SDMs) and the subsequent application of a systematic conservation tool. The distributions of heavy metal concentrations were generated using a geostatistical joint-simulation approach. The uncertainties in the heavy metal distributions were quantified in terms of variability among 1000 realization sets. Finally, a novel remediation decision-making approach was presented for delineating contaminated sites in need of remediation based on the spatial uncertainties of multiple realizations and the priorities of conservation areas. The results thus obtained demonstrate that up to 42% of areas of high conservation priority are also contaminated by one or more of the heavy metal contaminants of interest. Moreover, as the proportion of the land for proposed remediated increased, the projected area of the pollution-free habitat also increased. Overall uncertainty, in terms of the false positive contamination rate, also increased. These results indicate that the proposed decision-making approach successfully accounted for the intrinsic trade-offs among a high number of pollution-free habitats, low false positive rates and robustness of expected decision outcomes.

Biomonitoring of heavy metals in feathers of eleven common bird species in urban and rural environments of Tiruchirappalli, India

Heavy metals continue to remain as a major environmental concern in spite of emission control measures. In this study, we analyzed the concentrations of heavy metals (Fe, Cr, Mn, Ni, Cu, Zn, and Cd) in the feathers of 11 species of birds collected from urban and rural areas of Tiruchirappalli, Southern India. Metal concentrations followed the order: Fe > Cu > Zn > Cr > Mn > Ni > Cd. Irrespective of sample locations, heavy metals such as Fe, Cr, Ni, Zn, and Cu were detected in high concentrations, while Cd and Mn were observed in lower concentrations. In contrary to our assumption, there were no statistically significant intraspecific and urban-rural differences in the metal concentrations except for Zn. Pairwise comparisons among species irrespective of metal type showed significant interspecific differences between Acridotheres tristis and Centropus phasianinus, A. tristis and Milvus migrans, C. phasianinus and M. migrans, M. migrans and Eudynamys scolopaceus, and Psittacula krameri and E. scolopaceus. Principal component analysis carried out for urban data extracted Ni, Mn, Zn, Fe, and Cu accounting for 48% variance implying dietary intake and external contamination as important sources for metals. In the rural, association of Zn, Cd, Ni, and Cr suggests the impact of metal fabrication industries and leather tanning operations.