Oxidative stress biomarkers in Eurasian eagle owls (Bubo bubo) in three different scenarios of heavy metal exposure

A blood-based multi-biomarker approach reveals different physiological responses of common kestrels to contrasting environments

The increase of urbanization and agricultural activities is causing a dramatic reduction of natural environments. As a consequence, animals need to physiologically adjust to these novel environments, in order to exploit them for foraging and breeding. The aim of this work was to compare the physiological status among nestling common kestrels (Falco tinnunculus) that were raised in nest-boxes located in more natural, rural, or urban areas in a landscape with a mosaic of land uses around Rome in Central Italy. A blood-based multi-biomarker approach was applied to evaluate physiological responses at multiple levels, including antioxidant concentrations, immunological functions, genotoxicity, and neurotoxicity. We found lower concentrations of glutathione and GSH:GSSG ratio values and higher proportions of monocytes in urban birds compared to the other areas. We also found higher DNA damage in rural compared to urban and natural krestels and inhibition of butyrylcholinesterase activity in urban and natural birds compared to rural area. Finally, we found similar values among study areas for respiratory burst, complement system, bactericidal capacity, and plasma non-enzymatic antioxidant capacity. These results suggest that (i) city life does not necessarily cause physiological alterations in kestrels compared to life in other habitats, and (ii) environmental pressures are likely to differ in typology and intensity across habitats requiring specific responses that a multi-biomarker approach can help to detect. Further studies are needed to assess which factors are responsible for the physiological differences among city, rural, and natural birds, and whether these differences are consistent across time and space.

Mercury Exposure in Birds of Prey from Norway: Relation to Stable Carbon and Nitrogen Isotope Signatures in Body Feathers

Mercury (Hg) and stable carbon and nitrogen isotope ratios were analysed in body feathers from nestlings of white-tailed eagles (Haliaeetus albicilla) (WTE; n = 13) and Northern goshawks (Accipiter gentilis) (NG; n = 8) and in red blood cells (RBC) from NG (n = 11) from Norway. According to linear mixed model, species factor was significant in explaining the Hg concentration in feathers (LMM; p < 0.001, estimate (WTE) = 2.51, 95% CI = 1.26, 3.76), with concentrations higher in WTE (3.01 ± 1.34 µg g^-1 dry weight) than in NG (0.51 ± 0.34 µg g^-1 dry weight). This difference and the isotopic patterns for each species, likely reflect their diet, as WTE predominantly feed on a marine and higher trophic-chain diet compared to the terrestrial NG. In addition, Hg concentrations in RBCs of NG nestlings were positively correlated with feather Hg concentrations (Rho = 0.77, p = 0.03), supporting the potential usefulness of nestling body feathers to biomonitor and estimate Hg exposure. Hg levels in both species were generally below the commonly applied toxicity threshold of 5 µg g^-1 in feathers, although exceeded in two WTE (6.08 and 5.19 µg g^-1 dry weight).

Analysis of Toxic Heavy Metals in the Pellets of Owls: A Novel Approach for the Evaluation of Environmental Pollutants

Massive quantities of unadvisable synthetic pesticides are used in modern agricultural industries in order to increase productivity to convene food demands. Wild birds are an excellent bio-indicator of environmental contaminations as pesticides and heavy metals are intentionally highly hazardous pollutants. Considerably, raptorial birds (owls) attract consumers in the food chain and food web because they have wider forager and foraging grounds. In the current investigation, owl pellets were used as a viable tool and novel approach to detecting environmental contaminants. In total, 30 pellets comprising five species were collected from selected farmlands, and 11 metals (Cr, Mn, Co, Mo, Se, V, Cu, Ni, Pb, Zn, and Fe) were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Undeniably, the Brown Fish Owl showed more metal accumulation than the Barn Owl, Spotted Owl, Indian Eagle Owl, and Mottled Wood Owl. Among the species, the levels of metals such as Manganese (Mn), Molybdenum (Mo), Vanadium (V), Copper (Cu) and Zinc (Zn) varied significantly (p < 0.05). Nonetheless, the research revealed that the agroecosystem was contaminated with heavy metals. The present outcome highlights that the management of the environment, especially the agroecosystem, must be examined with a careful assessment of contaminants, and it is a vital resource for human and other related wildlife faunal communities.

Variation in Hematological Indices, Oxidative Stress, and Immune Function Among Male Song Sparrows From Rural and Low-Density Urban Habitats

A central theme in the field of ecology is understanding how environmental variables influence a species’ distribution. In the last 20 years, there has been particular attention given to understanding adaptive physiological traits that allow some species to persist in urban environments. However, there is no clear consensus on how urbanization influences physiology, and it is unclear whether physiological differences in urban birds are directly linked to adverse outcomes or are representative of urban birds adaptively responding to novel environmental variables. Moreover, though low-density suburban development is the fastest advancing form of urbanization, most studies have focused on animals inhabiting high intensity urban habitats. In this study, we measured a suite of physiological variables that reflect condition and immune function in male song sparrows (Melospiza melodia) from rural and suburban habitats. Specifically, we measured hematological indices [packed cell volume (PCV), hemoglobin concentration, mean corpuscular hemoglobin concentration (MCHC)], circulating glutathione (total, reduced, and oxidized), oxidative damage (d-ROM concentration), antioxidant capacity, and components of the innate immune system [bacteria killing ability (BKA), white blood cell counts]. We also measured whole-animal indices of health, including body condition (scaled mass index length) and furcular fat. Song sparrows inhabiting suburban environments exhibited lower hemoglobin and MCHC, but higher body condition and furcular fat scores. Additionally, suburban birds had higher heterophil counts and lower lymphocyte counts, but there were no differences in heterophil:lymphocyte ratio or BKA between suburban and rural birds. PCV, glutathione concentrations, and oxidative damage did not differ between suburban and rural sparrows. Overall, suburban birds did not exhibit physiological responses suggestive of adverse outcomes. Rather, there is some evidence that sparrows from rural and suburban habitats exhibit phenotypic differences in energy storage and metabolic demand, which may be related to behavioral differences previously observed in sparrows from these populations. Furthermore, this study highlights the need for measuring multiple markers of physiology across different types of urban development to accurately assess the effects of urbanization on wildlife.

Blood Toxic Elements and Effects on Plasma Vitamins and Carotenoids in Two Wild Bird Species: Turdus merula and Columba livia

Birds have historically suffered adverse effects by toxic elements, such as As, Pb, Hg, and Cd. However, reports on exposure to a wide range of elements, including rare earth elements and other minor elements of emerging concern, and the potential consequences for wildlife are still scarce. This study evaluates blood concentrations of 50 elements and their related effects on lutein and vitamin levels in the Eurasian blackbird (Turdus merula) and wild rock pigeon (Columba livia), inhabiting different scenarios of contaminant exposure. Blood concentrations of As, Cd, and Pb (and Mn in T. merula) were increased in both species captured in the mining area, compared to the control site. T. merula also showed increased As, Cd, and Pb concentrations in blood in the agricultural–urban area, as compared to the control area, together with the highest Hg levels, which could be related to agricultural practices and industrial activities. Decreases of 33 and 38% in the plasma retinol levels in T. merula inhabiting the mining and the agricultural–urban areas, respectively, as compared to the control site, were associated with increased Pb, As, and Cd exposure. This could be due to a metal-driven suppressive effect in retinol metabolism and/or its over-use for coping with metal-related oxidative stress.

Year-round element quantification of a wide-ranging seabird and their relationships with oxidative stress, trophic ecology, and foraging patterns

Multidisciplinary approaches are essential to diligently assess environmental health status of ecosystems. In this study, year-round chemical elements' exposure and impacts were assessed on the wide-ranging Cory's shearwater Calonectris borealis breeding in Berlenga Island, offshore Portugal, North Atlantic Ocean. The aim was to identify potential contamination and oxidative stress sources associated with trophic ecology, habitat and spatial use, and foraging patterns. A set of 20 chemical elements were quantified, along with oxidative stress biomarkers, stable isotope analyses, and GPS tracking data. Birds presented higher accumulation to some non-essential elements along the year (i.e. arsenic, As; cadmium, Cd; mercury, Hg; lead, Pb; and strontium, Sr), in which concentrations were similar or surpassed other procellariform seabird populations all over the world. No significant differences were found for any of the elements between different periods within the breeding season, with exception of Hg. However, a Principal Component Analysis taking into consideration a group of elements showed differences between pre-laying and chick-rearing periods, with overall higher concentrations in the former. Individuals spending more time engaging in an intensive search for food, and in more coastal environments, presented overall higher element concentrations, and particularly Hg. Contrary to expectations, no relationships were found between chemical elements and oxidative stress. On the other hand, spatial use and foraging patterns of Cory's shearwaters influenced their oxidative stress responses. Our results highlight the need for multidisciplinary approaches to deepen understanding of the large-scale vulnerability of bioindicators such as seabirds and, by extension, the overall environmental health of ecosystems in which they rely.

Application of Non-Destructive Methods: Biomarker Assays in Blood of White Stork (Ciconia ciconia) Nestlings

White stork (Ciconia ciconia) nestlings can provide quantitative information on the quality of the surrounding environment by indicating the presence of pollutants, as they depend on locally foraged food. This study represents the first comparison of biomarkers in two fractions of white stork nestling blood: plasma and S9 (the post-mitochondrial fraction). The aim of this study was to evaluate acetylcholinesterase (AChE), carboxylesterase (CES), glutathione S-transferase (GST), and glutathione reductase (GR), as well as to establish a novel fluorescence-based method for glutathione (GSH) and reactive oxygen species (ROS) detection in plasma and S9. Considering the enzymatic biomarkers, lower variability in plasma was detected only for AChE, as CES, GST, and GR had lower variability in S9. Enzyme activity was higher in plasma for AChE, CES, and GST, while GR had higher activity in S9. Regarding the fluorescence-based method, lower variability was detected in plasma for GSH and ROS, although higher GSH detection was reported in S9, and higher ROS was detected in plasma. The present study indicated valuable differences by successfully establishing protocols for biomarker measurement in plasma and S9 based on variability, enzyme activity, and fluorescence. For a better understanding of the environmental effects on nestlings' physiological condition, biomarkers can be measured in plasma and S9.

Pesticide and trace element bioaccumulation in wild owls in Brazil

Owls are outstanding environmental quality bioindicators due to their position at the top of the food chain and susceptibility to pollutant accumulation. Exposure to chemical contaminants is often a risk for these animals. Moreover, studies addressing the bioaccumulation of trace elements and pesticide residues in tropical nocturnal raptor species are scarce. We analyzed the 26 organs (heart, liver, and kidney) of Tyto furcata (n=3), Megascops spp. (n=5), Pulsatrix koeniswaldiana (n=1), and Asio stygius (n=1) carcasses, collected from June 2018 to May 2019 in the Southern region of Brazil. The original vegetation consisted of areas of Araucaria forests and grassy-woody steppes with gallery forests, which were greatly modified by the introduction of agriculture. In four animals and eight organs, the pesticides abamectin, atrazine, chlorpyrifos-ethyl, and diurom were analyzed through high-performance liquid chromatography coupled with a mass detector. In six animals and eighteen organs, the trace elements cadmium, lead, chromium, and nickel were identified via atomic absorption spectrophotometry. Chlorpyrifos-ethyl was detected in the livers of the genus Megascops. Chromium was found at high concentrations in all matrices analyzed for this trace element. Moreover, P. koeniswaldiana presented lead levels indicative of high exposure. The bioaccumulation of these toxics in owls described here can impact the population levels of these species, impact on its ecological function, and consequently unbalance the ecosystem. Moreover, owls are considered bioindicators; therefore, the occurrence of bioaccumulation indirectly gives us information about the quality of the environment.

Heavy Metal Assessment in Feathers of Eurasian Magpies (Pica pica): A Possible Strategy for Monitoring Environmental Contamination?

In the present study, the Eurasian magpie (Pica pica), was evaluated as a possible bioindicator of environmental pollution by heavy metals (HMs). Levels of Ni, Pb, Cd, and Hg in feathers of 64 magpies (31 males and 33 females) were measured by ICP-MS technique. Plasmatic biomarkers of oxidative stress (OS) were also assessed. The birds were captured in the province of Parma (Italy), in different capture sites within 1 km from urban area (UZ), and farther than 5 km from urban area (RZ). Median HM levels were 0.68 mg/kg (0.18–2.27), 2.80 mg/kg (0.41–17.7), <limit of detection (LOD) mg/kg (<LOD–0.25), 3.90 mg/kg (1.35–85.9) for Ni, Pb, Cd and Hg, respectively. No significant differences in HM levels were found according to sex, while Ni and Pb were significantly higher in adult compared to young birds (p = 0.047, p = 0.004). Conversely, Cd and Hg levels in young magpies resulted higher than those of adults (p = 0.001 and p = 0.004). No correlation was found between OS biomarkers and HM levels. No differences were found in HM levels according to capture area, except for Hg level, which resulted higher in magpies of RZ (4.05 mg/kg (1.35–12.7)) compared to UZ (2.99 mg/kg (1.54–85.9)). Further experiments are needed to establish whether magpie feathers could represent a suitable non-invasive tool for biomonitoring HMs in the environment.

Male zebra finches exposed to lead (Pb) during development have reduced volume of song nuclei, altered sexual traits, and received less attention from females as adults

Lead (Pb) is a pervasive global contaminant that interferes with sensitive windows for neurological development and causes oxidative damage to tissues. The effects of moderate and high exposure to Pb have been well-studied in birds, but whether low-level early-life exposure to Pb influences adult phenotype remains unclear. Female songbirds use a male's song and coloration to discriminate between high- and low-quality males. Therefore, if early-life exposure to Pb disrupts song learning ability or shifts the allocation of antioxidant pigments away from colorful secondary sexual traits, male birds exposed to Pb may be less attractive to females. We exposed developing zebra finches (Taeniopygia guttata) to Pb-contaminated drinking water (100 or 1000 parts per billion [ppb]) after hatching (days 0-100). Once male finches reached adulthood (120-150 days post hatch), we measured song learning ability, coloration of bill and cheek patches, and volume of song nuclei in the brain. We also measured female preference for Pb-exposed males relative to control males. Finally, we measured motoric and spatial cognitive performance in male and female finches to assess whether cognitive traits differed in their sensitivity to Pb exposure. Male zebra finches exposed to 1000 ppb Pb had impaired song learning ability, reduced volume of song nuclei, bills with less redness and received less attention from females. Additionally, Pb exposure impaired motoric performance in both male and female finches but did not affect performance in a spatial cognitive task. Adult finches exposed to Pb-contaminated water had higher blood-Pb levels, though in all cases blood-Pb levels were below 7.0 µg dL^-1. This study suggests that low-level exposure to Pb contributes to cognitive deficits that persist into adulthood and may indirectly influence fitness by altering secondary sexual traits and reducing male attractiveness.

Preliminary study of oxidative stress biomarkers and trace elements in North Sea Harbour Seals

This preliminary study investigated the potential correlations between trace elements (mercury, zinc, cadmium, copper, selenium, lead, nickel, chromium, lithium and vanadium) concentrations, measured in red blood cells, and oxidative stress biomarkers (total thiols, total glutathione, total and selenium-dependent glutathione peroxidases, triglycerides, malondialdehyde) assessed in the respective serum, in males and females P. vitulina, sampled in the Wadden Sea in spring and autumn 2015. Only concentrations of total mercury and zinc showed significant differences by sex, and only lipid peroxidation was different by season. Moreover, significant positive and negative correlations were observed between biomarkers (triglycerides, thiols, malondialdehyde, glutathione) and trace element concentrations (copper, lead, mercury, nickel, zinc). These findings suggest that the studied biomarkers could be useful for the assessment of oxidative stress in harbour seals exposed to trace elements, but further research with larger sample sizes is needed to better understand their specific associations.

A review of metal-induced effects on vitamins A, E and D3 in birds

Birds have been historically affected by metals and are considered powerful sentinels of environmental pollution. Some toxic elements (Pb, Cd, Hg, As) have been broadly studied in avian species and are well known for their accumulation capacity and deleterious effects, including alterations in vitamin levels. Vitamins A, E and D3 are fat-soluble nutrients involved in multiple physiological functions (e.g., immune function, vision, reproduction, growth and development). Publications reporting metal-induced effects on vitamins in birds are growing and, in some cases, results seem contradictory, making them difficult to interpret. Therefore, a clear view of the overall picture is needed. This mini-review article aims to compile relevant data and describe current knowledge on the effects of the most toxic elements (i.e., Pb, Cd, Hg, As) on vitamins A, E and D3 in birds. Although vitamins are diet dependent, they are strongly regulated and transformed in the organism, and metal-related disruption in their homeostasis may provoke alterations in different directions. Moreover, vitamin status and form in vivo is the result of complex interacting processes in the organism and metal exposure may produce cascade effects. Different factors that may contribute to the variable response of vitamins to metals in birds are discussed. Some final remarks and recommendations are provided for future studies. This mini-review shows an overview of the current knowledge in metal-induced alterations in vitamins of special concern for avian ecotoxicology, a research discipline facing important challenges in the coming years.

Metalliferous Mining Pollution and Its Impact on Terrestrial and Semi-terrestrial Vertebrates: A Review

Metalliferous mining, a major source of metals and metalloids, has severe potential environmental impacts. However, the number of papers published in international peer-reviewed journals seems to be low regarding its effects in terrestrial wildlife. To the best of our knowledge, our review is the first on this topic. We used 186 studies published in scientific journals concerning metalliferous mining or mining spill pollution and their effects on terrestrial and semi-terrestrial vertebrates. We identified the working status of the mine complexes studied, the different biomarkers of exposure and effect used, and the studied taxa. Most studies (128) were developed in former mine sites and 46 in active mining areas. Additionally, although several mining accidents have occurred throughout the world, all papers about effects on terrestrial vertebrates from mining spillages were from Aznalcóllar (Spain). We also observed a lack of studies in some countries with a prominent mining industry. Despite >50% of the studies used some biomarker of effect, 42% of them only assessed exposure by measuring metal content in internal tissues or by non-invasive sampling, without considering the effect in their populations. Most studied species were birds and small mammals, with a negligible representation of reptiles and amphibians. The information gathered in this review could be helpful for future studies and protocols on the topic and it facilitates a database with valuable information on risk assessment of metalliferous mining pollution.

Lead contamination in raptors in Europe: A systematic review and meta-analysis

Lead contamination is a widely recognised conservation problem for raptors worldwide. There are a number of studies in individual raptor species but those data have not been systematically evaluated to understand raptor-wide lead exposure and effects at a pan-European scale. To critically assess the extent of this problem, we performed a systematic review compiling all published data on lead in raptors (1983-2019) and, through a meta-analysis, determined if there was evidence for differences in exposure across feeding traits, geographical regions, between hunting and non-hunting periods, and changes over time. We also reviewed the impact of lead on raptors and the likely main source of exposure. We examined 114 studies that were unevenly distributed in terms of time of publication and the countries in which studies were performed. Peer-reviewed articles reported data for 39 raptor species but very few species were widely monitored across Europe. Obligate (vultures) and facultative scavengers (golden eagle, common buzzard and white-tailed sea eagle) accumulated the highest lead concentrations in tissues and generally were the species most at risk of lead poisoning. We found no evidence of a spatial or decadal trend in lead residues, but we demonstrated that high lead blood levels relate to hunting season. Exposure at levels associated with both subclinical and lethal effects is common and lead from rifle bullets and shot is often the likely source of exposure. Overall, our review illustrates the high incidence and ubiquity of lead contamination in raptors in Europe. However, we did not find studies that related exposure to quantitative impacts on European raptor populations nor detailed studies on the impact of mitigation measures. Such information is urgently needed and requires a more harmonised approach to quantifying lead contamination and effects in raptors across Europe.

Blood concentrations of 50 elements in Eagle owl (Bubo bubo) at different contamination scenarios and related effects on plasma vitamin levels

Some metals and metalloids (e.g. Pb, Hg, Cd and As) are well-known for their bioaccumulation capacity and their toxic effects on birds, but concerns on other minor elements and rare earth elements (ME and REE) are growing due to their intensive use in modern technology and potential toxicity. Vitamins and carotenoids play essential roles in nestling growth and proper development, and are known to be affected by the metals classically considered as toxic. However, we are unaware of any attempts to evaluate the exposure to 50 elements and related effects in plasma vitamins and carotenoids in raptor species. The main goals of this study are: (i) to assess the exposure to 50 elements (i.e. classic toxic elements, trace elements, REE and ME) in nestling Eagle owls (Bubo bubo) inhabiting three differently polluted environments (mining, industrial and control areas) in southeastern Spain, and (ii) to evaluate how element exposure affects plasma vitamin and carotenoid levels, hematocrit and body measurements (mass and wing length) of the individuals. Our results show that local contamination in the mining area contributes to increased blood concentrations of Pb, As and Tl in nestlings, while diet differences between control and mining/industrial areas may account for the different levels of Mn, Zn, and Sr in blood, and lutein in plasma. Plasma tocopherol levels were increased in the mining-impacted environment, which may be a mechanism of protection to prevent toxic element-related oxidative stress. Plasma α-tocopherol was enhanced by 20% at blood Pb concentrations ≥8 ng/ml, and nestlings exhibited up to 56% increase in α-tocopherol levels when blood Pb concentrations reached 170 ng/ml. Tocopherol seems to be a sensitive biomarker under an exposure to certain toxic elements (e.g. Pb, As, Tl).

Toxic elements in blood of red-necked nightjars (Caprimulgus ruficollis) inhabiting differently polluted environments

Toxic metals have been widely reported in avian tissues due to their well-known accumulation capacity and adverse effects. However, rare earth elements (REE) and other minor elements (ME) are becoming a new threat due to their use in modern technology. Presently, exposure data are limited and no studies have been reported in wildlife. The order Caprimulgiformes is among the most understudied groups of birds lacking blood ecotoxicological data. One major constraint is the small blood sample volume that can be collected to ensure animal welfare, which limits analyses. In order to shed light on these collective issues, we sampled 48 red-necked nightjars (Caprimulgus ruficollis) inhabiting three different scenarios of contaminant exposure (agricultural-urban area, n = 15; mining area, n = 17; and control area, n = 16) in southeastern Spain, and report for the first time concentrations of 50 elements (i.e. trace elements, ATSDR's list toxic elements, REE and ME) using a recently developed technique able to analyze them by ICP-MS in very small volumes of blood (130 μL). Concentrations of As, Cd, Pb and Mn were significantly higher in individuals captured at the mining area compared to the other sites. Lead levels in the mine site were of particular concern since it was in the range of blood concentrations related to subclinical/clinical effects in other species, and in our study were associated with decreased hematocrit values (up to 44% hematocrit depression at blood concentrations >1000 ng/ml w.w.). Moreover, additive effects related to metal cocktail exposure in the mining area could be expected. Age and gender-related differences in blood concentrations were found for some elements. Even though most REE and ME concentrations were close to the LOQ, some of these emerging contaminants may trigger sublethal effects that, together with the ATSDR's list toxic elements, need to be carefully evaluated in a future study.

Female oxidative status in relation to calcium availability, metal pollution and offspring development in a wild passerine

Both Ca deficiency and metal exposure may affect physiological and nutritional condition of breeding females altering their ability to deposit essential resources (e.g. Ca, antioxidants) into the eggs. This effect of the maternal investment into egg quality is not strictly limited to the embryonic period, but may persist after hatching, since nutrient levels in yolks can compromise nestling antioxidant status, growth and fledging success. The goal of this study was to investigate how metal pollution and Ca availability during the breeding season affect oxidative stress biomarkers and plasma biochemistry in adult female pied flycatchers (Ficedula hypoleuca). In addition, we aim to evaluate how maternal antioxidant status and body condition relate to breeding parameters and offspring oxidative balance. Females breeding in a metal-polluted area in SW Finland showed higher metal concentrations compared to the control area, although current levels were below the toxic level able to affect female physiology. In addition, Ca availability was not constraining female oxidative status and general health in the study area. Interestingly, our results suggested that antioxidant response to metals was better when Ca concentrations were high enough to cover the physiological Ca requirements in breeding females. There seems to be a subtle balance between the concentrations of Ca in the organism and the tolerance to metal-related effects that requires further research. This study supports that offspring oxidative balance and nestling development are affected by maternal body condition and antioxidant status.

Consequences of trace metal cocktail exposure in zebra finch (Taeniopygia guttata) and effect of calcium supplementation

Trace metal elements are significant stressors in urban areas. Their harmful effects on physiological parameters are demonstrated, but current laboratory studies are not representative of wild chronic exposure to a trace metal cocktail. Calcium can reduce the accumulation and toxicity of several metals, but soil acidification in cities leads to a decrease in bioavailability of this element. The objective of this study was to investigate the accumulation and toxicity of a trace metal cocktail representative of urban exposure on passerine birds, and test the importance of calcium availability on these toxic effects. We exposed zebra finches (Taeniopygia guttata) to a cocktail of seven metals and one metalloid in drinking water, with or without calcium supplementation. We monitored the concentration of metals in the blood and feathers, and their effects on oxidative status and telomere length. The metal cocktail led to higher concentration of all elements in the feathers, and of arsenic and lead in the blood. Birds with a higher concentration of cadmium, arsenic and lead in the feathers had shorter telomeres, but no impact of the cocktail was detected on oxidative status. Birds of the 'calcium' group and the 'calcium and metal' group accumulated higher concentrations of zinc, chromium and nickel in feathers. The 'calcium and metal' group also accumulated lower concentrations of arsenic and lead in feathers compared to the 'metal' group. Our results suggest that chronic exposure to a cocktail of metals at low concentrations has deleterious effects on birds, which can be limited through calcium intake.

Oxidative stress risk assessment through heavy metal and arsenic exposure in terrestrial and aquatic bird species of Pakistan

In this study, we investigated metal- and metalloid-induced oxidative stress response in two aquatic (cattle egret (Bubulcus ibis) (n = 10), pond heron (Ardeola grayii) (n = 10)), as well as two terrestrial (spotted owlet (Athene brama) (n = 6) and bank myna (Acridotheres ginginianus) (n = 16)) bird species collected from the outskirts of Lahore city, Pakistan. For this purpose, glutathione (tGSH) and lipid peroxidation (thiobarbituric acid-reactive substances (TBARS)) levels and activities of antioxidant enzymes (superoxide dismutase (SOD); catalase (CAT)) were analyzed as biomarkers of oxidative stress against metal (Pb, Cd, Cu, Zn) and metalloid (As) concentrations in kidney liver and blood of birds. Our results depicted significant correlation for Pb, Cd, and As with oxidative stress biomarkers in birds. The levels of heavy metals and As and their corresponding effects on oxidative stress biomarkers were comparably higher in aquatic species (p ≤ 0.01) except for Pb and Zn. In comparison of species, SOD and tGSH activities were higher in bank myna and cattle egret, while CAT activity and TBARS concentrations were higher in pond heron and cattle egret, respectively. We deduced that tissues with higher accumulation of metal(loid)s such as liver and kidney were under a great risk to oxidative damage. The overall order of metal accumulation and subsequent oxidative damage among families followed the pattern as Strigidae ≥Ardieda ≥ Sturnidae with their respective trophic levels. Globally, metal- and As-induced oxidative stress is least emphasized in multiple tissues of birds that is needed to be addressed with focus on case-control studies using dose-response approach. Graphical abstract .

Spatiotemporal variations of organochlorine pesticides in an apex predator: Influence of government regulations and farming practices

BACKGROUND

Intensification of agricultural practices has caused several negative effects to the environment. The use of fertilizers and pesticides may alter geochemical cycles or cause direct wildlife intoxication. Detrimental effects of organochlorine pesticides (OCPs) have forced the authorities to ban or restrict its use. This study evaluates the variation in levels of OCPs in a sentinel species in relation to changes in government regulations and the spatial configuration of agricultural practices around the nests.

METHODS

Between 2003 and 2007, we analysed OCP levels in 256 blood samples of Eurasian Eagle-owl (Bubo bubo) chicks nesting in area of intensive commercial agriculture with historical frequent use of pesticides, in South-eastern Spain. We studied year-to-year variations in OCP concentrations and their relation with land use configuration around raptor nests by Generalized Linear Mixed Models (GLMM).

RESULTS

OCPs were detected in 100% samples surveyed in 2003 and 2004, while dropped to 27% in 2005, 6.8% in 2006 and 6.3% in 2007, coinciding with the ban of OCPs. The presence of the main OCPs was related to agricultural practices. In particular, endosulfan and lindane were related to irrigated crops and urban areas, while DDT-related compounds and dieldrin were associated with dry land farming.

CONCLUSIONS

OCP concentrations in blood samples of Eurasian Eagle-owls may respond quickly to the implementations of new regulations about the use of agricultural products. This raptor was confirmed as a good sentinel species allowing rapid detection of changes in pesticides use.

Tools for non-invasive sampling of metal accumulation and its effects in Mediterranean pond turtle populations inhabiting mining areas

Among reptiles, freshwater turtle species have high potential for metal accumulation because of their long lifespan or their aquatic and terrestrial habits. In order to monitor metal bioaccumulation, determine potential toxic effects, and investigate tools for non-invasive metal sampling in reptiles, we studied lead (Pb) and mercury (Hg) accumulation in Mediterranean pond turtles (Mauremys leprosa) inhabiting two former mining areas, one of them with high environmental concentrations of Pb (Sierra Madrona-Alcudia Valley district) and the other one with high environmental concentrations of Hg (Almadén district). Individuals from the Pb mining area showed mean blood concentrations (i.e. 5.59 μg Pb/g dry weight, d.w.) that were higher than those measured in other populations. Blood Hg concentrations were highest (8.83 μg Hg/g d.w.) in the site close to the former Hg mines, whereas blood Hg concentrations in terrapins from another site of Almadén district, located ∼28 km downstream, were not different from locations at the non-mining area. Animals from the Pb-contaminated site showed evidence of oxidative stress, whereas those from the Hg-contaminated site showed increased activity of the antioxidant enzyme glutathione peroxidase, as well as reduced circulating levels of the main endogenous antioxidant peptide, glutathione. Concentrations measured in feces and carapace scutes were useful indicators to monitor blood concentrations of Pb, but not of Hg. Our results provide evidence of the usefulness of freshwater turtles as sentinels of chronic metal pollution, and validate non-invasive tools to advance Pb monitoring in reptiles.

From Mexico to the Beagle Channel: A review of metal and metalloid pollution studies on wildlife species in Latin America

Emissions of metals and metalloids (Hg; Cd; Cr; Cu; Pb; Ni; Zn; Fe; Mn; As; Se) generated by natural (e.g., geothermal activity) or anthropic causes (eg., industry or mining) represent a worldwide contamination problem, especially in developing countries. Exposure to high concentrations of these elements is harmful to living beings, including humans. Information on this type of contamination is scarce and fragmented, limiting research which could benefit from these data. To know the state of the research, we reviewed the studies of environmental pollution by metals and metalloids carried out on animal species in Latin America. The use of animals as biomonitors of contamination by metals and metalloids is a continuously expanding practice that allows for early detection of problems. With this work, we were able to identify the most studied areas in Latin America (Amazon, Gulf of California, coastal area between Rio de Janeiro and Florianopolis and River Plate Estuary). Moreover, we provide information on the most studied metals (Hg, Cd, Cu, Pb, Zn) and wild species, which evidence the use of endangered species. The data reviewed should help researchers to direct their efforts towards sparsely researched areas and facilitate bibliographic consultation of scientific information on exposure to metals and metalloids in Latin America.

Physiological impacts of pollution exposure in seabird's progeny nesting in a Mediterranean contaminated area

Aquatic wildlife is exposed through trophic transfer of hazardous substances to several threats inducing physiological impairments. We aimed at assessing the impact of contamination in one of the hot spots of pollution along Mediterranean coasts, the gulf of Gabes in Tunisia, on Common tern Sterna hirundo, a piscivorous top predator bird. Firstly, we compared the reproductive effort of breeding adults through clutch size distribution in three sites with different levels of pollution. Then, a battery of genotoxicity and oxidative stress biomarkers was carried out to assess physiological impairments in chicks. While defense mechanisms showed a depletion, lipid peroxidation and genotoxicity increased significantly according to pollution level. The multi-biomarker approach used here, discriminated chicks according to contamination degree of their nesting sites. Increases in genotoxicity and oxidative stress were correlated to a decrease in chick body mass known to lead to long-term impacts on juvenile survival and recruitment in birds.

Effect of urbanization on the micronucleus frequency in birds from forest fragments

The urbanization contributes to environment contamination, mainly by the increased vehicle traffic. This intense traffic releases in the air chemical compounds with mutagenic properties that can affect the entire ecosystem. The birds for the flight accumulate air, absorbing gases or particles. The absorption of this polluted air may be causative agent responsible for micronucleus (MN) induction in bird erythrocytes. The quantitative analysis of MN in birds can assists in the monitoring environmental quality of various places. The study aimed to quantify the MN frequency in birds and compare their variation: I) among forest fragments distant from and near to urbanization, II) among species and populations of birds and III) to find if there is a relation between vehicle traffic and MN induction. The capture of the birds took place in four forest fragments in central Brazil (two distant and two near the city) using mist nets. Blood smears were prepared with blood collected from the tarso-metatarsal vein. A total of 354 individuals were analyzed and MN were found in 52% of the individuals analyzed. All sampled birds were identified and resulted to belong to 50 different species, only 4 of which were captured in all the 4 forest fragments. The average MN frequency, regardless of bird species and sampling area, was 1.04/10,000 erythrocytes. From an overall analysis carried out on all birds, the MN frequencies were found to vary among forest fragments distant from and near to urbanization (x² =15.513; p < 0.001) and demonstrated positive correlation between vehicle traffic intensity and the MN frequency (r = 0.988; df=2; p = 0.011). The species of birds presented variation in the amount of MN (x² = 84.64; df=49; p = 0.001). Therefore, a restricted analysis carried out on the 4 species of birds present in all the forest fragments showed that the populations of Antilophia galeata (x² =6.029; p = 0.014), Basileuterus culicivorus (x² =9.53; p = 0.002), Eucometis penicillata (x² =8.067; p = 0.005) and Myiothlypis flaveola (x² =4.771; p = 0.029) showed difference in the MN frequency, when compared between forest fragments distant from and near to cities. The analysis demonstrated that birds living in forest areas near to the city presented higher MN frequency, probably because pollutants generated by urbanization affect birds and that the larger the vehicle traffic the greater the induced MN in the birds.

Effects of calcium supplementation on oxidative status and oxidative damage in great tit nestlings inhabiting a metal-polluted area

Calcium has been proposed to diminish metal toxicity by the modulation of the oxidative stress. This study explores the effects of Ca availability and metal exposure on oxidative stress biomarkers in great tit (Parus major) nestlings. Nests were supplemented with Ca (Ca-supplemented group) or not supplemented (Control group) in a metal-polluted and a background zone in SW Finland. Metal concentrations were analyzed from feces. We analyzed antioxidants (tGSH, GSH:GSSG ratio, CAT, GST, GPx, SOD), protein carbonylation and lipid peroxidation in red cells of nestlings. Ca-supplemented and fast-growing nestlings showed higher CAT activity to cope with reactive oxygen species (ROS) generated during intensive growth and metabolism. SOD and GPx (the latter not statistically significant) were more active in the polluted area, possibly reflecting higher ROS production in nestlings from this zone due to the enhanced metal exposure and smaller size. Antioxidant levels changed over the range of metal concentrations depending on the Ca levels in plasma, suggesting that higher Ca levels stimulate antioxidants and mitigate the impacts of metals. Ca supplementation may improve nestling traits and reproductive output when antioxidants are enhanced in a situation of oxidative challenge. Therefore, Ca should be considered in future studies assessing metal exposure and effects on wild birds.

Assessment of the exposure to heavy metals and arsenic in captive and free-living black kites (Milvus migrans) nesting in Portugal

Due to their high trophic level, raptor species may serve as important indicators of environmental contamination by heavy metals. This study was conducted to determine if the habitat of the black kite (Milvus migrans) is contaminated by heavy metals and arsenic and to assess the degree and type of exposure that may be present. For this purpose, this study was conducted on a group of captive birds (n = 12) and on a group of free-living birds admitted to two wildlife rehabilitation centers (n = 31). Blood samples were taken for analysis of arsenic (As), mercury (Hg) and lead (Pb) concentrations by inductively coupled plasma mass spectrometry (ICP-MS). Captive birds had the lowest blood concentrations for all toxic elements examined, but significant differences from the concentrations found in free-living birds were only observed for Hg and Pb (p < 0.01). Arsenic concentrations were almost three times higher in free-living birds (4.521 ± 5.695 µg/dl) then in captive birds (1.566 ± 0.753 µg/dl). In all the samples of captive birds' mercury was not detected, while in free-living birds we observed a concentration of 7.493 ± 8.464 µg/dl (p < 0.01). Regarding lead, we observed a concentration almost four-fold higher in free-living birds (19.430 ± 29.294 µg/dl) then in captive birds (4.449 ± 1.987 µg/dl) (p < 0.01). Therefore, available sources of Pb and Hg seem to be present in the habitat of the black kite.

Oxidative stress responses of two different ecophysiological species of earthworms (Eutyphoeus waltoni and Eisenia fetida) exposed to Cd-contaminated soil

The aim of this study was to assess the biomarkers of oxidative stress [reduced glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione reductase (GR), aldehyde dehydrogenase (ALDH) and lipid peroxidation (LPO)] in earthworms of different ecological categories [epigeic Eisenia fetida (E. fetida) and anecic Eutyphoeus waltoni (E. waltoni)] exposed to cadmium (Cd)-polluted soil (30, 60 and 120 mg kg^-1) for 28 days. Cd accumulation in earthworms increased significantly with increasing exposure dose and duration. However, E. fetida showed a relatively higher level of Cd accumulation until day 21; thereafter, depletion in the Cd level was recorded for the highest exposure dose. In E. waltoni, the detoxification enzymes and GSH level increased significantly with increasing exposure dose and Cd accumulation for 14 days (acute phase). In contrast, in E. fetida, acute exposure to Cd increased detoxification enzymes with decrease in GSH levels. For both species, sub-chronic exposures (28 days) increased lipid peroxidation with decrease in detoxification enzymes. GPx and ALDH responses of Cd-exposed earthworms showed a similar trend. Thus, these enzymes can be used as general biomarkers in these two species. The consistent variations in GST, GPx and ALDH activities suggest that E. waltoni may be used as a bioindicator species; this further signifies the use of endemic earthworms as a bioindicator to assess the risk of soil contamination. The present investigation indicates that Cd accumulation and biomarker responses in earthworms depend on dose and duration of exposure and on the concerned species.

House sparrow biomarkers as lead pollution bioindicators. Evaluation of dose and exposition length on hematological and oxidative stress parameters

House sparrows (Passer domesticus) have been proposed as a key ecological indicator of urban pollution. Remarkably, we lack knowledge about the physiological effects of lead on this bird species. Therefore, this study was aimed to evaluate the effect of Pb on several physiological parameters in house sparrows exposed to environmental Pb concentrations. In a first experiment, birds were exposed to Pb sub-lethal doses (from 1.3 to 14.0 µg of Pb/g animal/day) during 5 days, which resulted in a dose response increase of blood Pb levels and decrease of blood ALAD activity. However, at the higher doses tested (> 7 μg of Pb/g animal/day) the blood ALAD activity inhibition (~82%) remained constant. Hematocrit and hemoglobin were significantly reduced only at the highest-doses, and the stress indicator, heterophils to lymphocyte (H/L) ratio, did not show apparent changes. In a second experiment, house sparrows were exposed to Pb in drinking water (12.3 ppm) during either 15 or 30 days. Pb concentration used in this study was enough to produce blood lead levels equivalents to those found recently in house sparrows inhabiting urban areas, reduced blood ALAD activity and inversion of the H/L ratio. Decreasing blood ALAD activities were correlated with increasing blood Pb levels. In addition, Pb exposure produced modification in the levels of hepatic antioxidant enzymes, increased GST activity and decreased CAT activity, without lipid peroxidation. In conclusion, our results suggest that blood ALAD activity is a reliable and sensitive biomarker for environmental Pb exposure in house sparrows, additionally chronic exposure produce physiological stress (H/L inversion) and small changes in antioxidant enzyme activity. Finally, this specie could be considered a bioindicator for monitoring the urban Pb contamination.

Heavy metal accumulation, risk assessment and integrated biomarker responses of local vegetables: A case study along the Le'an river

In this research, Ganzhou Chinese Cabbage (Brassica rapa pekinensis), Native Purple Garlic (Allium sativum L) and Leping Radish (Raphanus sativus L) widely planted and distributed along the Le'an River were chosen in the present study. Soil physical-chemical properties, nutrients contents as well as heavy metals elements accumulated in both soils and vegetables collected from 24 sites were analyzed by lab analysis combined with statistical method which was also used for calculation of contamination factor, pollution indexes and hazardous index. Heavy metals accumulation in soils were revealed with higher level, and copper and cadmium exceeded the background values by 8.82 and 16.73 times on average, which were also significantly related with the distribution of nonferrous metal processing enterprises. Heavy metal elements accumulated in vegetables were fully consistent with the finding of pollution characteristics in soils. Peroxidase biomarkers in vegetables, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), reduced glutathione (GSH) and lipoperoxidation (as TBARS), as well as integrated biomarker responses (IBR) were determined to give a reliable response after exposing of contaminants. Heavy metals accumulation ability and biomarker responses for three vegetables were usually determined in the following decrease trend: Ganzhou Chinese Cabbage > Native Purple Garlic > Leping Radish. Compared with peroxidase biomarkers activities or contents of control site, all the measured biomarkers in polluted sites showed significantly responses, indicating potential relationship between pollutants stresses and biomarker responses. This study also revealed that the IBR values were coordinated well with the pollutants concentrations.

Reduction of the Oxidative Stress Status Using Steviol Glycosides in a Fish Model (Cyprinus carpio)

Steviol glycosides are sweetening compounds from the Stevia rebaudiana Bertoni plant. This product is considered safe for human consumption and was approved as a food additive by the Food and Drugs Administration (FDA) and European Food Safety Authority (EFSA). Its effects on the ecosystem have not been studied in depth; therefore, it is necessary to carry out ecotoxicological studies in organisms such as Cyprinus carpio. The present study aimed to evaluate the antioxidant activity by SGs on diverse tissues in C. carpio using oxidative stress (OS) biomarkers. To test the antioxidant activity, carps were exposed to four systems: (1) SGs free control, (2) CCl₄ 0.5 mL/kg, (3) SGs 1 g/L, and (4) CCl₄ 0.5 mL/kg + SGs 1 g/L at 96 h. The following biomarkers were analyzed: lipoperoxidation (LPX), hydroperoxide content (HPC), and protein carbonyl content (PCC), as well as antioxidant activity of superoxide dismutase (SOD) and catalase (CAT). It was found that both (3 and 4) systems' exposure decreases LPX, CHP, PCC, SOD, and CAT with respect to the CCl₄ system. The results of this study demonstrate that the concentrations of SGs used are not capable of generating oxidative stress and, on the contrary, would appear to induce an antioxidant effect.

From sport hunting to breeding success: Patterns of lead ammunition ingestion and its effects on an endangered raptor

Lead is highly toxic for wildlife, with pernicious consequences especially in long-lived predators. The causes of lead ammunition ingestion in Bonelli's eagle (Aquila fasciata) and its effects on breeding success were studied in one of the most important populations of this endangered species in Europe. Regurgitated pellets belonging to different pairs from 2004 to 2014 were analyzed, both in the breeding (1363 pellets from 12 territories) and non-breeding (172 pellets from 9 territories) seasons. From these territories, 57 molted feathers to study lead contamination were analyzed, and breeding success was monitored for 41 breeding attempts. The occurrence of lead shots in pellets was detected using X-ray photographs. Pellets were also used to describe eagle diet. Lead shots in pellets were present in 83.3% of the territories. The frequency of occurrence of lead shots in pellets (2.81% in spring and 1.31% in autumn) was primarily related to the consumption of red-legged partridge in the breeding season (when partridges are hunted from blinds using calling lures), and secondarily to rabbit consumption in the non-breeding season (coinciding with the main hunting season). Thus, our results indicate that injured small-game were the main source of lead contamination in the Bonelli's eagle. For the first time for a raptor species, a positive relationship between the frequency of occurrence of lead shots in pellets and lead concentration in eagles' feathers has been documented. Lead concentration in feathers (mean±SD: 816±426μgkg^-1, with no sex-related differences) was high for a species that rarely eats carrion or aquatic birds (the main prey-related lead source for raptors). This had negative effects on breeding success, which could jeopardize Bonelli's eagles in other European populations that are sustained by juvenile dispersal from the study population. Our work shows that some game modalities pose a potential threat to endangered raptors.

Metal Concentrations in Eurasian Eagle Owl Pellets as a Function of Reproductive Variables in Korea

Eight metals were analyzed in the pellet of Eurasian eagle owls (Bubo bubo) breeding in Korea: Paju, Ganghwa, Gimpo, and Sihwa, Gyeonggi-do (N = 15, respectively). Except for cadmium (Cd), concentrations of all metals differed among sites (ANOVA, p < 0.001); Sihwa had relatively higher metal concentrations compared with other sites. Clutch size did not differ among the four sites. However, Sihwa had the greatest nesting success and number of fledglings (per hatchlings and laid egg) and highest mean weight of diet. Lead concentrations in the pellets were generally lower than the excrements of various birds worldwide. We suggest that all metal concentrations in pellets do not negatively affect the reproduction of Eurasian eagle owls, and food supply at Sihwa seems likely more important to breeding success than metal contamination.

The role of density-dependence regulation in the misleading effect of the Aznalcollar mining spill on the booted eagle fecundity

The aim of this study was to assess the exposure and potential effects of the toxic elements released by the Aznalcollar spillage on the fecundity of the booted eagle (Hieraetus pennatus) population of Doñana National Park. We measured As, Cd, Cu, Pb, Zn, Sb and Tl levels in the blood of 24 individuals after the accident and also used data of reproductive performance of the species from 1976 to 2000. While As, Sb and Tl were below their detection limits and only 3 samples were above detection limit for Cd (0.02-0.04μg/dl), mean levels of Cu, Zn and Pb (μg/dl) were found to be 38.736, 532.937 and 0.719, respectively, in fledglings; and 66.112, 652.571 and 1.825, respectively, in adults. These levels were higher in adults, but they did not differ significantly between age classes and were at safe levels. In addition, a positive relationship between relative fecundity and the combination of Cu, Zn and Pb was observed. Following the mining spill, the mean population fecundity was lower (0.536 fledglings per pair in the population) than before (1.093). However, the decrease in fecundity over time was also related to the increase of breeding pairs, suggesting a density-dependent regulation and nullifying the mining spillage effect. Thus, although raptors have proved to be highly valuable biomonitors of environmental pollution, we must be especially cautious and go beyond the apparent effects that sometimes we quickly believe to detect, leading us to reach mistaken conclusions that could affect our management plans.

Oxidative stress responses in relationship to persistent organic pollutant levels in feathers and blood of two predatory bird species from Pakistan

To date, knowledge of persistent organic pollutant (POP) mediated oxidative stress responses in avian species is rather limited. We therefore investigated whether exposure to polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs) in two predatory bird species, namely black kite (Milvus migrans) and spotted owlet (Athene brama), was associated to activities of antioxidant enzymes, such as glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) and catalase (CAT), or expression of GPx and superoxide dismutase (SOD) genes. As part of this investigation, we evaluated whether feathers were suitable to reflect internal body burdens and their associated oxidative stress effects. p,p'-DDE was unanimously recorded with highest concentrations in feathers and blood of both species. In general, the non-significant associations reflect that feathers are not always a suitable indicator for internal body burdens of POPs, depending on the feather type and the age of the bird. The activity of GST and GR was significantly higher in spotted owlet whereas GPx and CAT was higher (albeit not significant) in spotted owlet and black kite respectively. In comparison, mRNA expression of GPx, SOD and Cu,ZnSOD was significantly higher in black kite. Regression analysis showed that the activity of GST and GR was significantly associated with p,p'-DDE in blood of spotted owlet. Similarly, activity of CAT and GR was significantly correlated with BDE-100 in feathers of spotted owlet. In comparison, mRNA expression of SOD was found significantly associated with ∑PBDEs in blood of spotted owlet as well as p,p'-DDE in feathers of black kite. Significant associations of various POPs with biological responses may suggest that POP exposure may be contributing to oxidative stress in the studied bird of prey species. This first investigation indicates the necessity for further research on cause-effect relationships between POP exposures and changes in general health of free ranging birds.

Blood and feather concentrations of toxic elements in a Baltic and an Arctic seabird population

We report blood and feather concentrations of elements in the Baltic Sea and Arctic population of common eiders (Somateria mollissima). The endangered Baltic Sea population of eiders was demonstrably affected by element pollution in the 1990s. While blood concentrations of Hg were higher in Baltic breeding eiders, blood Se, As and Cd concentrations were higher in Arctic eiders. Blood concentrations of Pb, Cr, Zn and Cu did not differ between the two populations. While blood Pb concentrations had declined in Baltic eiders since the 1990s, Hg concentrations had not declined, and were above concentrations associated with adverse oxidative effects in other bird species. Inconsistent with blood concentrations, feather concentrations suggested that Pb, Zn, and Cd exposure was higher in Baltic eiders, and that Hg exposure was higher in Arctic eiders. Our study thus emphasizes the need for comprehensive evaluation of toxic element status, covering the annual cycle of a species.

Oxidative stress and genotoxicity induced by ketorolac on the common carp Cyprinus carpio

The nonsteroidal anti-inflammatory drug ketorolac is extensively used in the treatment of acute postoperative pain. This pharmaceutical has been found at concentrations of 0.2-60 µg/L in diverse water bodies around the world; however, its effects on aquatic organisms remain unknown. The present study, evaluated the oxidative stress and genotoxicity induced by sublethal concentrations of ketorolac (1 and 60 µg/L) on liver, brain, and blood of the common carp Cyprinus carpio. This toxicant induced oxidative damage (increased lipid peroxidation, hydroperoxide content, and protein carbonyl content) as well as changes in antioxidant status (superoxide dismutase, catalase, and glutathione peroxidase activity) in liver and brain of carp. In blood, ketorolac increased the frequency of micronuclei and is therefore genotoxic for the test species. The effects observed were time and concentration dependent. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1035-1043, 2016.

Tracking pan-continental trends in environmental contamination using sentinel raptors-what types of samples should we use?

Biomonitoring using birds of prey as sentinel species has been mooted as a way to evaluate the success of European Union directives that are designed to protect people and the environment across Europe from industrial contaminants and pesticides. No such pan-European evaluation currently exists. Coordination of such large scale monitoring would require harmonisation across multiple countries of the types of samples collected and analysed-matrices vary in the ease with which they can be collected and the information they provide. We report the first ever pan-European assessment of which raptor samples are collected across Europe and review their suitability for biomonitoring. Currently, some 182 monitoring programmes across 33 European countries collect a variety of raptor samples, and we discuss the relative merits of each for monitoring current priority and emerging compounds. Of the matrices collected, blood and liver are used most extensively for quantifying trends in recent and longer-term contaminant exposure, respectively. These matrices are potentially the most effective for pan-European biomonitoring but are not so widely and frequently collected as others. We found that failed eggs and feathers are the most widely collected samples. Because of this ubiquity, they may provide the best opportunities for widescale biomonitoring, although neither is suitable for all compounds. We advocate piloting pan-European monitoring of selected priority compounds using these matrices and developing read-across approaches to accommodate any effects that trophic pathway and species differences in accumulation may have on our ability to track environmental trends in contaminants.

Interspecific differences in the antioxidant capacity of two Laridae species exposed to metals

The main aim of the present study was to assess the concentration of metals (Pb, Cd, Hg, Cu and Zn) in blood, and elucidate their potential effects on oxidative stress biomarkers in red blood cells of Audouin's gull (Ichthyaetus audouinii) and Slender-billed gull (Chroicocephalus genei) chicks in Southeastern Spain. For this purpose, total glutathione (GSH) content, antioxidant enzymes activities (glutathione peroxidase, GPx; superoxide dismutase, SOD; catalase, CAT and glutathione-S-transferase, GST), and lipid peroxidation (TBARS) were analyzed. In general, metal exposure in both species can be considered low, except for Hg in Audouin's gull. Our findings show higher antioxidant levels in Audouin's gull than in Slender-billed gull; probably due to a combination of different basal antioxidant capacity between species, and to an up-regulation of the antioxidant system in Audouin's gull as a response to the higher Hg, Cu and Zn concentrations. This could reduce the production of TBARS keeping them at lower levels than those found in Slender-billed gull. In spite of this, the significantly higher Hg levels found in Audouin's gull (13.6µg/dl wet weight) in comparison to Slender-billed gull (2.7µg/dl), likely related to their different diet and the former consuming discarded fish, were able to produce lipid peroxidation in this species. The positive effect of Hg on SOD activity in Slender-billed gull, and of Pb on GSH levels in Audouin's gull, could reflect the necessity of the organism to upregulate these antioxidants to balance the increased oxidative stress caused by metals. The degree of metal exposure seems to be essential in the response of the antioxidant system, which may suffer up or down-regulations depending on metal concentrations. This study supports the interactive effects of metals on oxidative stress biomarkers, the complexity of the antioxidant system and the close cooperation between antioxidants, which requires the study of several metals and biomarkers to evaluate oxidative stress and damage in wild birds.

Sex-associated differences in trace metals concentrations in and on the plumage of a common urban bird species

Urban areas encompass both favorable and stressful conditions linked with human activities and pollution. Pollutants remain of major ecological importance for synanthropic organisms living in the city. Plumage of urban birds harbour trace metals, which can result from external deposition or from internal accumulation. External and internal plumage concentrations likely differ between specific trace metals, and may further differ between males and females because of potential sex-linked differential urban use, physiology or behaviour. Here, we measured the concentrations in four trace metals (cadmium, copper, lead and zinc) in both unwashed and washed feathers of 49 male and 38 female feral pigeons (Columba livia) from Parisian agglomeration. We found that these concentrations indeed differed between unwashed and washed feathers, between males and females, and for some metals depended on the interaction between these factors. We discuss these results in the light of physiological and behavioural differences between males and females and of spatial repartition of the four trace metals in the city.

Application of biomarkers in Epaulet grouper (Epinephelus stoliczkae) to assess chromium pollution in the Chabahar Bay and Gulf of Oman

In the present study plasma levels of erythropoietin (EPO) hormone and kidney histological changes were assessed as biomarkers to evaluate the chromium pollution in Epaulet grouper (Epinephelus stoliczkae) obtained from different areas in Chabahar Bay and Gulf of Oman. Chemical analyses included the evaluation of chromium in the fish kidney tissue and sediment. The highest and lowest concentrations of chromium were measured in the kidney of fish and sediment collected from Konarak (47.53±1.23 and 110±1.4 μg g(-1)) and the mouth of Chabahar Bay (3.43±1.31 and 13.5±3.23 μg g(-1)), respectively. There was significant difference (P<0.05) of EPO plasma levels between Konarak, Beris and Ramin stations with the mouth of Chabahar Bay as the cleanest station. Reduction of Bowman's space, occlusion of the tubule lumen, leukocytes infiltration, melanomacrophage centers aggregation, nuclear vacuolation, nuclei hypertrophy of tubule cells, necrosis of the tubules, lifting of the tubular basement membrane and dilatation of glomerular capillaries were the most alterations observed in the kidney. The HAI values of Epaulet grouper from Konarak, Beris and Ramin stations were significantly higher than other stations (P<0.05). It was concluded that selected biomarkers as a first investigation could be useful tools to environmental biomonitoring programs.

A review on exposure and effects of arsenic in passerine birds

Arsenic (As) is a metalloid of high concern because of its toxic effects for plants and animals. However, it is hard to find information on this metalloid in passerines. This review presents a comprehensive overview of As exposure and effects in birds, and more particularly in passerines, as a result of an extensive search of the literature available. Internal tissues are the most frequently analyzed matrices for As determination in passerines (37.5% of the reviewed studies used internal tissues), followed by feathers and eggs (32.5% each), feces (27.5%), and finally blood (15%). A clear tendency is found in recent years to the use of non-destructive samples. Most studies on As concentrations in passerines have been done in great tit (Parus major; 50%), followed by pied flycatcher (Ficedula hypoleuca; 22.5%). Some factors such as diet and migratory status are crucial on the interspecific differences in As exposure. More studies are needed to elucidate if intraspecific factors like age or gender affect As concentrations in different tissues. The literature review shows that studies on As concentrations in passerines have been done mainly in the United States (30%), followed by Belgium (22.5%), and Finland (20%), making evident the scarce or even lack of information in some countries, so we recommend further research in order to overcome the data gap, particularly in the southern hemisphere. Studies on humans, laboratory animals and birds have found a wide range of effects on different organ systems when they are exposed to different forms of As. This review shows that few field studies on As exposure and effects in passerines have been done, and all of them are correlative so far. Arsenic manipulation experiments on passerines are recommended to explore the adverse effects of As in free-living populations at similar levels to those occurring in the environment.

CAPSULE

This review summarizes the most interesting published studies on As exposure and effects in passerines.

Assessment of the exposure to heavy metals in Griffon vultures (Gyps fulvus) from the Iberian Peninsula

Griffon vultures (Gyps fulvus), by virtue of their position at the top of the food chain and as obligate scavengers, are at risk of accumulating and concentrating heavy metals in their tissues and may be more predisposed to their toxic effects. The aim of this study is to investigate heavy metal concentrations in Griffon vultures in Portugal and Catalonia, Spain and to determine if heavy metal concentrations in the blood of weak and/or injured Griffon vultures admitted to wildlife rehabilitation centres (WRC) reflect contamination profiles in the local, free-living and outwardly healthy population. Whole-blood samples taken from 121 Griffon vultures caught in the wild or admitted to WRC in Portugal and Catalonia, Spain were examined for cadmium (Cd), mercury (Hg) and lead (Pb) by inductively coupled plasma mass spectrometry (ICP-MS). Cd and Hg were not detected in most samples (98.3% and 95%, respectively), while Pb was detected in all birds in concentrations ranging between 4.97 and 300.23 µg/dl. Birds admitted to WRC had significantly lower Pb concentrations (24.15 ± 15.07 and 25.98 ± 18.04 µg/dl in Portugal and Catalonia, Spain, respectively) than animals caught in the wild (29.67 ± 13.19 and 42.22 ± 50.08 µg/dl in Portugal and Catalonia, Spain, respectively) (p<0.05). This may be explained by the fact that malnutrition was the main cause of admission of Griffon vultures to WRC, as ingestion has been described as the most significant pathway for Pb exposure in raptors. Therefore Griffon vultures admitted to WRC do not seem to be representative of the local, free-flying populations, so it remains necessary to continue catching when one intends to monitor Pb exposure in this species. The population of vultures captured in Catalonia, Spain showed the highest mean blood Pb concentration, perhaps due to the municipal rubbish dump located near the feeding station, with rubbish providing a significant fraction of their trophic needs. The ingestion of game meat with bullet fragments in carcasses or with Pb shots embedded in their flesh could also be the cause of the high blood Pb concentrations found in some vultures. The potential risk of Pb exposure in Griffon vulture populations must be given consideration, since most individuals evaluated had Pb concentrations between 20 and 100µg/dl, which is considered to be subclinical exposure to Pb, and which is above the threshold level at which Pb can affect antioxidant system in this species (15 µg/dl).

Delta-aminolevulinic acid dehydratase (δALAD) activity in four free-living bird species exposed to different levels of lead under natural conditions

The purposes of this study were: (1) to determine the δALAD activity and δALAD ratio in blood of four free-living bird species (Griffon vulture, Eagle owl, Slender-billed gull and Audouin's gull); (2) and to investigate the correlations between δALAD activity/ratio and Pb concentrations in blood samples. A decrease was observed in δALAD activity in Griffon vultures and Eagle owls exposed to Pb. In addition, negative relationships were found between δALAD ratio or δALAD activity and Log blood Pb levels in Griffon vultures and Eagle owls, and these relationships were stronger in areas with the highest Pb exposure. We provide equations that may be helpful to estimate δALAD activity and δALAD ratio using blood Pb concentrations. Regarding gull species, δALAD activity found in the present study may be considered the normal activity in Slender-billed gull and Audouin's gull species, since very low blood Pb concentrations and no correlations were found in these species. Although both δALAD activity and δALAD ratio are sensitive biomarkers of Pb exposure and effect in birds, the use of δALAD ratio may improve the results. Besides, this study provides blood threshold concentrations at which Pb bears effects on δALAD enzyme (5µg/dl in Eagle owl; 8µg/dl in Griffon vulture; and probably >2µg/dl in Slender-billed gull and Audouin's gull). Our findings show that Eagle owl seems to be more sensitive to δALAD enzymatic inhibition by Pb than Griffon vultures. Eagle owls and Griffon vultures exhibited up to 79% and 94% decrease in δALAD activity when blood Pb concentrations exceeded 19 and 30µg/dl, respectively. Regarding the effects related with δALAD inhibition, significant negative correlations were found between δALAD activity and hematocrit in Eagle owls and Griffon vultures, which may be related to compensatory response associated with a decrease in δALAD activity. In addition, an effect on creatine kinase activity and total proteins in plasma was found in Griffon vultures. The significant negative correlations found between δALAD activity and tGSH in Griffon vulture, and between δALAD activity and Log CAT activity in Eagle owls, may be related to a protective response of antioxidant system against reactive oxygen species (ROS). The negative relationship found between δALAD activity and TBARS levels in Griffon vulture is probably related to an induction of lipid peroxidation by ROS that may be generated by δALA accumulation when δALAD activity is depressed. δALAD activity and δALAD ratio in blood are suggested as important nondestructive biomarkers for Pb exposure and effect for future biomonitoring studies in Griffon vulture and Eagle owl. Further studies are recommended to provide new data on Pb concentrations at which δALAD activity is affected in different wild bird species and to elucidate why different species tolerate Pb in different ways.

Elevated mercury levels in a wintering population of common eiders (Somateria mollissima) in the northeastern United States

In North America and Europe, sea ducks are important indicators of ecological health and inshore marine pollution. To explore spatial variation in mercury accumulation in common eiders in the northeastern United States, we compared concentrations of total mercury in common eider blood at several New England locations between 1998 and 2013. Eider food items (mollusks) were collected and analyzed to determine if mercury concentrations in eider blood were indicative of local mercury bioavailability. Eiders from Plum Island Sound, MA had a significantly higher mean blood mercury concentration (0.83 μg/g) than those in other locations. Mean mercury levels in this population were also nearly three times higher than any blood mercury concentrations reported for common eiders in published literature. We observed consistent patterns in eider blood mercury and blue mussel mercury concentrations between sites, suggesting a tentative predictive quality between the two species.