Relationships between heavy metal and metallothionein concentrations in lesser black-backed gulls, Larus fuscus, and Cory's shearwater, Calonectris diomedea

Heavy metals and metalloid levels in the tissues of yellow-legged gulls (Larus michahellis) from Spain: sex, age, and geographical location differences

In the present study, mercury (Hg), cadmium (Cd), lead (Pb), selenium (Se), and arsenic (As) were measured in liver, kidney, and feathers of adult, juvenile, and chick seagulls (Larus michahellis) collected from the northwest of Spain. Age, sex, and the geographical location of samples were considered variables that can influence metal bioaccumulation, for which concentrations were determined by means of ICP-MS. The mean concentrations (dry weight) found in seagulls were 7.01 ± 0.37 mg Hg/kg, 22.82 ± 2.83 mg Cd/kg, 7.36 ± 1.36 mg Pb/kg, 18.64 ± 0.63 mg Se/kg, and 10.64 ± 0.59 mg As/kg. Regarding the different factors analyzed, Hg was the only metal showing sex-related differences, being significantly higher (p < 0.05) the concentrations found in feathers of males (1.26 ± 0.12 mg/kg) than those in females (0.99 ± 0.11 mg/kg). A highly significant (p < 0.01) increase in levels of some metals was found in liver related to the increase of age: Hg (adults (A) 3.33 ± 0.22 mg/kg vs chicks (C) 1.76 ± 0.28 mg/kg), Cd (A 4.74 ± 0.62 mg/kg vs C 1.79 ± 0.2), Pb (A 0.65 ± 0.12 mg/kg vs juveniles 0.4 ± 0.11 mg/kg), and Se (A 7.56 ± 0.43 mg/kg vs C 5.24 ± 0.53 mg/kg). Positive correlations between Cd-Hg and Se-Hg were found in liver (p < 0.001), kidney (p < 0.001), and feathers (p < 0.05 and p < 0.001, respectively). The associations found may reflect antagonistic interactions between Se and Cd on Hg toxicity. The results suggest that L. michahellis can reveal local contamination around the foraging and breeding sites and can be a very useful monitoring instrument for assessing heavy metal contamination and sentinel species of environmental health.

Trace elements in stomach oil of Scopoli's shearwater (Calonectris diomedea) from Linosa's colony

Calonectris diomedea is a colonial Procellariiform breeding on Mediterranean islands. The stomach oil produced during chick rearing is a peculiar trait of this species. The composition of the stomach oil is likely to reflect the composition of the prey ingested and might reveal the contaminants uptake with prey becoming a possible tool for the marine pollution monitoring. We examined the concentration of 15 trace elements by ICP-MS and direct mercury analyser. The principal component analysis revealed a heterogeneous pattern of metal concentration, showing a significant separation between samples collected 20 and 70 days after hatching. The data obtained in this work give preliminary information on the feeding habits and breeding ecology of Linosa's colony of Scopoli's shearwater. The trace metals variability found suggest that the stomach oil may have a role as trophic markers to understand predator-prey relationships and to have evidence on the accumulation of pollutants in the latter.

Assessing the association and predictability of heavy metals in avian organs, feathers, and bones using crowdsourced samples

Birds are bioindicators for research on the relationship between environmental heavy metal concentration levels and accumulation levels in bird tissues. We use roadkill samples, collected by citizen science participants, to investigate the accumulation levels and associations of seven heavy metals in internal organs (heart, liver, and kidney), feathers (primary and breast), and bones (sternum and femur) of two focal species, Amaurornis phoenicurus and Gallinula chloropus. We found that heavy metal accumulation varied by target tissue, and that variables are associated with bird species and heavy metal type. Although Zn and Cu were highest by concentration among both species, Cu was mostly accumulated in internal organs, As in feathers, and Pb in bones. Concentrations of As, Ni, and Pb in feathers of both focal species were lower than those reported in literature, whereas Cd and Cr were above toxic levels. The results also showed that spatial correlation for heavy metal concentration among bird tissues were weaker than non-spatial correlation, suggesting low spatial autocorrelations and variability. In addition, multiple regression analysis revealed significant correlation for Cr, As, and Pb estimations in A. phoenicurus heart, sternum, and kidney, respectively; and potentially Cr in G. chloropus femur by using feathers. These results support the feasibility of using feathers as indicators of As, Cr, and Pb heavy metal contamination to enhance our understanding of heavy metal accumulation in birds, although caution is required for feather-based estimations of Cd, Cu, and Ni concentration.

Temporal changes in metal concentrations in Andean condor feathers: a potential influence of volcanic activity

Geothermal activities (e.g., volcanic eruptions) represent one of the most important natural sources of metal emissions (heavy metals and metalloids). They can be one of the main risks for the ecosystems in regions like North of Argentiniean Patagonia, a sparsely populated area, close to an extensive network of active volcanoes on the Andes Range. The 2011 eruption of the Puyehue-Cordon Caulle volcanic complex (PCCVC) has been the largest volcanic event of the last decades. The effects of exposure to ashes on wildlife and humans have been sparsely studied, and only one biomonitoring study has used higher trophic species. The exposure to metals of the species in Patagonia has been poorly studied. The main objectives of our study were to assess metal screening and to evaluate a possible relation between the levels of metals in the Andean condor (Vultur gryphus) population and the volcanic activity of the area. We investigated the effects of the eruption of the PCCVC in 2011, using samples of molt primary feathers of the Andean condor, collected in nine roosts around Bariloche, Argentina (maximum distance 85 km). Data available suggest the molt of the primary feathers of the Andean condor has a duration of 6 years. We carried out sampling before (2007, 2009) and after (2017) the volcanic eruption (2011). The feathers sampled in 2017 should have been developed in 2011-2012, reflecting the environmental situation of the period immediately following the eruption of the PCCVC. For the first time, we have screened metals in 48 molted primary feathers of Andean condor, showing the levels of 9 metals and metalloids (Si, Cr, Cu, Zn, As, Se, Cd, Pb, Hg). Si, Zn, As, and Cd showed higher levels in the feathers sampled after the eruption. The levels of Cr and Pb (although apparently not related to the volcanic eruption) in some samples are compatible with potential adverse effects in living organisms. The screening results represent an important database (the first for this species) that can be used in in future studies for comparative purposes. HIGHLIGHTS: •We present the first database of metals in condor feathers, which may be useful for future studies. •Volcanic eruptions might represent an important source of metal and metalloid emissions in this area. •The Andean condor from Argentine Patagonia could be affected by volcanic activity in the area. •Andean condor feathers may be good biomonitoring units of this contamination. •Pb pollution does not seem to be related to the volcano's eruption.

Trace metal blood concentrations in Scopoli's shearwaters (Calonectris diomedea) during 2007-2014: A systematic analysis of the largest species colony in Greece

In this study, the concentrations of cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), cobalt (Co), nickel (Ni), manganese (Mn) and zinc (Zn) were investigated in the blood of Scopoli's shearwaters (Calonectris diomedea). Blood samples (N=238) were collected from both juvenile and adult individuals during seven breeding seasons between 2007 and 2014, excluding 2013. Sampling was performed in the pristine environment of the Strofades island complex, Greece, where the largest colony of Scopoli's shearwaters is located in the Eastern Mediterranean basin. The median concentrations of the toxic metals, Cd and Pb, were 0.010 and 0.24μg/g (dry weight; dw), respectively, which were in good agreement with previous studies. The median concentrations of Co, Cr, Cu, Mn, Ni, Zn were 0.18, 1.11, 3.41, 0.29, 0.61, and 22.9μg/g dw, respectively. Inter-annual differences were observed among the concentrations of all assessed metals, except for Ni and Cd, which demonstrated similarities among female individuals. Age-group related differences were observed in both genders for Cd, Cu and Cr, but only among males for Zn. To the best of our knowledge, this is the longest multi-year biomonitoring study of select trace metals that has been conducted thus far on blood samples from Scopoli's shearwater species.

Metals and metalloids in blood and feathers of common moorhens (Gallinula chloropus) from wetlands that receive treated wastewater

We addressed the hypothesis that birds in eutrophic wetlands receiving wastewater treatment plant (WWTP) effluents are exposed to high levels of metals and metalloids and this may drive an ecological trap in some species attracted to these highly productive ecosystems. Levels of metals and metalloids were determined in sediment and in blood and feathers of common moorhens (Gallinula chloropus) from two wetlands in Central Spain: Navaseca Pond, which receives directly the effluent of a WWTP; and Tablas de Daimiel National Park, which is a floodplain less affected by urban discharges. Sediment concentrations of Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb were higher in Navaseca Pond than in Tablas de Daimiel; only Se was higher in Tablas de Daimiel than in Navaseca. Blood levels of Hg and Se were higher in moorhens from Tablas de Daimiel than those from Navaseca. In the case of Hg these levels were below the threshold of adverse effect, but Se levels in 24% of moorhens from Tablas de Daimiel were above the threshold value associated with Se toxicity in birds (1000 ng/mL). In feathers, Hg, Se, Mn, Cu and As levels were higher in Tablas de Daimiel than in Navaseca. Body condition of moorhens was negatively associated with blood Se levels in the moorhens from Tablas de Daimiel. We can reject the hypothesis of a higher accumulation of metals and metalloids in birds associated with the WWTP effluent, but Se levels may need further research considering the nature of the floodplain of Tablas de Daimiel National Park.

Contamination status and accumulation characteristics of heavy metals and arsenic in five seabird species from the central Bering Sea

Seabirds are marine top predators and accumulate high levels of metals and metalloids in their tissues. Contamination by metals in the highly productive offshore region has become a matter of public concern. It is home to 80% of the seabird population in the U.S.A., 95% of northern fur seals (Callorhinus ursinus), and major populations of Steller sea lions (Eumetopias jubatus), walruses (Odobenus rosmarus) and whales. Here, the concentrations of eight heavy metals (Hg, Cd, Cr, Co, Ni, Cu, Zn and Pb) and a metalloid (As) in the liver and kidneys of the northern fulmar (Fulmarus glacialis), thick-billed murre (Uria lomvia), short-tailed shearwater (Puffinus tenuirostris), tufted puffin (Fratercula cirrhata) and horned puffin (Fratercula corniculata) collected in the Bering Sea were measured. As proxies of trophic level and habitat, nitrogen (δ¹⁵N) and carbon (δ¹³C) stable isotope ratios of breast muscles were also measured. Hepatic Hg concentration was high in northern fulmar, whereas Cd level was high in tufted puffin and northern fulmar. The Hg concentration and δ¹⁵N value were positively correlated across individual birds, suggesting that Hg uptake was linked to the trophic status of consumed prey. Furthermore, Hg concentration in our study was higher than those of the same species of seabirds collected in 1990.

Heavy metal concentrations in Black-tailed Gull (Larus crassirostris) chicks, Korea

The objectives of this study were to quantify concentrations of heavy metals in livers and stomach contents of Black-tailed Gull (Larus crassirostris) chicks from two islands in Korea. Iron and manganese concentrations were significantly higher in chick livers at Hongdo Island compared to Rando Islnad. In contrast, zinc, copper and cadmium concentrations were significantly higher at Rando Island than Hongdo Island. On Hongdo Island, Black-tailed Gull chicks at a lighthouse site had higher lead concentrations in livers and stomach contents than at a nearby reference site and stomach contents of Black-tailed Gull chicks had significantly higher lead concentrations than regurgitated diets. In Hongdo Island, manganese, lead and cadmium concentrations were significantly correlated between livers and stomach contents. Essential elements such as iron, zinc, manganese and copper concentrations from the present study were within the range reported for other seabird species including gulls. Livers of four individual gull chicks (13.3%) were at a level considered lead exposed (6-30 μg g(-1) dry weight), but cadmium concentrations in all specimens were within the background level (<3 μg g(-1) dry weight) for wild birds. Elevated lead concentrations on lighthouse site may be attributed to ingestion of paint chips and these concentrations may negatively affect chick behavior, growth and survival.

Breeding near a landfill may influence blood metals (Cd, Pb, Hg, Fe, Zn) and metalloids (Se, As) in white stork (Ciconia ciconia) nestlings

Cadmium, lead, mercury, selenium, iron, zinc and arsenic levels were measured in blood samples from 59 free-ranging white stork nestlings from colonies located in three different environmental conditions in Western Spain. The reference colony was situated in "Llanos de Cáceres y Sierra de Fuentes", an Area of Special Interest for Bird Protection. A second colony was located close to (4.9 km) an urban landfill and a third one was close to both an intensive agricultural area and an urban landfill (1.5 km). Blood samples were diluted and elemental analysis was performed using inductively coupled plasma mass spectrometer. In all cases, the essential metals zinc and iron were found at the highest mean concentrations followed by lead > selenium > mercury > arsenic > cadmium. Regarding toxic metals, the highest concentrations were found for lead (ranging from 23.27 to 146.4 µg/L) although in all cases the concentrations were lower than those considered to cause subclinical effects. The metals levels detected in the chick's blood were not related to the previously reported levels in the soil next to the colonies, which may indicate that landfills are the main source of metals in white stork nestlings. The present data showed that metal levels in white stork chicks may be influenced by the use of landfills as feeding areas by the parents. However, more studies on the metal content in the feed of white stork and the influence of the distance to the landfill are necessary to establish the causality of these findings.

Heavy metal contamination and metallothionein mRNA in blood and feathers of Black-tailed gulls (Larus crassirostris) from South Korea

The objectives of this study were to determine levels of heavy metal in the feathers and blood of Black-tailed gulls (Larus crassirostris), to evaluate metallothionein (MT) mRNA level in Black-tailed gulls on three independent islets, and to examine the correlation between heavy metal concentrations and MT mRNA expression. Eleven heavy metals (Al, Cd, Mn, Pb, Cr, Fe, Cu, Zn, Se, Hg, and As) were investigated in blood and feathers of 65 chicks from breeding colonies (Seomando, Hongdo, and Dokdo islet) of South Korea in 2010. Heavy metals were assayed by PerkinElmer NexION 300 inductively coupled plasma mass spectrometry. The mean concentrations of non-essential heavy metals were found to blood containing Cd (0.002 ~ 0.02 ppm), Pb (0.06 ~ 0.18) ppm, Hg (0.03 ~ 0.05) ppm, and As (0.26 ~ 0.48 ppm), and feather containing Cd (0.05 ~ 0.30 ppm), Pb (2.47 ~ 10.80 ppm), Hg (1.18 ~ 1.57 ppm), and As (0.15 ~ 0.44 ppm). Chicks on Seomando islet showed the highest levels of metals (Cd, Pb, Mn, Cr, Cu, and Se in blood; Al, As, Mn, Cr, Fe, Cu, and Se in feathers) among the colonies. Concentrations of Pb and Hg in feathers were the highest on Hongdo, and the levels of Cd and Zn in feathers were the highest on Dokdo islet. MT mRNA in the blood of Black-tailed gulls was relatively higher in gulls from Seomando than in gulls from Hongdo and Dokdo islet. MT mRNA level is thus positively correlated to heavy metal concentrations in Black-tailed gulls.

Insight on trace element detoxification in the Black-tailed Godwit (Limosa limosa) through genetic, enzymatic and metallothionein analyses

Trace element concentrations (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Zn) were investigated in the liver, kidneys, muscle and feathers of 31 black-tailed godwits (Limosa limosa) accidentally killed during catches by mist net in the Pertuis Charentais, Atlantic coast of France. Analyses of carbon and nitrogen stable isotope ratios were carried out in liver, muscle and feathers in order to elucidate dietary patterns and to determine whether differences in diet explained the variation in elemental uptake. This study also aimed to have a preliminary assessment of sub-lethal effects triggered by trace elements through the investigation of gene expressions by quantitative real-time PCR, antioxidant enzyme activities (catalase, superoxide dismutase, glutathione peroxidase), and metallothionein (MT) levels. The results showed that Cr and Ni concentrations in tissues of adults were lower than in juveniles in part because adults may have eliminated these trace elements through moulting. Except for Cd and Ni, trace element concentrations were negatively correlated to the body mass of godwits. Ag, As, Hg and Se concentrations were positively linked with the trophic position of birds. The diet could be considered as a fundamental route of exposure for these elements demonstrating therefore the qualitative linkage between dietary habits of godwits and their contaminant concentrations. Our results strongly suggest that even though trace element concentrations were mostly below toxicity threshold level, the elevated concentrations of As, Ag, Cd, Cu, Fe and Se may however trigger sub-lethal effects. Trace elements appear to enhance expression of genes involved in oxidative stress defence, which indicates the production of reactive oxygen species. Moreover, birds with the highest concentrations appeared to have an increased mitochondrial metabolism suggesting that the fight against trace element toxicity requires additional energetic needs notably to produce detoxification mechanisms such as metallothioneins.

Metal levels in livers of waterfowl from Korea

This study presents concentrations of heavy metals (iron, zinc, manganese, copper, lead and cadmium) in livers of white-fronted geese (Anser albifrons), eurasian wigeons (Anas penelope), mallards (Anas platyrhynchos) and spot-billed ducks (Anas poecilorhyncha) from Korea in February 2006 and 2008. Iron concentrations were significantly lower in spot-billed ducks than in other species (ANOVA, p<0.001). Zinc concentrations were greater in white-fronted geese and spot-billed ducks than in eurasian wigeons and mallards (ANOVA, p<0.001). Manganese and copper concentrations in white-fronted geese were significantly higher than in other species (ANOVA, p<0.001). Cadmium concentrations were significantly higher in mallards and spot-billed ducks than in white-fronted geese (ANOVA, p=0.007). However, lead concentrations did not differ among species. Iron, zinc, manganese and copper concentrations from this study were within the range of other waterfowl studies. Therefore, we suggest that essential elements such as iron, zinc, manganese and copper are within normal range and are maintained there by normal homeostatic mechanism. Twenty individuals (29.0 percent) exceeded the threshold level for abnormal lead exposure (5 μg/g dry weight) in waterfowl in this study and it is a higher proportion than in herons, egrets and owls from Korea. We suggest that the result was attributed to ingestion of lead shot and sinkers. However, cadmium concentrations in waterfowl except one specimen were within the background concentrations for wild birds. In livers of four waterfowl species found in Korea, lead and cadmium concentrations were similar to previously reported in other geese and ducks; except for poisoning of lead shot or sinkers as shown in earlier studies.

Biological monitoring of heavy metal contaminations using owls

Iron, manganese, copper, lead and cadmium were measured in the livers, muscles, kidneys and bones of Eurasian Eagle Owls (Bubo bubo), Brown Hawk Owls (Nixos scutulata) and Collared Scops Owls (Otus lempiji) from Korea. Iron concentrations by tissue within species did not differ, but there were significant differences among tissues across all species. Manganese and copper concentrations in muscles, kidneys and bones, but not livers, differed among species and also differed among tissues in the three owl species. We suggest that manganese and copper concentrations from this study were far below the level associated with their toxicity. Lead concentrations significantly differed among all species for livers and bones, and among tissues for each species. Cadmium concentrations were significantly different among species for all tissues and among tissues in Eurasian Eagle Owls and Collared Scops Owls. For most samples, lead concentrations in livers and bones, and cadmium in livers and kidneys, were within the background levels for wild birds. For some Eurasian Eagle Owls and Collared Scops Owls, lead concentrations were at an acute exposure level, whilst lead concentrations were at a chronic exposure level in Brown Hawk Owls. Cadmium concentrations were at a chronic exposure level in all three owl species. Acute and chronic poisoning was significantly correlated between indicator tissues. We suggest that lead and cadmium contamination in Eurasian Eagle Owls may reflect a Korean source, Brown Hawk Owls may reflect Korean and wintering sites, and Collared Scops Owls may reflect breeding and/or wintering sites.

A new index for evaluation of cadmium pollution in birds and mammals

The degree of cadmium (Cd) contamination in wildlife is often used as an indicator in the environmental monitoring of Cd poisoning. However, previous studies have not clarified the correlation between levels in wildlife and levels in the environment by comparing levels among different species of animals; therefore, assessing the level of pollution in this manner is not considered a reliably accurate indicator of levels in the environment. The aim of this study was to establish a new indicator for the non-polluted warm-blooded animals, one that is not species-dependent, which will facilitate using different species for Cd monitoring. First, the previous publications regarding Cd contents in wildlife, 27 reports in which Cd contents were represented as arithmetic means and described for both kidney and liver were selected. A regression line (CSRL) between Cd contents of kidney and that of liver was obtained in a high correlation coefficient (R (2) = 0.943, P < 0.01). The mean values from land and waterfowl, terrestrial mammals, seabirds, marine mammals, and non-polluted humans were located on the line and aligned in order. CSRL might allow an accurate determination of whether an animal is polluted by Cd. CSRL was confirmed using well-established and widely recognized pollution models such as Itai-itai patients and Cd-exposed experimental animals. The Cd contents from these models were located in different positions relative to CSRL depending on the level of contamination. Thus, this new indicator determining the Cd-pollution status of animals would be useful for environmental monitoring.

Contamination with nonessential metals from a solid-waste incinerator correlates with nutritional and immunological stress in prefledgling black kites (Milvus migrans)

We assessed whether levels of heavy metals in blood have detrimental effects on the health of prefledgling black kites (Milvus migrans) exposed to emissions from a solid waste incinerator near Madrid, central Spain. As health indexes, we considered body mass corrected by structural size as a general indicator of nutritional condition and white blood cell counts (especially the heterophil:lymphocyte ratio) as an indirect measure of immune function. Nutritional condition was positively related to levels of Zn, an essential element with a major role in many physiological pathways, while the opposite trend was found for the essential Cu, the concentration of which tends to increase with decreasing nutritional condition. We found an interaction between Zn and Cd, indicating that high levels of Zn produce smaller effects of Cd on body mass. Potential immunological stress, expressed as an increase in the heterophil:lymphocyte ratio, caused by the toxic Cd increased as levels of Cu decreased. Thus, nestlings with low levels of Cu and poor nutritional condition suffered more immunological stress due to Cd contamination than nestlings with higher levels of Cu. We also found a negative interaction between Zn and Cd, indicating a response of essential Zn to increasing levels of Cd, which may be indicative of the negative effects of Cd on the immune system. These results suggest that the participation of metallothioneins in detoxification and metal regulation may also indirectly enhance the adrenal stress response to contaminants, probably through a competition of Cd and Zn for Zn binding sites on metallothioneins, reducing the ability of Cd to stress the immune system.

Influence of age, sex and body condition on zinc, copper, cadmium and metallothioneins in common guillemots (Uria aalge) stranded at the Belgian coast

The common guillemots, Uria aalge, found stranded at the Belgian coast, display high levels of Cu in both liver and kidneys. The condition index of the animals, defined as the ratio of liver to kidneys mass (Wenzel & Adelung, 1996, The suitability of oiled Guillemots (Uria aalge) as monitoring organisms for geographical comparisons of trace element contaminants. Archives of Environmental Contamination and Toxicology, 31, 368-377), influences both the metal concentration and its binding to metallothioneins (MT): the lower the condition index, the more emaciated the animals, and the higher the total Cu concentration and the concentration of Cu bound to MT. In less robust individuals, our results suggest that Cu could displace Zn from MT, rendering the Zn ions available to induce a new MT synthesis. Sex-related effects also emerged as significantly higher hepatic MT as well as Cu- and Zn-MT concentrations were found in emaciated male guillemots compared to females. In both organs, Cd concentrations remained low and typically demonstrated an age-dependent renal accumulation, with no noticeable effect of the condition index. As a whole, these results suggest that, for guillemots found stranded at the Belgian coast. Cu binding to hepatic and renal MT could function as a protective mechanism, rendering the metal ions unavailable to exert any cytotoxic activity.

Lead and cadmium in eggs of colonially nesting waterbirds of different position in the food chain of Greek wetlands of international importance

Lead and cadmium concentrations were measured in eggs of collonially nesting waterbirds with different position in the food chains of Greek wetlands of international importance. Differences were found between species in the levels of both lead and cadmium in the Evros and Axios Deltas attributable to their different diets. Nevertheless, the concentration in eggs was unrelated to the position of each species studied in its food chain. There was no significant difference in lead levels among four wetlands sampled for the cormorant and in Cd levels among three wetlands sampled for the Mediterranean gull, probably implying species-specific accumulation patterns. A higher lead pollution of the Axios Delta area was only reflected in the eggs of the Mediterranean gull. The very low concentrations of both metals found in the eggs may either suggest low environmental inputs or lack of sensitivity in using eggs as lead and cadmium biomonitors, thus a more sensitive bioindicator still remains to be found.