High levels of PFOS in eggs of three bird species in the neighbourhood of a fluoro-chemical plant.

We studied perfluorooctane sulfonate (PFOS) levels in the eggs of three primarily invertivorous bird species sampled in 2006 near a fluoro-chemical plant: the great tit (Parus major), the northern lapwing (Vanellus vanellus) and the Mediterranean gull (Larus melanocephalus). Our study reported some of the highest PFOS levels ever measured in wildlife to date (i.e. up to 46182ng/g ww in lapwing eggs). A pronounced decrease in PFOS concentration in the Northern lapwing eggs with distance from the fluoro-chemical plant was found. A similar relationship was found for the great tit, with eggs being collected close to the fluoro-chemical plant having significantly higher PFOS levels than eggs collected 1700m further away. When comparing the PFOS levels in eggs for the three species, collected between 1700 and 5500m no significant differences were observed. In addition, when comparing PFOS levels in eggs between Northern lapwing and great tits closer to the plant (900-1700m) no significant differences were found neither. Despite the high levels found in great tit eggs, plasmatic biochemical biomarker responses did not appear to be affected.

Haematological status of wintering great tits (Parus major) along a metal pollution gradient.

In the long-term biomonitoring of wild populations inhabiting polluted areas, the use of non-destructive biomarkers as markers of condition is very important. We examined the possible effects of metal pollution on the haematological status of adult great tits (Parus major) along a well-established pollution gradient near a non-ferrous smelter in Belgium. We measured blood and feather metal concentrations and assessed the haematological status (amount of red blood cells, haemoglobin concentration, haematocrit, mean corpuscular volume and mean corpuscular haemoglobin) of adult great tits during winter at four study sites. Metal concentrations in blood and feathers indicated that cadmium and lead were the most important metals in the pollution gradient under study. Measurements of haematological parameters revealed that haemoglobin concentration, haematocrit, mean corpuscular volume and mean corpuscular haemoglobin were lower in great tits from the more polluted sites. These parameters were significantly negatively correlated with blood lead concentration. The amount of red blood cells, however, did not significantly differ among study sites. Our results indicate that the haematological status of great tits is negatively affected by metal pollution and may therefore be used as a successful biomarker for monitoring the negative impact of metal exposure in the wild.

Nitrates and herbicides cause higher mortality than the traditional organic fertilizers on the grain beetle, Tenebrio molitor.

We examined experimentally whether fertilizers or herbicides commonly used by farmers affect mortality of the adult grain beetle Tenebrio molitor. After a period of 4 weeks in direct contact with all treatments, a higher percentage of mortality occurred in contact with nitrates than with pig manure or turkey litter. Herbicides (a mixture of glyphosate and 2,4-D: ) caused 100% mortality. Our results also indicate that more beetles escaped from the herbicides and nitrate treatments than from the others, suggesting some kind of behavioural avoidance of toxic environments. The traditional organic fertilizers appear to be less toxic than inorganic fertilizers for Tenebrio molitor.

Does anthropogenic metal pollution affect carotenoid colouration, antioxidative capacity and physiological condition of great tits (Parus major)?

Although several studies have shown that carotenoid-based signals are negatively affected by (metal) pollution, the underlying mechanisms are not well understood. There are two possible, not mutually exclusive, hypotheses to explain the metal-induced fading of carotenoid colouration. Metal pollution could affect oxidative stress levels and/or the diet. We assessed the expression of the yellow breast of adult and nestling great tits (Parus major) and related this to physiological parameters in plasma indicative of oxidative stress (total antioxidative capacity) and nutritional condition (albumin, triglyceride, total protein, cholesterol and uric acid concentrations). In four study sites along a metal pollution gradient, both adult and nestling great tits had significantly reduced carotenoid colouration at the most polluted sites. While nestlings' total antioxidative capacity was significantly affected by metal pollution, there was no significant effect on adults' total antioxidative capacity. Both for adult and nestling birds, no clear relation between total antioxidative capacity and carotenoid colouration was found. However, there were significant differences among sites in nutritional parameters, indicating that metal pollution might affect diet composition and quality. We found strong among brood variation in nestlings for all variables (except cholesterol), suggesting that there might be a considerable genetic and/or parental investment factor involved.

Interspecific differences in concentrations and congener profiles of chlorinated and brominated organic pollutants in three insectivorous bird species.

We investigated the accumulation of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs) in eggs of three insectivorous bird species, the great tit (Parus major), the Northern lapwing (Vanellus vanellus) and the Mediterranean gull (Larus melanocephalus), near the harbour of Antwerp (Belgium). Our results show that lapwing eggs had the highest median concentrations of PCBs (4358 ng/g lw) and PBDEs (109 ng/g lw). Mediterranean gulls feed during breeding on ground-dwelling invertebrates on agricultural fields, which is reflected in higher OCP concentrations in eggs (1235 ng/g lw). Apart from differences in accumulation, also interspecific differences in contaminant profiles were investigated. Significant differences among species were found in the profile of PCBs, PBDEs and OCPs. These differences could be attributed to differences in diet, behaviour and metabolic capacity. Interestingly, the OCP profile in lapwing eggs deviated extremely from the two other species. In both great tit and Mediterranean gull eggs p,p'-DDE was by far the most important compound, whereas in lapwing eggs hexachlorobenzene, oxychlordane, trans-nonachlor and even p,p'-DDT were relatively more abundant than p,p'-DDE. The high p,p'-DDT/p,p'-DDE ratio has previously been described in lapwings, which suggests that low p,p'-DDE accumulation in eggs might be inherent for this species.

Melanin- and carotenoid-dependent signals of great tits (Parus major) relate differently to metal pollution.

Due to their high phenotypic plasticity, the expression of secondary sexual characteristics is particularly sensitive to stress. Here, we investigated the expression of two conspicuous visual signals in great tits (Parus major) in a metal pollution gradient. In three study sites with marked differences in metal contamination (mainly lead, cadmium, copper and zinc), we compared melanin and carotenoid colouration of great tits. While carotenoid colouration (yellow breast) was negatively related to metal pollution, the size of a melanin trait (breast stripe) was larger in the most polluted sites. Environmental pollutants not only affect the expression of conspicuous signals but may even enhance, directly or indirectly, a signal of male quality such as breast stripe. Our results also support the multiple messages hypothesis predicting that different signals highlight different aspects of geno- and phenotypic condition of the bearer.

Metallothioneins (MTs) and delta-aminolevulinic acid dehydratase (ALAd) as biomarkers of metal pollution in great tits (Parus major) along a pollution gradient.

Biomonitoring allows an integrated evaluation of different aspects of exposure, accumulation and effects to environmental pollution, simultaneously accounting for the natural variety between individuals in an ecosystem. In this study, the effects of increased metal accumulation were evaluated at the biochemical level in terms of two biomarker responses in the great tit (Parus major), a small insectivorous songbird, along an established metal pollution gradient. Metal concentrations in internal tissues (liver and kidney) and blood indicated that lead and cadmium were the most important metals in the pollution gradient under study. At the biochemical level, induction of metal binding protein metallothionein (MT) in liver and kidney reflected cadmium concentrations in these tissues (R(2)=0.42 and R(2)=0.94 respectively, n=19), although in kidney, MT induction was not sufficient to complex all cadmium present. Secondly, the activity of the enzyme delta-aminolevulinic acid dehydratase (ALAd) in blood decreased exponentially in response to increased lead accumulation (R(2)=0.70, n=18) and represents therefore a specific effect marker for lead exposure. In the highest polluted area, an ALAd inhibition of 85% was reported. Since a higher metal exposure resulted in an increased metal accumulation and subsequent biomarker responses in a dose-dependent way, this study indicates the applicability of ALAd and MT levels in great tits for biomonitoring responses to heavy metal pollution.

Variation, levels and profiles of organochlorines and brominated flame retardants in great tit (Parus major) eggs from different types of sampling locations in Flanders (Belgium).

Small-scale geographical variation in the occurrence of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) was investigated using the eggs of a terrestrial residential songbird species, the great tit (Parus major). In addition, we investigated the influence of the type of sampling location on the presence of these pollutants. To achieve this, 10 different sampling locations in Flanders (Belgium) were classified into 3 groups based on the extent of urbanisation, industrialisation and agriculture. The higher variance among sampling locations for the levels and profiles of PCBs and OCPs, suggests that local contamination sources are more important for the PCBs and OCPs compared to the PBDEs. Levels of PCBs and PBDEs were significantly higher in the industrialised sampling locations compared to the other locations. Sum PCB and sum PBDE levels reached up to 6050 and 79 ng/g lipid weight, respectively. PCBs and PBDEs were highly positively correlated for all groups, suggesting similar exposure pathways and/or mechanisms of accumulation. Significantly higher levels of OCPs (sum OCPs up to 2683 ng/g lipid weight) were detected in the rural sampling locations situated in a residential area. This suggests that local historical usage of OCPs by inhabitants may be an important source of contamination in Flanders. Contamination profiles differed also among the sampling locations. The rural sampling locations had a higher contribution of lower brominated BDE congeners, whereas the industrialised locations had a higher contribution of higher brominated congeners. The differences in contamination profiles among the sampling locations are probably due to differences in exposure. In conclusion, our results showed that the characteristics of a sampling location influence both the levels and profiles of PCBs, OCPs and PBDEs.

PFOS levels in the blood and liver of a small insectivorous songbird near a fluorochemical plant.

Perfluorooctane sulfonate (PFOS) is the stable end product of the degradation of various perfluorinated compounds and is the predominant compound found in the environment and biota. PFOS is a widespread environmental contaminant that is found in a great diversity of wildlife species with more elevated tissue concentrations in animals from populated and industrialized areas. In this study we determined the PFOS accumulation in blood and livers of a small songbird, the great tit (Parus major), in the vicinity of a large fluorochemical plant in Antwerp, Belgium. PFOS concentrations ranged from 553 ng/g to 11359 ng/g in liver and ranged from 24 to 1625 ng/ml in blood, which are among the highest ever reported in free-living animals, and exceeded in almost all birds the hepatic benchmark concentrations for the protection of avian species [Beach SA, Newsted JL, Coady K, Giesy JP. Ecotoxicological evaluation of perfluorooctanesulfonate (PFOS). Rev Environ Contam Toxicol 2006;186:133-174]. Although PFOS concentrations in liver and blood decreased significantly within approximately 5.5 km of the plant, differences were smaller than previously described for wood mice (Apodemus sylvaticus) and nestling great tits. PFOS concentrations in liver and blood were higher in young birds (one-year old). No significant sex differences were found. A highly significant correlation between liver and blood concentrations indicates the usefulness of blood as a non-destructive matrix for biomonitoring purposes.

Accumulation of organochlorines and brominated flame retardants in the eggs and nestlings of great tits, Parus major.

Insectivorous birds may be very useful sentinels for local point-source contamination with persistent pollutants, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs). Eggs have been used extensively to monitor lipophilic contaminants, as females can pass contaminants stored in their body tissues into their eggs. Concentrations and profiles in eggs therefore relate to contamination in the female. Because nestlings are raised on food items collected locally, it is expected that the body burden in nestlings would reflect their diet and local pollution levels better than eggs. In this study we compared the accumulation and the profile of PCBs, PBDEs, and OCPs in great tit (Parus major) eggs, nestlings (5-, 10-, and 15-days old), and their food in two study sites. Our results showed that concentrations in great tit eggs were 4 to 6 times higher than those in nestlings. Concentrations in nestling great tits corresponded with concentrations predicted by a bioenergetics-based model. Most of the persistent organic pollutants in 15-day old nestlings were still from maternal origin. The profile of these persistent pollutants in eggs and nestlings also gradually changed during development. With increasing age, the proportion of the most persistent compounds decreased. This study shows that most of the persistent pollutants in fully grown nestlings may still be from maternal origin. For nestlings to be suitable as indicators of local contamination, most of the POPs they accumulate should originate from dietary sources rather than from maternal transfer via the egg. Nestling birds may therefore not be good sentinels for local contamination with persistent pollutants.

A link between eumelanism and calcium physiology in the barn owl.

In many animals, melanin-based coloration is strongly heritable and is largely insensitive to the environment and body condition. According to the handicap principle, such a trait may not reveal individual quality because the production of different melanin-based colorations often entails similar costs. However, a recent study showed that the production of eumelanin pigments requires relatively large amounts of calcium, potentially implying that melanin-based coloration is associated with physiological processes requiring calcium. If this is the case, eumelanism may be traded-off against other metabolic processes that require the same elements. We used a correlative approach to examine, for the first time, this proposition in the barn owl, a species in which individuals vary in the amount, size, and blackness of eumelanic spots. For this purpose, we measured calcium concentration in the left humerus of 85 dead owls. Results showed that the humeri of heavily spotted individuals had a higher concentration of calcium. This suggests either that plumage spottiness signals the ability to absorb calcium from the diet for both eumelanin production and storage in bones, or that lightly spotted individuals use more calcium for metabolic processes at the expense of calcium storage in bones. Our study supports the idea that eumelanin-based coloration is associated with a number of physiological processes requiring calcium.

Effects of heavy metal exposure on the condition and health of adult great tits (Parus major).

We examined the possible effects of heavy metal exposure on the quality and health of adult great tits (Parus major) at four study sites along a pollution gradient near a non-ferrous smelter in Belgium. Tarsus length, wing length, body mass and condition of great tits were compared with respect to study site, age (first-year and older great tits), sex and season (birds caught in winter and during breeding). Tarsus length did not differ significantly among study sites. The wing length of great tits was larger at the study site furthest from the smelter, especially for older great tits. The length of the outermost tail feathers, however, did not differ significantly among study sites. We found no signs of loss of body mass or condition towards the pollution source. The body mass and condition was lowest for female great tits at the site furthest from the smelter, especially during winter. Haematocrit values did not differ significantly among sites. Overall, we found no clear significant effects of heavy metal pollution on morphological measurements and health parameters of great tits.

Evaluation of biochemical effects related to perfluorooctane sulfonic acid exposure in organohalogen-contaminated great tit (Parus major) and blue tit (Parus caeruleus) nestlings.

A perfluorooctane sulfonic acid (PFOS) biomonitoring survey was conducted on great tit (Parus major) and blue tit (Parus caeruleus) nestlings from Blokkersdijk, a bird reserve in the proximity of a fluorochemical plant in Antwerp (Belgium) and Fort IV, a control area. PFOS, together with 11 organochlorine pesticides, 20 polychlorinated biphenyl congeners and 7 polybrominated diphenyl ethers were measured in liver tissue. The hepatic PFOS concentrations at Blokkersdijk (86-2788 and 317-3322 ng/g wet weight (ww) for great and blue tit, respectively) were among the highest ever measured and were significantly higher than at the control area (17-206 and 69-514 ng/g ww for great and blue tit, respectively). The hepatic PFOS concentration was species- and sex-independent and correlated significantly and positively with the serum alanine aminotransferase activity and negatively with the serum cholesterol and triglyceride levels in both species but did not correlate with condition or serum protein concentration. In the great tit, a significant positive correlation was observed between the liver PFOS concentration and the relative liver weight. In the blue tit, the hepatic PFOS concentration correlated positively and significantly with hematocrite values. None of the investigated organohalogen pollutants except for PFOS were suggested to be involved in the observed biological alterations.

Brominated flame retardants and organochlorine pollutants in eggs of little owls (Athene noctua) from Belgium.

Residues of brominated diphenylethers (PBDEs), organochlorinated pesticides (OCPs) and polychlorinated biphenyls (PCBs) were measured in 40 eggs of little owls (Athene noctua), a terrestrial top predator from Belgium. The major organohalogens detected were PCBs (median 2,600 ng/g lipid, range 790-23 000 ng/g lipid). PCB 153,138/163, 170, 180 and 187 were the predominant congeners and constituted 71% of total sum PCBs. PBDEs were measurable in all samples, but their concentrations were much lower than for PCBs, with a range from 29-572 ng/g lipid (median 108 ng/g lipid). The most prevalent PBDE congeners in little owl egg samples were BDE 47, 99 and 153. This profile differs from the profile in marine bird species, for which BDE 47 was the dominant congener, indicating that terrestrial birds may be more exposed to higher brominated BDE congeners than marine birds. The fully brominated BDE 209 could be detected in one egg sample (17 ng/g lipid), suggesting that higher brominated BDEs may accumulate in terrestrial food chains. Brominated biphenyl (BB) 153 was determined in all egg samples, with levels ranging from 0.6 to 5.6 ng/g lipid (median 1.3 ng/g lipid). Additionally, hexabromocyclododecane (HBCD) could be identified and quantified in only two eggs at levels of 20 and 50 ng/g lipid. OCPs were present at low concentrations, suggesting a rather low contamination of the sampled environment with OCPs (median concentrations of sum DDTs: 826 ng/g lipid, sum chlordanes: 1,016 ng/g lipid, sum HCHs: 273 ng/g lipid). Hexachlorobenzene (HCB) and octachlorostyrene (OCS) were also found at low median levels of 134 and 3.4 ng/g lipid, respectively. Concentrations of most analytes were significantly higher in eggs collected from deserted nests in comparison to addled (unhatched) eggs, while eggshell thickness did not differ between deserted and addled eggs. No significant correlations were found between eggshell thickness and the analysed organohalogens.

The reproductive success and quality of blue tits (Parus caeruleus) in a heavy metal pollution gradient.

Studying the effects of pollution on the reproductive performance of birds in the natural environment is of increasing importance due to the need to monitor environmental quality biologically. In this study we investigated the reproductive success and the quality of blue tits in four study sites (at 0.1, 1, 2.5 and 4 km from a metallurgic smelter) located within a heavy metal pollution gradient during three consecutive years. At the two sites closest to the pollution source, a significantly higher proportion of females had egg laying interruptions, and the interruptions also lasted longer (although not significantly). Although the hatching success differed significantly among sites, these differences could not be related to differences in pollution levels. Other important breeding parameters such as the start of egg laying, the clutch size and the breeding success did not differ significantly among sites. Our results suggest that exposure to heavy metal pollution did not influence blue tit reproduction in an important way.

Feathers as a nondestructive biomonitor for persistent organic pollutants.

Keratinous tissues of mammals and humans, such as hair, have been used to determine the exposure to polychlorinated biphenyls (PCBs) and organochlorine pesticides. In the present study, we investigated the accumulation of persistent organic pollutants (POPs; PCBs, p,p'-DDT, p,p'-dichlorodiphenyldichloroethane [DDD], p,p'-dichlorodiphenyldichloroethylene [DDE], hexachlorobenzene [HCB], oxychlordane, trans-nonachlor, polybrominated diphenyl ethers, and polybrominated biphenyls [PBBs]) in feathers of the great tit (Parus major). The accumulation of POPs in feathers and fat samples of 27 adult great tits collected in April 2000 and December 2002 was compared with regard to possible temporal and spatial differences. Polybrominated diphenyl ethers, PBBs, trans-nonachlor, and HCB could not be quantified in feathers. Most PCB congeners and DDTs (p,p'-DDE, p,p'-DDD, and p,p'-DDT) could be determined in feathers, although concentrations in feathers were markedly lower (sigmaPCB concentration range, 28.2-87.1 ng/g) than concentrations in fat (sigmaPCB concentration range, 1244-10074 ng/g). Feathers had relatively higher levels of low-chlorinated PCBs (tetra- and pentachlorinated biphenyls) and p,p'-DDD compared to levels in fat, presumably reflecting levels in blood. Persistent organic pollutant concentrations did not increase with the age of the feather, suggesting that exogenous or aerial depositions of POPs onto the feather surface had no, or only minimal, influence on levels in feathers. For almost all compounds studied, POPs in feathers and fat were significantly positively correlated in samples collected during the breeding season but not in samples collected during the winter. This temporal difference may have been caused by seasonal changes in lipid reserves. Although further research is required, feathers appear to be a promising new, nondestructive biomonitor for PCBs and DDTs in avian wildlife.

The combined effect of lead exposure and high or low dietary calcium on health and immunocompetence in the zebra finch (Taeniopygia guttata).

The widespread contamination by lead and the acidification of the environment ask for a better understanding of the effects of the interaction between lead and calcium on various aspects of health, including disease defense, in wildlife. Here, we investigated the effects of chronic exposure to sublethal levels of lead, combined with high or low dietary calcium, on health and several components of immunity in male and female zebra finches (Taeniopygia guttata). Thirty individuals of each sex were randomly assigned to three groups: a control group, a group exposed to lead with an additional calcium source (i.e. grit) and a group exposed to lead without access to an extra calcium source. Lead was administered as lead acetate via the drinking water (20 ppm) for 38 consecutive days. Exposure to lead increased significantly the concentrations of lead in kidney and bone in individuals of the experimental groups. Furthermore, the lack of a calcium supplement significantly enhanced the uptake of lead. Lead did not affect health indices such as hematocrit, spleen mass and body mass, nor the adrenal stress response. Cell-mediated immune responsiveness, assessed by a delayed-type hypersensitivity response to phytohaemagglutinin, was also not affected by lead exposure. On the other hand, lead exposure did significantly suppress the secondary humoral immune response towards sheep red blood cells in females, but only when the additional calcium source was not available. This effect was not found in males, suggesting sexual differences in susceptibility of humoral immunity to lead treatment in zebra finches.

Relationships between metal concentrations in great tit nestlings and their environment and food.

Metal concentrations (Ag, As, Cd, Cu, Hg, Ni, Pb, Zn) were determined in the feathers and excreta of nestling great tits (Parus major), in their main invertebrate prey (Lepidoptera larvae) and in vegetation samples, all collected from four sites along a pollution gradient. Metal contamination in vegetation samples increased significantly towards the pollution source. The Ag, As, Hg, Ni and Pb concentrations in food samples were significantly higher at the site closest to the pollution source compared to the other three sites. Great tit nestlings from the site closest to the pollution source had significantly higher concentrations of Ag, As, Hg and Pb in their excreta than did nestlings at the other three sites. For five metals (Ag, As, Cu, Ni and Pb), we found concentrations in caterpillars to be significantly positively correlated with vegetation samples. We also found clear significant positive correlations between excreta and caterpillars for Ag, As, Hg and Pb and between feathers and caterpillars for As and Pb. Our data suggest that excreta are a good monitor for the presence and concentrations of non-essential metals in the food and the environment of passerine birds.

Heavy metal exposure affects the humoral immune response in a free-living small songbird, the great tit (Parus major).

Although many studies have investigated possible effects of heavy metal contamination on components of the immune system in captive birds, studies on the effects of chronic exposure to heavy metals on the immune system of free-living birds are rare. Therefore we studied the effect of heavy metal exposure on the humoral immune responsiveness in free-living great tit (Parus major) populations from four study sites along a pollution gradient near a metallurgic smelter. Although there were no differences in body condition or hematocrit values among great tits from the four study sites, the heavy metal exposure appeared to affect an individual's humoral immune responsiveness, as measured by antibody titers to sheep red blood cells. Great tits from the study site farthest away from the smelter complex had a significantly higher immune responsiveness than birds from the two areas closest to the metallurgic smelter. Further work is now necessary to establish a causal association between heavy metal contamination and immunosuppression.