Physiological effects of PFAS exposure in seabird chicks: A multi-species study of thyroid hormone triiodothyronine, body condition and telomere length in South Western France.

There is growing evidence that poly and perfluoroalkyl substances (PFAS) exposure leads to the disruption of thyroid hormones including thyroxine (T4) and triiodothyronine (T3), and may affect telomeres, repetitive nucleotide sequences which protect chromosome ends. Many seabird species are long-lived top predators thus exhibit high contaminant levels, and PFAS-disrupting effects on their physiology have been documented especially in relation to the endocrine system in adults. On the contrary, studies on the developmental period (i.e., chicks), during which exposure to environmental contaminants may have a greater impact on physiological traits, remain scarce to this date. We carried out a multi-species study with the aim to assess whether and to which extent chicks of four gull species (herring gull, great and lesser black-backed gull, yellow-legged gull) in South Western France are contaminated by PFAS, and to bring further evidence about their potential physiological consequences. Linear PFOS showed concentrations of concern as it was generally >10 times higher than the other PFAS, and exceeded a threshold toxicity level (calculated from previous studies in birds) in almost all sampled chicks. Nonetheless, in herring gull male chicks, total T3 levels were significantly and negatively associated with perfluorodecanoate (PFDA) and perfluorododecanoate (PFDoDA) and positively associated with perfluorotetradecanoate (PFTeDA) in female chicks. Total T3 levels were also positively associated with PFDoDA in great black backed gull male chicks and with perfluorotridecanoate (PFTrDA) in lesser black backed gull chicks. In lesser and great black-backed gulls, both females and males showed significant negative associations between several PFAS and their body condition, and a positive association between telomere length and L-PFOS in the yellow-legged gull was also found. These results corroborate previous findings and need to be further explored as they suggest that PFAS may interfere with the physiological status of chicks during the developmental period, potentially inducing long-lasting consequences.

High levels of fluoroalkyl substances and potential disruption of thyroid hormones in three gull species from South Western France.

Per- and poly-fluoroalkyl substances (PFAS) raised increasing concerns over the past years due to their persistence and global distribution. Understanding their occurrence in the environment and their disruptive effect on the physiology of humans and wildlife remains a major challenge in ecotoxicological studies. Here, we investigate the occurrence of several carboxylic and sulfonic PFAS in 105 individuals of three seabird species (27 great black-backed gull Larus marinus; 44 lesser black-backed gull Larus fuscus graellsii; and 34 European herring gull Larus argentatus) from South western France. We further estimated the relationship between plasma concentrations of PFAS and i) the body condition of the birds and ii) plasma concentrations of thyroid hormone triiodothyronine (TT3). We found that great and lesser black-backed gulls from South Western France are exposed to PFAS levels comparable to highly contaminated species from other geographical areas, although major emission sources (i.e. related to industrial activities) are absent in the region. We additionally found that PFAS are negatively associated with the body condition of the birds in two of the studied species, and that these results are sex-dependent. Finally, we found positive associations between exposure to PFAS and TT3 in the great black-backed gull, suggesting a potential disrupting mechanism of PFAS exposure. Although only three years of data have been collected, we investigated PFAS trend over the study period, and found that great black-backed gulls document an increasing trend of plasma PFAS concentration from 2016 to 2018. Because PFAS might have detrimental effects on birds, French seabird populations should be monitored since an increase of PFAS exposure may impact on population viability both in the short- and long-term.

Demographic, endocrine and behavioral responses to mirex in the South polar skua.

Population consequences of chronic exposure to multiple pollutants at low environmental doses remain speculative, because of the lack of appropriate long-term monitoring surveys. This study integrates proximate and ultimate aspects of persistent organic pollutants (POP) burden in free-living vertebrates, by coupling hormonal and behavioral endpoints, life-history traits, and population dynamics. Blood samples (N=70) were collected in South polar skuas during two breeding periods, in 2003 and 2005, and individuals were annually monitored until 2011. Multi-state mark recapture models were used to test the effects of POP levels on demographic traits. Survival rate and long-term breeding probability were not related to individual POP levels, whereas long-term breeding success significantly decreased with increasing blood levels of mirex, an organochlorine insecticide. At the proximate level, corticosterone (stress hormone) and prolactin (parental care hormone) levels were not linked to individual POP burden. Nest defense in 2005 was significantly less intensive in chick-rearing skuas bearing higher mirex levels, suggesting reproductive behavioral impairment. Matrix population models were then built to project the rate of population decline according to increasing mirex burden. Although mirex levels were 2.8 times higher in 2003 than in 2005, the population-level effect of mirex was only detected in 2005, the year of higher corticosterone levels. The combination of endocrine traits with demographic analysis thereby enables to provide new support of synergistic interactions between pollutants and stress levels on long-term breeding outputs and population dynamics.

Corticosterone, prolactin and egg neglect behavior in relation to mercury and legacy POPs in a long-lived Antarctic bird.

Seabirds often have high loads of contaminants. These contaminants have endocrine disrupting properties but their relationships with some endocrine mechanisms are still poorly investigated in free-living organisms. This is the case for the stress response which shifts energy investment away from reproduction and redirects it towards survival. In birds, this stress response is achieved through a release of corticosterone and is also accompanied by a decrease in circulating prolactin, an anterior pituitary hormone widely involved in regulating parental cares. We measured blood concentrations of some legacy persistent organic pollutants (POPs) and mercury (Hg) and examined their relationships with the corticosterone and prolactin responses of known-age (9-46 years old) incubating snow petrels (Pagodroma nivea) to a standardized capture/handling stress protocol. In this Antarctic seabird, we also investigated whether high contaminant burden correlates with a higher occurrence of egg neglect, a frequently observed behavior in snow petrels. POPs and Hg were unrelated to age. Stress-induced corticosterone concentrations were positively related to POPs in both sexes, and stress-induced prolactin concentrations were negatively related to Hg in males. Egg-neglect behavior was not related to POPs burden, but males with higher Hg concentrations were more likely to neglect their egg. This suggests that in birds, relationships between age and contaminants are complex and that even low to moderate concentrations of POPs and Hg are significantly related to hormonal secretion. In this Antarctic species, exposure to legacy POPs and Hg could make individuals more susceptible to environmental stressors such as ongoing disturbances in Polar Regions.

Polychlorinated biphenyl exposure and corticosterone levels in seven polar seabird species.

The role of polychlorinated biphenyls (PCBs) on exposure-related endocrine effects has been poorly investigated in wild birds. This is the case for stress hormones including corticosterone (CORT). Some studies have suggested that environmental exposure to PCBs and altered CORT secretion might be associated. Here we investigated the relationships between blood PCB concentrations and circulating CORT levels in seven free-ranging polar seabird species occupying different trophic positions, and hence covering a wide range of PCB exposure. Blood ∑7PCB concentrations (range: 61-115,632 ng/g lw) were positively associated to baseline or stress-induced CORT levels in three species and negatively associated to stress-induced CORT levels in one species. Global analysis suggests that in males, baseline CORT levels generally increase with increasing blood ∑7PCB concentrations, whereas stress-induced CORT levels decrease when reaching high blood ∑7PCB concentrations. This study suggests that the nature of the PCB-CORT relationships may depend on the level of PCB exposure.

Demographic responses to mercury exposure in two closely related Antarctic top predators.

Although toxic chemicals constitute a major threat for wildlife, their effects have been mainly assessed at the individual level and under laboratory conditions. Predicting population-level responses to pollutants in natural conditions is a major and ultimate task in ecological and ecotoxicological research. The present study aims to estimate the effect of mercury (Hg) levels on future apparent survival rates and breeding performances. We used a long-term data set (-10 years) and recently developed methodological tools on two closely related Antarctic top predators, the South Polar Skua Catharacta maccormicki from Adélie Land and the Brown Skua C. lonnbergi from the Kerguelen Archipelago. Adult survival rates and breeding probabilities were not affected by Hg levels, but breeding success in the following year decreased with increasing Hg levels. Although South Polar Skuas exhibited much lower Hg levels than Brown Skuas, they suffered from higher Hg-induced breeding failure. This species difference could be attributed to an interaction between Hg and other environmental perturbations, including climate change and a complex cocktail of pollutants. By including Hg-dependent demographic parameters in population models, we showed a weak population decline in response to increasing Hg levels. This demographic decline was more pronounced in South Polar Skuas than in Brown Skuas. Hence, Hg exposure differently affects closely related species. The wide range of environmental perturbations in Antarctic regions could exacerbate the demographic responses to Hg levels. In that respect, we urge future population modeling to take into account the coupled effects of climate change and anthropogenic pollution to estimate population projections.

Persistent organic pollutants in benthic and pelagic organisms off Adélie Land, Antarctica.

The concentrations of polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), pentachlorobenzene (PeCB) and polybrominated diphenylethers (PBDE) were described in benthic and pelagic species collected off Adélie Land, Antarctica. Strong differences were observed among species, with reduced PeCB and HCB levels in benthic species, and elevated PCB levels in the Antarctic yellowbelly rockcod, the Antarctic sea urchin and the snow petrel. Lower-chlorinated congeners were predominant in krill; penta-PCBs in benthic organisms; hexa- and hepta-PCBs in seabirds and cryopelagic fish. This segregation may result from sedimentation process, specific accumulation and excretion, and/or biotransformation processes. The presence of PBDEs in Antarctic coastal organisms may originate from atmospheric transport and partly from a contamination by local sources. Although POP levels in Antarctic marine organisms were substantially lower than in Arctic and temperate organisms, very little is known about their toxic effects on these cold-adapted species, with high degree of endemism.

Hormonal response of nestlings to predator calls.

Chicks of altricial birds may perceive predation risk by acoustic cues produced by predators. This capacity involves changes to a less conspicuous behavior to avoid being detected and predated. However, little is known about the physiological mechanisms underlying this capacity. Potential mechanisms may involve corticosterone and testosterone, two hormones related to begging, an acoustic signal, which could be used by predators to locate and predate the nest. However, given the species-specificity of this relationship, it is difficult to make particular predictions. We manipulated perceived risk of nest predation in the common blackbird (Turdus merula) and analyzed nestlings' plasma levels of these hormones to look for nest predation risk effects. Our experimental manipulation showed hormonal changes in response to nest predation risk. Chicks under a high risk of nest predation reduced their corticosterone plasma levels but increased their testosterone levels in comparison with nestlings exposed to a low nest predation risk. We explain our results as mechanisms to reduce begging activity and discuss them within the framework of hormonal modifications in developing animals. These findings highlight the importance of studying nest predation from the unusually considered chick perspective and underlined the benefits from including physiological variables in the study of predator-prey interactions.

Ambient temperature and pregnancy influence cortisol levels in female guinea pigs and entail long-term effects on the stress response of their offspring.

Mammals generally respond to the important metabolic requirements imposed by thermoregulation and pregnancy by increasing plasma concentrations of glucocorticoid that promote the mobilization of body reserves and enhance energy use by tissues. This study examined the impact of distinct ambient temperatures and reproductive status on cortisol plasma levels in female guinea pigs (Cavia aperea f. porcellus). We also examined cortisol profiles of their offspring. Forty adult females were placed in individual boxes, 20 were exposed to a neutral thermal regime (mean ambient temperature 22.1 ± 1.5 °C) and 20 were maintained under a cool thermal regime (15.1 ± 1.5 °C). Within each treatment, 12 females were pregnant and 8 were non-pregnant. Pregnancy generated a marked elevation of baseline cortisol. Ambient temperature also affected cortisol concentrations. Compared to the pregnant females from the neutral thermal regime, pregnant females maintained under cool conditions exhibited lower baseline levels of cortisol, were less active, but they displayed a greater stress response (i.e. rapid increase of plasma cortisol) following handling. Thermal treatment did not influence reproductive output, reproductive effort, or offspring characteristics. This suggests that pregnant female guinea pigs cope with cool (but not extreme) thermal conditions by reducing activity and baseline cortisol levels, possibly to save energy via an adaptive response. Interestingly, the greater amplitude of the stress response of the cool regime females was also observed in their offspring 2 months after parturition, suggesting that hormonal ambience experienced by the individuals in utero shaped their stress response long after birth.

Yolk androgen deposition in rockhopper penguins, a species with reversed hatching asynchrony.

To maximize fitness, females should invest optimally in the siblings within a litter or brood and adapt this investment to environmental conditions. Chick mass and yolk androgens have been shown to influence the outcome of sibling competition. In birds, asynchronous hatching plays a major role in this process and often leads to brood reduction. We studied maternal deposition of yolk androgens in eggs of southern rockhopper penguins (Eudyptes chrysocome chrysocome). Contrary to other avian models, laying and hatching sequences do not coincide in this species, which exhibits reversed hatching asynchrony. This provides a unique model to test whether the first egg to hatch (B-egg), which is the most likely to survive, differs in composition from the second egg to hatch (A-egg). We found that B-eggs had higher egg masses, yolk masses, yolk androgen concentrations and total yolk androgen amounts than A-eggs. This was observed consistently for the three androgens analyzed (testosterone, androstenedione and 5α-dihydrotestosterone). Laying date affected androgen deposition into A- and B-eggs differently. Interestingly, late clutches had proportionally higher androgen levels in the B-egg compared to the A-egg than early clutches. We discuss these results in relation to the chronology of egg formation and the potential effect of the observed differences on embryo development and brood reduction.

The oxidation handicap hypothesis and the carotenoid allocation trade-off.

The oxidation handicap hypothesis proposes that testosterone mediates the trade-off between the expression of secondary sexual traits and the fight against free radicals. Coloured traits controlled by testosterone can be produced by carotenoid pigments (yellow-orange-red traits), but carotenoids also help to quench free radicals. Recently, it has been shown that testosterone increases the amount of circulating carotenoids in birds. Here, a testosterone-mediated trade-off in the carotenoid allocation between colour expression and the fight against oxidative stress is proposed. Male red-legged partridges were treated with testosterone, anti-androgens or manipulated as controls. Testosterone-treated males maintained the highest circulating carotenoid levels, but showed the palest red traits and no evidence of oxidative damage. Increased levels of a key intracellular antioxidant (i.e. glutathione) indicated that an oxidative challenge was in fact induced but controlled. The trade-off was apparently solved by reducing redness, allowing increased carotenoid availability, which could have contributed to buffer oxidative stress.

Simultaneous pituitary-gonadal recrudescence in two Corsican populations of male blue tits with asynchronous breeding dates.

Animal populations living in geographically variable environments respond to different selection pressures. The adaptive character of the responses to environmental information determines the degree of synchrony of the breeding period with local optimal conditions. An example is provided by two populations of Mediterranean blue tits (Parus caeruleus) in Corsica, breeding in different habitats, with a 1-month difference in the onset of egg laying. This difference in the onset of lay is supposed to be adaptive because, although chicks from both populations are raised mostly on caterpillars, the timing of the appearance of caterpillars is earlier for populations of tits associated with deciduous oak trees than those associated with evergreen oak trees. Here, we show that, despite the difference in the timing of egg laying, males from these two populations start seasonal hypothalamo-hypophysial-testicular development at approximately the same time, in late winter. Specifically, the vernal recrudescence of brain GnRH-I perikarya and fibers, testes volume and song activity began around the same dates and proceeded at the same pace in late winter in both populations. Plasma testosterone and LH levels displayed seasonal variations that were shifted by less than 2 weeks compared to the 1-month difference in egg laying periods. We hypothesize that the strong selection pressures on these two populations to adapt the timing of their breeding seasons to their local environment may have acted mostly on the female egg laying dates, and not so much on the initiation and rate of seasonal recrudescence of the hypothalamo-hypophysial-testicular activity in males.

Reproductive endocrinology of tropical seabirds: sex-specific patterns in LH, steroids, and prolactin secretion in relation to parental care.

Plasma levels of luteinizing hormone, prolactin, testosterone, and progesterone were measured throughout breeding in masked boobies, red-footed boobies, and red-tailed tropicbirds at Europa and Tromelin Islands (Indian Ocean). LH secretion showed a dampened pattern in the three species, particularly in tropicbirds. Such specific differences may be related to the less elaborate courtship displays in tropicbirds. Testosterone levels were very low throughout breeding in all three species, particularly in boobies. Low testosterone values in boobies may be related to their year-round attendance at the colony. Prolactin secretion increased from the prelaying period until the incubation and brooding periods and declined thereafter in boobies but stayed relatively unchanged throughout the breeding cycle in tropicbirds. The relatively constant prolactin secretion in the more pelagic tropicbirds might allow them to undertake parental care despite long absences at sea. Boobies perform postfledging care with basal prolactin levels. For all species, females always have higher prolactin levels than males. This hormonal dimorphism, being more pronounced in boobies, may be associated with differences in parental care between mates.

Endocrine correlates of parental care in an Antarctic winter breeding seabird, the emperor penguin, Aptenodytes forsteri.

Plasma levels of luteinizing hormone (LH) and prolactin associated with parental behavior were measured in the Antarctic winter breeding emperor penguin, Aptenodytes forsteri. Males exclusively incubate the egg while females exclusively brood the nonhomeothermic young; both sexes alternate in rearing the homeothermic young. Birds were sampled on arrival from the sea through egg laying, incubation, and brooding. All parent birds lost their chicks at the end of the brooding period due to harsh weather but sampling continued. In females, LH titers dropped after egg laying but levels were restored when the birds returned from the sea to brood the chicks and were not depressed by high prolactin levels. Plasma prolactin remained low in males captured on arrival and kept until the free-living males finished incubation. In breeders, prolactin secretion increased during the prelaying period when day length decreased. Prolactin levels stayed elevated in males during incubation and in brooding females returning after a 2-month absence at sea. Prolactin values were higher in brooding females than in males ending incubation or returning in late brooding. These levels did not drop after chick loss, and the sexual difference in prolactin values was maintained after breeding failure. In emperor penguins, increased prolactin secretion appears to be triggered around the time of egg laying and continues, driven by an endogenous mechanism, through incubation and brooding until rearing is completed. Prolactin secretion independent of external stimuli may have evolved in pelagic seabirds to maintain parental care despite long absences at sea from the breeding colony.

Chizé virus, a new phlebovirus isolated in France from Ixodes (Trichotoixodes) frontalis.

A new phlebovirus (Bunyaviridae family, Phlebovirus genus), provisionally designed Chizé virus, was isolated from a nymph of Ixodes (Trichotoixodes) frontalis collected on a wren (Troglodytes troglodytes) found dead in the Chizé forest, western France. Chizé virus produced a lethal encephalitis in one-day-old mice and cytopathic effect (CPE) in Vero cells. Extracellular particles with a mean diameter of 105 nm with surface spikes characteristic of Uukuniemi (UUK) serogroup viruses were observed in Vero cells. Chizé virus reacted in complement-fixation test with several UUK serogroup viruses but was readily distinguished from all registered viruses in the serogroup. I. frontalis is highly specific for birds and unlikely to transmit Chizé virus to humans or domestic animals; the pathogenicity of the new virus to wild birds remains to be clarified.

A rickettsia-like organism from Ixodes uriae ticks collected on the Kerguelen Islands (French Subantarctic Territories).

A rickettsia-like microorganism was isolated in suckling mice from Ixodes uriae ticks collected from penguins breeding on Mayes Island, Kerguelen Archipelago, French Subantarctic Territories. At isolation, this agent mimicked a tick-borne arbovirus. Finally, electron microscopy studies of infected suckling mouse livers showed the presence of inclusions filled with pleomorphic microorganism in the cytoplasm of some hepatocytes, sometimes dividing by binary fission and thus of obviously non-viral nature. No firm serological relationship was demonstrated with Chlamydia psittaci, C. trachomatis, C. pneumoniae, Coxiella burnetti, Cowdria ruminentium, Ehrlichia canis, E. phagocytophila, E. risticii or the WSU/1044 agent. The exact taxonomic position of the "Mayes" agent remains to be clarified.

High annual variability in reproductive success and survival of an Antarctic seabird, the snow petrel Pagodroma nivea : A 27-year study.

Demographic parameters were estimated for snow petrels Pagodroma nivea nesting at Pointe Géologie Archipelago, Adélie Land, Antarctica between 1963 and 1990; 21 years of data on adult survival and 27 years of data on breeding success are available. The average age of first return and first breeding were 8.1 and 9.9 years respectively and there was no signifcant difference between the sexes. The overall breeding success averaged 51.3% and was very variable between years (21-80%). Breeding failure was mostly due to incubation failure and annual breeding success was negatively correlated with average snow falls in October-November and October-March. Breeding frequency was very low, averaging 52% of seasons during a reproductive lifetime. Good quality sites, with high occupancy rate and high breeding success were few in the study plots. Poor years in 1966-1967, 1976-1977 and 1983-1984, with low breeding success, very low proportions of nets with breeding attempts and high numbers of non-breeders, occurred 1 year after large-scale El Niño Southern Oscillation (ENSO) events. Snow petrels exhibited very low philopatry. Only 45 birds have been recovered in the study plots from a total of 1115 banded fledglings giving an estimated rate of return of 12.9% between fledging and 3 years old. Annual survival between 3 and 10 years was 91.4%. Annual adult survival (93.4%), though variable, was low during poor years of 1977-1978 and 1983-1984. Adult survival of males (94.7%) was not significantly different from that of females (93.9%). Over the study period, the population of Pointe Géologie was stable. Using the estimated parameters, a Leslie model gave a growth rate of 0.948%, which was probably compensated by immigration (5.7% per year). Restricted numbers of good-quality sites at the place of birth could have led young birds to prospect other colonies and could have selected low philopatry. High adult survival, strong site tenacity and capacity to spread breeding over a long lifetime are probably part of the adaptive strategy of this small fulmarine petrel facing highly variable environmental conditions.

Electrochemical behavior of marcellomycin at lipid-modified carbon-paste electrodes.

A lipid-modified carbon-paste electrode is prepared by mixing phospholipids with the carbon-paste matrix. The resulting electrodes have polar head-groups which allow interactions with positively charged drugs and improved preconcentration/extraction steps. The accumulation of the antitumor drug, marcellomycin, is enhanced in the presence of lipids, giving an 8-fold enhancement of current. The electrode response has been optimized with respect to paste composition, nature of the lipid, pH, temperature, and stirring time. A mechanism for marcellomycin accumulation is proposed, based on electrochemical and UV-visible spectrometric measurements as a function of pH. The electrode response is linearly related to the marcellomycin concentration within the range 1 x 10(-8)-6 x 10(-6)M. Known amounts of marcellomycin added to a urine sample diluted sixfold with water have been measured by use of the medium-exchange technique.