Assessing the fate of both legacy and newer persistent organic pollutants (POPs) is an ongoing challenge. Top predators, including seabirds, are effective monitors of POPs because they forage over a range of marine habitats, integrating signals over space and time. However, migration patterns can make unravelling contaminant sources, and potentially assessments of the effectiveness of regulations, challenging if chemicals are acquired at distant sites. In 2014, we fitted geolocators on ancient murrelets (Synthliboramphus antiqueus) at four colonies on the Pacific Coast of Canada to obtain movement data throughout an annual cycle. All birds underwent a post-breeding moult in the Bering Sea. Around one-third then returned to overwinter on the British Columbia (BC) coast while the rest migrated to overwinter in waters along the north Asian coast. Such a stark difference in migration destination provided an opportunity to examine the influence of wintering location on contaminant signals. In summer 2015, we collected blood samples from returned geo-tagged birds and analyzed them for a suite of contaminants, including polybrominated diphenyl ethers (PBDEs), non-PBDE halogenated flame retardants, perfluoroalkyl substances (PFASs), organochlorines, and mercury. Feathers were also collected and analyzed for stable isotopes (δ¹³C, δ¹⁵N, and δ³⁴S). We found no significant differences in blood concentrations of any contaminant between murrelets from the two different overwinter areas, a result that indicates relatively rapid clearance of POPs accumulated during winter. Spatial variation in diet (i.e., δ¹³C) was associated with both BDE-47 and -99 concentrations. However, individual variation in trophic level had little influence on concentrations of any other examined contaminants. Thus, blood from these murrelets is a good indicator of recent, local contaminants, as most signals appear independent of overwintering location.

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.

Particulate matter (PM) released from the processes of livestock production has a negative impact on the health of animals and workers. Herein, the concentration, major chemical components, morphology and microbiological compositions of particulate matter 2.5 (PM2.5, particles with aerodynamic diameter less than 2.5 μm) in a broiler breeding house were investigated. The results showed that the PM2.5 distribution in the chicken house was affected by the illumination, draught fans, chicken frame structure and activity of the chickens in the broiler breeding house. Component analysis showed that organic carbon (OC) accounted for the largest proportion, and followed by element carbon (EC), SO42−, NO3−, NH4+, Na+, K+ and Ca2+. Ultrastructural observations revealed that the shape of PM2.5 had a round, rectangular, chain-like and irregular shape. The concentration of endotoxin was approximately 0.3 EU/m3. Microbiological analysis showed that at the genus level, the pathogenic bacteria included Staphylococcus, Corynebacterium, Enterococcus, Parabacteroides, Escherichia and Megamonas. The abundant harmful fungi were Aspergillus, Scopulariopsis, Wallemia, and Fusarium. Through redundancy analysis (RDA) analysis, we determined that OC, EC, Na+, K+, and NH4+ had strong correlations with Brachybacterium, Brevibacterium, Corynebacterium, Escherichia, Scopulariopsis and Microascus. SO42− was closely related to Scopulariopsis and Salinicoccus. Salinicoccus was also strongly correlated with NO3−. Our results indicated that feed, faeces, and outside soot are contributed to the increase in PM2.5 concentration in the chicken house, while the sources of the dominant bacterial and fungi might be feed, faeces, suspended outside soil and cereal crops.

The Mediterranean basin is a hotspot of mercury (Hg) contamination owing to intense anthropogenic emissions, volcanic activity and oligotrophic conditions. Little work has been done to assess the sources of Hg exposure for seabirds and, particularly, the physiological consequences of Hg bioaccumulation. In this study, we (i) describe the individual and temporal variation in blood concentration of total Hg (THg) over three breeding seasons, (ii) identify the factors that affect the THg exposure and (iii) determine the individual- and population-level connections between THg and blood-based markers of oxidative status in chicks of Scopoli’s shearwaters (Calonectris diomedea) breeding on the island of Linosa in the southern Mediterranean. We carried out the work on chicks near fledging because they are fed with prey captured near the colony, thus their Hg levels reflect local contamination. The concentration of THg in erythrocytes varied from 0.23 to 4.29 μg g⁻¹ dw. Chicks that were fed upon higher trophic level prey (i.e., higher δ¹⁵N values) had higher THg levels. Individual variation in THg concentrations was not explained by parental identity, sex nor δ¹³C values. There was significant variation in THg among chicks born from the same mother in different years. We found significant correlations between THg and markers of oxidative status; however, these correlations were no longer significant when we took into account the annual variation in mean values of all metrics. Males with higher values of body condition index had higher blood THg, while THg and body condition index were not correlated in females. Our data indicate that THg levels were moderate to high if compared to other seabirds. However, there is little evidence for harmful short-term detrimental effects owing to THg exposure.

Endocrine disrupting chemicals (EDCs) include a wide array of pollutants, such as some metals and other toxic elements, which may cause changes in hormonal homeostasis. In addition to affecting physiology of individuals directly, EDCs may alter the transfer of maternal hormones to offspring, i.e. causing transgenerational endocrine disruption. However, such effects have been rarely studied, especially in wild populations. We studied the associations between environmental elemental pollution (As, Cd, Cu, Ni, Pb) and maternally-derived egg thyroid hormones (THs) as well as nestling THs in great tits (Parus major) using extensive sampling of four pairs of polluted and reference populations across Europe (Finland, Belgium, Hungary, Portugal). Previous studies in these populations showed that breeding success, nestling growth and adult and nestling physiology were altered in polluted zones compared to reference zones. We sampled non-incubated eggs to measure maternally-derived egg THs, measured nestling plasma THs and used nestling faeces for assessing local elemental exposure. We also studied whether the effect of elemental pollution on endocrine traits is dependent on calcium (Ca) availability (faecal Ca as a proxy) as low Ca increases toxicity of some elements. Birds in the polluted zones were exposed to markedly higher levels of toxic elements than in reference zones at the populations in Finland, Belgium and Hungary. In contrast to our predictions, we did not find any associations between overall elemental pollution, or individual element concentrations and egg TH and nestling plasma TH levels. However, we found some indication that the effect of metals (Cd and Cu) on egg THs is dependent on Ca availability. In summary, our results suggest that elemental pollution at the studied populations is unlikely to cause overall TH disruption and affect breeding via altered egg or nestling TH levels with the current elemental pollution loads. Associations with Ca availability should be further studied.

The laboratory reproduction test with the predatory mite Hypoaspis aculeifer is currently a mandatory test in the new EU data requirements for prospective environmental risk assessment of Plant Protection Products (PPPs). However, the low sensitivity often shown by this mite towards PPPs, when compared to other invertebrates (namely Folsomia candida and Eisenia fetida), makes the test with this species not very useful in the lower tier test battery. However, the current test protocol only considers exposure to contaminants via contaminated soil, disregarding exposure via contaminated food and does not take into account the fact that H. aculeifer is a predatory species. Therefore, through this protocol, the toxicity of contaminants to soil mites might be underestimated and, thus, an adaptation of the test performance, by including exposure via contaminated food, may be necessary. With this aim, two reproduction tests with H. aculeifer were performed using copper chloride as model substance, artificial soil as test substrate and cheese mites as food. The OECD guideline was followed but, while in one test cheese mites from normal laboratory breeding cultures (clean prey mites) were provided, in the other test, cheese mites previously exposed to copper (Cu pre-exposed prey mites) were provided. Predatory mites were affected at lower concentrations in tests using Cu pre-exposed prey compared to test with clean-prey (NOEC = 1225 and 1508 mg kg⁻¹ and EC₁₀ = 1204 and 1903 mg kg⁻¹ using Cu pre-exposed and clean prey, respectively). However, this higher sensitivity was not detected by EC₅₀ values (EC₅₀ = 2634 and 2814 mg kg⁻¹ using Cu pre-exposed and clean prey, respectively). Further tests are needed in order to (i) investigate the relevance of oral exposure to different PPPs, (ii) optimize the contamination of prey mites according to the chemical properties of each substance and (iii) substantiate a proposal to adapt the standard protocol.

Birds may act as biovectors of nutrients and contaminants at the regional scale and potentially increase the exposure to such substances in ecosystems frequented by these birds. However, no study has estimated biotransport of contaminants by individual birds through their feces (guano). Elevated concentrations of halogenated flame retardants (HFRs) have been reported in ring-billed gulls (Larus delawarensis) breeding near Montreal (QC, Canada)- a known hotspot for HFRs. The objective of the present study was to investigate the concentrations of polybrominated diphenyl ethers (PBDEs) and selected emerging HFRs (e.g., Dechlorane-related compounds) in guano of individual ring-billed gulls, and to assess the relative accumulation of these HFRs by comparing concentrations in plasma (absorbed) versus guano (excreted). A second objective was to determine the importance of one of the largest ring-billed gull colony (Deslauriers Island) in North America located near Montreal as a vector of HFR biotransport at the regional scale. Elevated concentrations of PBDEs and Dechlorane plus were determined in guano and plasma of ring-billed gulls, although in general no difference was found between males and females. However, plasma to guano concentration ratios were significantly greater in females for the highly hydrophobic BDE-209 and Dechlorane plus compared to males. Overall, for both sexes combined, the total amount of HFRs (sum of the 16 major PBDEs and five emerging HFRs) deposited by this entire colony (64,980 gulls) in the Montreal area through guano during the 28-days incubation period was estimated to 1 g. This study showed that urban-adapted ring-billed gulls from this large colony represent an underestimated biovector of HFRs, which may contribute to augment exposure to these toxic compounds in nearby ecosystems.

Crested ibis (Nipponia nippon), one of the rarest birds in the world, was almost extinct in the historically widespread areas partly due to the environmental pollution. Therefore, non-invasive indicators of feather, eggshell, and excrement were used to investigate the exposure of this endangered bird to eleven trace elements in this study. The results indicated that crested ibises under in situ and ex situ conservations were diversely exposed to trace elements, with higher exposure levels of As, Cd, and Mn in the wild, but higher exposure levels of Hg, Se, and Zn in the captive breeding center. In addition, concentrations of As, Co, Cr, and Ni were significantly greater in the sediments of three types of foraging habitats for wild crested ibis, but concentration of Se was greater in the soil of captive cages. Feather and eggshell of crested ibis exhibited a very consistent indication for most of the trace elements, and concentrations of almost all of the elements in the excrements were very consistent with the results in the environmental samples (sediments or soils). Concentrations of As, Hg, Mn, and Zn in feathers, and Mn and Zn in eggshells of wild and captive crested ibis were greater than those in other similar species. Moreover, As, Cd, Cu, and Mn concentrations in excrement of wild crested ibises were greater than that in captive individuals and other species, but Se and Zn concentrations in excrement of captive crested ibises were greater than that of the wild and other species. The present study provided evidence that both of the wild and captive crested ibis were exposed to trace elements, which may be harmful to their health.

Mercury (Hg) is a pervasive contaminant reaching Antarctic environments through atmospheric transport and deposition. Seabirds as meso to top predators can accumulate high quantities of Hg through diet. Reproduction is one of the most sensitive endpoints of Hg toxicity in marine birds. Yet, few studies have explored Hg exposure and effects in Antarctic seabirds, where increasing environmental perturbations challenge animal populations. This study focuses on the Antarctic petrel Thalassoica antarctica from Svarthamaren, Antarctica, where the world's largest breeding population is thought to be in decline. Hg and the stable isotopes of carbon (δ13C, proxy of feeding habitat) and nitrogen (δ15N, trophic position/diet) were measured in red blood cells from 266 individuals over two breeding years (2012–13, 2013–14). Our aims were to 1) quantify the influence of individual traits (size and sex) and feeding ecology (foraging location, δ13C and δ15N values) on Hg exposure, and 2) test the relationship between Hg concentrations with body condition and breeding output (hatching success and chick survival). Hg concentrations in Antarctic petrels (mean ± SD, 0.84 ± 0.25, min-max, 0.42–2.71 μg g−1 dw) were relatively low when compared to other Antarctic seabirds. Hg concentrations increased significantly with δ15N values, indicating that individuals with a higher trophic level (i.e. feeding more on fish) had higher Hg exposure. By contrast, Hg exposure was not driven by feeding habitat (inferred from both foraging location and δ13C values), suggesting that Hg transfer to predators in Antarctic waters is relatively homogeneous over a large geographical scale. Hg concentrations were not related to body condition, hatching date and short-term breeding output. At present, Hg exposure is likely not of concern for this population. Nevertheless, further studies on other fitness parameters and long-term breeding output are warranted because Hg can have long-term population-level effects without consequences on current breeding success.

We assessed the potential role played by two vital Northeastern Pacific Ocean forage fishes, the Pacific sand lance (Ammodytes personatus) and Pacific herring (Clupea pallasii), as conduits for the vertical transfer of microfibres in food webs. We quantified the number of microfibres found in the stomachs of 734 sand lance and 205 herring that had been captured by an abundant seabird, the rhinoceros auklet (Cerorhinca monocerata). Sampling took place on six widely-dispersed breeding colonies in British Columbia, Canada, and Washington State, USA, over one to eight years. The North Pacific Ocean is a global hotspot for pollution, yet few sand lance (1.5%) or herring (2.0%) had ingested microfibres. In addition, there was no systematic relationship between the prevalence of microplastics in the fish stomachs vs. in waters around three of our study colonies (measured in an earlier study). Sampling at a single site (Protection Island, WA) in a single year (2016) yielded most (sand lance) or all (herring) of the microfibres recovered over the 30 colony-years of sampling involved in this study, yet no microfibres had been recovered there, in either species, in the previous year. We thus found no evidence that sand lance and herring currently act as major food-web conduits for microfibres along British Columbia's outer coast, nor that the local at-sea density of plastic necessarily determines how much plastic enters marine food webs via zooplanktivores. Extensive urban development around the Salish Sea probably explains the elevated microfibre loads in fishes collected on Protection Island, but we cannot account for the between-year variation. Nonetheless, the existence of such marked interannual variation indicates the importance of measuring year-to-year variation in microfibre pollution both at sea and in marine biota.