Contaminant biomonitoring augmented with a qPCR array indicates hepatic mRNA gene expression effects in wild-collected seabird embryos.

Birds can bioaccumulate persistent contaminants, and maternal transfer to eggs may expose embryos to concentrations sufficient to cause adverse effects during sensitive early-life stages. However, using tissue residue concentrations alone to infer whether contaminant effects are occurring suffers from uncertainty, and efficient, sensitive biomarkers remain limited in wildlife. We studied relationships between whole embryo contaminant concentrations (total mercury, organochlorine pesticides, perfluoroalkyl substances, polychlorinated biphenyls, and halogenated flame retardants) together with mRNA expression in embryonic liver tissue from a Pacific Ocean seabird, the rhinoceros auklet (Cerorhinca monocerata). Fresh eggs were collected, incubated under controlled conditions, and from the pre-hatch embryo, hepatic RNA was extracted for qPCR array analysis to measure gene expression (2-∆Cq), while the remaining embryo was analyzed for contaminant residues. Contaminant and gene expression data were assessed with a combination of multivariate approaches and linear models. Results indicated correlations between embryonic total mercury and several genes such as sepp1, which encodes selenoprotein P. Correlation between the biotransformation gene cyp1a4 and the C7 perfluoroalkyl carboxylic acid PFHpA was also evident. This study demonstrates that egg collection from free-living populations for contaminant biomonitoring programs can relate chemical residues to in ovo mRNA gene expression effects in embryo hepatic tissue.

Perfluoroalkyl Substances in Seabird Eggs from Canada's Pacific Coast: Temporal Trends (1973-2019) and Interspecific Patterns.

Whether perfluoroalkyl sulfonates (PFSAs) and perfluoroalkyl carboxylates (PFCAs) are responding to legislative restrictions and showing decreasing trends in top marine predators that range across the eastern North Pacific Ocean is unclear. Here, we examined longer-term temporal trends (1973-2019) of 4 PFSAs and 13 PFCAs, as well stable isotopes of δ13C and δ15N, in the eggs of 4 seabird species sampled along a nearshore-offshore gradient; double-crested cormorants (Nannopterum auritum), pelagic cormorants (Urile pelagicus), rhinoceros auklets (Cerorhinca monocerata), and Leach's storm-petrels (Hydrobates leucorhous) from the Pacific coast of British Columbia, Canada. PFOS was the most abundant PFSA (79-94%) detected in all eggs regardless of colony and year, with the highest concentrations, on average, measured in auklet eggs (mean = 58 ng g-1, range = 11-286 ng g-1 ww). Perfluoroundecanoic acid (PFUdA) and perfluorotridecanoic acid (PFTriDA) were the dominant long-chain PFCAs (≥30% combined). The majority of PFSAs (including PFOS) are statistically declining (p < 0.001) in the eggs of all 4 species with PFOS half-lives ranging from 2.6 to 7.8 years. Concentrations of long-chain PFCAs exhibited a trajectory comprised of linear increases and second-order declines, suggesting that the rate of uptake of PFCAs is slowing or leveling off. These trends are consistent with the voluntarily ceased production of PFSAs by 3M circa 2000-2003 and are among the first from the northeast Pacific to indicate a positive response to several regulations and restrictions on PFCAs from facility emissions and product content.

Temporal trends (1968-2019) of legacy persistent organic pollutants (POPs) in seabird eggs from the northeast Pacific: Is it finally twilight for old POPs?

Legacy persistent organic pollutants (POPs), such as organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs), are known to persist in the marine environment; however, whether concentrations of these POPs have decreased or stabilized from Canada's Pacific coast in recent years is unclear. Here, we examined temporal trends of various legacy POPs in the eggs of five seabird species; two cormorants (Nannopterum auritum and Urile pelagicus), an auklet (Cerorhinca monocerata), a murrelet (Synthliboramphus antiquus), and a storm-petrel (Hydrobates leucorhous), sampled 1968 to 2019 from 23 colonies along the Pacific coast of British Columbia, Canada. The contaminant profile in the eggs of all species and sampling years was dominated by ΣPCBs, followed by ΣDDT (mostly p,p'-DDE), ΣHCH (ß-HCH), ΣCHLOR (oxychlordane), and ΣCBz (HCB). ΣOC and ΣPCB concentrations were generally higher in double-crested cormorant eggs than in the other four species. The majority of legacy POPs are either significantly declining (e.g. p,p'-DDE, HCB, HE, oxychlordane, ΣPCBs) or showing no directional change over time (ΣMirex) in the eggs of our monitoring species. Contaminants such as α-HCH, cis- and trans-chlordane, p,p'-DDT, dieldrin, and octachlorostyrene also showed evidence of downward trends, largely influenced by non-detect values during more recent sampling periods. Increasing trends were observed for ß-HCH in the eggs of some species; however, mean concentrations eventually returned to early 2000 levels by the end of the study period. Although bulk δ15N and δ13C egg values varied interannually, compound-specific amino acid analyses suggested no major changes in trophic position or baseline food web signature. Temporal trends observed here were comparable to those found in other seabird species and pelagic food webs. As most legacy POPs in our data set were at very low levels in recent years, we support the general consensus that it is indeed the twilight years for old POPs, and we attribute these declines largely to voluntary regulations and international restrictions on the production and use of these compounds, and thus their release into the marine environment.

Exposure to persistent organic pollutants is linked to over-wintering latitude in a Pacific seabird, the rhinoceros auklet, Cerorhinca monocerata.

Seabirds are wide-ranging organisms often used to track marine pollution, yet the effect of migration on exposure over the annual cycle is often unclear. We used solar geolocation loggers and stable isotope analysis to study the effects of post breeding dispersal and diet on persistent organic pollutant (POP) and mercury (Hg) burdens in rhinoceros auklets, Cerorhinca monocerata, breeding on islands along the Pacific Coast of Canada. Hg and four classes of POPs were measured in auklet eggs: organochlorine insecticides (OCs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and perfluoralkyl substances (PFASs). Stable isotope values of adult breast feathers grown during winter were used in conjunction with geolocation to elucidate adult wintering latitude. Wintering latitude was the most consistent and significant predictor of some POP and of Hg concentrations in eggs. The magnitude and pattern of exposure varied by contaminant, with ∑PCBs, ∑PBDEs and DDE decreasing with wintering latitude, and mirex, perfluoro-n-tridecanoic acid, and Hg increasing with latitude. We suggest that concentrations of these contaminants in rhinoceros auklet eggs are influenced by variation in uptake at adult wintering locations related to anthropogenic inputs and oceanic and atmospheric transport.

Increased rodenticide exposure rate and risk of toxicosis in barn owls (Tyto alba) from southwestern Canada and linkage with demographic but not genetic factors.

Among many anthropogenic drivers of population decline, continual rapid urbanization and industrialization pose major challenges for the survival of wildlife species. Barn owls (Tyto alba) in southwestern British Columbia (BC) face a multitude of threats ranging from habitat fragmentation to vehicle strikes. They are also at risk from secondary poisoning of second-generation anticoagulant rodenticides (SGARs), a suite of toxic compounds which at high doses results in a depletion of blood clotting factors leading to internal bleeding and death. Here, using long-term data (N = 119) for the hepatic residue levels of SGAR, we assessed the risk of toxicosis from SGAR for the BC barn owl population over the past two decades. We also investigated whether sensitivity to SGAR is associated with genetic factors, namely Single Nucleotide Polymorphisms (SNPs) found in the CYP2C45 gene of barn owls. We found that residue concentration for total SGAR was significantly higher in 2006-2013 (141 ng/g) relative to 1992-2003 (57 ng/g). The proportion of owls exposed to multiple SGAR types was also significantly higher in 2006-2013. Those measures accordingly translate directly into an increase in toxicosis risk level. We also detected demographic differences, where adult females showed on average lower concentration of total SGAR (64 ng/g) when compared to adult males (106 ng/g). Juveniles were overall more likely to show signs of toxicosis than adults (33.3 and 6.9 %, respectively), and those symptoms were positively predicted by SGAR concentrations. We found no evidence that SNPs in the CYP2C45 gene of barn owls were associated with intraspecific variation in SGAR sensitivity. We recommend several preventative measures be taken to minimize wildlife exposure to SGAR.

PBDEs and other POPs in urban birds of prey partly explained by trophic level and carbon source.

As urban sprawl and agricultural intensification continue to invade prime wildlife habitat, some animals, even apex predators, are managing to adapt to this new environment. Chemical pollution is one of many stressors that wildlife encounter in urban environments. Predators are particularly sensitive to persistent chemical pollutants because they feed at a high trophic level where such pollution is biomagnified. To examine levels of pollution in urban birds of prey in the Lower Mainland region of British Columbia, Canada, we analyzed persistent organic contaminants in adult birds found dead of trauma injury. The hepatic geometric mean concentration of sum polybrominated diphenyl ethers (∑PBDEs) in 13 Cooper's hawks (Accipiter cooperii) from Greater Vancouver was 1873 ng/g (lipid weight) with one bird reaching 197,000n g/g lipid weight, the highest exposure reported to date for a wild bird. Concentrations of ∑PBDEs, ∑PCBs (polychlorinated biphenyls) and, surprisingly, cyclodiene insecticides were greatest in the urban environment while those of DDE (1,1-dichloroethylene bis[p-chlorophenyl) were highest in a region of intensive agriculture. The level of most chlorinated and brominated contaminants increased with trophic level (δ(15)N). The concentrations of some contaminants, PBDEs in particular, in these birds of prey may have some toxicological consequences. Apex predators in urban environments continue to be exposed to elevated concentrations of legacy pollutants as well as more recent brominated pollutants.