Plastic ingestion, accumulated heavy metals, and health metrics of four Larus gull species feeding at a coastal landfill in eastern Canada.

The objectives of this research were to assess ingested plastics and accumulated heavy metals in four urban gull species. Additionally, the relationships between ingested plastics and selected demographic and health metrics were assessed. Between 2020-2021 during the non-breeding seasons, 105 gulls (46 American herring gulls (HERG, Larus argentatus smithsonianus), 39 great black-backed gulls (GBBG, Larus marinus), 16 Iceland gulls (Larus glaucoides), 4 glaucous gulls (Larus hyperboreus)) were killed at a landfill in coastal Newfoundland and Labrador, Canada, as part of separate, permitted kill-to-scare operations related to aircraft safety. Birds were necropsied, the upper gastrointestinal tract contents were processed using standard techniques, and livers were analyzed for accumulated As, Cd, Hg, and Pb. The relationships between ingested plastics, demographics, and health metrics were assessed in HERG and GBBG. Across all four species, 85 % of birds had ingested at least one piece of anthropogenic debris, with 79 % ingesting at least one piece of plastic. We detected interspecific differences in plastic ingestion and hepatic trace metals, with increased ingested plastics detected in GBBG compared with HERG. For GBBG, levels of ingested plastic were relatively greater for birds with higher scaled mass index, while HERG with more ingested plastic had higher liver lead concentrations.

Stable Mercury Trends Support a Long-Term Diet Shift Away from Marine Foraging in Salish Sea Glaucous-Winged Gulls over the Last Century.

Marine predators are monitored as indicators of pollution, but such trends can be complicated by variation in diet. Glaucous-winged gulls (Larus glaucescens) have experienced a dietary shift over the past century, from mainly marine to including more terrestrial/freshwater inputs, with unknown impacts on mercury (Hg) trends. We examined 109-year trends in total mercury (THg) and methylmercury (MeHg) concentrations in glaucous-winged gull feathers (1887-1996) from the Salish Sea. Adult flank feathers had higher MeHg concentrations than immature feathers, and males head feathers had higher THg concentrations than females. Overall, we found no evidence of a trend in feather MeHg or THg concentrations over time from 1887 to 1996. In the same individuals, δ15N, δ13C, and δ34S declined over time in gull feathers. In comparison, egg THg concentrations declined from 1970 to 2019 in two species of cormorants, likely reflecting decreases in local Hg sources. We conclude that diet shifts through time may have countered increased Hg deposition from long-range transport in glaucous-winged gulls. The lack of Hg trends over time in glaucous-winged gull feathers provides additional support that these gulls have decreased the amount of marine forage fish in their diet.

Rapid determination of thyroid hormones in blood plasma from Glaucous gulls and Baikal seals by HybridSPE®-LC-MS/MS.

A rapid hybrid solid phase extraction (HybridSPE®) protocol tailored to liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) analysis, was developed for the determination of four thyroid hormones, L-Thyroxine (T4), 3,3',5-triiodo-L-thyronine (T3), 3,3',5'-triiodo-L-thyronine (rT3) and 3,3'-diiodo-L-thyronine (T2) in blood plasma from Glaucous gulls (Larus hyperboreus) and Baikal seals (Phoca sibirica). The use of target analyte specific 13C internal standards allowed quantification to be performed through the standard solvent calibration curves and alleviated the need to perform quantification with matrix match curves. The relative recoveries were 100.0-110.1 % for T4, 99.1-102.2 % for T3, 100.5-108.0 % for rT3, and 100.5-104.6 % for T2. The matrix effects ranged from -1.52 to -6.10 %, demonstrating minor signal suppression during analysis. The method intra-day precision (method repeatability, RSD %, N = 5, k = 1 day) and inter-day precision (method reproducibility, RSD %, N = 10, k = 2 days) at the 1 ng/mL concentration of fortification were 8.54-15.4 % and 15.4-24.8 %, respectively, indicating acceptable chromatographic peak stabilities for all target THs even at trace level concentrations. The method limit of detection (LOD) for T4, T3, rT3 and T2 was 0.17, 0.16, 0.30 and 0.17 ng/mL, respectively. The HybridSPE® protocol was simple and rapid (<1 min) upon application, while the HybridSPE® cartridge did not require (as in classical SPE cartridges) any additional equilibration nor conditioning step prior sample loading. A total of 46 blood plasma samples, 30 samples collected from Glaucous gulls and 16 samples collected from Baikal seals, were analyzed for thyroid hormones to demonstrate the applicability of the developed method in these wildlife species. The concentrations of T4 and T3 in blood plasma from the Glaucous gulls were 5.95-44.2 and 0.37-5.61 ng/mL, respectively, whereas those from Baikal seals were 3.57-46.5 and 0.45-2.07 ng/mL, respectively. In both species, rT3 demonstrated low detection rate, while T2 was not detected. Furthermore, cross-array comparison between the HybridSPE®-LC-MS/MS protocol and an established routine radioimmunoassay (RIA) kit-based method was performed for T4 and T3 concentrations from selected Baikal seal plasma samples.

Evidence of avian influenza virus in seabirds breeding on a Norwegian high-Arctic archipelago.

BACKGROUND: Wild aquatic birds serve as the natural reservoir for avian influenza virus (AIV), a disease with significant implications for avian and mammalian health. Climate change is predicted to impact the dynamics of AIV, particularly in areas such as the Arctic, but the baseline data needed to detect these shifts is often unavailable. In this study, plasma from two species of gulls breeding on the high-Arctic Svalbard archipelago were screened for antibodies to AIV. RESULTS: AIV antibodies were found in black-legged kittiwake (Rissa tridactyla) samples from multiple years, as well as in glaucous gulls (Larus hyperboreous) samples. CONCLUSIONS: Despite small sample sizes, evidence of exposure to AIV was found among Svalbard gulls. A wider survey of Svalbard avian species is warranted to establish knowledge on the extent of AIV exposure on Svalbard and to determine whether active infections are present.

Differential response of cuticular wax and photosynthetic capacity by glaucous and non-glaucous wheat cultivars under mild and severe droughts.

Cuticular wax is known to play an important role in non-stomatal transpiration. However, support is lacking regarding the waxy phenotype for wheat breeding against drought. In this study, four wheat cultivars with different wax phenotypes (glaucous and non-glaucous types) were used to evaluate their responses to drought stress and impact on photosynthetic capability of wheat. Xinong 291 and HY 2912, with the glaucous trait, demonstrated higher diketone ratios and contents compared with Pubing 201 and Jinmai 47, which are the non-glaucous type. The cultivars HY 2912 and Jinmai 47 had 35% higher biomass than did Xinong 291 and Pubing 201 under severe drought condition. HY 2912 exhibited the highest wax load with or without drought stress. Jinmai 47 showed the highest ratio of alkane content. Among glaucous cultivars, drought-resistant HY 2912 may promote growth by decreasing water loss, increasing the diketone content, increasing the total wax load, and maintaining mesophyll and stomatal conductance. Among non-glaucous cultivars, drought-resistant Jinmai 47 may enhance growth via stomatal closure and increased mesophyll conductance and alkane ratios. The glaucous trait was not always associated with drought resistance, and correlation analysis revealed that the diketone ratio was positively related to the intercellular CO2 concentration. These results suggest that the mechanism of drought resistance in wheat is systematically regulated by wax alteration, stomatal conductance and mesophyll conductance. Therefore, wax content and composition as well as mesophyll and stomatal regulation should be considered in the breeding and selection of drought-resistant wheat cultivars.

Predator-prey dynamics of bald eagles and glaucous-winged gulls at Protection Island, Washington, USA.

Bald eagle (Haliaeetus leucocephalus) populations in North America rebounded in the latter part of the twentieth century, the result of tightened protection and outlawing of pesticides such as DDT. An unintended consequence of recovery may be a negative impact on seabirds. During the 1980s, few bald eagles disturbed a large glaucous-winged gull (Larus glaucescens) colony on Protection Island, Washington, USA, in the Salish Sea. Breeding gull numbers in this colony rose nearly 50% during the 1980s and early 1990s. Beginning in the 1990s, a dramatic increase in bald eagle activity ensued within the colony, after which began a significant decline in gull numbers.To examine whether trends in the gull colony could be explained by eagle activity, we fit a Lotka-Volterra-type predator-prey model to gull nest count data and Washington State eagle territory data collected in most years between 1980 and 2016. Both species were assumed to grow logistically in the absence of the other.The model fits the data with generalized R 2 = 0.82, supporting the hypothesis that gull dynamics were due largely to eagle population dynamics.Point estimates of the model parameters indicated approach to stable coexistence. Within the 95% confidence intervals for the parameters, however, 11.0% of bootstrapped parameter vectors predicted gull colony extinction.Our results suggest that the effects of bald eagle activity on the dynamics of a large gull colony were explained by a predator-prey relationship that included the possibility of coexistence but also the possibility of gull colony extinction. This study serves as a cautionary exploration of the future, not only for gulls on Protection Island, but for other seabirds in the Salish Sea. Managers should monitor numbers of nests in seabird colonies as well as eagle activity within colonies to document trends that may lead to colony extinction.

Long noncoding miRNA gene represses wheat ß-diketone waxes.

The cuticle of terrestrial plants functions as a protective barrier against many biotic and abiotic stresses. In wheat and other Triticeae, ß-diketone waxes are major components of the epicuticular layer leading to the bluish-white glaucous trait in reproductive-age plants. Glaucousness in durum wheat is controlled by a metabolic gene cluster at the WAX1 (W1) locus and a dominant suppressor INHIBITOR of WAX1 (Iw1) on chromosome 2B. The wheat D subgenome from progenitor Aegilops tauschii contains W2 and Iw2 paralogs on chromosome 2D. Here we identify the Iw1 gene from durum wheat and demonstrate the unique regulatory mechanism by which Iw1 acts to suppress a carboxylesterase-like protein gene, W1-COE, within the W1 multigene locus. Iw1 is a long noncoding RNA (lncRNA) containing an inverted repeat (IR) with >80% identity to W1-COE The Iw1 transcript forms a miRNA precursor-like long hairpin producing a 21-nt predominant miRNA, miRW1, and smaller numbers of related sRNAs associated with the nonglaucous phenotype. When Iw1 was introduced into glaucous bread wheat, miRW1 accumulated, W1-COE and its paralog W2-COE were down-regulated, and the phenotype was nonglaucous and ß-diketone-depleted. The IR region of Iw1 has >94% identity to an IR region on chromosome 2 in Ae. tauschii that also produces miRW1 and lies within the marker-based location of Iw2 We propose the Iw loci arose from an inverted duplication of W1-COE and/or W2-COE in ancestral wheat to form evolutionarily young miRNA genes that act to repress the glaucous trait.

Changing gull diet in a changing world: a 150-year stable isotope (δ13C, δ15N) record from feathers collected in the Pacific Northwest of North America.

The world's oceans have undergone significant ecological changes following European colonial expansion and associated industrialization. Seabirds are useful indicators of marine food web structure and can be used to track multidecadal environmental change, potentially reflecting long-term human impacts. We used stable isotope (δ(13)C, δ(15)N) analysis of feathers from glaucous-winged gulls (Larus glaucescens) in a heavily disturbed region of the northeast Pacific to ask whether diets of this generalist forager changed in response to shifts in food availability over 150 years, and whether any detected change might explain long-term trends in gull abundance. Sampled feathers came from birds collected between 1860 and 2009 at nesting colonies in the Salish Sea, a transboundary marine system adjacent to Washington, USA and British Columbia, Canada. To determine whether temporal trends in stable isotope ratios might simply reflect changes to baseline environmental values, we also analysed muscle tissue from forage fishes collected in the same region over a multidecadal timeframe. Values of δ(13)C and δ(15)N declined since 1860 in both subadult and adult gulls (δ(13)C, ~ 2-6‰; δ(15)N, ~4-5‰), indicating that their diet has become less marine over time, and that birds now feed at a lower trophic level than previously. Conversely, forage fish δ(13)C and δ(15)N values showed no trends, supporting our conclusion that gull feather values were indicative of declines in marine food availability rather than of baseline environmental change. Gradual declines in feather isotope values are consistent with trends predicted had gulls consumed less fish over time, but were equivocal with respect to whether gulls had switched to a more garbage-based diet, or one comprising marine invertebrates. Nevertheless, our results suggest a long-term decrease in diet quality linked to declining fish abundance or other anthropogenic influences, and may help to explain regional population declines in this species and other piscivores.